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author | David Walter Seikel | 2014-01-13 19:47:58 +1000 |
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committer | David Walter Seikel | 2014-01-13 19:47:58 +1000 |
commit | f9158592e1478b2013afc7041d9ed041cf2d2f4a (patch) | |
tree | b16e389d7988700e21b4c9741044cefa536dcbae /libraries/irrlicht-1.8/source/Irrlicht/jpeglib/install.txt | |
parent | Libraries readme updated with change markers and more of the Irrlicht changes. (diff) | |
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Update Irrlicht to 1.8.1. Include actual change markers this time. lol
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1 | INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software | ||
2 | |||
3 | Copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding. | ||
4 | This file is part of the Independent JPEG Group's software. | ||
5 | For conditions of distribution and use, see the accompanying README file. | ||
6 | |||
7 | |||
8 | This file explains how to configure and install the IJG software. We have | ||
9 | tried to make this software extremely portable and flexible, so that it can be | ||
10 | adapted to almost any environment. The downside of this decision is that the | ||
11 | installation process is complicated. We have provided shortcuts to simplify | ||
12 | the task on common systems. But in any case, you will need at least a little | ||
13 | familiarity with C programming and program build procedures for your system. | ||
14 | |||
15 | If you are only using this software as part of a larger program, the larger | ||
16 | program's installation procedure may take care of configuring the IJG code. | ||
17 | For example, Ghostscript's installation script will configure the IJG code. | ||
18 | You don't need to read this file if you just want to compile Ghostscript. | ||
19 | |||
20 | If you are on a Unix machine, you may not need to read this file at all. | ||
21 | Try doing | ||
22 | ./configure | ||
23 | make | ||
24 | make test | ||
25 | If that doesn't complain, do | ||
26 | make install | ||
27 | (better do "make -n install" first to see if the makefile will put the files | ||
28 | where you want them). Read further if you run into snags or want to customize | ||
29 | the code for your system. | ||
30 | |||
31 | |||
32 | TABLE OF CONTENTS | ||
33 | ----------------- | ||
34 | |||
35 | Before you start | ||
36 | Configuring the software: | ||
37 | using the automatic "configure" script | ||
38 | using one of the supplied jconfig and makefile files | ||
39 | by hand | ||
40 | Building the software | ||
41 | Testing the software | ||
42 | Installing the software | ||
43 | Optional stuff | ||
44 | Optimization | ||
45 | Hints for specific systems | ||
46 | |||
47 | |||
48 | BEFORE YOU START | ||
49 | ================ | ||
50 | |||
51 | Before installing the software you must unpack the distributed source code. | ||
52 | Since you are reading this file, you have probably already succeeded in this | ||
53 | task. However, there is a potential for error if you needed to convert the | ||
54 | files to the local standard text file format (for example, if you are on | ||
55 | MS-DOS you may have converted LF end-of-line to CR/LF). You must apply | ||
56 | such conversion to all the files EXCEPT those whose names begin with "test". | ||
57 | The test files contain binary data; if you change them in any way then the | ||
58 | self-test will give bad results. | ||
59 | |||
60 | Please check the last section of this file to see if there are hints for the | ||
61 | specific machine or compiler you are using. | ||
62 | |||
63 | |||
64 | CONFIGURING THE SOFTWARE | ||
65 | ======================== | ||
66 | |||
67 | To configure the IJG code for your system, you need to create two files: | ||
68 | * jconfig.h: contains values for system-dependent #define symbols. | ||
69 | * Makefile: controls the compilation process. | ||
70 | (On a non-Unix machine, you may create "project files" or some other | ||
71 | substitute for a Makefile. jconfig.h is needed in any environment.) | ||
72 | |||
73 | We provide three different ways to generate these files: | ||
74 | * On a Unix system, you can just run the "configure" script. | ||
75 | * We provide sample jconfig files and makefiles for popular machines; | ||
76 | if your machine matches one of the samples, just copy the right sample | ||
77 | files to jconfig.h and Makefile. | ||
78 | * If all else fails, read the instructions below and make your own files. | ||
79 | |||
80 | |||
81 | Configuring the software using the automatic "configure" script | ||
82 | --------------------------------------------------------------- | ||
83 | |||
84 | If you are on a Unix machine, you can just type | ||
85 | ./configure | ||
86 | and let the configure script construct appropriate configuration files. | ||
87 | If you're using "csh" on an old version of System V, you might need to type | ||
88 | sh configure | ||
89 | instead to prevent csh from trying to execute configure itself. | ||
90 | Expect configure to run for a few minutes, particularly on slower machines; | ||
91 | it works by compiling a series of test programs. | ||
92 | |||
93 | Configure was created with GNU Autoconf and it follows the usual conventions | ||
94 | for GNU configure scripts. It makes a few assumptions that you may want to | ||
95 | override. You can do this by providing optional switches to configure: | ||
96 | |||
97 | * Configure will build both static and shared libraries, if possible. | ||
98 | If you want to build libjpeg only as a static library, say | ||
99 | ./configure --disable-shared | ||
100 | If you want to build libjpeg only as a shared library, say | ||
101 | ./configure --disable-static | ||
102 | Configure uses GNU libtool to take care of system-dependent shared library | ||
103 | building methods. | ||
104 | |||
105 | * Configure will use gcc (GNU C compiler) if it's available, otherwise cc. | ||
106 | To force a particular compiler to be selected, use the CC option, for example | ||
107 | ./configure CC='cc' | ||
108 | The same method can be used to include any unusual compiler switches. | ||
109 | For example, on HP-UX you probably want to say | ||
110 | ./configure CC='cc -Aa' | ||
111 | to get HP's compiler to run in ANSI mode. | ||
112 | |||
113 | * The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc. | ||
114 | You can override this by saying, for example, | ||
115 | ./configure CFLAGS='-O2' | ||
116 | if you want to compile without debugging support. | ||
117 | |||
118 | * Configure will set up the makefile so that "make install" will install files | ||
119 | into /usr/local/bin, /usr/local/man, etc. You can specify an installation | ||
120 | prefix other than "/usr/local" by giving configure the option "--prefix=PATH". | ||
121 | |||
122 | * If you don't have a lot of swap space, you may need to enable the IJG | ||
123 | software's internal virtual memory mechanism. To do this, give the option | ||
124 | "--enable-maxmem=N" where N is the default maxmemory limit in megabytes. | ||
125 | This is discussed in more detail under "Selecting a memory manager", below. | ||
126 | You probably don't need to worry about this on reasonably-sized Unix machines, | ||
127 | unless you plan to process very large images. | ||
128 | |||
129 | Configure has some other features that are useful if you are cross-compiling | ||
130 | or working in a network of multiple machine types; but if you need those | ||
131 | features, you probably already know how to use them. | ||
132 | |||
133 | |||
134 | Configuring the software using one of the supplied jconfig and makefile files | ||
135 | ----------------------------------------------------------------------------- | ||
136 | |||
137 | If you have one of these systems, you can just use the provided configuration | ||
138 | files: | ||
139 | |||
140 | Makefile jconfig file System and/or compiler | ||
141 | |||
142 | makefile.manx jconfig.manx Amiga, Manx Aztec C | ||
143 | makefile.sas jconfig.sas Amiga, SAS C | ||
