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Diffstat (limited to 'libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctfst.c')
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diff --git a/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctfst.c b/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctfst.c deleted file mode 100644 index dba4216..0000000 --- a/libraries/irrlicht-1.8/source/Irrlicht/jpeglib/jidctfst.c +++ /dev/null | |||
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1 | /* | ||
2 | * jidctfst.c | ||
3 | * | ||
4 | * Copyright (C) 1994-1998, Thomas G. Lane. | ||
5 | * This file is part of the Independent JPEG Group's software. | ||
6 | * For conditions of distribution and use, see the accompanying README file. | ||
7 | * | ||
8 | * This file contains a fast, not so accurate integer implementation of the | ||
9 | * inverse DCT (Discrete Cosine Transform). In the IJG code, this routine | ||
10 | * must also perform dequantization of the input coefficients. | ||
11 | * | ||
12 | * A 2-D IDCT can be done by 1-D IDCT on each column followed by 1-D IDCT | ||
13 | * on each row (or vice versa, but it's more convenient to emit a row at | ||
14 | * a time). Direct algorithms are also available, but they are much more | ||
15 | * complex and seem not to be any faster when reduced to code. | ||
16 | * | ||
17 | * This implementation is based on Arai, Agui, and Nakajima's algorithm for | ||
18 | * scaled DCT. Their original paper (Trans. IEICE E-71(11):1095) is in | ||
19 | * Japanese, but the algorithm is described in the Pennebaker & Mitchell | ||
20 | * JPEG textbook (see REFERENCES section in file README). The following code | ||
21 | * is based directly on figure 4-8 in P&M. | ||
22 | * While an 8-point DCT cannot be done in less than 11 multiplies, it is | ||
23 | * possible to arrange the computation so that many of the multiplies are | ||
24 | * simple scalings of the final outputs. These multiplies can then be | ||
25 | * folded into the multiplications or divisions by the JPEG quantization | ||
26 | * table entries. The AA&N method leaves only 5 multiplies and 29 adds | ||
27 | * to be done in the DCT itself. | ||
28 | * The primary disadvantage of this method is that with fixed-point math, | ||
29 | * accuracy is lost due to imprecise representation of the scaled | ||
30 | * quantization values. The smaller the quantization table entry, the less | ||
31 | * precise the scaled value, so this implementation does worse with high- | ||
32 | * quality-setting files than with low-quality ones. | ||
33 | */ | ||
34 | |||
35 | #define JPEG_INTERNALS | ||
36 | #include "jinclude.h" | ||
37 | #include "jpeglib.h" | ||
38 | #include "jdct.h" /* Private declarations for DCT subsystem */ | ||
39 | |||
40 | #ifdef DCT_IFAST_SUPPORTED | ||
41 | |||
42 | |||
43 | /* | ||
44 | * This module is specialized to the case DCTSIZE = 8. | ||
45 | */ | ||
46 | |||
47 | #if DCTSIZE != 8 | ||
48 | Sorry, this code only copes with 8x8 DCTs. /* deliberate syntax err */ | ||
49 | #endif | ||
50 | |||
51 | |||
52 | /* Scaling decisions are generally the same as in the LL&M algorithm; | ||
53 | * see jidctint.c for more details. However, we choose to descale | ||
54 | * (right shift) multiplication products as soon as they are formed, | ||
