1 files changed, 1096 insertions, 1096 deletions

diff --git a/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/install.txt b/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/install.txt
index d8f2495..04bed91 100644
--- a/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/install.txt
+++ b/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/install.txt
@@ -1,1096 +1,1096 @@
-INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software

-

-Copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding.

-This file is part of the Independent JPEG Group's software.

-For conditions of distribution and use, see the accompanying README file.

-

-

-This file explains how to configure and install the IJG software.  We have

-tried to make this software extremely portable and flexible, so that it can be

-adapted to almost any environment.  The downside of this decision is that the

-installation process is complicated.  We have provided shortcuts to simplify

-the task on common systems.  But in any case, you will need at least a little

-familiarity with C programming and program build procedures for your system.

-

-If you are only using this software as part of a larger program, the larger

-program's installation procedure may take care of configuring the IJG code.

-For example, Ghostscript's installation script will configure the IJG code.

-You don't need to read this file if you just want to compile Ghostscript.

-

-If you are on a Unix machine, you may not need to read this file at all.

-Try doing

-        ./configure

-        make

-        make test

-If that doesn't complain, do

-        make install

-(better do "make -n install" first to see if the makefile will put the files

-where you want them).  Read further if you run into snags or want to customize

-the code for your system.

-

-

-TABLE OF CONTENTS

------------------

-

-Before you start

-Configuring the software:

-        using the automatic "configure" script

-        using one of the supplied jconfig and makefile files

-        by hand

-Building the software

-Testing the software

-Installing the software

-Optional stuff

-Optimization

-Hints for specific systems

-

-

-BEFORE YOU START

-================

-

-Before installing the software you must unpack the distributed source code.

-Since you are reading this file, you have probably already succeeded in this

-task.  However, there is a potential for error if you needed to convert the

-files to the local standard text file format (for example, if you are on

-MS-DOS you may have converted LF end-of-line to CR/LF).  You must apply

-such conversion to all the files EXCEPT those whose names begin with "test".

-The test files contain binary data; if you change them in any way then the

-self-test will give bad results.

-

-Please check the last section of this file to see if there are hints for the

-specific machine or compiler you are using.

-

-

-CONFIGURING THE SOFTWARE

-========================

-

-To configure the IJG code for your system, you need to create two files:

-  * jconfig.h: contains values for system-dependent #define symbols.

-  * Makefile: controls the compilation process.

-(On a non-Unix machine, you may create "project files" or some other

-substitute for a Makefile.  jconfig.h is needed in any environment.)

-

-We provide three different ways to generate these files:

-  * On a Unix system, you can just run the "configure" script.

-  * We provide sample jconfig files and makefiles for popular machines;

-    if your machine matches one of the samples, just copy the right sample

-    files to jconfig.h and Makefile.

-  * If all else fails, read the instructions below and make your own files.

-

-

-Configuring the software using the automatic "configure" script

----------------------------------------------------------------

-

-If you are on a Unix machine, you can just type

-        ./configure

-and let the configure script construct appropriate configuration files.

-If you're using "csh" on an old version of System V, you might need to type

-        sh configure

-instead to prevent csh from trying to execute configure itself.

-Expect configure to run for a few minutes, particularly on slower machines;

-it works by compiling a series of test programs.

-

-Configure was created with GNU Autoconf and it follows the usual conventions

-for GNU configure scripts.  It makes a few assumptions that you may want to

-override.  You can do this by providing optional switches to configure:

-

-* Configure will build both static and shared libraries, if possible.

-If you want to build libjpeg only as a static library, say

-        ./configure --disable-shared

-If you want to build libjpeg only as a shared library, say

-        ./configure --disable-static

-Configure uses GNU libtool to take care of system-dependent shared library

-building methods.

-

-* Configure will use gcc (GNU C compiler) if it's available, otherwise cc.

-To force a particular compiler to be selected, use the CC option, for example

-        ./configure CC='cc'

-The same method can be used to include any unusual compiler switches.

-For example, on HP-UX you probably want to say

-        ./configure CC='cc -Aa'

-to get HP's compiler to run in ANSI mode.

-

-* The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc.

-You can override this by saying, for example,

-        ./configure CFLAGS='-O2'

-if you want to compile without debugging support.

-

-* Configure will set up the makefile so that "make install" will install files

-into /usr/local/bin, /usr/local/man, etc.  You can specify an installation

-prefix other than "/usr/local" by giving configure the option "--prefix=PATH".

-

-* If you don't have a lot of swap space, you may need to enable the IJG

-software's internal virtual memory mechanism.  To do this, give the option

-"--enable-maxmem=N" where N is the default maxmemory limit in megabytes.

-This is discussed in more detail under "Selecting a memory manager", below.

-You probably don't need to worry about this on reasonably-sized Unix machines,

-unless you plan to process very large images.

-

-Configure has some other features that are useful if you are cross-compiling

-or working in a network of multiple machine types; but if you need those

-features, you probably already know how to use them.

-

-

-Configuring the software using one of the supplied jconfig and makefile files

------------------------------------------------------------------------------

-

-If you have one of these systems, you can just use the provided configuration

-files:

-

-Makefile        jconfig file    System and/or compiler

-

-makefile.manx   jconfig.manx    Amiga, Manx Aztec C

-makefile.sas    jconfig.sas     Amiga, SAS C

-makeproj.mac    jconfig.mac     Apple Macintosh, Metrowerks CodeWarrior

-mak*jpeg.st     jconfig.st      Atari ST/STE/TT, Pure C or Turbo C

-makefile.bcc    jconfig.bcc     MS-DOS or OS/2, Borland C

-makefile.dj     jconfig.dj      MS-DOS, DJGPP (Delorie's port of GNU C)

-makefile.mc6    jconfig.mc6     MS-DOS, Microsoft C (16-bit only)

-makefile.wat    jconfig.wat     MS-DOS, OS/2, or Windows NT, Watcom C

-makefile.vc     jconfig.vc      Windows NT/95, MS Visual C++

-make*.vc6       jconfig.vc      Windows NT/95, MS Visual C++ 6

-make*.v10       jconfig.vc      Windows NT/95, MS Visual C++ 2010 (v10)

-makefile.mms    jconfig.vms     Digital VMS, with MMS software

-makefile.vms    jconfig.vms     Digital VMS, without MMS software

-

-Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or

-whatever your system uses as the standard makefile name).  For more info see

-the appropriate system-specific hints section near the end of this file.

-

-

-Configuring the software by hand

---------------------------------

-

-First, generate a jconfig.h file.  If you are moderately familiar with C,

-the comments in jconfig.txt should be enough information to do this; just

-copy jconfig.txt to jconfig.h and edit it appropriately.  Otherwise, you may

-prefer to use the ckconfig.c program.  You will need to compile and execute

-ckconfig.c by hand --- we hope you know at least enough to do that.

-ckconfig.c may not compile the first try (in fact, the whole idea is for it

-to fail if anything is going to).  If you get compile errors, fix them by

-editing ckconfig.c according to the directions given in ckconfig.c.  Once

-you get it to run, it will write a suitable jconfig.h file, and will also

-print out some advice about which makefile to use.

-

-You may also want to look at the canned jconfig files, if there is one for a

-system similar to yours.

-

-Second, select a makefile and copy it to Makefile (or whatever your system

-uses as the standard makefile name).  The most generic makefiles we provide

-are

-        makefile.ansi:  if your C compiler supports function prototypes

-        makefile.unix:  if not.

-(You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES"

-in jconfig.h.)  You may want to start from one of the other makefiles if

-there is one for a system similar to yours.

-

-Look over the selected Makefile and adjust options as needed.  In particular

-you may want to change the CC and CFLAGS definitions.  For instance, if you

-are using GCC, set CC=gcc.  If you had to use any compiler switches to get

-ckconfig.c to work, make sure the same switches are in CFLAGS.

-

-If you are on a system that doesn't use makefiles, you'll need to set up

-project files (or whatever you do use) to compile all the source files and

-link them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom.

-See the file lists in any of the makefiles to find out which files go into

-each program.  Note that the provided makefiles all make a "library" file

-libjpeg first, but you don't have to do that if you don't want to; the file

-lists identify which source files are actually needed for compression,

-decompression, or both.  As a last resort, you can make a batch script that

-just compiles everything and links it all together; makefile.vms is an example

-of this (it's for VMS systems that have no make-like utility).

-

-Here are comments about some specific configuration decisions you'll

-need to make:

-

-Command line style

-------------------

-

-These programs can use a Unix-like command line style which supports

-redirection and piping, like this:

-        cjpeg inputfile >outputfile

-        cjpeg <inputfile >outputfile

-        source program | cjpeg >outputfile

-The simpler "two file" command line style is just

-        cjpeg inputfile outputfile

-You may prefer the two-file style, particularly if you don't have pipes.

-

-You MUST use two-file style on any system that doesn't cope well with binary

-data fed through stdin/stdout; this is true for some MS-DOS compilers, for

-example.  If you're not on a Unix system, it's safest to assume you need

-two-file style.  (But if your compiler provides either the Posix-standard

-fdopen() library routine or a Microsoft-compatible setmode() routine, you

-can safely use the Unix command line style, by defining USE_FDOPEN or

-USE_SETMODE respectively.)

-

-To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE".

-

-Selecting a memory manager

---------------------------

-

-The IJG code is capable of working on images that are too big to fit in main

-memory; data is swapped out to temporary files as necessary.  However, the

-code to do this is rather system-dependent.  We provide five different

-memory managers:

-

-* jmemansi.c    This version uses the ANSI-standard library routine tmpfile(),

-                which not all non-ANSI systems have.  On some systems

-                tmpfile() may put the temporary file in a non-optimal

-                location; if you don't like what it does, use jmemname.c.

-

-* jmemname.c    This version creates named temporary files.  For anything

-                except a Unix machine, you'll need to configure the

-                select_file_name() routine appropriately; see the comments

-                near the head of jmemname.c.  If you use this version, define

-                NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files

-                are removed if the program is aborted.

-

-* jmemnobs.c    (That stands for No Backing Store :-).)  This will compile on

-                almost any system, but it assumes you have enough main memory

-                or virtual memory to hold the biggest images you work with.

-

-* jmemdos.c     This should be used with most 16-bit MS-DOS compilers.

-                See the system-specific notes about MS-DOS for more info.

-                IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in

-                jconfig.h, and include the assembly file jmemdosa.asm in the

-                programs.  The supplied makefiles and jconfig files for

-                16-bit MS-DOS compilers already do both.

-

-* jmemmac.c     Custom version for Apple Macintosh; see the system-specific

-                notes for Macintosh for more info.

-

-To use a particular memory manager, change the SYSDEPMEM variable in your

-makefile to equal the corresponding object file name (for example, jmemansi.o

-or jmemansi.obj for jmemansi.c).

-

-If you have plenty of (real or virtual) main memory, just use jmemnobs.c.

-"Plenty" means about ten bytes for every pixel in the largest images

-you plan to process, so a lot of systems don't meet this criterion.

-If yours doesn't, try jmemansi.c first.  If that doesn't compile, you'll have

-to use jmemname.c; be sure to adjust select_file_name() for local conditions.

-You may also need to change unlink() to remove() in close_backing_store().

-

-Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEM

-setting to a reasonable value for your system (either by adding a #define for

-DEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile).

-This value limits the amount of data space the program will attempt to

-allocate.  Code and static data space isn't counted, so the actual memory

-needs for cjpeg or djpeg are typically 100 to 150Kb more than the max-memory

-setting.  Larger max-memory settings reduce the amount of I/O needed to

-process a large image, but too large a value can result in "insufficient

-memory" failures.  On most Unix machines (and other systems with virtual

-memory), just set DEFAULT_MAX_MEM to several million and forget it.  At the

-other end of the spectrum, for MS-DOS machines you probably can't go much

-above 300K to 400K.  (On MS-DOS the value refers to conventional memory only.

-Extended/expanded memory is handled separately by jmemdos.c.)

-

-

-BUILDING THE SOFTWARE

-=====================

-

-Now you should be able to compile the software.  Just say "make" (or

-whatever's necessary to start the compilation).  Have a cup of coffee.

-

-Here are some things that could go wrong:

-

-If your compiler complains about undefined structures, you should be able to

-shut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h.