144 | makeproj.mac jconfig.mac Apple Macintosh, Metrowerks CodeWarrior | ||
145 | mak*jpeg.st jconfig.st Atari ST/STE/TT, Pure C or Turbo C | ||
146 | makefile.bcc jconfig.bcc MS-DOS or OS/2, Borland C | ||
147 | makefile.dj jconfig.dj MS-DOS, DJGPP (Delorie's port of GNU C) | ||
148 | makefile.mc6 jconfig.mc6 MS-DOS, Microsoft C (16-bit only) | ||
149 | makefile.wat jconfig.wat MS-DOS, OS/2, or Windows NT, Watcom C | ||
150 | makefile.vc jconfig.vc Windows NT/95, MS Visual C++ | ||
151 | make*.vc6 jconfig.vc Windows NT/95, MS Visual C++ 6 | ||
152 | make*.v10 jconfig.vc Windows NT/95, MS Visual C++ 2010 (v10) | ||
153 | makefile.mms jconfig.vms Digital VMS, with MMS software | ||
154 | makefile.vms jconfig.vms Digital VMS, without MMS software | ||
155 | |||
156 | Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or | ||
157 | whatever your system uses as the standard makefile name). For more info see | ||
158 | the appropriate system-specific hints section near the end of this file. | ||
159 | |||
160 | |||
161 | Configuring the software by hand | ||
162 | -------------------------------- | ||
163 | |||
164 | First, generate a jconfig.h file. If you are moderately familiar with C, | ||
165 | the comments in jconfig.txt should be enough information to do this; just | ||
166 | copy jconfig.txt to jconfig.h and edit it appropriately. Otherwise, you may | ||
167 | prefer to use the ckconfig.c program. You will need to compile and execute | ||
168 | ckconfig.c by hand --- we hope you know at least enough to do that. | ||
169 | ckconfig.c may not compile the first try (in fact, the whole idea is for it | ||
170 | to fail if anything is going to). If you get compile errors, fix them by | ||
171 | editing ckconfig.c according to the directions given in ckconfig.c. Once | ||
172 | you get it to run, it will write a suitable jconfig.h file, and will also | ||
173 | print out some advice about which makefile to use. | ||
174 | |||
175 | You may also want to look at the canned jconfig files, if there is one for a | ||
176 | system similar to yours. | ||
177 | |||
178 | Second, select a makefile and copy it to Makefile (or whatever your system | ||
179 | uses as the standard makefile name). The most generic makefiles we provide | ||
180 | are | ||
181 | makefile.ansi: if your C compiler supports function prototypes | ||
182 | makefile.unix: if not. | ||
183 | (You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES" | ||
184 | in jconfig.h.) You may want to start from one of the other makefiles if | ||
185 | there is one for a system similar to yours. | ||
186 | |||
187 | Look over the selected Makefile and adjust options as needed. In particular | ||
188 | you may want to change the CC and CFLAGS definitions. For instance, if you | ||
189 | are using GCC, set CC=gcc. If you had to use any compiler switches to get | ||
190 | ckconfig.c to work, make sure the same switches are in CFLAGS. | ||
191 | |||
192 | If you are on a system that doesn't use makefiles, you'll need to set up | ||
193 | project files (or whatever you do use) to compile all the source files and | ||
194 | link them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom. | ||
195 | See the file lists in any of the makefiles to find out which files go into | ||
196 | each program. Note that the provided makefiles all make a "library" file | ||
197 | libjpeg first, but you don't have to do that if you don't want to; the file | ||
198 | lists identify which source files are actually needed for compression, | ||
199 | decompression, or both. As a last resort, you can make a batch script that | ||
200 | just compiles everything and links it all together; makefile.vms is an example | ||
201 | of this (it's for VMS systems that have no make-like utility). | ||
202 | |||
203 | Here are comments about some specific configuration decisions you'll | ||
204 | need to make: | ||
205 | |||
206 | Command line style | ||
207 | ------------------ | ||
208 | |||
209 | These programs can use a Unix-like command line style which supports | ||
210 | redirection and piping, like this: | ||
211 | cjpeg inputfile >outputfile | ||
212 | cjpeg <inputfile >outputfile | ||
213 | source program | cjpeg >outputfile | ||
214 | The simpler "two file" command line style is just | ||
215 | cjpeg inputfile outputfile | ||
216 | You may prefer the two-file style, particularly if you don't have pipes. | ||
217 | |||
218 | You MUST use two-file style on any system that doesn't cope well with binary | ||
219 | data fed through stdin/stdout; this is true for some MS-DOS compilers, for | ||
220 | example. If you're not on a Unix system, it's safest to assume you need | ||
221 | two-file style. (But if your compiler provides either the Posix-standard | ||
222 | fdopen() library routine or a Microsoft-compatible setmode() routine, you | ||
223 | can safely use the Unix command line style, by defining USE_FDOPEN or | ||
224 | USE_SETMODE respectively.) | ||
225 | |||
226 | To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE". | ||
227 | |||
228 | Selecting a memory manager | ||
229 | -------------------------- | ||
230 | |||
231 | The IJG code is capable of working on images that are too big to fit in main | ||
232 | memory; data is swapped out to temporary files as necessary. However, the | ||
233 | code to do this is rather system-dependent. We provide five different | ||
234 | memory managers: | ||
235 | |||
236 | * jmemansi.c This version uses the ANSI-standard library routine tmpfile(), | ||
237 | which not all non-ANSI systems have. On some systems | ||
238 | tmpfile() may put the temporary file in a non-optimal | ||
239 | location; if you don't like what it does, use jmemname.c. | ||
240 | |||
241 | * jmemname.c This version creates named temporary files. For anything | ||
242 | except a Unix machine, you'll need to configure the | ||
243 | select_file_name() routine appropriately; see the comments | ||
244 | near the head of jmemname.c. If you use this version, define | ||
245 | NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files | ||
246 | are removed if the program is aborted. | ||
247 | |||
248 | * jmemnobs.c (That stands for No Backing Store :-).) This will compile on | ||
249 | almost any system, but it assumes you have enough main memory | ||
250 | or virtual memory to hold the biggest images you work with. | ||
251 | |||
252 | * jmemdos.c This should be used with most 16-bit MS-DOS compilers. | ||
253 | See the system-specific notes about MS-DOS for more info. | ||
254 | IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in | ||
255 | jconfig.h, and include the assembly file jmemdosa.asm in the | ||
256 | programs. The supplied makefiles and jconfig files for | ||
257 | 16-bit MS-DOS compilers already do both. | ||
258 | |||
259 | * jmemmac.c Custom version for Apple Macintosh; see the system-specific | ||
260 | notes for Macintosh for more info. | ||
261 | |||
262 | To use a particular memory manager, change the SYSDEPMEM variable in your | ||
263 | makefile to equal the corresponding object file name (for example, jmemansi.o | ||
264 | or jmemansi.obj for jmemansi.c). | ||
265 | |||
266 | If you have plenty of (real or virtual) main memory, just use jmemnobs.c. | ||
267 | "Plenty" means about ten bytes for every pixel in the largest images | ||
268 | you plan to process, so a lot of systems don't meet this criterion. | ||
269 | If yours doesn't, try jmemansi.c first. If that doesn't compile, you'll have | ||
270 | to use jmemname.c; be sure to adjust select_file_name() for local conditions. | ||
271 | You may also need to change unlink() to remove() in close_backing_store(). | ||
272 | |||
273 | Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEM | ||
274 | setting to a reasonable value for your system (either by adding a #define for | ||
275 | DEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile). | ||
276 | This value limits the amount of data space the program will attempt to | ||
277 | allocate. Code and static data space isn't counted, so the actual memory | ||