55 | * rather than carrying additional fractional bits into subsequent additions. | ||
56 | * This compromises accuracy slightly, but it lets us save a few shifts. | ||
57 | * More importantly, 16-bit arithmetic is then adequate (for 8-bit samples) | ||
58 | * everywhere except in the multiplications proper; this saves a good deal | ||
59 | * of work on 16-bit-int machines. | ||
60 | * | ||
61 | * The dequantized coefficients are not integers because the AA&N scaling | ||
62 | * factors have been incorporated. We represent them scaled up by PASS1_BITS, | ||
63 | * so that the first and second IDCT rounds have the same input scaling. | ||
64 | * For 8-bit JSAMPLEs, we choose IFAST_SCALE_BITS = PASS1_BITS so as to | ||
65 | * avoid a descaling shift; this compromises accuracy rather drastically | ||
66 | * for small quantization table entries, but it saves a lot of shifts. | ||
67 | * For 12-bit JSAMPLEs, there's no hope of using 16x16 multiplies anyway, | ||
68 | * so we use a much larger scaling factor to preserve accuracy. | ||
69 | * | ||
70 | * A final compromise is to represent the multiplicative constants to only | ||
71 | * 8 fractional bits, rather than 13. This saves some shifting work on some | ||
72 | * machines, and may also reduce the cost of multiplication (since there | ||
73 | * are fewer one-bits in the constants). | ||
74 | */ | ||
75 | |||
76 | #if BITS_IN_JSAMPLE == 8 | ||
77 | #define CONST_BITS 8 | ||
78 | #define PASS1_BITS 2 | ||
79 | #else | ||
80 | #define CONST_BITS 8 | ||
81 | #define PASS1_BITS 1 /* lose a little precision to avoid overflow */ | ||
82 | #endif | ||
83 | |||
84 | /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus | ||
85 | * causing a lot of useless floating-point operations at run time. | ||
86 | * To get around this we use the following pre-calculated constants. | ||
87 | * If you change CONST_BITS you may want to add appropriate values. | ||
88 | * (With a reasonable C compiler, you can just rely on the FIX() macro...) | ||
89 | */ | ||
90 | |||
91 | #if CONST_BITS == 8 | ||
92 | #define FIX_1_082392200 ((INT32) 277) /* FIX(1.082392200) */ | ||
93 | #define FIX_1_414213562 ((INT32) 362) /* FIX(1.414213562) */ | ||
94 | #define FIX_1_847759065 ((INT32) 473) /* FIX(1.847759065) */ | ||
95 | #define FIX_2_613125930 ((INT32) 669) /* FIX(2.613125930) */ | ||
96 | #else | ||
97 | #define FIX_1_082392200 FIX(1.082392200) | ||
98 | #define FIX_1_414213562 FIX(1.414213562) | ||
99 | #define FIX_1_847759065 FIX(1.847759065) | ||
100 | #define FIX_2_613125930 FIX(2.613125930) | ||
101 | #endif | ||
102 | |||
103 | |||
104 | /* We can gain a little more speed, with a further compromise in accuracy, | ||
105 | * by omitting the addition in a descaling shift. This yields an incorrectly | ||
106 | * rounded result half the time... | ||
107 | */ | ||
108 | |||
109 | #ifndef USE_ACCURATE_ROUNDING | ||
110 | #undef DESCALE | ||
111 | #define DESCALE(x,n) RIGHT_SHIFT(x, n) | ||
112 | #endif | ||
113 | |||
114 | |||
115 | /* Multiply a DCTELEM variable by an INT32 constant, and immediately | ||
116 | * descale to yield a DCTELEM result. | ||
117 | */ | ||
118 | |||
119 | #define MULTIPLY(var,const) ((DCTELEM) DESCALE((var) * (const), CONST_BITS)) | ||
120 | |||
121 | |||
122 | /* Dequantize a coefficient by multiplying it by the multiplier-table | ||