-

-If you have trouble with missing system include files or inclusion of the

-wrong ones, read jinclude.h.  This shouldn't happen if you used configure

-or ckconfig.c to set up jconfig.h.

-

-There are a fair number of routines that do not use all of their parameters;

-some compilers will issue warnings about this, which you can ignore.  There

-are also a few configuration checks that may give "unreachable code" warnings.

-Any other warning deserves investigation.

-

-If you don't have a getenv() library routine, define NO_GETENV.

-

-Also see the system-specific hints, below.

-

-

-TESTING THE SOFTWARE

-====================

-

-As a quick test of functionality we've included a small sample image in

-several forms:

-        testorig.jpg    Starting point for the djpeg tests.

-        testimg.ppm     The output of djpeg testorig.jpg

-        testimg.bmp     The output of djpeg -bmp -colors 256 testorig.jpg

-        testimg.jpg     The output of cjpeg testimg.ppm

-        testprog.jpg    Progressive-mode equivalent of testorig.jpg.

-        testimgp.jpg    The output of cjpeg -progressive -optimize testimg.ppm

-(The first- and second-generation .jpg files aren't identical since the

-default compression parameters are lossy.)  If you can generate duplicates

-of the testimg* files then you probably have working programs.

-

-With most of the makefiles, "make test" will perform the necessary

-comparisons.

-

-If you're using a makefile that doesn't provide the test option, run djpeg

-and cjpeg by hand and compare the output files to testimg* with whatever

-binary file comparison tool you have.  The files should be bit-for-bit

-identical.

-

-If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then you

-need to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t.

-Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h.  A less likely

-configuration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPE

-as long should take care of that one.

-

-If the cjpeg test run fails with "Missing Huffman code table entry", it's a

-good bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED.  Go back to the

-configuration step and run ckconfig.c.  (This is a good plan for any other

-test failure, too.)

-

-If you are using Unix (one-file) command line style on a non-Unix system,

-it's a good idea to check that binary I/O through stdin/stdout actually

-works.  You should get the same results from "djpeg <testorig.jpg >out.ppm"

-as from "djpeg -outfile out.ppm testorig.jpg".  Note that the makefiles all

-use the latter style and therefore do not exercise stdin/stdout!  If this

-check fails, try recompiling with USE_SETMODE or USE_FDOPEN defined.

-If it still doesn't work, better use two-file style.

-

-If you chose a memory manager other than jmemnobs.c, you should test that

-temporary-file usage works.  Try "djpeg -bmp -colors 256 -max 0 testorig.jpg"

-and make sure its output matches testimg.bmp.  If you have any really large

-images handy, try compressing them with -optimize and/or decompressing with

--colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large.

-

-NOTE: this is far from an exhaustive test of the JPEG software; some modules,

-such as 1-pass color quantization, are not exercised at all.  It's just a

-quick test to give you some confidence that you haven't missed something

-major.

-

-

-INSTALLING THE SOFTWARE

-=======================

-

-Once you're done with the above steps, you can install the software by

-copying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom)

-to wherever you normally install programs.  On Unix systems, you'll also want

-to put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1)

-in the man-page directory.  The pre-fab makefiles don't support this step

-since there's such a wide variety of installation procedures on different

-systems.

-

-If you generated a Makefile with the "configure" script, you can just say

-        make install

-to install the programs and their man pages into the standard places.

-(You'll probably need to be root to do this.)  We recommend first saying

-        make -n install

-to see where configure thought the files should go.  You may need to edit

-the Makefile, particularly if your system's conventions for man page

-filenames don't match what configure expects.

-

-If you want to install the IJG library itself, for use in compiling other

-programs besides ours, then you need to put the four include files

-        jpeglib.h jerror.h jconfig.h jmorecfg.h

-into your include-file directory, and put the library file libjpeg.a

-(extension may vary depending on system) wherever library files go.

-If you generated a Makefile with "configure", it will do what it thinks

-is the right thing if you say

-        make install-lib

-

-

-OPTIONAL STUFF

-==============

-

-Progress monitor:

-

-If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable display

-of percent-done progress reports.  The routine provided in cdjpeg.c merely

-prints percentages to stderr, but you can customize it to do something

-fancier.

-

-Utah RLE file format support:

-

-We distribute the software with support for RLE image files (Utah Raster

-Toolkit format) disabled, because the RLE support won't compile without the

-Utah library.  If you have URT version 3.1 or later, you can enable RLE

-support as follows:

-        1.  #define RLE_SUPPORTED in jconfig.h.

-        2.  Add a -I option to CFLAGS in the Makefile for the directory

-            containing the URT .h files (typically the "include"

-            subdirectory of the URT distribution).

-        3.  Add -L... -lrle to LDLIBS in the Makefile, where ... specifies

-            the directory containing the URT "librle.a" file (typically the

-            "lib" subdirectory of the URT distribution).

-

-Support for 12-bit-deep pixel data:

-

-The JPEG standard allows either 8-bit or 12-bit data precision.  (For color,

-this means 8 or 12 bits per channel, of course.)  If you need to work with

-deeper than 8-bit data, you can compile the IJG code for 12-bit operation.

-To do so:

-  1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8.

-  2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED,

-     because the code for those formats doesn't handle 12-bit data and won't

-     even compile.  (The PPM code does work, as explained below.  The GIF

-     code works too; it scales 8-bit GIF data to and from 12-bit depth

-     automatically.)

-  3. Compile.  Don't expect "make test" to pass, since the supplied test

-     files are for 8-bit data.

-

-Currently, 12-bit support does not work on 16-bit-int machines.

-

-Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa;

-so you'll want to keep around a regular 8-bit compilation as well.

-(Run-time selection of data depth, to allow a single copy that does both,

-is possible but would probably slow things down considerably; it's very low

-on our to-do list.)

-

-The PPM reader (rdppm.c) can read 12-bit data from either text-format or

-binary-format PPM and PGM files.  Binary-format PPM/PGM files which have a

-maxval greater than 255 are assumed to use 2 bytes per sample, MSB first

-(big-endian order).  As of early 1995, 2-byte binary format is not

-officially supported by the PBMPLUS library, but it is expected that a

-future release of PBMPLUS will support it.  Note that the PPM reader will

-read files of any maxval regardless of the BITS_IN_JSAMPLE setting; incoming

-data is automatically rescaled to either maxval=255 or maxval=4095 as

-appropriate for the cjpeg bit depth.

-

-The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGM

-format, maxval 4095, when compiled with BITS_IN_JSAMPLE=12.  Since this

-format is not yet widely supported, you can disable it by compiling wrppm.c

-with PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make a

-standard 1-byte/sample PPM or PGM file.  (Yes, this means still another copy

-of djpeg to keep around.  But hopefully you won't need it for very long.

-Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.)

-

-Of course, if you are working with 12-bit data, you probably have it stored

-in some other, nonstandard format.  In that case you'll probably want to

-write your own I/O modules to read and write your format.

-

-Note that a 12-bit version of cjpeg always runs in "-optimize" mode, in

-order to generate valid Huffman tables.  This is necessary because our

-default Huffman tables only cover 8-bit data.

-

-Removing code:

-

-If you need to make a smaller version of the JPEG software, some optional

-functions can be removed at compile time.  See the xxx_SUPPORTED #defines in

-jconfig.h and jmorecfg.h.  If at all possible, we recommend that you leave in

-decoder support for all valid JPEG files, to ensure that you can read anyone's

-output.  Taking out support for image file formats that you don't use is the

-most painless way to make the programs smaller.  Another possibility is to

-remove some of the DCT methods: in particular, the "IFAST" method may not be

-enough faster than the others to be worth keeping on your machine.  (If you

-do remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTEST

-to a supported method, by adding a #define in jconfig.h.)

-

-

-OPTIMIZATION

-============

-

-Unless you own a Cray, you'll probably be interested in making the JPEG

-software go as fast as possible.  This section covers some machine-dependent

-optimizations you may want to try.  We suggest that before trying any of

-this, you first get the basic installation to pass the self-test step.

-Repeat the self-test after any optimization to make sure that you haven't

-broken anything.

-

-The integer DCT routines perform a lot of multiplications.  These

-multiplications must yield 32-bit results, but none of their input values

-are more than 16 bits wide.  On many machines, notably the 680x0 and 80x86

-CPUs, a 16x16=>32 bit multiply instruction is faster than a full 32x32=>32

-bit multiply.  Unfortunately there is no portable way to specify such a

-multiplication in C, but some compilers can generate one when you use the

-right combination of casts.  See the MULTIPLYxxx macro definitions in

-jdct.h.  If your compiler makes "int" be 32 bits and "short" be 16 bits,

-defining SHORTxSHORT_32 is fairly likely to work.  When experimenting with

-alternate definitions, be sure to test not only whether the code still works

-(use the self-test), but also whether it is actually faster --- on some

-compilers, alternate definitions may compute the right answer, yet be slower

-than the default.  Timing cjpeg on a large PGM (grayscale) input file is the

-best way to check this, as the DCT will be the largest fraction of the runtime

-in that mode.  (Note: some of the distributed compiler-specific jconfig files

-already contain #define switches to select appropriate MULTIPLYxxx

-definitions.)

-

-If your machine has sufficiently fast floating point hardware, you may find

-that the float DCT method is faster than the integer DCT methods, even

-after tweaking the integer multiply macros.  In that case you may want to

-make the float DCT be the default method.  (The only objection to this is

-that float DCT results may vary slightly across machines.)  To do that, add

-"#define JDCT_DEFAULT JDCT_FLOAT" to jconfig.h.  Even if you don't change

-the default, you should redefine JDCT_FASTEST, which is the method selected

-by djpeg's -fast switch.  Don't forget to update the documentation files

-(usage.txt and/or cjpeg.1, djpeg.1) to agree with what you've done.

-

-If access to "short" arrays is slow on your machine, it may be a win to

-define type JCOEF as int rather than short.  This will cost a good deal of

-memory though, particularly in some multi-pass modes, so don't do it unless

-you have memory to burn and short is REALLY slow.

-

-If your compiler can compile function calls in-line, make sure the INLINE

-macro in jmorecfg.h is defined as the keyword that marks a function

-inline-able.  Some compilers have a switch that tells the compiler to inline

-any function it thinks is profitable (e.g., -finline-functions for gcc).

-Enabling such a switch is likely to make the compiled code bigger but faster.

-

-In general, it's worth trying the maximum optimization level of your compiler,

-and experimenting with any optional optimizations such as loop unrolling.

-(Unfortunately, far too many compilers have optimizer bugs ... be prepared to

-back off if the code fails self-test.)  If you do any experimentation along

-these lines, please report the optimal settings to jpeg-info@jpegclub.org so

-we can mention them in future releases.  Be sure to specify your machine and

-compiler version.

-

-

-HINTS FOR SPECIFIC SYSTEMS

-==========================

-

-We welcome reports on changes needed for systems not mentioned here.  Submit

-'em to jpeg-info@jpegclub.org.  Also, if configure or ckconfig.c is wrong

-about how to configure the JPEG software for your system, please let us know.

-

-

-Acorn RISC OS:

-

-(Thanks to Simon Middleton for these hints on compiling with Desktop C.)

-After renaming the files according to Acorn conventions, take a copy of

-makefile.ansi, change all occurrences of 'libjpeg.a' to 'libjpeg.o' and

-change these definitions as indicated:

-

-CFLAGS= -throwback -IC: -Wn

-LDLIBS=C:o.Stubs

-SYSDEPMEM=jmemansi.o

-LN=Link

-AR=LibFile -c -o

-

-Also add a new line '.c.o:; $(cc) $< $(cflags) -c -o $@'.  Remove the

-lines '$(RM) libjpeg.o' and '$(AR2) libjpeg.o' and the 'jconfig.h'

-dependency section.

-

-Copy jconfig.txt to jconfig.h.  Edit jconfig.h to define TWO_FILE_COMMANDLINE

-and CHAR_IS_UNSIGNED.

-

-Run the makefile using !AMU not !Make.  If you want to use the 'clean' and

-'test' makefile entries then you will have to fiddle with the syntax a bit

-and rename the test files.

-

-

-Amiga:

-

-SAS C 6.50 reportedly is too buggy to compile the IJG code properly.

-A patch to update to 6.51 is available from SAS or AmiNet FTP sites.