278 | needs for cjpeg or djpeg are typically 100 to 150Kb more than the max-memory | ||
279 | setting. Larger max-memory settings reduce the amount of I/O needed to | ||
280 | process a large image, but too large a value can result in "insufficient | ||
281 | memory" failures. On most Unix machines (and other systems with virtual | ||
282 | memory), just set DEFAULT_MAX_MEM to several million and forget it. At the | ||
283 | other end of the spectrum, for MS-DOS machines you probably can't go much | ||
284 | above 300K to 400K. (On MS-DOS the value refers to conventional memory only. | ||
285 | Extended/expanded memory is handled separately by jmemdos.c.) | ||
286 | |||
287 | |||
288 | BUILDING THE SOFTWARE | ||
289 | ===================== | ||
290 | |||
291 | Now you should be able to compile the software. Just say "make" (or | ||
292 | whatever's necessary to start the compilation). Have a cup of coffee. | ||
293 | |||
294 | Here are some things that could go wrong: | ||
295 | |||
296 | If your compiler complains about undefined structures, you should be able to | ||
297 | shut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h. | ||
298 | |||
299 | If you have trouble with missing system include files or inclusion of the | ||
300 | wrong ones, read jinclude.h. This shouldn't happen if you used configure | ||
301 | or ckconfig.c to set up jconfig.h. | ||
302 | |||
303 | There are a fair number of routines that do not use all of their parameters; | ||
304 | some compilers will issue warnings about this, which you can ignore. There | ||
305 | are also a few configuration checks that may give "unreachable code" warnings. | ||
306 | Any other warning deserves investigation. | ||
307 | |||
308 | If you don't have a getenv() library routine, define NO_GETENV. | ||
309 | |||
310 | Also see the system-specific hints, below. | ||
311 | |||
312 | |||
313 | TESTING THE SOFTWARE | ||
314 | ==================== | ||
315 | |||
316 | As a quick test of functionality we've included a small sample image in | ||
317 | several forms: | ||
318 | testorig.jpg Starting point for the djpeg tests. | ||
319 | testimg.ppm The output of djpeg testorig.jpg | ||
320 | testimg.bmp The output of djpeg -bmp -colors 256 testorig.jpg | ||
321 | testimg.jpg The output of cjpeg testimg.ppm | ||
322 | testprog.jpg Progressive-mode equivalent of testorig.jpg. | ||
323 | testimgp.jpg The output of cjpeg -progressive -optimize testimg.ppm | ||
324 | (The first- and second-generation .jpg files aren't identical since the | ||
325 | default compression parameters are lossy.) If you can generate duplicates | ||
326 | of the testimg* files then you probably have working programs. | ||
327 | |||
328 | With most of the makefiles, "make test" will perform the necessary | ||
329 | comparisons. | ||
330 | |||
331 | If you're using a makefile that doesn't provide the test option, run djpeg | ||
332 | and cjpeg by hand and compare the output files to testimg* with whatever | ||
333 | binary file comparison tool you have. The files should be bit-for-bit | ||
334 | identical. | ||
335 | |||
336 | If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then you | ||
337 | need to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t. | ||
338 | Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h. A less likely | ||
339 | configuration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPE | ||
340 | as long should take care of that one. | ||
341 | |||
342 | If the cjpeg test run fails with "Missing Huffman code table entry", it's a | ||
343 | good bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED. Go back to the | ||
344 | configuration step and run ckconfig.c. (This is a good plan for any other | ||
345 | test failure, too.) | ||
346 | |||
347 | If you are using Unix (one-file) command line style on a non-Unix system, | ||
348 | it's a good idea to check that binary I/O through stdin/stdout actually | ||
349 | works. You should get the same results from "djpeg <testorig.jpg >out.ppm" | ||
350 | as from "djpeg -outfile out.ppm testorig.jpg". Note that the makefiles all | ||
351 | use the latter style and therefore do not exercise stdin/stdout! If this | ||
352 | check fails, try recompiling with USE_SETMODE or USE_FDOPEN defined. | ||
353 | If it still doesn't work, better use two-file style. | ||
354 | |||
355 | If you chose a memory manager other than jmemnobs.c, you should test that | ||
356 | temporary-file usage works. Try "djpeg -bmp -colors 256 -max 0 testorig.jpg" | ||
357 | and make sure its output matches testimg.bmp. If you have any really large | ||
358 | images handy, try compressing them with -optimize and/or decompressing with | ||
359 | -colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large. | ||
360 | |||
361 | NOTE: this is far from an exhaustive test of the JPEG software; some modules, | ||
362 | such as 1-pass color quantization, are not exercised at all. It's just a | ||
363 | quick test to give you some confidence that you haven't missed something | ||
364 | major. | ||
365 | |||
366 | |||
367 | INSTALLING THE SOFTWARE | ||
368 | ======================= | ||
369 | |||
370 | Once you're done with the above steps, you can install the software by | ||
371 | copying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom) | ||
372 | to wherever you normally install programs. On Unix systems, you'll also want | ||
373 | to put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1) | ||
374 | in the man-page directory. The pre-fab makefiles don't support this step | ||
375 | since there's such a wide variety of installation procedures on different | ||
376 | systems. | ||
377 | |||
378 | If you generated a Makefile with the "configure" script, you can just say | ||
379 | make install | ||
380 | to install the programs and their man pages into the standard places. | ||
381 | (You'll probably need to be root to do this.) We recommend first saying | ||
382 | make -n install | ||
383 | to see where configure thought the files should go. You may need to edit | ||
384 | the Makefile, particularly if your system's conventions for man page | ||
385 | filenames don't match what configure expects. | ||
386 | |||
387 | If you want to install the IJG library itself, for use in compiling other | ||
388 | programs besides ours, then you need to put the four include files | ||
389 | jpeglib.h jerror.h jconfig.h jmorecfg.h | ||
390 | into your include-file directory, and put the library file libjpeg.a | ||
391 | (extension may vary depending on system) wherever library files go. | ||
392 | If you generated a Makefile with "configure", it will do what it thinks | ||
393 | is the right thing if you say | ||
394 | make install-lib | ||
395 | |||
396 | |||
397 | OPTIONAL STUFF | ||
398 | ============== | ||
399 | |||
400 | Progress monitor: | ||
401 | |||
402 | If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable display | ||
403 | of percent-done progress reports. The routine provided in cdjpeg.c merely | ||
404 | prints percentages to stderr, but you can customize it to do something | ||
405 | fancier. | ||
406 | |||
407 | Utah RLE file format support: | ||
408 | |||
409 | We distribute the software with support for RLE image files (Utah Raster | ||
410 | Toolkit format) disabled, because the RLE support won't compile without the | ||
411 | Utah library. If you have URT version 3.1 or later, you can enable RLE | ||
412 | support as follows: | ||
413 | 1. #define RLE_SUPPORTED in jconfig.h. | ||
414 | 2. Add a -I option to CFLAGS in the Makefile for the directory | ||
415 | containing the URT .h files (typically the "include" | ||
416 | subdirectory of the URT distribution). | ||
417 | 3. Add -L... -lrle to LDLIBS in the Makefile, where ... specifies | ||
418 | the directory containing the URT "librle.a" file (typically the | ||
419 | "lib" subdirectory of the URT distribution). | ||
420 | |||
421 | Support for 12-bit-deep pixel data: | ||
422 | |||
423 | The JPEG standard allows either 8-bit or 12-bit data precision. (For color, | ||
424 | this means 8 or 12 bits per channel, of course.) If you need to work with | ||