123 | * entry; produce a DCTELEM result. For 8-bit data a 16x16->16 | ||
124 | * multiplication will do. For 12-bit data, the multiplier table is | ||
125 | * declared INT32, so a 32-bit multiply will be used. | ||
126 | */ | ||
127 | |||
128 | #if BITS_IN_JSAMPLE == 8 | ||
129 | #define DEQUANTIZE(coef,quantval) (((IFAST_MULT_TYPE) (coef)) * (quantval)) | ||
130 | #else | ||
131 | #define DEQUANTIZE(coef,quantval) \ | ||
132 | DESCALE((coef)*(quantval), IFAST_SCALE_BITS-PASS1_BITS) | ||
133 | #endif | ||
134 | |||
135 | |||
136 | /* Like DESCALE, but applies to a DCTELEM and produces an int. | ||
137 | * We assume that int right shift is unsigned if INT32 right shift is. | ||
138 | */ | ||
139 | |||
140 | #ifdef RIGHT_SHIFT_IS_UNSIGNED | ||
141 | #define ISHIFT_TEMPS DCTELEM ishift_temp; | ||
142 | #if BITS_IN_JSAMPLE == 8 | ||
143 | #define DCTELEMBITS 16 /* DCTELEM may be 16 or 32 bits */ | ||
144 | #else | ||
145 | #define DCTELEMBITS 32 /* DCTELEM must be 32 bits */ | ||
146 | #endif | ||
147 | #define IRIGHT_SHIFT(x,shft) \ | ||
148 | ((ishift_temp = (x)) < 0 ? \ | ||
149 | (ishift_temp >> (shft)) | ((~((DCTELEM) 0)) << (DCTELEMBITS-(shft))) : \ | ||
150 | (ishift_temp >> (shft))) | ||
151 | #else | ||
152 | #define ISHIFT_TEMPS | ||
153 | #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) | ||
154 | #endif | ||
155 | |||
156 | #ifdef USE_ACCURATE_ROUNDING | ||
157 | #define IDESCALE(x,n) ((int) IRIGHT_SHIFT((x) + (1 << ((n)-1)), n)) | ||
158 | #else | ||
159 | #define IDESCALE(x,n) ((int) IRIGHT_SHIFT(x, n)) | ||
160 | #endif | ||
161 | |||
162 | |||
163 | /* | ||
164 | * Perform dequantization and inverse DCT on one block of coefficients. | ||
165 | */ | ||
166 | |||
167 | GLOBAL(void) | ||
168 | jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info * compptr, | ||
169 | JCOEFPTR coef_block, | ||
170 | JSAMPARRAY output_buf, JDIMENSION output_col) | ||
171 | { | ||
172 | DCTELEM tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | ||
173 | DCTELEM tmp10, tmp11, tmp12, tmp13; | ||
174 | DCTELEM z5, z10, z11, z12, z13; | ||
175 | JCOEFPTR inptr; | ||
176 | IFAST_MULT_TYPE * quantptr; | ||
177 | int * wsptr; | ||
178 | JSAMPROW outptr; | ||
179 | JSAMPLE *range_limit = IDCT_range_limit(cinfo); | ||
180 | int ctr; | ||
181 | int workspace[DCTSIZE2]; /* buffers data between passes */ | ||
182 | SHIFT_TEMPS /* for DESCALE */ | ||
183 | ISHIFT_TEMPS /* for IDESCALE */ | ||
184 | |||
185 | /* Pass 1: process columns from input, store into work array. */ | ||
186 | |||
187 | inptr = coef_block; | ||
188 | quantptr = (IFAST_MULT_TYPE *) compptr->dct_table; | ||
189 | wsptr = workspace; | ||
190 | for (ctr = DCTSIZE; ctr > 0; ctr--) { | ||
191 | /* Due to quantization, we will usually find that many of the input | ||
192 | * coefficients are zero, especially the AC terms. We can exploit this | ||
193 | * by short-circuiting the IDCT calculation for any column in which all | ||
194 | * the AC terms are zero. In that case each output is equal to the | ||
195 | * DC coefficient (with scale factor as needed). | ||
196 | * With typical images and quantization tables, half or more of the | ||
197 | * column DCT calculations can be simplified this way. | ||
198 | */ | ||
199 | |||
200 | if (inptr[DCTSIZE*1] == 0 && inptr[DCTSIZE*2] == 0 && | ||
201 | inptr[DCTSIZE*3] == 0 && inptr[DCTSIZE*4] == 0 && | ||