-

-The supplied config files are set up to use jmemname.c as the memory

-manager, with temporary files being created on the device named by

-"JPEGTMP:".

-

-

-Atari ST/STE/TT:

-

-Copy the project files makcjpeg.st, makdjpeg.st, maktjpeg.st, and makljpeg.st

-to cjpeg.prj, djpeg.prj, jpegtran.prj, and libjpeg.prj respectively.  The

-project files should work as-is with Pure C.  For Turbo C, change library

-filenames "pc..." to "tc..." in each project file.  Note that libjpeg.prj

-selects jmemansi.c as the recommended memory manager.  You'll probably want to

-adjust the DEFAULT_MAX_MEM setting --- you want it to be a couple hundred K

-less than your normal free memory.  Put "#define DEFAULT_MAX_MEM nnnn" into

-jconfig.h to do this.

-

-To use the 68881/68882 coprocessor for the floating point DCT, add the

-compiler option "-8" to the project files and replace pcfltlib.lib with

-pc881lib.lib in cjpeg.prj and djpeg.prj.  Or if you don't have a

-coprocessor, you may prefer to remove the float DCT code by undefining

-DCT_FLOAT_SUPPORTED in jmorecfg.h (since without a coprocessor, the float

-code will be too slow to be useful).  In that case, you can delete

-pcfltlib.lib from the project files.

-

-Note that you must make libjpeg.lib before making cjpeg.ttp, djpeg.ttp,

-or jpegtran.ttp.  You'll have to perform the self-test by hand.

-

-We haven't bothered to include project files for rdjpgcom and wrjpgcom.

-Those source files should just be compiled by themselves; they don't

-depend on the JPEG library.  You can use the default.prj project file

-of the Pure C distribution to make the programs.

-

-There is a bug in some older versions of the Turbo C library which causes the

-space used by temporary files created with "tmpfile()" not to be freed after

-an abnormal program exit.  If you check your disk afterwards, you will find

-cluster chains that are allocated but not used by a file.  This should not

-happen in cjpeg/djpeg/jpegtran, since we enable a signal catcher to explicitly

-close temp files before exiting.  But if you use the JPEG library with your

-own code, be sure to supply a signal catcher, or else use a different

-system-dependent memory manager.

-

-

-Cray:

-

-Should you be so fortunate as to be running JPEG on a Cray YMP, there is a

-compiler bug in old versions of Cray's Standard C (prior to 3.1).  If you

-still have an old compiler, you'll need to insert a line reading

-"#pragma novector" just before the loop 

-    for (i = 1; i <= (int) htbl->bits[l]; i++)

-      huffsize[p++] = (char) l;

-in fix_huff_tbl (in V5beta1, line 204 of jchuff.c and line 176 of jdhuff.c).

-[This bug may or may not still occur with the current IJG code, but it's

-probably a dead issue anyway...]

-

-

-HP-UX:

-

-If you have HP-UX 7.05 or later with the "software development" C compiler,

-you should run the compiler in ANSI mode.  If using the configure script,

-say

-        ./configure CC='cc -Aa'

-(or -Ae if you prefer).  If configuring by hand, use makefile.ansi and add

-"-Aa" to the CFLAGS line in the makefile.

-

-If you have a pre-7.05 system, or if you are using the non-ANSI C compiler

-delivered with a minimum HP-UX system, then you must use makefile.unix

-(and do NOT add -Aa); or just run configure without the CC option.

-

-On HP 9000 series 800 machines, the HP C compiler is buggy in revisions prior

-to A.08.07.  If you get complaints about "not a typedef name", you'll have to

-use makefile.unix, or run configure without the CC option.

-

-

-Macintosh, generic comments:

-

-The supplied user-interface files (cjpeg.c, djpeg.c, etc) are set up to

-provide a Unix-style command line interface.  You can use this interface on

-the Mac by means of the ccommand() library routine provided by Metrowerks

-CodeWarrior or Think C.  This is only appropriate for testing the library,

-however; to make a user-friendly equivalent of cjpeg/djpeg you'd really want

-to develop a Mac-style user interface.  There isn't a complete example

-available at the moment, but there are some helpful starting points:

-1. Sam Bushell's free "To JPEG" applet provides drag-and-drop conversion to

-JPEG under System 7 and later.  This only illustrates how to use the

-compression half of the library, but it does a very nice job of that part.

-The CodeWarrior source code is available from http://www.pobox.com/~jsam.

-2. Jim Brunner prepared a Mac-style user interface for both compression and

-decompression.  Unfortunately, it hasn't been updated since IJG v4, and

-the library's API has changed considerably since then.  Still it may be of

-some help, particularly as a guide to compiling the IJG code under Think C.

-Jim's code is available from the Info-Mac archives, at sumex-aim.stanford.edu

-or mirrors thereof; see file /info-mac/dev/src/jpeg-convert-c.hqx.

-

-jmemmac.c is the recommended memory manager back end for Macintosh.  It uses

-NewPtr/DisposePtr instead of malloc/free, and has a Mac-specific

-implementation of jpeg_mem_available().  It also creates temporary files that

-follow Mac conventions.  (That part of the code relies on System-7-or-later OS

-functions.  See the comments in jmemmac.c if you need to run it on System 6.)

-NOTE that USE_MAC_MEMMGR must be defined in jconfig.h to use jmemmac.c.

-

-You can also use jmemnobs.c, if you don't care about handling images larger

-than available memory.  If you use any memory manager back end other than

-jmemmac.c, we recommend replacing "malloc" and "free" by "NewPtr" and

-"DisposePtr", because Mac C libraries often have peculiar implementations of

-malloc/free.  (For instance, free() may not return the freed space to the

-Mac Memory Manager.  This is undesirable for the IJG code because jmemmgr.c

-already clumps space requests.)

-

-

-Macintosh, Metrowerks CodeWarrior:

-

-The Unix-command-line-style interface can be used by defining USE_CCOMMAND.

-You'll also need to define TWO_FILE_COMMANDLINE to avoid stdin/stdout.

-This means that when using the cjpeg/djpeg programs, you'll have to type the

-input and output file names in the "Arguments" text-edit box, rather than

-using the file radio buttons.  (Perhaps USE_FDOPEN or USE_SETMODE would

-eliminate the problem, but I haven't heard from anyone who's tried it.)

-

-On 680x0 Macs, Metrowerks defines type "double" as a 10-byte IEEE extended

-float.  jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power

-of 2.  Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.

-

-The supplied configuration file jconfig.mac can be used for your jconfig.h;

-it includes all the recommended symbol definitions.  If you have AppleScript

-installed, you can run the supplied script makeproj.mac to create CodeWarrior

-project files for the library and the testbed applications, then build the

-library and applications.  (Thanks to Dan Sears and Don Agro for this nifty

-hack, which saves us from trying to maintain CodeWarrior project files as part

-of the IJG distribution...)

-

-

-Macintosh, Think C:

-

-The documentation in Jim Brunner's "JPEG Convert" source code (see above)

-includes detailed build instructions for Think C; it's probably somewhat

-out of date for the current release, but may be helpful.

-

-If you want to build the minimal command line version, proceed as follows.

-You'll have to prepare project files for the programs; we don't include any

-in the distribution since they are not text files.  Use the file lists in

-any of the supplied makefiles as a guide.  Also add the ANSI and Unix C

-libraries in a separate segment.  You may need to divide the JPEG files into

-more than one segment; we recommend dividing compression and decompression

-modules.  Define USE_CCOMMAND in jconfig.h so that the ccommand() routine is

-called.  You must also define TWO_FILE_COMMANDLINE because stdin/stdout

-don't handle binary data correctly.

-

-On 680x0 Macs, Think C defines type "double" as a 12-byte IEEE extended float.

-jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power of 2.

-Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.

-

-jconfig.mac should work as a jconfig.h configuration file for Think C,

-but the makeproj.mac AppleScript script is specific to CodeWarrior.  Sorry.

-

-

-MIPS R3000:

-

-MIPS's cc version 1.31 has a rather nasty optimization bug.  Don't use -O

-if you have that compiler version.  (Use "cc -V" to check the version.)

-Note that the R3000 chip is found in workstations from DEC and others.

-

-

-MS-DOS, generic comments for 16-bit compilers:

-

-The IJG code is designed to work well in 80x86 "small" or "medium" memory

-models (i.e., data pointers are 16 bits unless explicitly declared "far";

-code pointers can be either size).  You may be able to use small model to

-compile cjpeg or djpeg by itself, but you will probably have to use medium

-model for any larger application.  This won't make much difference in

-performance.  You *will* take a noticeable performance hit if you use a

-large-data memory model, and you should avoid "huge" model if at all

-possible.  Be sure that NEED_FAR_POINTERS is defined in jconfig.h if you use

-a small-data memory model; be sure it is NOT defined if you use a large-data

-model.  (The supplied makefiles and jconfig files for Borland and Microsoft C

-compile in medium model and define NEED_FAR_POINTERS.)

-

-The DOS-specific memory manager, jmemdos.c, should be used if possible.

-It needs some assembly-code routines which are in jmemdosa.asm; make sure

-your makefile assembles that file and includes it in the library.  If you

-don't have a suitable assembler, you can get pre-assembled object files for

-jmemdosa by FTP from ftp.uu.net:/graphics/jpeg/jdosaobj.zip.  (DOS-oriented

-distributions of the IJG source code often include these object files.)

-

-When using jmemdos.c, jconfig.h must define USE_MSDOS_MEMMGR and must set

-MAX_ALLOC_CHUNK to less than 64K (65520L is a typical value).  If your

-C library's far-heap malloc() can't allocate blocks that large, reduce

-MAX_ALLOC_CHUNK to whatever it can handle.

-

-If you can't use jmemdos.c for some reason --- for example, because you

-don't have an assembler to assemble jmemdosa.asm --- you'll have to fall

-back to jmemansi.c or jmemname.c.  You'll probably still need to set

-MAX_ALLOC_CHUNK in jconfig.h, because most DOS C libraries won't malloc()

-more than 64K at a time.  IMPORTANT: if you use jmemansi.c or jmemname.c,

-you will have to compile in a large-data memory model in order to get the

-right stdio library.  Too bad.

-

-wrjpgcom needs to be compiled in large model, because it malloc()s a 64KB

-work area to hold the comment text.  If your C library's malloc can't

-handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c.

-

-Most MS-DOS compilers treat stdin/stdout as text files, so you must use

-two-file command line style.  But if your compiler has either fdopen() or

-setmode(), you can use one-file style if you like.  To do this, define

-USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode.

-(USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.)  You

-should test that I/O through stdin/stdout produces the same results as I/O

-to explicitly named files... the "make test" procedures in the supplied

-makefiles do NOT use stdin/stdout.

-

-

-MS-DOS, generic comments for 32-bit compilers:

-

-None of the above comments about memory models apply if you are using a

-32-bit flat-memory-space environment, such as DJGPP or Watcom C.  (And you

-should use one if you have it, as performance will be much better than

-8086-compatible code!)  For flat-memory-space compilers, do NOT define

-NEED_FAR_POINTERS, and do NOT use jmemdos.c.  Use jmemnobs.c if the

-environment supplies adequate virtual memory, otherwise use jmemansi.c or

-jmemname.c.

-

-You'll still need to be careful about binary I/O through stdin/stdout.

-See the last paragraph of the previous section.

-

-

-MS-DOS, Borland C:

-

-Be sure to convert all the source files to DOS text format (CR/LF newlines).

-Although Borland C will often work OK with unmodified Unix (LF newlines)

-source files, sometimes it will give bogus compile errors.

-"Illegal character '#'" is the most common such error.  (This is true with

-Borland C 3.1, but perhaps is fixed in newer releases.)

-

-If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.

-jconfig.bcc already includes #define USE_SETMODE to make this work.

-(fdopen does not work correctly.)

-

-

-MS-DOS, Microsoft C:

-

-makefile.mc6 works with Microsoft C, DOS Visual C++, etc.  It should only

-be used if you want to build a 16-bit (small or medium memory model) program.

-

-If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.

-jconfig.mc6 already includes #define USE_SETMODE to make this work.

-(fdopen does not work correctly.)

-

-Note that this makefile assumes that the working copy of itself is called

-"makefile".  If you want to call it something else, say "makefile.mak",

-be sure to adjust the dependency line that reads "$(RFILE) : makefile".