425 | deeper than 8-bit data, you can compile the IJG code for 12-bit operation. | ||
426 | To do so: | ||
427 | 1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8. | ||
428 | 2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED, | ||
429 | because the code for those formats doesn't handle 12-bit data and won't | ||
430 | even compile. (The PPM code does work, as explained below. The GIF | ||
431 | code works too; it scales 8-bit GIF data to and from 12-bit depth | ||
432 | automatically.) | ||
433 | 3. Compile. Don't expect "make test" to pass, since the supplied test | ||
434 | files are for 8-bit data. | ||
435 | |||
436 | Currently, 12-bit support does not work on 16-bit-int machines. | ||
437 | |||
438 | Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa; | ||
439 | so you'll want to keep around a regular 8-bit compilation as well. | ||
440 | (Run-time selection of data depth, to allow a single copy that does both, | ||
441 | is possible but would probably slow things down considerably; it's very low | ||
442 | on our to-do list.) | ||
443 | |||
444 | The PPM reader (rdppm.c) can read 12-bit data from either text-format or | ||
445 | binary-format PPM and PGM files. Binary-format PPM/PGM files which have a | ||
446 | maxval greater than 255 are assumed to use 2 bytes per sample, MSB first | ||
447 | (big-endian order). As of early 1995, 2-byte binary format is not | ||
448 | officially supported by the PBMPLUS library, but it is expected that a | ||
449 | future release of PBMPLUS will support it. Note that the PPM reader will | ||
450 | read files of any maxval regardless of the BITS_IN_JSAMPLE setting; incoming | ||
451 | data is automatically rescaled to either maxval=255 or maxval=4095 as | ||
452 | appropriate for the cjpeg bit depth. | ||
453 | |||
454 | The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGM | ||
455 | format, maxval 4095, when compiled with BITS_IN_JSAMPLE=12. Since this | ||
456 | format is not yet widely supported, you can disable it by compiling wrppm.c | ||
457 | with PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make a | ||
458 | standard 1-byte/sample PPM or PGM file. (Yes, this means still another copy | ||
459 | of djpeg to keep around. But hopefully you won't need it for very long. | ||
460 | Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.) | ||
461 | |||
462 | Of course, if you are working with 12-bit data, you probably have it stored | ||
463 | in some other, nonstandard format. In that case you'll probably want to | ||
464 | write your own I/O modules to read and write your format. | ||
465 | |||
466 | Note that a 12-bit version of cjpeg always runs in "-optimize" mode, in | ||
467 | order to generate valid Huffman tables. This is necessary because our | ||
468 | default Huffman tables only cover 8-bit data. | ||
469 | |||
470 | Removing code: | ||
471 | |||
472 | If you need to make a smaller version of the JPEG software, some optional | ||
473 | functions can be removed at compile time. See the xxx_SUPPORTED #defines in | ||
474 | jconfig.h and jmorecfg.h. If at all possible, we recommend that you leave in | ||
475 | decoder support for all valid JPEG files, to ensure that you can read anyone's | ||
476 | output. Taking out support for image file formats that you don't use is the | ||
477 | most painless way to make the programs smaller. Another possibility is to | ||
478 | remove some of the DCT methods: in particular, the "IFAST" method may not be | ||
479 | enough faster than the others to be worth keeping on your machine. (If you | ||
480 | do remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTEST | ||
481 | to a supported method, by adding a #define in jconfig.h.) | ||
482 | |||
483 | |||
484 | OPTIMIZATION | ||
485 | ============ | ||
486 | |||
487 | Unless you own a Cray, you'll probably be interested in making the JPEG | ||
488 | software go as fast as possible. This section covers some machine-dependent | ||
489 | optimizations you may want to try. We suggest that before trying any of | ||
490 | this, you first get the basic installation to pass the self-test step. | ||
491 | Repeat the self-test after any optimization to make sure that you haven't | ||
492 | broken anything. | ||
493 | |||
494 | The integer DCT routines perform a lot of multiplications. These | ||
495 | multiplications must yield 32-bit results, but none of their input values | ||
496 | are more than 16 bits wide. On many machines, notably the 680x0 and 80x86 | ||
497 | CPUs, a 16x16=>32 bit multiply instruction is faster than a full 32x32=>32 | ||
498 | bit multiply. Unfortunately there is no portable way to specify such a | ||
499 | multiplication in C, but some compilers can generate one when you use the | ||
500 | right combination of casts. See the MULTIPLYxxx macro definitions in | ||
501 | jdct.h. If your compiler makes "int" be 32 bits and "short" be 16 bits, | ||
502 | defining SHORTxSHORT_32 is fairly likely to work. When experimenting with | ||
503 | alternate definitions, be sure to test not only whether the code still works | ||
504 | (use the self-test), but also whether it is actually faster --- on some | ||
505 | compilers, alternate definitions may compute the right answer, yet be slower | ||
506 | than the default. Timing cjpeg on a large PGM (grayscale) input file is the | ||
507 | best way to check this, as the DCT will be the largest fraction of the runtime | ||
508 | in that mode. (Note: some of the distributed compiler-specific jconfig files | ||
509 | already contain #define switches to select appropriate MULTIPLYxxx | ||
510 | definitions.) | ||
511 | |||
512 | If your machine has sufficiently fast floating point hardware, you may find | ||
513 | that the float DCT method is faster than the integer DCT methods, even | ||
514 | after tweaking the integer multiply macros. In that case you may want to | ||
515 | make the float DCT be the default method. (The only objection to this is | ||
516 | that float DCT results may vary slightly across machines.) To do that, add | ||
517 | "#define JDCT_DEFAULT JDCT_FLOAT" to jconfig.h. Even if you don't change | ||
518 | the default, you should redefine JDCT_FASTEST, which is the method selected | ||
519 | by djpeg's -fast switch. Don't forget to update the documentation files | ||
520 | (usage.txt and/or cjpeg.1, djpeg.1) to agree with what you've done. | ||
521 | |||
522 | If access to "short" arrays is slow on your machine, it may be a win to | ||
523 | define type JCOEF as int rather than short. This will cost a good deal of | ||
524 | memory though, particularly in some multi-pass modes, so don't do it unless | ||
525 | you have memory to burn and short is REALLY slow. | ||
526 | |||
527 | If your compiler can compile function calls in-line, make sure the INLINE | ||
528 | macro in jmorecfg.h is defined as the keyword that marks a function | ||
529 | inline-able. Some compilers have a switch that tells the compiler to inline | ||
530 | any function it thinks is profitable (e.g., -finline-functions for gcc). | ||
531 | Enabling such a switch is likely to make the compiled code bigger but faster. | ||
532 | |||
533 | In general, it's worth trying the maximum optimization level of your compiler, | ||
534 | and experimenting with any optional optimizations such as loop unrolling. | ||
535 | (Unfortunately, far too many compilers have optimizer bugs ... be prepared to | ||
536 | back off if the code fails self-test.) If you do any experimentation along | ||
537 | these lines, please report the optimal settings to jpeg-info@jpegclub.org so | ||
538 | we can mention them in future releases. Be sure to specify your machine and | ||
539 | compiler version. | ||
540 | |||
541 | |||
542 | HINTS FOR SPECIFIC SYSTEMS | ||
543 | ========================== | ||
544 | |||
545 | We welcome reports on changes needed for systems not mentioned here. Submit | ||
546 | 'em to jpeg-info@jpegclub.org. Also, if configure or ckconfig.c is wrong | ||
547 | about how to configure the JPEG software for your system, please let us know. | ||
548 | |||