202 | inptr[DCTSIZE*5] == 0 && inptr[DCTSIZE*6] == 0 && | ||
203 | inptr[DCTSIZE*7] == 0) { | ||
204 | /* AC terms all zero */ | ||
205 | int dcval = (int) DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); | ||
206 | |||
207 | wsptr[DCTSIZE*0] = dcval; | ||
208 | wsptr[DCTSIZE*1] = dcval; | ||
209 | wsptr[DCTSIZE*2] = dcval; | ||
210 | wsptr[DCTSIZE*3] = dcval; | ||
211 | wsptr[DCTSIZE*4] = dcval; | ||
212 | wsptr[DCTSIZE*5] = dcval; | ||
213 | wsptr[DCTSIZE*6] = dcval; | ||
214 | wsptr[DCTSIZE*7] = dcval; | ||
215 | |||
216 | inptr++; /* advance pointers to next column */ | ||
217 | quantptr++; | ||
218 | wsptr++; | ||
219 | continue; | ||
220 | } | ||
221 | |||
222 | /* Even part */ | ||
223 | |||
224 | tmp0 = DEQUANTIZE(inptr[DCTSIZE*0], quantptr[DCTSIZE*0]); | ||
225 | tmp1 = DEQUANTIZE(inptr[DCTSIZE*2], quantptr[DCTSIZE*2]); | ||
226 | tmp2 = DEQUANTIZE(inptr[DCTSIZE*4], quantptr[DCTSIZE*4]); | ||
227 | tmp3 = DEQUANTIZE(inptr[DCTSIZE*6], quantptr[DCTSIZE*6]); | ||
228 | |||
229 | tmp10 = tmp0 + tmp2; /* phase 3 */ | ||
230 | tmp11 = tmp0 - tmp2; | ||
231 | |||
232 | tmp13 = tmp1 + tmp3; /* phases 5-3 */ | ||
233 | tmp12 = MULTIPLY(tmp1 - tmp3, FIX_1_414213562) - tmp13; /* 2*c4 */ | ||
234 | |||
235 | tmp0 = tmp10 + tmp13; /* phase 2 */ | ||
236 | tmp3 = tmp10 - tmp13; | ||
237 | tmp1 = tmp11 + tmp12; | ||
238 | tmp2 = tmp11 - tmp12; | ||
239 | |||
240 | /* Odd part */ | ||
241 | |||
242 | tmp4 = DEQUANTIZE(inptr[DCTSIZE*1], quantptr[DCTSIZE*1]); | ||
243 | tmp5 = DEQUANTIZE(inptr[DCTSIZE*3], quantptr[DCTSIZE*3]); | ||
244 | tmp6 = DEQUANTIZE(inptr[DCTSIZE*5], quantptr[DCTSIZE*5]); | ||
245 | tmp7 = DEQUANTIZE(inptr[DCTSIZE*7], quantptr[DCTSIZE*7]); | ||
246 | |||
247 | z13 = tmp6 + tmp5; /* phase 6 */ | ||
248 | z10 = tmp6 - tmp5; | ||
249 | z11 = tmp4 + tmp7; | ||
250 | z12 = tmp4 - tmp7; | ||
251 | |||
252 | tmp7 = z11 + z13; /* phase 5 */ | ||
253 | tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); /* 2*c4 */ | ||
254 | |||
255 | z5 = MULTIPLY(z10 + z12, FIX_1_847759065); /* 2*c2 */ | ||
256 | tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; /* 2*(c2-c6) */ | ||
257 | tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; /* -2*(c2+c6) */ | ||
258 | |||
259 | tmp6 = tmp12 - tmp7; /* phase 2 */ | ||
260 | tmp5 = tmp11 - tmp6; | ||
261 | tmp4 = tmp10 + tmp5; | ||
262 | |||
263 | wsptr[DCTSIZE*0] = (int) (tmp0 + tmp7); | ||
264 | wsptr[DCTSIZE*7] = (int) (tmp0 - tmp7); | ||
265 | wsptr[DCTSIZE*1] = (int) (tmp1 + tmp6); | ||
266 | wsptr[DCTSIZE*6] = (int) (tmp1 - tmp6); | ||
267 | wsptr[DCTSIZE*2] = (int) (tmp2 + tmp5); | ||
268 | wsptr[DCTSIZE*5] = (int) (tmp2 - tmp5); | ||
269 | wsptr[DCTSIZE*4] = (int) (tmp3 + tmp4); | ||
270 | wsptr[DCTSIZE*3] = (int) (tmp3 - tmp4); | ||
271 | |||
272 | inptr++; /* advance pointers to next column */ | ||
273 | quantptr++; | ||
274 | wsptr++; | ||
275 | } | ||
276 | |||
277 | /* Pass 2: process rows from work array, store into output array. */ | ||
278 | /* Note that we must descale the results by a factor of 8 == 2**3, */ | ||
279 | /* and also undo the PASS1_BITS scaling. */ | ||
280 | |||
281 | wsptr = workspace; | ||
282 | for (ctr = 0; ctr < DCTSIZE; ctr++) { | ||
283 | outptr = output_buf[ctr] + output_col; | ||
284 | /* Rows of zeroes can be exploited in the same way as we did with columns. | ||