-Otherwise the make will fail because it doesn't know how to create "makefile".

-Worse, some releases of Microsoft's make utilities give an incorrect error

-message in this situation.

-

-Old versions of MS C fail with an "out of macro expansion space" error

-because they can't cope with the macro TRACEMS8 (defined in jerror.h).

-If this happens to you, the easiest solution is to change TRACEMS8 to

-expand to nothing.  You'll lose the ability to dump out JPEG coefficient

-tables with djpeg -debug -debug, but at least you can compile.

-

-Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn

-off optimization entirely (remove -O from CFLAGS).  6.00A is better, but it

-still generates bad code if you enable loop optimizations (-Ol or -Ox).

-

-MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ...

-which is on by default.  To work around this bug, compile that one file

-with /Oo-.

-

-

-Microsoft Windows (all versions), generic comments:

-

-Some Windows system include files define typedef boolean as "unsigned char".

-The IJG code also defines typedef boolean, but we make it "int" by default.

-This doesn't affect the IJG programs because we don't import those Windows

-include files.  But if you use the JPEG library in your own program, and some

-of your program's files import one definition of boolean while some import the

-other, you can get all sorts of mysterious problems.  A good preventive step

-is to make the IJG library use "unsigned char" for boolean.  To do that,

-add something like this to your jconfig.h file:

-        /* Define "boolean" as unsigned char, not int, per Windows custom */

-        #ifndef __RPCNDR_H__    /* don't conflict if rpcndr.h already read */

-        typedef unsigned char boolean;

-        #endif

-        #define HAVE_BOOLEAN    /* prevent jmorecfg.h from redefining it */

-(This is already in jconfig.vc, by the way.)

-

-windef.h contains the declarations

-        #define far

-        #define FAR far

-Since jmorecfg.h tries to define FAR as empty, you may get a compiler

-warning if you include both jpeglib.h and windef.h (which windows.h

-includes).  To suppress the warning, you can put "#ifndef FAR"/"#endif"

-around the line "#define FAR" in jmorecfg.h.

-(Something like this is already in jmorecfg.h, by the way.)

-

-When using the library in a Windows application, you will almost certainly

-want to modify or replace the error handler module jerror.c, since our

-default error handler does a couple of inappropriate things:

-  1. it tries to write error and warning messages on stderr;

-  2. in event of a fatal error, it exits by calling exit().

-

-A simple stopgap solution for problem 1 is to replace the line

-        fprintf(stderr, "%s\n", buffer);

-(in output_message in jerror.c) with

-        MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR);

-It's highly recommended that you at least do that much, since otherwise

-error messages will disappear into nowhere.  (Beginning with IJG v6b, this

-code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in

-jconfig.h to enable it.)

-

-The proper solution for problem 2 is to return control to your calling

-application after a library error.  This can be done with the setjmp/longjmp

-technique discussed in libjpeg.txt and illustrated in example.c.  (NOTE:

-some older Windows C compilers provide versions of setjmp/longjmp that

-don't actually work under Windows.  You may need to use the Windows system

-functions Catch and Throw instead.)

-

-The recommended memory manager under Windows is jmemnobs.c; in other words,

-let Windows do any virtual memory management needed.  You should NOT use

-jmemdos.c nor jmemdosa.asm under Windows.

-

-For Windows 3.1, we recommend compiling in medium or large memory model;

-for newer Windows versions, use a 32-bit flat memory model.  (See the MS-DOS

-sections above for more info about memory models.)  In the 16-bit memory

-models only, you'll need to put

-        #define MAX_ALLOC_CHUNK 65520L  /* Maximum request to malloc() */

-into jconfig.h to limit allocation chunks to 64Kb.  (Without that, you'd

-have to use huge memory model, which slows things down unnecessarily.)

-jmemnobs.c works without modification in large or flat memory models, but to

-use medium model, you need to modify its jpeg_get_large and jpeg_free_large

-routines to allocate far memory.  In any case, you might like to replace

-its calls to malloc and free with direct calls on Windows memory allocation

-functions.

-

-You may also want to modify jdatasrc.c and jdatadst.c to use Windows file

-operations rather than fread/fwrite.  This is only necessary if your C

-compiler doesn't provide a competent implementation of C stdio functions.

-

-You might want to tweak the RGB_xxx macros in jmorecfg.h so that the library

-will accept or deliver color pixels in BGR sample order, not RGB; BGR order

-is usually more convenient under Windows.  Note that this change will break

-the sample applications cjpeg/djpeg, but the library itself works fine.

-

-

-Many people want to convert the IJG library into a DLL.  This is reasonably

-straightforward, but watch out for the following:

-

-  1. Don't try to compile as a DLL in small or medium memory model; use

-large model, or even better, 32-bit flat model.  Many places in the IJG code

-assume the address of a local variable is an ordinary (not FAR) pointer;

-that isn't true in a medium-model DLL.

-

-  2. Microsoft C cannot pass file pointers between applications and DLLs.

-(See Microsoft Knowledge Base, PSS ID Number Q50336.)  So jdatasrc.c and

-jdatadst.c don't work if you open a file in your application and then pass

-the pointer to the DLL.  One workaround is to make jdatasrc.c/jdatadst.c

-part of your main application rather than part of the DLL.

-

-  3. You'll probably need to modify the macros GLOBAL() and EXTERN() to

-attach suitable linkage keywords to the exported routine names.  Similarly,

-you'll want to modify METHODDEF() and JMETHOD() to ensure function pointers

-are declared in a way that lets application routines be called back through

-the function pointers.  These macros are in jmorecfg.h.  Typical definitions

-for a 16-bit DLL are:

-        #define GLOBAL(type)            type _far _pascal _loadds _export

-        #define EXTERN(type)            extern type _far _pascal _loadds

-        #define METHODDEF(type)         static type _far _pascal

-        #define JMETHOD(type,methodname,arglist)  \

-                type (_far _pascal *methodname) arglist

-For a 32-bit DLL you may want something like

-        #define GLOBAL(type)            __declspec(dllexport) type

-        #define EXTERN(type)            extern __declspec(dllexport) type

-Although not all the GLOBAL routines are actually intended to be called by

-the application, the performance cost of making them all DLL entry points is

-negligible.

-

-The unmodified IJG library presents a very C-specific application interface,

-so the resulting DLL is only usable from C or C++ applications.  There has

-been some talk of writing wrapper code that would present a simpler interface

-usable from other languages, such as Visual Basic.  This is on our to-do list

-but hasn't been very high priority --- any volunteers out there?

-

-

-Microsoft Windows, Borland C:

-

-The provided jconfig.bcc should work OK in a 32-bit Windows environment,

-but you'll need to tweak it in a 16-bit environment (you'd need to define

-NEED_FAR_POINTERS and MAX_ALLOC_CHUNK).  Beware that makefile.bcc will need

-alteration if you want to use it for Windows --- in particular, you should

-use jmemnobs.c not jmemdos.c under Windows.

-

-Borland C++ 4.5 fails with an internal compiler error when trying to compile

-jdmerge.c in 32-bit mode.  If enough people complain, perhaps Borland will fix

-it.  In the meantime, the simplest known workaround is to add a redundant

-definition of the variable range_limit in h2v1_merged_upsample(), at the head

-of the block that handles odd image width (about line 268 in v6 jdmerge.c):

-  /* If image width is odd, do the last output column separately */

-  if (cinfo->output_width & 1) {

-    register JSAMPLE * range_limit = cinfo->sample_range_limit; /* ADD THIS */

-    cb = GETJSAMPLE(*inptr1);

-Pretty bizarre, especially since the very similar routine h2v2_merged_upsample

-doesn't trigger the bug.

-Recent reports suggest that this bug does not occur with "bcc32a" (the

-Pentium-optimized version of the compiler).

-

-Another report from a user of Borland C 4.5 was that incorrect code (leading

-to a color shift in processed images) was produced if any of the following

-optimization switch combinations were used: 

-        -Ot -Og

-        -Ot -Op

-        -Ot -Om

-So try backing off on optimization if you see such a problem.  (Are there

-several different releases all numbered "4.5"??)

-

-

-Microsoft Windows, Microsoft Visual C++:

-

-jconfig.vc should work OK with any Microsoft compiler for a 32-bit memory

-model.  makefile.vc is intended for command-line use.  (If you are using

-the Developer Studio environment, you may prefer the DevStudio project

-files; see below.)

-

-IJG JPEG 7 adds extern "C" to jpeglib.h.  This avoids the need to put

-extern "C" { ... } around #include "jpeglib.h" in your C++ application.

-You can also force VC++ to treat the library as C++ code by renaming

-all the *.c files to *.cpp (and adjusting the makefile to match).

-In this case you also need to define the symbol DONT_USE_EXTERN_C in

-the configuration to prevent jpeglib.h from using extern "C".

-

-

-Microsoft Windows, Microsoft Visual C++ 6 Developer Studio:

-

-We include makefiles that should work as project files in DevStudio 6.0 or

-later.  There is a library makefile that builds the IJG library as a static

-Win32 library, and application makefiles that build the sample applications

-as Win32 console applications.  (Even if you only want the library, we

-recommend building the applications so that you can run the self-test.)

-

-To use:

-1. Open the command prompt, change to the main directory and execute the

-   command line

-        NMAKE /f makefile.vc  setup-vc6

-   This will move jconfig.vc to jconfig.h and makefiles to project files.

-   (Note that the renaming is critical!)

-2. Open the workspace file jpeg.dsw, build the library project.

-   (If you are using DevStudio more recent than 6.0, you'll probably

-   get a message saying that the project files are being updated.)

-3. Open the workspace file apps.dsw, build the application projects.

-4. To perform the self-test, execute the command line

-        NMAKE /f makefile.vc  test-build

-5. Move the application .exe files from `app`\Release to an

-   appropriate location on your path.

-

-

-Microsoft Windows, Microsoft Visual C++ 2010 Developer Studio (v10):

-

-We include makefiles that should work as project files in Visual Studio

-2010 or later.  There is a library makefile that builds the IJG library

-as a static Win32 library, and application makefiles that build the sample

-applications as Win32 console applications.  (Even if you only want the

-library, we recommend building the applications so that you can run the

-self-test.)

-

-To use:

-1. Open the command prompt, change to the main directory and execute the

-   command line

-        NMAKE /f makefile.vc  setup-v10

-   This will move jconfig.vc to jconfig.h and makefiles to project files.

-   (Note that the renaming is critical!)

-2. Open the solution file jpeg.sln, build the library project.

-   (If you are using Visual Studio more recent than 2010 (v10), you'll

-   probably get a message saying that the project files are being updated.)

-3. Open the solution file apps.sln, build the application projects.

-4. To perform the self-test, execute the command line

-        NMAKE /f makefile.vc  test-build

-5. Move the application .exe files from `app`\Release to an

-   appropriate location on your path.

-

-Note:

-There seems to be an optimization bug in the compiler which causes the

-self-test to fail with the color quantization option.

-We have disabled optimization for the file jquant2.c in the library

-project file which causes the self-test to pass properly.

-

-

-OS/2, Borland C++:

-

-Watch out for optimization bugs in older Borland compilers; you may need

-to back off the optimization switch settings.  See the comments in

-makefile.bcc.

-

-

-SGI:

-

-On some SGI systems, you may need to set "AR2= ar -ts" in the Makefile.

-If you are using configure, you can do this by saying

-        ./configure RANLIB='ar -ts'

-This change is not needed on all SGIs.  Use it only if the make fails at the

-stage of linking the completed programs.

-

-On the MIPS R4000 architecture (Indy, etc.), the compiler option "-mips2"

-reportedly speeds up the float DCT method substantially, enough to make it

-faster than the default int method (but still slower than the fast int

-method).  If you use -mips2, you may want to alter the default DCT method to

-be float.  To do this, put "#define JDCT_DEFAULT JDCT_FLOAT" in jconfig.h.

-

-

-VMS:

-

-On an Alpha/VMS system with MMS, be sure to use the "/Marco=Alpha=1"

-qualifier with MMS when building the JPEG package.

-

-VAX/VMS v5.5-1 may have problems with the test step of the build procedure

-reporting differences when it compares the original and test images.  If the

-error points to the last block of the files, it is most likely bogus and may

-be safely ignored.  It seems to be because the files are Stream_LF and

-Backup/Compare has difficulty with the (presumably) null padded files.