549 | |||
550 | Acorn RISC OS: | ||
551 | |||
552 | (Thanks to Simon Middleton for these hints on compiling with Desktop C.) | ||
553 | After renaming the files according to Acorn conventions, take a copy of | ||
554 | makefile.ansi, change all occurrences of 'libjpeg.a' to 'libjpeg.o' and | ||
555 | change these definitions as indicated: | ||
556 | |||
557 | CFLAGS= -throwback -IC: -Wn | ||
558 | LDLIBS=C:o.Stubs | ||
559 | SYSDEPMEM=jmemansi.o | ||
560 | LN=Link | ||
561 | AR=LibFile -c -o | ||
562 | |||
563 | Also add a new line '.c.o:; $(cc) $< $(cflags) -c -o $@'. Remove the | ||
564 | lines '$(RM) libjpeg.o' and '$(AR2) libjpeg.o' and the 'jconfig.h' | ||
565 | dependency section. | ||
566 | |||
567 | Copy jconfig.txt to jconfig.h. Edit jconfig.h to define TWO_FILE_COMMANDLINE | ||
568 | and CHAR_IS_UNSIGNED. | ||
569 | |||
570 | Run the makefile using !AMU not !Make. If you want to use the 'clean' and | ||
571 | 'test' makefile entries then you will have to fiddle with the syntax a bit | ||
572 | and rename the test files. | ||
573 | |||
574 | |||
575 | Amiga: | ||
576 | |||
577 | SAS C 6.50 reportedly is too buggy to compile the IJG code properly. | ||
578 | A patch to update to 6.51 is available from SAS or AmiNet FTP sites. | ||
579 | |||
580 | The supplied config files are set up to use jmemname.c as the memory | ||
581 | manager, with temporary files being created on the device named by | ||
582 | "JPEGTMP:". | ||
583 | |||
584 | |||
585 | Atari ST/STE/TT: | ||
586 | |||
587 | Copy the project files makcjpeg.st, makdjpeg.st, maktjpeg.st, and makljpeg.st | ||
588 | to cjpeg.prj, djpeg.prj, jpegtran.prj, and libjpeg.prj respectively. The | ||
589 | project files should work as-is with Pure C. For Turbo C, change library | ||
590 | filenames "pc..." to "tc..." in each project file. Note that libjpeg.prj | ||
591 | selects jmemansi.c as the recommended memory manager. You'll probably want to | ||
592 | adjust the DEFAULT_MAX_MEM setting --- you want it to be a couple hundred K | ||
593 | less than your normal free memory. Put "#define DEFAULT_MAX_MEM nnnn" into | ||
594 | jconfig.h to do this. | ||
595 | |||
596 | To use the 68881/68882 coprocessor for the floating point DCT, add the | ||
597 | compiler option "-8" to the project files and replace pcfltlib.lib with | ||
598 | pc881lib.lib in cjpeg.prj and djpeg.prj. Or if you don't have a | ||
599 | coprocessor, you may prefer to remove the float DCT code by undefining | ||
600 | DCT_FLOAT_SUPPORTED in jmorecfg.h (since without a coprocessor, the float | ||
601 | code will be too slow to be useful). In that case, you can delete | ||
602 | pcfltlib.lib from the project files. | ||
603 | |||
604 | Note that you must make libjpeg.lib before making cjpeg.ttp, djpeg.ttp, | ||
605 | or jpegtran.ttp. You'll have to perform the self-test by hand. | ||
606 | |||
607 | We haven't bothered to include project files for rdjpgcom and wrjpgcom. | ||
608 | Those source files should just be compiled by themselves; they don't | ||
609 | depend on the JPEG library. You can use the default.prj project file | ||
610 | of the Pure C distribution to make the programs. | ||
611 | |||
612 | There is a bug in some older versions of the Turbo C library which causes the | ||
613 | space used by temporary files created with "tmpfile()" not to be freed after | ||
614 | an abnormal program exit. If you check your disk afterwards, you will find | ||
615 | cluster chains that are allocated but not used by a file. This should not | ||
616 | happen in cjpeg/djpeg/jpegtran, since we enable a signal catcher to explicitly | ||
617 | close temp files before exiting. But if you use the JPEG library with your | ||
618 | own code, be sure to supply a signal catcher, or else use a different | ||
619 | system-dependent memory manager. | ||
620 | |||
621 | |||
622 | Cray: | ||
623 | |||
624 | Should you be so fortunate as to be running JPEG on a Cray YMP, there is a | ||
625 | compiler bug in old versions of Cray's Standard C (prior to 3.1). If you | ||
626 | still have an old compiler, you'll need to insert a line reading | ||
627 | "#pragma novector" just before the loop | ||
628 | for (i = 1; i <= (int) htbl->bits[l]; i++) | ||
629 | huffsize[p++] = (char) l; | ||
630 | in fix_huff_tbl (in V5beta1, line 204 of jchuff.c and line 176 of jdhuff.c). | ||
631 | [This bug may or may not still occur with the current IJG code, but it's | ||
632 | probably a dead issue anyway...] | ||
633 | |||
634 | |||
635 | HP-UX: | ||
636 | |||
637 | If you have HP-UX 7.05 or later with the "software development" C compiler, | ||
638 | you should run the compiler in ANSI mode. If using the configure script, | ||
639 | say | ||
640 | ./configure CC='cc -Aa' | ||
641 | (or -Ae if you prefer). If configuring by hand, use makefile.ansi and add | ||
642 | "-Aa" to the CFLAGS line in the makefile. | ||
643 | |||
644 | If you have a pre-7.05 system, or if you are using the non-ANSI C compiler | ||
645 | delivered with a minimum HP-UX system, then you must use makefile.unix | ||
646 | (and do NOT add -Aa); or just run configure without the CC option. | ||
647 | |||
648 | On HP 9000 series 800 machines, the HP C compiler is buggy in revisions prior | ||
649 | to A.08.07. If you get complaints about "not a typedef name", you'll have to | ||
650 | use makefile.unix, or run configure without the CC option. | ||
651 | |||
652 | |||
653 | Macintosh, generic comments: | ||
654 | |||
655 | The supplied user-interface files (cjpeg.c, djpeg.c, etc) are set up to | ||
656 | provide a Unix-style command line interface. You can use this interface on | ||
657 | the Mac by means of the ccommand() library routine provided by Metrowerks | ||
658 | CodeWarrior or Think C. This is only appropriate for testing the library, | ||
659 | however; to make a user-friendly equivalent of cjpeg/djpeg you'd really want | ||
660 | to develop a Mac-style user interface. There isn't a complete example | ||
661 | available at the moment, but there are some helpful starting points: | ||
662 | 1. Sam Bushell's free "To JPEG" applet provides drag-and-drop conversion to | ||
663 | JPEG under System 7 and later. This only illustrates how to use the | ||
664 | compression half of the library, but it does a very nice job of that part. | ||
665 | The CodeWarrior source code is available from http://www.pobox.com/~jsam. | ||
666 | 2. Jim Brunner prepared a Mac-style user interface for both compression and | ||
667 | decompression. Unfortunately, it hasn't been updated since IJG v4, and | ||
668 | the library's API has changed considerably since then. Still it may be of | ||
669 | some help, particularly as a guide to compiling the IJG code under Think C. | ||
670 | Jim's code is available from the Info-Mac archives, at sumex-aim.stanford.edu | ||
671 | or mirrors thereof; see file /info-mac/dev/src/jpeg-convert-c.hqx. | ||
672 | |||
673 | jmemmac.c is the recommended memory manager back end for Macintosh. It uses | ||
674 | NewPtr/DisposePtr instead of malloc/free, and has a Mac-specific | ||
675 | implementation of jpeg_mem_available(). It also creates temporary files that | ||
676 | follow Mac conventions. (That part of the code relies on System-7-or-later OS | ||
677 | functions. See the comments in jmemmac.c if you need to run it on System 6.) | ||
678 | NOTE that USE_MAC_MEMMGR must be defined in jconfig.h to use jmemmac.c. | ||
679 | |||
680 | You can also use jmemnobs.c, if you don't care about handling images larger | ||
681 | than available memory. If you use any memory manager back end other than | ||
682 | jmemmac.c, we recommend replacing "malloc" and "free" by "NewPtr" and | ||
683 | "DisposePtr", because Mac C libraries often have peculiar implementations of | ||
684 | malloc/free. (For instance, free() may not return the freed space to the | ||
685 | Mac Memory Manager. This is undesirable for the IJG code because jmemmgr.c | ||
686 | already clumps space requests.) | ||
687 | |||
688 | |||
689 | Macintosh, Metrowerks CodeWarrior: | ||
690 | |||