285 | * However, the column calculation has created many nonzero AC terms, so | ||
286 | * the simplification applies less often (typically 5% to 10% of the time). | ||
287 | * On machines with very fast multiplication, it's possible that the | ||
288 | * test takes more time than it's worth. In that case this section | ||
289 | * may be commented out. | ||
290 | */ | ||
291 | |||
292 | #ifndef NO_ZERO_ROW_TEST | ||
293 | if (wsptr[1] == 0 && wsptr[2] == 0 && wsptr[3] == 0 && wsptr[4] == 0 && | ||
294 | wsptr[5] == 0 && wsptr[6] == 0 && wsptr[7] == 0) { | ||
295 | /* AC terms all zero */ | ||
296 | JSAMPLE dcval = range_limit[IDESCALE(wsptr[0], PASS1_BITS+3) | ||
297 | & RANGE_MASK]; | ||
298 | |||
299 | outptr[0] = dcval; | ||
300 | outptr[1] = dcval; | ||
301 | outptr[2] = dcval; | ||
302 | outptr[3] = dcval; | ||
303 | outptr[4] = dcval; | ||
304 | outptr[5] = dcval; | ||
305 | outptr[6] = dcval; | ||
306 | outptr[7] = dcval; | ||
307 | |||
308 | wsptr += DCTSIZE; /* advance pointer to next row */ | ||
309 | continue; | ||
310 | } | ||
311 | #endif | ||
312 | |||
313 | /* Even part */ | ||
314 | |||
315 | tmp10 = ((DCTELEM) wsptr[0] + (DCTELEM) wsptr[4]); | ||
316 | tmp11 = ((DCTELEM) wsptr[0] - (DCTELEM) wsptr[4]); | ||
317 | |||
318 | tmp13 = ((DCTELEM) wsptr[2] + (DCTELEM) wsptr[6]); | ||
319 | tmp12 = MULTIPLY((DCTELEM) wsptr[2] - (DCTELEM) wsptr[6], FIX_1_414213562) | ||
320 | - tmp13; | ||
321 | |||
322 | tmp0 = tmp10 + tmp13; | ||
323 | tmp3 = tmp10 - tmp13; | ||
324 | tmp1 = tmp11 + tmp12; | ||
325 | tmp2 = tmp11 - tmp12; | ||
326 | |||
327 | /* Odd part */ | ||
328 | |||
329 | z13 = (DCTELEM) wsptr[5] + (DCTELEM) wsptr[3]; | ||
330 | z10 = (DCTELEM) wsptr[5] - (DCTELEM) wsptr[3]; | ||
331 | z11 = (DCTELEM) wsptr[1] + (DCTELEM) wsptr[7]; | ||
332 | z12 = (DCTELEM) wsptr[1] - (DCTELEM) wsptr[7]; | ||
333 | |||
334 | tmp7 = z11 + z13; /* phase 5 */ | ||
335 | tmp11 = MULTIPLY(z11 - z13, FIX_1_414213562); /* 2*c4 */ | ||
336 | |||
337 | z5 = MULTIPLY(z10 + z12, FIX_1_847759065); /* 2*c2 */ | ||
338 | tmp10 = MULTIPLY(z12, FIX_1_082392200) - z5; /* 2*(c2-c6) */ | ||
339 | tmp12 = MULTIPLY(z10, - FIX_2_613125930) + z5; /* -2*(c2+c6) */ | ||
340 | |||
341 | tmp6 = tmp12 - tmp7; /* phase 2 */ | ||
342 | tmp5 = tmp11 - tmp6; | ||
343 | tmp4 = tmp10 + tmp5; | ||
344 | |||
345 | /* Final output stage: scale down by a factor of 8 and range-limit */ | ||
346 | |||
347 | outptr[0] = range_limit[IDESCALE(tmp0 + tmp7, PASS1_BITS+3) | ||
348 | & RANGE_MASK]; | ||
349 | outptr[7] = range_limit[IDESCALE(tmp0 - tmp7, PASS1_BITS+3) | ||
350 | & RANGE_MASK]; | ||
351 | outptr[1] = range_limit[IDESCALE(tmp1 + tmp6, PASS1_BITS+3) | ||
352 | & RANGE_MASK]; | ||
353 | outptr[6] = range_limit[IDESCALE(tmp1 - tmp6, PASS1_BITS+3) | ||
354 | & RANGE_MASK]; | ||
355 | outptr[2] = range_limit[IDESCALE(tmp2 + tmp5, PASS1_BITS+3) | ||
356 | & RANGE_MASK]; | ||
357 | outptr[5] = range_limit[IDESCALE(tmp2 - tmp5, PASS1_BITS+3) | ||
358 | & RANGE_MASK]; | ||
359 | outptr[4] = range_limit[IDESCALE(tmp3 + tmp4, PASS1_BITS+3) | ||
360 | & RANGE_MASK]; | ||
361 | outptr[3] = range_limit[IDESCALE(tmp3 - tmp4, PASS1_BITS+3) | ||
362 | & RANGE_MASK]; | ||
363 | |||
364 | wsptr += DCTSIZE; /* advance pointer to next row */ | ||
365 | } | ||
366 | } | ||
367 | |||
368 | #endif /* DCT_IFAST_SUPPORTED */ | ||