-This problem was not observed on VAX/VMS v6.1 or AXP/VMS v6.1.

+INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software
+
+Copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding.
+This file is part of the Independent JPEG Group's software.
+For conditions of distribution and use, see the accompanying README file.
+
+
+This file explains how to configure and install the IJG software.  We have
+tried to make this software extremely portable and flexible, so that it can be
+adapted to almost any environment.  The downside of this decision is that the
+installation process is complicated.  We have provided shortcuts to simplify
+the task on common systems.  But in any case, you will need at least a little
+familiarity with C programming and program build procedures for your system.
+
+If you are only using this software as part of a larger program, the larger
+program's installation procedure may take care of configuring the IJG code.
+For example, Ghostscript's installation script will configure the IJG code.
+You don't need to read this file if you just want to compile Ghostscript.
+
+If you are on a Unix machine, you may not need to read this file at all.
+Try doing
+        ./configure
+        make
+        make test
+If that doesn't complain, do
+        make install
+(better do "make -n install" first to see if the makefile will put the files
+where you want them).  Read further if you run into snags or want to customize
+the code for your system.
+
+
+TABLE OF CONTENTS
+-----------------
+
+Before you start
+Configuring the software:
+        using the automatic "configure" script
+        using one of the supplied jconfig and makefile files
+        by hand
+Building the software
+Testing the software
+Installing the software
+Optional stuff
+Optimization
+Hints for specific systems
+
+
+BEFORE YOU START
+================
+
+Before installing the software you must unpack the distributed source code.
+Since you are reading this file, you have probably already succeeded in this
+task.  However, there is a potential for error if you needed to convert the
+files to the local standard text file format (for example, if you are on
+MS-DOS you may have converted LF end-of-line to CR/LF).  You must apply
+such conversion to all the files EXCEPT those whose names begin with "test".
+The test files contain binary data; if you change them in any way then the
+self-test will give bad results.
+
+Please check the last section of this file to see if there are hints for the
+specific machine or compiler you are using.
+
+
+CONFIGURING THE SOFTWARE
+========================
+
+To configure the IJG code for your system, you need to create two files:
+  * jconfig.h: contains values for system-dependent #define symbols.
+  * Makefile: controls the compilation process.
+(On a non-Unix machine, you may create "project files" or some other
+substitute for a Makefile.  jconfig.h is needed in any environment.)
+
+We provide three different ways to generate these files:
+  * On a Unix system, you can just run the "configure" script.
+  * We provide sample jconfig files and makefiles for popular machines;
+    if your machine matches one of the samples, just copy the right sample
+    files to jconfig.h and Makefile.
+  * If all else fails, read the instructions below and make your own files.
+
+
+Configuring the software using the automatic "configure" script
+---------------------------------------------------------------
+
+If you are on a Unix machine, you can just type
+        ./configure
+and let the configure script construct appropriate configuration files.
+If you're using "csh" on an old version of System V, you might need to type
+        sh configure
+instead to prevent csh from trying to execute configure itself.
+Expect configure to run for a few minutes, particularly on slower machines;
+it works by compiling a series of test programs.
+
+Configure was created with GNU Autoconf and it follows the usual conventions
+for GNU configure scripts.  It makes a few assumptions that you may want to
+override.  You can do this by providing optional switches to configure:
+
+* Configure will build both static and shared libraries, if possible.
+If you want to build libjpeg only as a static library, say
+        ./configure --disable-shared
+If you want to build libjpeg only as a shared library, say
+        ./configure --disable-static
+Configure uses GNU libtool to take care of system-dependent shared library
+building methods.
+
+* Configure will use gcc (GNU C compiler) if it's available, otherwise cc.
+To force a particular compiler to be selected, use the CC option, for example
+        ./configure CC='cc'
+The same method can be used to include any unusual compiler switches.
+For example, on HP-UX you probably want to say
+        ./configure CC='cc -Aa'
+to get HP's compiler to run in ANSI mode.
+
+* The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc.
+You can override this by saying, for example,
+        ./configure CFLAGS='-O2'
+if you want to compile without debugging support.
+
+* Configure will set up the makefile so that "make install" will install files
+into /usr/local/bin, /usr/local/man, etc.  You can specify an installation
+prefix other than "/usr/local" by giving configure the option "--prefix=PATH".
+
+* If you don't have a lot of swap space, you may need to enable the IJG
+software's internal virtual memory mechanism.  To do this, give the option
+"--enable-maxmem=N" where N is the default maxmemory limit in megabytes.
+This is discussed in more detail under "Selecting a memory manager", below.
+You probably don't need to worry about this on reasonably-sized Unix machines,
+unless you plan to process very large images.
+
+Configure has some other features that are useful if you are cross-compiling
+or working in a network of multiple machine types; but if you need those
+features, you probably already know how to use them.
+
+
+Configuring the software using one of the supplied jconfig and makefile files
+-----------------------------------------------------------------------------
+
+If you have one of these systems, you can just use the provided configuration
+files:
+
+Makefile        jconfig file    System and/or compiler
+
+makefile.manx   jconfig.manx    Amiga, Manx Aztec C
+makefile.sas    jconfig.sas     Amiga, SAS C
+makeproj.mac    jconfig.mac     Apple Macintosh, Metrowerks CodeWarrior
+mak*jpeg.st     jconfig.st      Atari ST/STE/TT, Pure C or Turbo C
+makefile.bcc    jconfig.bcc     MS-DOS or OS/2, Borland C
+makefile.dj     jconfig.dj      MS-DOS, DJGPP (Delorie's port of GNU C)
+makefile.mc6    jconfig.mc6     MS-DOS, Microsoft C (16-bit only)
+makefile.wat    jconfig.wat     MS-DOS, OS/2, or Windows NT, Watcom C
+makefile.vc     jconfig.vc      Windows NT/95, MS Visual C++
+make*.vc6       jconfig.vc      Windows NT/95, MS Visual C++ 6
+make*.v10       jconfig.vc      Windows NT/95, MS Visual C++ 2010 (v10)
+makefile.mms    jconfig.vms     Digital VMS, with MMS software
+makefile.vms    jconfig.vms     Digital VMS, without MMS software
+
+Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or
+whatever your system uses as the standard makefile name).  For more info see
+the appropriate system-specific hints section near the end of this file.
+
+
+Configuring the software by hand
+--------------------------------
+
+First, generate a jconfig.h file.  If you are moderately familiar with C,
+the comments in jconfig.txt should be enough information to do this; just
+copy jconfig.txt to jconfig.h and edit it appropriately.  Otherwise, you may
+prefer to use the ckconfig.c program.  You will need to compile and execute
+ckconfig.c by hand --- we hope you know at least enough to do that.
+ckconfig.c may not compile the first try (in fact, the whole idea is for it
+to fail if anything is going to).  If you get compile errors, fix them by
+editing ckconfig.c according to the directions given in ckconfig.c.  Once
+you get it to run, it will write a suitable jconfig.h file, and will also
+print out some advice about which makefile to use.
+
+You may also want to look at the canned jconfig files, if there is one for a
+system similar to yours.
+
+Second, select a makefile and copy it to Makefile (or whatever your system
+uses as the standard makefile name).  The most generic makefiles we provide
+are
+        makefile.ansi:  if your C compiler supports function prototypes
+        makefile.unix:  if not.
+(You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES"
+in jconfig.h.)  You may want to start from one of the other makefiles if
+there is one for a system similar to yours.
+
+Look over the selected Makefile and adjust options as needed.  In particular
+you may want to change the CC and CFLAGS definitions.  For instance, if you
+are using GCC, set CC=gcc.  If you had to use any compiler switches to get
+ckconfig.c to work, make sure the same switches are in CFLAGS.
+
+If you are on a system that doesn't use makefiles, you'll need to set up
+project files (or whatever you do use) to compile all the source files and
+link them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom.
+See the file lists in any of the makefiles to find out which files go into
+each program.  Note that the provided makefiles all make a "library" file
+libjpeg first, but you don't have to do that if you don't want to; the file
+lists identify which source files are actually needed for compression,
+decompression, or both.  As a last resort, you can make a batch script that
+just compiles everything and links it all together; makefile.vms is an example
+of this (it's for VMS systems that have no make-like utility).
+
+Here are comments about some specific configuration decisions you'll
+need to make:
+
+Command line style
+------------------
+
+These programs can use a Unix-like command line style which supports
+redirection and piping, like this:
+        cjpeg inputfile >outputfile
+        cjpeg <inputfile >outputfile
+        source program | cjpeg >outputfile
+The simpler "two file" command line style is just
+        cjpeg inputfile outputfile
+You may prefer the two-file style, particularly if you don't have pipes.
+
+You MUST use two-file style on any system that doesn't cope well with binary
+data fed through stdin/stdout; this is true for some MS-DOS compilers, for
+example.  If you're not on a Unix system, it's safest to assume you need
+two-file style.  (But if your compiler provides either the Posix-standard
+fdopen() library routine or a Microsoft-compatible setmode() routine, you
+can safely use the Unix command line style, by defining USE_FDOPEN or
+USE_SETMODE respectively.)
+
+To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE".
+
+Selecting a memory manager
+--------------------------
+
+The IJG code is capable of working on images that are too big to fit in main
+memory; data is swapped out to temporary files as necessary.  However, the
+code to do this is rather system-dependent.  We provide five different
+memory managers:
+
+* jmemansi.c    This version uses the ANSI-standard library routine tmpfile(),
+                which not all non-ANSI systems have.  On some systems
+                tmpfile() may put the temporary file in a non-optimal
+                location; if you don't like what it does, use jmemname.c.
+
+* jmemname.c    This version creates named temporary files.  For anything
+                except a Unix machine, you'll need to configure the
+                select_file_name() routine appropriately; see the comments
+                near the head of jmemname.c.  If you use this version, define
+                NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files
+                are removed if the program is aborted.
+
+* jmemnobs.c    (That stands for No Backing Store :-).)  This will compile on
+                almost any system, but it assumes you have enough main memory
+                or virtual memory to hold the biggest images you work with.
+
+* jmemdos.c     This should be used with most 16-bit MS-DOS compilers.
+                See the system-specific notes about MS-DOS for more info.
+                IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in
+                jconfig.h, and include the assembly file jmemdosa.asm in the
+                programs.  The supplied makefiles and jconfig files for
+                16-bit MS-DOS compilers already do both.
+
+* jmemmac.c     Custom version for Apple Macintosh; see the system-specific
+                notes for Macintosh for more info.
+
+To use a particular memory manager, change the SYSDEPMEM variable in your
+makefile to equal the corresponding object file name (for example, jmemansi.o
+or jmemansi.obj for jmemansi.c).
+
+If you have plenty of (real or virtual) main memory, just use jmemnobs.c.
+"Plenty" means about ten bytes for every pixel in the largest images
+you plan to process, so a lot of systems don't meet this criterion.
+If yours doesn't, try jmemansi.c first.  If that doesn't compile, you'll have
+to use jmemname.c; be sure to adjust select_file_name() for local conditions.
+You may also need to change unlink() to remove() in close_backing_store().
+
+Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEM
+setting to a reasonable value for your system (either by adding a #define for
+DEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile).
+This value limits the amount of data space the program will attempt to
+allocate.  Code and static data space isn't counted, so the actual memory
+needs for cjpeg or djpeg are typically 100 to 150Kb more than the max-memory
+setting.  Larger max-memory settings reduce the amount of I/O needed to