691 | The Unix-command-line-style interface can be used by defining USE_CCOMMAND. | ||
692 | You'll also need to define TWO_FILE_COMMANDLINE to avoid stdin/stdout. | ||
693 | This means that when using the cjpeg/djpeg programs, you'll have to type the | ||
694 | input and output file names in the "Arguments" text-edit box, rather than | ||
695 | using the file radio buttons. (Perhaps USE_FDOPEN or USE_SETMODE would | ||
696 | eliminate the problem, but I haven't heard from anyone who's tried it.) | ||
697 | |||
698 | On 680x0 Macs, Metrowerks defines type "double" as a 10-byte IEEE extended | ||
699 | float. jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power | ||
700 | of 2. Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint. | ||
701 | |||
702 | The supplied configuration file jconfig.mac can be used for your jconfig.h; | ||
703 | it includes all the recommended symbol definitions. If you have AppleScript | ||
704 | installed, you can run the supplied script makeproj.mac to create CodeWarrior | ||
705 | project files for the library and the testbed applications, then build the | ||
706 | library and applications. (Thanks to Dan Sears and Don Agro for this nifty | ||
707 | hack, which saves us from trying to maintain CodeWarrior project files as part | ||
708 | of the IJG distribution...) | ||
709 | |||
710 | |||
711 | Macintosh, Think C: | ||
712 | |||
713 | The documentation in Jim Brunner's "JPEG Convert" source code (see above) | ||
714 | includes detailed build instructions for Think C; it's probably somewhat | ||
715 | out of date for the current release, but may be helpful. | ||
716 | |||
717 | If you want to build the minimal command line version, proceed as follows. | ||
718 | You'll have to prepare project files for the programs; we don't include any | ||
719 | in the distribution since they are not text files. Use the file lists in | ||
720 | any of the supplied makefiles as a guide. Also add the ANSI and Unix C | ||
721 | libraries in a separate segment. You may need to divide the JPEG files into | ||
722 | more than one segment; we recommend dividing compression and decompression | ||
723 | modules. Define USE_CCOMMAND in jconfig.h so that the ccommand() routine is | ||
724 | called. You must also define TWO_FILE_COMMANDLINE because stdin/stdout | ||
725 | don't handle binary data correctly. | ||
726 | |||
727 | On 680x0 Macs, Think C defines type "double" as a 12-byte IEEE extended float. | ||
728 | jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power of 2. | ||
729 | Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint. | ||
730 | |||
731 | jconfig.mac should work as a jconfig.h configuration file for Think C, | ||
732 | but the makeproj.mac AppleScript script is specific to CodeWarrior. Sorry. | ||
733 | |||
734 | |||
735 | MIPS R3000: | ||
736 | |||
737 | MIPS's cc version 1.31 has a rather nasty optimization bug. Don't use -O | ||
738 | if you have that compiler version. (Use "cc -V" to check the version.) | ||
739 | Note that the R3000 chip is found in workstations from DEC and others. | ||
740 | |||
741 | |||
742 | MS-DOS, generic comments for 16-bit compilers: | ||
743 | |||
744 | The IJG code is designed to work well in 80x86 "small" or "medium" memory | ||
745 | models (i.e., data pointers are 16 bits unless explicitly declared "far"; | ||
746 | code pointers can be either size). You may be able to use small model to | ||
747 | compile cjpeg or djpeg by itself, but you will probably have to use medium | ||
748 | model for any larger application. This won't make much difference in | ||
749 | performance. You *will* take a noticeable performance hit if you use a | ||
750 | large-data memory model, and you should avoid "huge" model if at all | ||
751 | possible. Be sure that NEED_FAR_POINTERS is defined in jconfig.h if you use | ||
752 | a small-data memory model; be sure it is NOT defined if you use a large-data | ||
753 | model. (The supplied makefiles and jconfig files for Borland and Microsoft C | ||
754 | compile in medium model and define NEED_FAR_POINTERS.) | ||
755 | |||
756 | The DOS-specific memory manager, jmemdos.c, should be used if possible. | ||
757 | It needs some assembly-code routines which are in jmemdosa.asm; make sure | ||
758 | your makefile assembles that file and includes it in the library. If you | ||
759 | don't have a suitable assembler, you can get pre-assembled object files for | ||
760 | jmemdosa by FTP from ftp.uu.net:/graphics/jpeg/jdosaobj.zip. (DOS-oriented | ||
761 | distributions of the IJG source code often include these object files.) | ||
762 | |||
763 | When using jmemdos.c, jconfig.h must define USE_MSDOS_MEMMGR and must set | ||
764 | MAX_ALLOC_CHUNK to less than 64K (65520L is a typical value). If your | ||
765 | C library's far-heap malloc() can't allocate blocks that large, reduce | ||
766 | MAX_ALLOC_CHUNK to whatever it can handle. | ||
767 | |||
768 | If you can't use jmemdos.c for some reason --- for example, because you | ||
769 | don't have an assembler to assemble jmemdosa.asm --- you'll have to fall | ||
770 | back to jmemansi.c or jmemname.c. You'll probably still need to set | ||
771 | MAX_ALLOC_CHUNK in jconfig.h, because most DOS C libraries won't malloc() | ||
772 | more than 64K at a time. IMPORTANT: if you use jmemansi.c or jmemname.c, | ||
773 | you will have to compile in a large-data memory model in order to get the | ||
774 | right stdio library. Too bad. | ||
775 | |||
776 | wrjpgcom needs to be compiled in large model, because it malloc()s a 64KB | ||
777 | work area to hold the comment text. If your C library's malloc can't | ||
778 | handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c. | ||
779 | |||
780 | Most MS-DOS compilers treat stdin/stdout as text files, so you must use | ||
781 | two-file command line style. But if your compiler has either fdopen() or | ||
782 | setmode(), you can use one-file style if you like. To do this, define | ||
783 | USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode. | ||
784 | (USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.) You | ||
785 | should test that I/O through stdin/stdout produces the same results as I/O | ||
786 | to explicitly named files... the "make test" procedures in the supplied | ||
787 | makefiles do NOT use stdin/stdout. | ||
788 | |||
789 | |||
790 | MS-DOS, generic comments for 32-bit compilers: | ||
791 | |||
792 | None of the above comments about memory models apply if you are using a | ||
793 | 32-bit flat-memory-space environment, such as DJGPP or Watcom C. (And you | ||
794 | should use one if you have it, as performance will be much better than | ||
795 | 8086-compatible code!) For flat-memory-space compilers, do NOT define | ||
796 | NEED_FAR_POINTERS, and do NOT use jmemdos.c. Use jmemnobs.c if the | ||
797 | environment supplies adequate virtual memory, otherwise use jmemansi.c or | ||
798 | jmemname.c. | ||
799 | |||
800 | You'll still need to be careful about binary I/O through stdin/stdout. | ||
801 | See the last paragraph of the previous section. | ||
802 | |||
803 | |||
804 | MS-DOS, Borland C: | ||
805 | |||
806 | Be sure to convert all the source files to DOS text format (CR/LF newlines). | ||
807 | Although Borland C will often work OK with unmodified Unix (LF newlines) | ||
808 | source files, sometimes it will give bogus compile errors. | ||
809 | "Illegal character '#'" is the most common such error. (This is true with | ||
810 | Borland C 3.1, but perhaps is fixed in newer releases.) | ||
811 | |||
812 | If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE. | ||
813 | jconfig.bcc already includes #define USE_SETMODE to make this work. | ||
814 | (fdopen does not work correctly.) | ||
815 | |||
816 | |||
817 | MS-DOS, Microsoft C: | ||
818 | |||
819 | makefile.mc6 works with Microsoft C, DOS Visual C++, etc. It should only | ||
820 | be used if you want to build a 16-bit (small or medium memory model) program. | ||
821 | |||
822 | If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE. | ||
823 | jconfig.mc6 already includes #define USE_SETMODE to make this work. | ||