+process a large image, but too large a value can result in "insufficient
+memory" failures.  On most Unix machines (and other systems with virtual
+memory), just set DEFAULT_MAX_MEM to several million and forget it.  At the
+other end of the spectrum, for MS-DOS machines you probably can't go much
+above 300K to 400K.  (On MS-DOS the value refers to conventional memory only.
+Extended/expanded memory is handled separately by jmemdos.c.)
+
+
+BUILDING THE SOFTWARE
+=====================
+
+Now you should be able to compile the software.  Just say "make" (or
+whatever's necessary to start the compilation).  Have a cup of coffee.
+
+Here are some things that could go wrong:
+
+If your compiler complains about undefined structures, you should be able to
+shut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h.
+
+If you have trouble with missing system include files or inclusion of the
+wrong ones, read jinclude.h.  This shouldn't happen if you used configure
+or ckconfig.c to set up jconfig.h.
+
+There are a fair number of routines that do not use all of their parameters;
+some compilers will issue warnings about this, which you can ignore.  There
+are also a few configuration checks that may give "unreachable code" warnings.
+Any other warning deserves investigation.
+
+If you don't have a getenv() library routine, define NO_GETENV.
+
+Also see the system-specific hints, below.
+
+
+TESTING THE SOFTWARE
+====================
+
+As a quick test of functionality we've included a small sample image in
+several forms:
+        testorig.jpg    Starting point for the djpeg tests.
+        testimg.ppm     The output of djpeg testorig.jpg
+        testimg.bmp     The output of djpeg -bmp -colors 256 testorig.jpg
+        testimg.jpg     The output of cjpeg testimg.ppm
+        testprog.jpg    Progressive-mode equivalent of testorig.jpg.
+        testimgp.jpg    The output of cjpeg -progressive -optimize testimg.ppm
+(The first- and second-generation .jpg files aren't identical since the
+default compression parameters are lossy.)  If you can generate duplicates
+of the testimg* files then you probably have working programs.
+
+With most of the makefiles, "make test" will perform the necessary
+comparisons.
+
+If you're using a makefile that doesn't provide the test option, run djpeg
+and cjpeg by hand and compare the output files to testimg* with whatever
+binary file comparison tool you have.  The files should be bit-for-bit
+identical.
+
+If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then you
+need to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t.
+Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h.  A less likely
+configuration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPE
+as long should take care of that one.
+
+If the cjpeg test run fails with "Missing Huffman code table entry", it's a
+good bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED.  Go back to the
+configuration step and run ckconfig.c.  (This is a good plan for any other
+test failure, too.)
+
+If you are using Unix (one-file) command line style on a non-Unix system,
+it's a good idea to check that binary I/O through stdin/stdout actually
+works.  You should get the same results from "djpeg <testorig.jpg >out.ppm"
+as from "djpeg -outfile out.ppm testorig.jpg".  Note that the makefiles all
+use the latter style and therefore do not exercise stdin/stdout!  If this
+check fails, try recompiling with USE_SETMODE or USE_FDOPEN defined.
+If it still doesn't work, better use two-file style.
+
+If you chose a memory manager other than jmemnobs.c, you should test that
+temporary-file usage works.  Try "djpeg -bmp -colors 256 -max 0 testorig.jpg"
+and make sure its output matches testimg.bmp.  If you have any really large
+images handy, try compressing them with -optimize and/or decompressing with
+-colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large.
+
+NOTE: this is far from an exhaustive test of the JPEG software; some modules,
+such as 1-pass color quantization, are not exercised at all.  It's just a
+quick test to give you some confidence that you haven't missed something
+major.
+
+
+INSTALLING THE SOFTWARE
+=======================
+
+Once you're done with the above steps, you can install the software by
+copying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom)
+to wherever you normally install programs.  On Unix systems, you'll also want
+to put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1)
+in the man-page directory.  The pre-fab makefiles don't support this step
+since there's such a wide variety of installation procedures on different
+systems.
+
+If you generated a Makefile with the "configure" script, you can just say
+        make install
+to install the programs and their man pages into the standard places.
+(You'll probably need to be root to do this.)  We recommend first saying
+        make -n install
+to see where configure thought the files should go.  You may need to edit
+the Makefile, particularly if your system's conventions for man page
+filenames don't match what configure expects.
+
+If you want to install the IJG library itself, for use in compiling other
+programs besides ours, then you need to put the four include files
+        jpeglib.h jerror.h jconfig.h jmorecfg.h
+into your include-file directory, and put the library file libjpeg.a
+(extension may vary depending on system) wherever library files go.
+If you generated a Makefile with "configure", it will do what it thinks
+is the right thing if you say
+        make install-lib
+
+
+OPTIONAL STUFF
+==============
+
+Progress monitor:
+
+If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable display
+of percent-done progress reports.  The routine provided in cdjpeg.c merely
+prints percentages to stderr, but you can customize it to do something
+fancier.
+
+Utah RLE file format support:
+
+We distribute the software with support for RLE image files (Utah Raster
+Toolkit format) disabled, because the RLE support won't compile without the
+Utah library.  If you have URT version 3.1 or later, you can enable RLE
+support as follows:
+        1.  #define RLE_SUPPORTED in jconfig.h.
+        2.  Add a -I option to CFLAGS in the Makefile for the directory
+            containing the URT .h files (typically the "include"
+            subdirectory of the URT distribution).
+        3.  Add -L... -lrle to LDLIBS in the Makefile, where ... specifies
+            the directory containing the URT "librle.a" file (typically the
+            "lib" subdirectory of the URT distribution).
+
+Support for 12-bit-deep pixel data:
+
+The JPEG standard allows either 8-bit or 12-bit data precision.  (For color,
+this means 8 or 12 bits per channel, of course.)  If you need to work with
+deeper than 8-bit data, you can compile the IJG code for 12-bit operation.
+To do so:
+  1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8.
+  2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED,
+     because the code for those formats doesn't handle 12-bit data and won't
+     even compile.  (The PPM code does work, as explained below.  The GIF
+     code works too; it scales 8-bit GIF data to and from 12-bit depth
+     automatically.)
+  3. Compile.  Don't expect "make test" to pass, since the supplied test
+     files are for 8-bit data.
+
+Currently, 12-bit support does not work on 16-bit-int machines.
+
+Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa;
+so you'll want to keep around a regular 8-bit compilation as well.
+(Run-time selection of data depth, to allow a single copy that does both,
+is possible but would probably slow things down considerably; it's very low
+on our to-do list.)
+
+The PPM reader (rdppm.c) can read 12-bit data from either text-format or
+binary-format PPM and PGM files.  Binary-format PPM/PGM files which have a
+maxval greater than 255 are assumed to use 2 bytes per sample, MSB first
+(big-endian order).  As of early 1995, 2-byte binary format is not
+officially supported by the PBMPLUS library, but it is expected that a
+future release of PBMPLUS will support it.  Note that the PPM reader will
+read files of any maxval regardless of the BITS_IN_JSAMPLE setting; incoming
+data is automatically rescaled to either maxval=255 or maxval=4095 as
+appropriate for the cjpeg bit depth.
+
+The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGM
+format, maxval 4095, when compiled with BITS_IN_JSAMPLE=12.  Since this
+format is not yet widely supported, you can disable it by compiling wrppm.c
+with PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make a
+standard 1-byte/sample PPM or PGM file.  (Yes, this means still another copy
+of djpeg to keep around.  But hopefully you won't need it for very long.
+Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.)
+
+Of course, if you are working with 12-bit data, you probably have it stored
+in some other, nonstandard format.  In that case you'll probably want to
+write your own I/O modules to read and write your format.
+
+Note that a 12-bit version of cjpeg always runs in "-optimize" mode, in
+order to generate valid Huffman tables.  This is necessary because our
+default Huffman tables only cover 8-bit data.
+
+Removing code:
+
+If you need to make a smaller version of the JPEG software, some optional
+functions can be removed at compile time.  See the xxx_SUPPORTED #defines in
+jconfig.h and jmorecfg.h.  If at all possible, we recommend that you leave in
+decoder support for all valid JPEG files, to ensure that you can read anyone's
+output.  Taking out support for image file formats that you don't use is the
+most painless way to make the programs smaller.  Another possibility is to
+remove some of the DCT methods: in particular, the "IFAST" method may not be
+enough faster than the others to be worth keeping on your machine.  (If you
+do remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTEST
+to a supported method, by adding a #define in jconfig.h.)
+
+
+OPTIMIZATION
+============
+
+Unless you own a Cray, you'll probably be interested in making the JPEG
+software go as fast as possible.  This section covers some machine-dependent
+optimizations you may want to try.  We suggest that before trying any of
+this, you first get the basic installation to pass the self-test step.
+Repeat the self-test after any optimization to make sure that you haven't
+broken anything.
+
+The integer DCT routines perform a lot of multiplications.  These
+multiplications must yield 32-bit results, but none of their input values
+are more than 16 bits wide.  On many machines, notably the 680x0 and 80x86
+CPUs, a 16x16=>32 bit multiply instruction is faster than a full 32x32=>32
+bit multiply.  Unfortunately there is no portable way to specify such a
+multiplication in C, but some compilers can generate one when you use the
+right combination of casts.  See the MULTIPLYxxx macro definitions in
+jdct.h.  If your compiler makes "int" be 32 bits and "short" be 16 bits,
+defining SHORTxSHORT_32 is fairly likely to work.  When experimenting with
+alternate definitions, be sure to test not only whether the code still works
+(use the self-test), but also whether it is actually faster --- on some
+compilers, alternate definitions may compute the right answer, yet be slower
+than the default.  Timing cjpeg on a large PGM (grayscale) input file is the
+best way to check this, as the DCT will be the largest fraction of the runtime
+in that mode.  (Note: some of the distributed compiler-specific jconfig files
+already contain #define switches to select appropriate MULTIPLYxxx
+definitions.)
+
+If your machine has sufficiently fast floating point hardware, you may find
+that the float DCT method is faster than the integer DCT methods, even
+after tweaking the integer multiply macros.  In that case you may want to
+make the float DCT be the default method.  (The only objection to this is
+that float DCT results may vary slightly across machines.)  To do that, add
+"#define JDCT_DEFAULT JDCT_FLOAT" to jconfig.h.  Even if you don't change
+the default, you should redefine JDCT_FASTEST, which is the method selected
+by djpeg's -fast switch.  Don't forget to update the documentation files
+(usage.txt and/or cjpeg.1, djpeg.1) to agree with what you've done.
+
+If access to "short" arrays is slow on your machine, it may be a win to
+define type JCOEF as int rather than short.  This will cost a good deal of
+memory though, particularly in some multi-pass modes, so don't do it unless
+you have memory to burn and short is REALLY slow.
+
+If your compiler can compile function calls in-line, make sure the INLINE
+macro in jmorecfg.h is defined as the keyword that marks a function
+inline-able.  Some compilers have a switch that tells the compiler to inline
+any function it thinks is profitable (e.g., -finline-functions for gcc).
+Enabling such a switch is likely to make the compiled code bigger but faster.
+
+In general, it's worth trying the maximum optimization level of your compiler,
+and experimenting with any optional optimizations such as loop unrolling.
+(Unfortunately, far too many compilers have optimizer bugs ... be prepared to
+back off if the code fails self-test.)  If you do any experimentation along
+these lines, please report the optimal settings to jpeg-info@jpegclub.org so
+we can mention them in future releases.  Be sure to specify your machine and
+compiler version.
+
+
+HINTS FOR SPECIFIC SYSTEMS
+==========================
+
+We welcome reports on changes needed for systems not mentioned here.  Submit
+'em to jpeg-info@jpegclub.org.  Also, if configure or ckconfig.c is wrong
+about how to configure the JPEG software for your system, please let us know.