824 | (fdopen does not work correctly.) | ||
825 | |||
826 | Note that this makefile assumes that the working copy of itself is called | ||
827 | "makefile". If you want to call it something else, say "makefile.mak", | ||
828 | be sure to adjust the dependency line that reads "$(RFILE) : makefile". | ||
829 | Otherwise the make will fail because it doesn't know how to create "makefile". | ||
830 | Worse, some releases of Microsoft's make utilities give an incorrect error | ||
831 | message in this situation. | ||
832 | |||
833 | Old versions of MS C fail with an "out of macro expansion space" error | ||
834 | because they can't cope with the macro TRACEMS8 (defined in jerror.h). | ||
835 | If this happens to you, the easiest solution is to change TRACEMS8 to | ||
836 | expand to nothing. You'll lose the ability to dump out JPEG coefficient | ||
837 | tables with djpeg -debug -debug, but at least you can compile. | ||
838 | |||
839 | Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn | ||
840 | off optimization entirely (remove -O from CFLAGS). 6.00A is better, but it | ||
841 | still generates bad code if you enable loop optimizations (-Ol or -Ox). | ||
842 | |||
843 | MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ... | ||
844 | which is on by default. To work around this bug, compile that one file | ||
845 | with /Oo-. | ||
846 | |||
847 | |||
848 | Microsoft Windows (all versions), generic comments: | ||
849 | |||
850 | Some Windows system include files define typedef boolean as "unsigned char". | ||
851 | The IJG code also defines typedef boolean, but we make it "int" by default. | ||
852 | This doesn't affect the IJG programs because we don't import those Windows | ||
853 | include files. But if you use the JPEG library in your own program, and some | ||
854 | of your program's files import one definition of boolean while some import the | ||
855 | other, you can get all sorts of mysterious problems. A good preventive step | ||
856 | is to make the IJG library use "unsigned char" for boolean. To do that, | ||
857 | add something like this to your jconfig.h file: | ||
858 | /* Define "boolean" as unsigned char, not int, per Windows custom */ | ||
859 | #ifndef __RPCNDR_H__ /* don't conflict if rpcndr.h already read */ | ||
860 | typedef unsigned char boolean; | ||
861 | #endif | ||
862 | #define HAVE_BOOLEAN /* prevent jmorecfg.h from redefining it */ | ||
863 | (This is already in jconfig.vc, by the way.) | ||
864 | |||
865 | windef.h contains the declarations | ||
866 | #define far | ||
867 | #define FAR far | ||
868 | Since jmorecfg.h tries to define FAR as empty, you may get a compiler | ||
869 | warning if you include both jpeglib.h and windef.h (which windows.h | ||
870 | includes). To suppress the warning, you can put "#ifndef FAR"/"#endif" | ||
871 | around the line "#define FAR" in jmorecfg.h. | ||
872 | (Something like this is already in jmorecfg.h, by the way.) | ||
873 | |||
874 | When using the library in a Windows application, you will almost certainly | ||
875 | want to modify or replace the error handler module jerror.c, since our | ||
876 | default error handler does a couple of inappropriate things: | ||
877 | 1. it tries to write error and warning messages on stderr; | ||
878 | 2. in event of a fatal error, it exits by calling exit(). | ||
879 | |||
880 | A simple stopgap solution for problem 1 is to replace the line | ||
881 | fprintf(stderr, "%s\n", buffer); | ||
882 | (in output_message in jerror.c) with | ||
883 | MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR); | ||
884 | It's highly recommended that you at least do that much, since otherwise | ||
885 | error messages will disappear into nowhere. (Beginning with IJG v6b, this | ||
886 | code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in | ||
887 | jconfig.h to enable it.) | ||
888 | |||
889 | The proper solution for problem 2 is to return control to your calling | ||
890 | application after a library error. This can be done with the setjmp/longjmp | ||
891 | technique discussed in libjpeg.txt and illustrated in example.c. (NOTE: | ||
892 | some older Windows C compilers provide versions of setjmp/longjmp that | ||
893 | don't actually work under Windows. You may need to use the Windows system | ||
894 | functions Catch and Throw instead.) | ||
895 | |||
896 | The recommended memory manager under Windows is jmemnobs.c; in other words, | ||
897 | let Windows do any virtual memory management needed. You should NOT use | ||
898 | jmemdos.c nor jmemdosa.asm under Windows. | ||
899 | |||
900 | For Windows 3.1, we recommend compiling in medium or large memory model; | ||
901 | for newer Windows versions, use a 32-bit flat memory model. (See the MS-DOS | ||
902 | sections above for more info about memory models.) In the 16-bit memory | ||
903 | models only, you'll need to put | ||
904 | #define MAX_ALLOC_CHUNK 65520L /* Maximum request to malloc() */ | ||
905 | into jconfig.h to limit allocation chunks to 64Kb. (Without that, you'd | ||
906 | have to use huge memory model, which slows things down unnecessarily.) | ||
907 | jmemnobs.c works without modification in large or flat memory models, but to | ||
908 | use medium model, you need to modify its jpeg_get_large and jpeg_free_large | ||
909 | routines to allocate far memory. In any case, you might like to replace | ||
910 | its calls to malloc and free with direct calls on Windows memory allocation | ||
911 | functions. | ||
912 | |||
913 | You may also want to modify jdatasrc.c and jdatadst.c to use Windows file | ||
914 | operations rather than fread/fwrite. This is only necessary if your C | ||
915 | compiler doesn't provide a competent implementation of C stdio functions. | ||
916 | |||
917 | You might want to tweak the RGB_xxx macros in jmorecfg.h so that the library | ||
918 | will accept or deliver color pixels in BGR sample order, not RGB; BGR order | ||
919 | is usually more convenient under Windows. Note that this change will break | ||
920 | the sample applications cjpeg/djpeg, but the library itself works fine. | ||
921 | |||
922 | |||
923 | Many people want to convert the IJG library into a DLL. This is reasonably | ||
924 | straightforward, but watch out for the following: | ||
925 | |||
926 | 1. Don't try to compile as a DLL in small or medium memory model; use | ||
927 | large model, or even better, 32-bit flat model. Many places in the IJG code | ||
928 | assume the address of a local variable is an ordinary (not FAR) pointer; | ||
929 | that isn't true in a medium-model DLL. | ||
930 | |||
931 | 2. Microsoft C cannot pass file pointers between applications and DLLs. | ||
932 | (See Microsoft Knowledge Base, PSS ID Number Q50336.) So jdatasrc.c and | ||
933 | jdatadst.c don't work if you open a file in your application and then pass | ||
934 | the pointer to the DLL. One workaround is to make jdatasrc.c/jdatadst.c | ||
935 | part of your main application rather than part of the DLL. | ||
936 | |||
937 | 3. You'll probably need to modify the macros GLOBAL() and EXTERN() to | ||
938 | attach suitable linkage keywords to the exported routine names. Similarly, | ||
939 | you'll want to modify METHODDEF() and JMETHOD() to ensure function pointers | ||
940 | are declared in a way that lets application routines be called back through | ||
941 | the function pointers. These macros are in jmorecfg.h. Typical definitions | ||
942 | for a 16-bit DLL are: | ||
943 | #define GLOBAL(type) type _far _pascal _loadds _export | ||
944 | #define EXTERN(type) extern type _far _pascal _loadds | ||
945 | #define METHODDEF(type) static type _far _pascal | ||
946 | #define JMETHOD(type,methodname,arglist) \ | ||
947 | type (_far _pascal *methodname) arglist | ||
948 | For a 32-bit DLL you may want something like | ||
949 | #define GLOBAL(type) __declspec(dllexport) type | ||
950 | #define EXTERN(type) extern __declspec(dllexport) type | ||
951 | Although not all the GLOBAL routines are actually intended to be called by | ||
952 | the application, the performance cost of making them all DLL entry points is | ||
953 | negligible. | ||
954 | |||
955 | The unmodified IJG library presents a very C-specific application interface, | ||
956 | so the resulting DLL is only usable from C or C++ applications. There has | ||
957 | been some talk of writing wrapper code that would present a simpler interface | ||
958 | usable from other languages, such as Visual Basic. This is on our to-do list | ||
959 | but hasn't been very high priority --- any volunteers out there? | ||
960 | |||
961 | |||
962 | Microsoft Windows, Borland C: | ||
963 | |||
964 | The provided jconfig.bcc should work OK in a 32-bit Windows environment, | ||
965 | but you'll need to tweak it in a 16-bit environment (you'd need to define | ||
966 | NEED_FAR_POINTERS and MAX_ALLOC_CHUNK). Beware that makefile.bcc will need | ||
967 | alteration if you want to use it for Windows --- in particular, you should | ||
968 | use jmemnobs.c not jmemdos.c under Windows. | ||
969 | |||
970 | Borland C++ 4.5 fails with an internal compiler error when trying to compile | ||
971 | jdmerge.c in 32-bit mode. If enough people complain, perhaps Borland will fix | ||
972 | it. In the meantime, the simplest known workaround is to add a redundant | ||
973 | definition of the variable range_limit in h2v1_merged_upsample(), at the head | ||
974 | of the block that handles odd image width (about line 268 in v6 jdmerge.c): | ||
975 | /* If image width is odd, do the last output column separately */ | ||
976 | if (cinfo->output_width & 1) { | ||
977 | register JSAMPLE * range_limit = cinfo->sample_range_limit; /* ADD THIS */ | ||
978 | cb = GETJSAMPLE(*inptr1); | ||
979 | Pretty bizarre, especially since the very similar routine h2v2_merged_upsample | ||
980 | doesn't trigger the bug. | ||
981 | Recent reports suggest that this bug does not occur with "bcc32a" (the | ||
982 | Pentium-optimized version of the compiler). | ||
983 | |||
984 | Another report from a user of Borland C 4.5 was that incorrect code (leading | ||
985 | to a color shift in processed images) was produced if any of the following | ||
986 | optimization switch combinations were used: | ||
987 | -Ot -Og | ||
988 | -Ot -Op | ||
989 | -Ot -Om | ||
990 | So try backing off on optimization if you see such a problem. (Are there | ||
991 | several different releases all numbered "4.5"??) | ||
992 | |||
993 | |||
994 | Microsoft Windows, Microsoft Visual C++: | ||
995 | |||
996 | jconfig.vc should work OK with any Microsoft compiler for a 32-bit memory | ||
997 | model. makefile.vc is intended for command-line use. (If you are using | ||
998 | the Developer Studio environment, you may prefer the DevStudio project | ||
999 | files; see below.) | ||
1000 | |||
1001 | IJG JPEG 7 adds extern "C" to jpeglib.h. This avoids the need to put | ||
1002 | extern "C" { ... } around #include "jpeglib.h" in your C++ application. | ||
1003 | You can also force VC++ to treat the library as C++ code by renaming | ||
1004 | all the *.c files to *.cpp (and adjusting the makefile to match). | ||
1005 | In this case you also need to define the symbol DONT_USE_EXTERN_C in | ||
1006 | the configuration to prevent jpeglib.h from using extern "C". | ||
1007 | |||
1008 | |||
1009 | Microsoft Windows, Microsoft Visual C++ 6 Developer Studio: | ||
1010 | |||
1011 | We include makefiles that should work as project files in DevStudio 6.0 or | ||
1012 | later. There is a library makefile that builds the IJG library as a static | ||
1013 | Win32 library, and application makefiles that build the sample applications | ||
1014 | as Win32 console applications. (Even if you only want the library, we | ||
1015 | recommend building the applications so that you can run the self-test.) | ||
1016 | |||
1017 | To use: | ||
1018 | 1. Open the command prompt, change to the main directory and execute the | ||
1019 | command line | ||
1020 | NMAKE /f makefile.vc setup-vc6 | ||
1021 | This will move jconfig.vc to jconfig.h and makefiles to project files. | ||
1022 | (Note that the renaming is critical!) | ||
1023 | 2. Open the workspace file jpeg.dsw, build the library project. | ||
1024 | (If you are using DevStudio more recent than 6.0, you'll probably | ||
1025 | get a message saying that the project files are being updated.) | ||
1026 | 3. Open the workspace file apps.dsw, build the application projects. | ||
1027 | 4. To perform the self-test, execute the command line | ||
1028 | NMAKE /f makefile.vc test-build | ||
1029 | 5. Move the application .exe files from `app`\Release to an | ||
1030 | appropriate location on your path. | ||
1031 | |||
1032 | |||
1033 | Microsoft Windows, Microsoft Visual C++ 2010 Developer Studio (v10): | ||
1034 | |||
1035 | We include makefiles that should work as project files in Visual Studio | ||
1036 | 2010 or later. There is a library makefile that builds the IJG library | ||
1037 | as a static Win32 library, and application makefiles that build the sample | ||
1038 | applications as Win32 console applications. (Even if you only want the | ||
1039 | library, we recommend building the applications so that you can run the | ||
1040 | self-test.) | ||
1041 | |||
1042 | To use: | ||
1043 | 1. Open the command prompt, change to the main directory and execute the | ||
1044 | command line | ||
1045 | NMAKE /f makefile.vc setup-v10 | ||
1046 | This will move jconfig.vc to jconfig.h and makefiles to project files. | ||
1047 | (Note that the renaming is critical!) | ||
1048 | 2. Open the solution file jpeg.sln, build the library project. | ||
1049 | (If you are using Visual Studio more recent than 2010 (v10), you'll | ||
1050 | probably get a message saying that the project files are being updated.) | ||
1051 | 3. Open the solution file apps.sln, build the application projects. | ||
1052 | 4. To perform the self-test, execute the command line | ||
1053 | NMAKE /f makefile.vc test-build | ||
1054 | 5. Move the application .exe files from `app`\Release to an | ||
1055 | appropriate location on your path. | ||
1056 | |||
1057 | Note: | ||
1058 | There seems to be an optimization bug in the compiler which causes the | ||
1059 | self-test to fail with the color quantization option. | ||
1060 | We have disabled optimization for the file jquant2.c in the library | ||
1061 | project file which causes the self-test to pass properly. | ||
1062 | |||
1063 | |||
1064 | OS/2, Borland C++: | ||
1065 | |||
1066 | Watch out for optimization bugs in older Borland compilers; you may need | ||
1067 | to back off the optimization switch settings. See the comments in | ||
1068 | makefile.bcc. | ||
1069 | |||
1070 | |||
1071 | SGI: | ||
1072 | |||
1073 | On some SGI systems, you may need to set "AR2= ar -ts" in the Makefile. | ||
1074 | If you are using configure, you can do this by saying | ||
1075 | ./configure RANLIB='ar -ts' | ||
1076 | This change is not needed on all SGIs. Use it only if the make fails at the | ||
1077 | stage of linking the completed programs. | ||
1078 | |||
1079 | On the MIPS R4000 architecture (Indy, etc.), the compiler option "-mips2" | ||
1080 | reportedly speeds up the float DCT method substantially, enough to make it | ||
1081 | faster than the default int method (but still slower than the fast int | ||
1082 | method). If you use -mips2, you may want to alter the default DCT method to | ||
1083 | be float. To do this, put "#define JDCT_DEFAULT JDCT_FLOAT" in jconfig.h. | ||
1084 | |||
1085 | |||
1086 | VMS: | ||
1087 | |||
1088 | On an Alpha/VMS system with MMS, be sure to use the "/Marco=Alpha=1" | ||
1089 | qualifier with MMS when building the JPEG package. | ||
1090 | |||
1091 | VAX/VMS v5.5-1 may have problems with the test step of the build procedure | ||
1092 | reporting differences when it compares the original and test images. If the | ||
1093 | error points to the last block of the files, it is most likely bogus and may | ||
1094 | be safely ignored. It seems to be because the files are Stream_LF and | ||
1095 | Backup/Compare has difficulty with the (presumably) null padded files. | ||
1096 | This problem was not observed on VAX/VMS v6.1 or AXP/VMS v6.1. | ||