+
+
+Acorn RISC OS:
+
+(Thanks to Simon Middleton for these hints on compiling with Desktop C.)
+After renaming the files according to Acorn conventions, take a copy of
+makefile.ansi, change all occurrences of 'libjpeg.a' to 'libjpeg.o' and
+change these definitions as indicated:
+
+CFLAGS= -throwback -IC: -Wn
+LDLIBS=C:o.Stubs
+SYSDEPMEM=jmemansi.o
+LN=Link
+AR=LibFile -c -o
+
+Also add a new line '.c.o:; $(cc) $< $(cflags) -c -o $@'.  Remove the
+lines '$(RM) libjpeg.o' and '$(AR2) libjpeg.o' and the 'jconfig.h'
+dependency section.
+
+Copy jconfig.txt to jconfig.h.  Edit jconfig.h to define TWO_FILE_COMMANDLINE
+and CHAR_IS_UNSIGNED.
+
+Run the makefile using !AMU not !Make.  If you want to use the 'clean' and
+'test' makefile entries then you will have to fiddle with the syntax a bit
+and rename the test files.
+
+
+Amiga:
+
+SAS C 6.50 reportedly is too buggy to compile the IJG code properly.
+A patch to update to 6.51 is available from SAS or AmiNet FTP sites.
+
+The supplied config files are set up to use jmemname.c as the memory
+manager, with temporary files being created on the device named by
+"JPEGTMP:".
+
+
+Atari ST/STE/TT:
+
+Copy the project files makcjpeg.st, makdjpeg.st, maktjpeg.st, and makljpeg.st
+to cjpeg.prj, djpeg.prj, jpegtran.prj, and libjpeg.prj respectively.  The
+project files should work as-is with Pure C.  For Turbo C, change library
+filenames "pc..." to "tc..." in each project file.  Note that libjpeg.prj
+selects jmemansi.c as the recommended memory manager.  You'll probably want to
+adjust the DEFAULT_MAX_MEM setting --- you want it to be a couple hundred K
+less than your normal free memory.  Put "#define DEFAULT_MAX_MEM nnnn" into
+jconfig.h to do this.
+
+To use the 68881/68882 coprocessor for the floating point DCT, add the
+compiler option "-8" to the project files and replace pcfltlib.lib with
+pc881lib.lib in cjpeg.prj and djpeg.prj.  Or if you don't have a
+coprocessor, you may prefer to remove the float DCT code by undefining
+DCT_FLOAT_SUPPORTED in jmorecfg.h (since without a coprocessor, the float
+code will be too slow to be useful).  In that case, you can delete
+pcfltlib.lib from the project files.
+
+Note that you must make libjpeg.lib before making cjpeg.ttp, djpeg.ttp,
+or jpegtran.ttp.  You'll have to perform the self-test by hand.
+
+We haven't bothered to include project files for rdjpgcom and wrjpgcom.
+Those source files should just be compiled by themselves; they don't
+depend on the JPEG library.  You can use the default.prj project file
+of the Pure C distribution to make the programs.
+
+There is a bug in some older versions of the Turbo C library which causes the
+space used by temporary files created with "tmpfile()" not to be freed after
+an abnormal program exit.  If you check your disk afterwards, you will find
+cluster chains that are allocated but not used by a file.  This should not
+happen in cjpeg/djpeg/jpegtran, since we enable a signal catcher to explicitly
+close temp files before exiting.  But if you use the JPEG library with your
+own code, be sure to supply a signal catcher, or else use a different
+system-dependent memory manager.
+
+
+Cray:
+
+Should you be so fortunate as to be running JPEG on a Cray YMP, there is a
+compiler bug in old versions of Cray's Standard C (prior to 3.1).  If you
+still have an old compiler, you'll need to insert a line reading
+"#pragma novector" just before the loop 
+    for (i = 1; i <= (int) htbl->bits[l]; i++)
+      huffsize[p++] = (char) l;
+in fix_huff_tbl (in V5beta1, line 204 of jchuff.c and line 176 of jdhuff.c).
+[This bug may or may not still occur with the current IJG code, but it's
+probably a dead issue anyway...]
+
+
+HP-UX:
+
+If you have HP-UX 7.05 or later with the "software development" C compiler,
+you should run the compiler in ANSI mode.  If using the configure script,
+say
+        ./configure CC='cc -Aa'
+(or -Ae if you prefer).  If configuring by hand, use makefile.ansi and add
+"-Aa" to the CFLAGS line in the makefile.
+
+If you have a pre-7.05 system, or if you are using the non-ANSI C compiler
+delivered with a minimum HP-UX system, then you must use makefile.unix
+(and do NOT add -Aa); or just run configure without the CC option.
+
+On HP 9000 series 800 machines, the HP C compiler is buggy in revisions prior
+to A.08.07.  If you get complaints about "not a typedef name", you'll have to
+use makefile.unix, or run configure without the CC option.
+
+
+Macintosh, generic comments:
+
+The supplied user-interface files (cjpeg.c, djpeg.c, etc) are set up to
+provide a Unix-style command line interface.  You can use this interface on
+the Mac by means of the ccommand() library routine provided by Metrowerks
+CodeWarrior or Think C.  This is only appropriate for testing the library,
+however; to make a user-friendly equivalent of cjpeg/djpeg you'd really want
+to develop a Mac-style user interface.  There isn't a complete example
+available at the moment, but there are some helpful starting points:
+1. Sam Bushell's free "To JPEG" applet provides drag-and-drop conversion to
+JPEG under System 7 and later.  This only illustrates how to use the
+compression half of the library, but it does a very nice job of that part.
+The CodeWarrior source code is available from http://www.pobox.com/~jsam.
+2. Jim Brunner prepared a Mac-style user interface for both compression and
+decompression.  Unfortunately, it hasn't been updated since IJG v4, and
+the library's API has changed considerably since then.  Still it may be of
+some help, particularly as a guide to compiling the IJG code under Think C.
+Jim's code is available from the Info-Mac archives, at sumex-aim.stanford.edu
+or mirrors thereof; see file /info-mac/dev/src/jpeg-convert-c.hqx.
+
+jmemmac.c is the recommended memory manager back end for Macintosh.  It uses
+NewPtr/DisposePtr instead of malloc/free, and has a Mac-specific
+implementation of jpeg_mem_available().  It also creates temporary files that
+follow Mac conventions.  (That part of the code relies on System-7-or-later OS
+functions.  See the comments in jmemmac.c if you need to run it on System 6.)
+NOTE that USE_MAC_MEMMGR must be defined in jconfig.h to use jmemmac.c.
+
+You can also use jmemnobs.c, if you don't care about handling images larger
+than available memory.  If you use any memory manager back end other than
+jmemmac.c, we recommend replacing "malloc" and "free" by "NewPtr" and
+"DisposePtr", because Mac C libraries often have peculiar implementations of
+malloc/free.  (For instance, free() may not return the freed space to the
+Mac Memory Manager.  This is undesirable for the IJG code because jmemmgr.c
+already clumps space requests.)
+
+
+Macintosh, Metrowerks CodeWarrior:
+
+The Unix-command-line-style interface can be used by defining USE_CCOMMAND.
+You'll also need to define TWO_FILE_COMMANDLINE to avoid stdin/stdout.
+This means that when using the cjpeg/djpeg programs, you'll have to type the
+input and output file names in the "Arguments" text-edit box, rather than
+using the file radio buttons.  (Perhaps USE_FDOPEN or USE_SETMODE would
+eliminate the problem, but I haven't heard from anyone who's tried it.)
+
+On 680x0 Macs, Metrowerks defines type "double" as a 10-byte IEEE extended
+float.  jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power
+of 2.  Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.
+
+The supplied configuration file jconfig.mac can be used for your jconfig.h;
+it includes all the recommended symbol definitions.  If you have AppleScript
+installed, you can run the supplied script makeproj.mac to create CodeWarrior
+project files for the library and the testbed applications, then build the
+library and applications.  (Thanks to Dan Sears and Don Agro for this nifty
+hack, which saves us from trying to maintain CodeWarrior project files as part
+of the IJG distribution...)
+
+
+Macintosh, Think C:
+
+The documentation in Jim Brunner's "JPEG Convert" source code (see above)
+includes detailed build instructions for Think C; it's probably somewhat
+out of date for the current release, but may be helpful.
+
+If you want to build the minimal command line version, proceed as follows.
+You'll have to prepare project files for the programs; we don't include any
+in the distribution since they are not text files.  Use the file lists in
+any of the supplied makefiles as a guide.  Also add the ANSI and Unix C
+libraries in a separate segment.  You may need to divide the JPEG files into
+more than one segment; we recommend dividing compression and decompression
+modules.  Define USE_CCOMMAND in jconfig.h so that the ccommand() routine is
+called.  You must also define TWO_FILE_COMMANDLINE because stdin/stdout
+don't handle binary data correctly.
+
+On 680x0 Macs, Think C defines type "double" as a 12-byte IEEE extended float.
+jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power of 2.
+Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.
+
+jconfig.mac should work as a jconfig.h configuration file for Think C,
+but the makeproj.mac AppleScript script is specific to CodeWarrior.  Sorry.
+
+
+MIPS R3000:
+
+MIPS's cc version 1.31 has a rather nasty optimization bug.  Don't use -O
+if you have that compiler version.  (Use "cc -V" to check the version.)
+Note that the R3000 chip is found in workstations from DEC and others.
+
+
+MS-DOS, generic comments for 16-bit compilers:
+
+The IJG code is designed to work well in 80x86 "small" or "medium" memory
+models (i.e., data pointers are 16 bits unless explicitly declared "far";
+code pointers can be either size).  You may be able to use small model to
+compile cjpeg or djpeg by itself, but you will probably have to use medium
+model for any larger application.  This won't make much difference in
+performance.  You *will* take a noticeable performance hit if you use a
+large-data memory model, and you should avoid "huge" model if at all
+possible.  Be sure that NEED_FAR_POINTERS is defined in jconfig.h if you use
+a small-data memory model; be sure it is NOT defined if you use a large-data
+model.  (The supplied makefiles and jconfig files for Borland and Microsoft C
+compile in medium model and define NEED_FAR_POINTERS.)
+
+The DOS-specific memory manager, jmemdos.c, should be used if possible.
+It needs some assembly-code routines which are in jmemdosa.asm; make sure
+your makefile assembles that file and includes it in the library.  If you
+don't have a suitable assembler, you can get pre-assembled object files for
+jmemdosa by FTP from ftp.uu.net:/graphics/jpeg/jdosaobj.zip.  (DOS-oriented
+distributions of the IJG source code often include these object files.)
+
+When using jmemdos.c, jconfig.h must define USE_MSDOS_MEMMGR and must set
+MAX_ALLOC_CHUNK to less than 64K (65520L is a typical value).  If your
+C library's far-heap malloc() can't allocate blocks that large, reduce
+MAX_ALLOC_CHUNK to whatever it can handle.
+
+If you can't use jmemdos.c for some reason --- for example, because you
+don't have an assembler to assemble jmemdosa.asm --- you'll have to fall
+back to jmemansi.c or jmemname.c.  You'll probably still need to set
+MAX_ALLOC_CHUNK in jconfig.h, because most DOS C libraries won't malloc()
+more than 64K at a time.  IMPORTANT: if you use jmemansi.c or jmemname.c,
+you will have to compile in a large-data memory model in order to get the
+right stdio library.  Too bad.
+
+wrjpgcom needs to be compiled in large model, because it malloc()s a 64KB
+work area to hold the comment text.  If your C library's malloc can't
+handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c.
+
+Most MS-DOS compilers treat stdin/stdout as text files, so you must use
+two-file command line style.  But if your compiler has either fdopen() or
+setmode(), you can use one-file style if you like.  To do this, define
+USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode.
+(USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.)  You
+should test that I/O through stdin/stdout produces the same results as I/O
+to explicitly named files... the "make test" procedures in the supplied
+makefiles do NOT use stdin/stdout.
+
+
+MS-DOS, generic comments for 32-bit compilers:
+
+None of the above comments about memory models apply if you are using a
+32-bit flat-memory-space environment, such as DJGPP or Watcom C.  (And you
+should use one if you have it, as performance will be much better than
+8086-compatible code!)  For flat-memory-space compilers, do NOT define
+NEED_FAR_POINTERS, and do NOT use jmemdos.c.  Use jmemnobs.c if the
+environment supplies adequate virtual memory, otherwise use jmemansi.c or
+jmemname.c.
+
+You'll still need to be careful about binary I/O through stdin/stdout.
+See the last paragraph of the previous section.
+
+
+MS-DOS, Borland C:
+
+Be sure to convert all the source files to DOS text format (CR/LF newlines).
+Although Borland C will often work OK with unmodified Unix (LF newlines)
+source files, sometimes it will give bogus compile errors.
+"Illegal character '#'" is the most common such error.  (This is true with
+Borland C 3.1, but perhaps is fixed in newer releases.)
+
+If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
+jconfig.bcc already includes #define USE_SETMODE to make this work.
+(fdopen does not work correctly.)
+
+
+MS-DOS, Microsoft C:
+
+makefile.mc6 works with Microsoft C, DOS Visual C++, etc.  It should only
+be used if you want to build a 16-bit (small or medium memory model) program.
+
+If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
+jconfig.mc6 already includes #define USE_SETMODE to make this work.
+(fdopen does not work correctly.)
+
+Note that this makefile assumes that the working copy of itself is called
+"makefile".  If you want to call it something else, say "makefile.mak",
+be sure to adjust the dependency line that reads "$(RFILE) : makefile".
+Otherwise the make will fail because it doesn't know how to create "makefile".
+Worse, some releases of Microsoft's make utilities give an incorrect error
+message in this situation.
+
+Old versions of MS C fail with an "out of macro expansion space" error
+because they can't cope with the macro TRACEMS8 (defined in jerror.h).
+If this happens to you, the easiest solution is to change TRACEMS8 to
+expand to nothing.  You'll lose the ability to dump out JPEG coefficient
+tables with djpeg -debug -debug, but at least you can compile.
+
+Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn
+off optimization entirely (remove -O from CFLAGS).  6.00A is better, but it
+still generates bad code if you enable loop optimizations (-Ol or -Ox).
+
+MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ...
+which is on by default.  To work around this bug, compile that one file
+with /Oo-.
+
+
+Microsoft Windows (all versions), generic comments:
+
+Some Windows system include files define typedef boolean as "unsigned char".
+The IJG code also defines typedef boolean, but we make it "int" by default.
+This doesn't affect the IJG programs because we don't import those Windows
+include files.  But if you use the JPEG library in your own program, and some
+of your program's files import one definition of boolean while some import the
+other, you can get all sorts of mysterious problems.  A good preventive step
+is to make the IJG library use "unsigned char" for boolean.  To do that,
+add something like this to your jconfig.h file:
+        /* Define "boolean" as unsigned char, not int, per Windows custom */
+        #ifndef __RPCNDR_H__    /* don't conflict if rpcndr.h already read */
+        typedef unsigned char boolean;
+        #endif
+        #define HAVE_BOOLEAN    /* prevent jmorecfg.h from redefining it */
+(This is already in jconfig.vc, by the way.)
+
+windef.h contains the declarations
+        #define far
+        #define FAR far
+Since jmorecfg.h tries to define FAR as empty, you may get a compiler
+warning if you include both jpeglib.h and windef.h (which windows.h
+includes).  To suppress the warning, you can put "#ifndef FAR"/"#endif"
+around the line "#define FAR" in jmorecfg.h.
+(Something like this is already in jmorecfg.h, by the way.)
+
+When using the library in a Windows application, you will almost certainly
+want to modify or replace the error handler module jerror.c, since our
+default error handler does a couple of inappropriate things:
+  1. it tries to write error and warning messages on stderr;
+  2. in event of a fatal error, it exits by calling exit().
+
+A simple stopgap solution for problem 1 is to replace the line
+        fprintf(stderr, "%s\n", buffer);
+(in output_message in jerror.c) with
+        MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR);
+It's highly recommended that you at least do that much, since otherwise
+error messages will disappear into nowhere.  (Beginning with IJG v6b, this
+code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in
+jconfig.h to enable it.)
+
+The proper solution for problem 2 is to return control to your calling
+application after a library error.  This can be done with the setjmp/longjmp
+technique discussed in libjpeg.txt and illustrated in example.c.  (NOTE:
+some older Windows C compilers provide versions of setjmp/longjmp that
+don't actually work under Windows.  You may need to use the Windows system
+functions Catch and Throw instead.)
+
+The recommended memory manager under Windows is jmemnobs.c; in other words,
+let Windows do any virtual memory management needed.  You should NOT use
+jmemdos.c nor jmemdosa.asm under Windows.
+
+For Windows 3.1, we recommend compiling in medium or large memory model;
+for newer Windows versions, use a 32-bit flat memory model.  (See the MS-DOS
+sections above for more info about memory models.)  In the 16-bit memory
+models only, you'll need to put
+        #define MAX_ALLOC_CHUNK 65520L  /* Maximum request to malloc() */
+into jconfig.h to limit allocation chunks to 64Kb.  (Without that, you'd
+have to use huge memory model, which slows things down unnecessarily.)
+jmemnobs.c works without modification in large or flat memory models, but to
+use medium model, you need to modify its jpeg_get_large and jpeg_free_large
+routines to allocate far memory.  In any case, you might like to replace
+its calls to malloc and free with direct calls on Windows memory allocation
+functions.
+
+You may also want to modify jdatasrc.c and jdatadst.c to use Windows file
+operations rather than fread/fwrite.  This is only necessary if your C
+compiler doesn't provide a competent implementation of C stdio functions.
+
+You might want to tweak the RGB_xxx macros in jmorecfg.h so that the library
+will accept or deliver color pixels in BGR sample order, not RGB; BGR order
+is usually more convenient under Windows.  Note that this change will break
+the sample applications cjpeg/djpeg, but the library itself works fine.
+
+
+Many people want to convert the IJG library into a DLL.  This is reasonably
+straightforward, but watch out for the following:
+
+  1. Don't try to compile as a DLL in small or medium memory model; use
+large model, or even better, 32-bit flat model.  Many places in the IJG code
+assume the address of a local variable is an ordinary (not FAR) pointer;
+that isn't true in a medium-model DLL.
+
+  2. Microsoft C cannot pass file pointers between applications and DLLs.
+(See Microsoft Knowledge Base, PSS ID Number Q50336.)  So jdatasrc.c and
+jdatadst.c don't work if you open a file in your application and then pass
+the pointer to the DLL.  One workaround is to make jdatasrc.c/jdatadst.c
+part of your main application rather than part of the DLL.
+
+  3. You'll probably need to modify the macros GLOBAL() and EXTERN() to
+attach suitable linkage keywords to the exported routine names.  Similarly,
+you'll want to modify METHODDEF() and JMETHOD() to ensure function pointers
+are declared in a way that lets application routines be called back through
+the function pointers.  These macros are in jmorecfg.h.  Typical definitions
+for a 16-bit DLL are:
+        #define GLOBAL(type)            type _far _pascal _loadds _export
+        #define EXTERN(type)            extern type _far _pascal _loadds
+        #define METHODDEF(type)         static type _far _pascal
+        #define JMETHOD(type,methodname,arglist)  \
+                type (_far _pascal *methodname) arglist
+For a 32-bit DLL you may want something like
+        #define GLOBAL(type)            __declspec(dllexport) type
+        #define EXTERN(type)            extern __declspec(dllexport) type
+Although not all the GLOBAL routines are actually intended to be called by
+the application, the performance cost of making them all DLL entry points is
+negligible.
+
+The unmodified IJG library presents a very C-specific application interface,
+so the resulting DLL is only usable from C or C++ applications.  There has
+been some talk of writing wrapper code that would present a simpler interface
+usable from other languages, such as Visual Basic.  This is on our to-do list
+but hasn't been very high priority --- any volunteers out there?
+
+
+Microsoft Windows, Borland C:
+
+The provided jconfig.bcc should work OK in a 32-bit Windows environment,
+but you'll need to tweak it in a 16-bit environment (you'd need to define
+NEED_FAR_POINTERS and MAX_ALLOC_CHUNK).  Beware that makefile.bcc will need
+alteration if you want to use it for Windows --- in particular, you should
+use jmemnobs.c not jmemdos.c under Windows.
+
+Borland C++ 4.5 fails with an internal compiler error when trying to compile
+jdmerge.c in 32-bit mode.  If enough people complain, perhaps Borland will fix
+it.  In the meantime, the simplest known workaround is to add a redundant
+definition of the variable range_limit in h2v1_merged_upsample(), at the head
+of the block that handles odd image width (about line 268 in v6 jdmerge.c):
+  /* If image width is odd, do the last output column separately */
+  if (cinfo->output_width & 1) {
+    register JSAMPLE * range_limit = cinfo->sample_range_limit; /* ADD THIS */
+    cb = GETJSAMPLE(*inptr1);
+Pretty bizarre, especially since the very similar routine h2v2_merged_upsample
+doesn't trigger the bug.
+Recent reports suggest that this bug does not occur with "bcc32a" (the
+Pentium-optimized version of the compiler).
+
+Another report from a user of Borland C 4.5 was that incorrect code (leading
+to a color shift in processed images) was produced if any of the following
+optimization switch combinations were used: 
+        -Ot -Og
+        -Ot -Op
+        -Ot -Om
+So try backing off on optimization if you see such a problem.  (Are there
+several different releases all numbered "4.5"??)
+
+
+Microsoft Windows, Microsoft Visual C++:
+
+jconfig.vc should work OK with any Microsoft compiler for a 32-bit memory
+model.  makefile.vc is intended for command-line use.  (If you are using
+the Developer Studio environment, you may prefer the DevStudio project
+files; see below.)
+
+IJG JPEG 7 adds extern "C" to jpeglib.h.  This avoids the need to put
+extern "C" { ... } around #include "jpeglib.h" in your C++ application.
+You can also force VC++ to treat the library as C++ code by renaming
+all the *.c files to *.cpp (and adjusting the makefile to match).
+In this case you also need to define the symbol DONT_USE_EXTERN_C in
+the configuration to prevent jpeglib.h from using extern "C".
+
+
+Microsoft Windows, Microsoft Visual C++ 6 Developer Studio:
+
+We include makefiles that should work as project files in DevStudio 6.0 or
+later.  There is a library makefile that builds the IJG library as a static
+Win32 library, and application makefiles that build the sample applications
+as Win32 console applications.  (Even if you only want the library, we
+recommend building the applications so that you can run the self-test.)
+
+To use:
+1. Open the command prompt, change to the main directory and execute the
+   command line
+        NMAKE /f makefile.vc  setup-vc6
+   This will move jconfig.vc to jconfig.h and makefiles to project files.
+   (Note that the renaming is critical!)
+2. Open the workspace file jpeg.dsw, build the library project.
+   (If you are using DevStudio more recent than 6.0, you'll probably
+   get a message saying that the project files are being updated.)
+3. Open the workspace file apps.dsw, build the application projects.
+4. To perform the self-test, execute the command line
+        NMAKE /f makefile.vc  test-build
+5. Move the application .exe files from `app`\Release to an
+   appropriate location on your path.
+
+
+Microsoft Windows, Microsoft Visual C++ 2010 Developer Studio (v10):
+
+We include makefiles that should work as project files in Visual Studio
+2010 or later.  There is a library makefile that builds the IJG library
+as a static Win32 library, and application makefiles that build the sample
+applications as Win32 console applications.  (Even if you only want the
+library, we recommend building the applications so that you can run the
+self-test.)
+
+To use:
+1. Open the command prompt, change to the main directory and execute the
+   command line
+        NMAKE /f makefile.vc  setup-v10
+   This will move jconfig.vc to jconfig.h and makefiles to project files.
+   (Note that the renaming is critical!)
+2. Open the solution file jpeg.sln, build the library project.
+   (If you are using Visual Studio more recent than 2010 (v10), you'll
+   probably get a message saying that the project files are being updated.)
+3. Open the solution file apps.sln, build the application projects.
+4. To perform the self-test, execute the command line
+        NMAKE /f makefile.vc  test-build
+5. Move the application .exe files from `app`\Release to an
+   appropriate location on your path.
+
+Note:
+There seems to be an optimization bug in the compiler which causes the
+self-test to fail with the color quantization option.
+We have disabled optimization for the file jquant2.c in the library
+project file which causes the self-test to pass properly.
+
+
+OS/2, Borland C++:
+
+Watch out for optimization bugs in older Borland compilers; you may need
+to back off the optimization switch settings.  See the comments in
+makefile.bcc.
+
+
+SGI:
+
+On some SGI systems, you may need to set "AR2= ar -ts" in the Makefile.
+If you are using configure, you can do this by saying
+        ./configure RANLIB='ar -ts'
+This change is not needed on all SGIs.  Use it only if the make fails at the
+stage of linking the completed programs.
+
+On the MIPS R4000 architecture (Indy, etc.), the compiler option "-mips2"
+reportedly speeds up the float DCT method substantially, enough to make it
+faster than the default int method (but still slower than the fast int
+method).  If you use -mips2, you may want to alter the default DCT method to
+be float.  To do this, put "#define JDCT_DEFAULT JDCT_FLOAT" in jconfig.h.
+
+
+VMS:
+
+On an Alpha/VMS system with MMS, be sure to use the "/Marco=Alpha=1"
+qualifier with MMS when building the JPEG package.
+
+VAX/VMS v5.5-1 may have problems with the test step of the build procedure
+reporting differences when it compares the original and test images.  If the
+error points to the last block of the files, it is most likely bogus and may
+be safely ignored.  It seems to be because the files are Stream_LF and
+Backup/Compare has difficulty with the (presumably) null padded files.
+This problem was not observed on VAX/VMS v6.1 or AXP/VMS v6.1.