| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * This file is part of the Independent JPEG Group's software. | ||
| 3 | * | ||
| 4 | * The authors make NO WARRANTY or representation, either express or implied, | ||
| 5 | * with respect to this software, its quality, accuracy, merchantability, or | ||
| 6 | * fitness for a particular purpose. This software is provided "AS IS", and | ||
| 7 | * you, its user, assume the entire risk as to its quality and accuracy. | ||
| 8 | * | ||
| 9 | * This software is copyright (C) 1991-1996, Thomas G. Lane. | ||
| 10 | * All Rights Reserved except as specified below. | ||
| 11 | * | ||
| 12 | * Permission is hereby granted to use, copy, modify, and distribute this | ||
| 13 | * software (or portions thereof) for any purpose, without fee, subject to | ||
| 14 | * these conditions: | ||
| 15 | * (1) If any part of the source code for this software is distributed, then | ||
| 16 | * this README file must be included, with this copyright and no-warranty | ||
| 17 | * notice unaltered; and any additions, deletions, or changes to the original | ||
| 18 | * files must be clearly indicated in accompanying documentation. | ||
| 19 | * (2) If only executable code is distributed, then the accompanying | ||
| 20 | * documentation must state that "this software is based in part on the work | ||
| 21 | * of the Independent JPEG Group". | ||
| 22 | * (3) Permission for use of this software is granted only if the user accepts | ||
| 23 | * full responsibility for any undesirable consequences; the authors accept | ||
| 24 | * NO LIABILITY for damages of any kind. | ||
| 25 | * | ||
| 26 | * These conditions apply to any software derived from or based on the IJG | ||
| 27 | * code, not just to the unmodified library. If you use our work, you ought | ||
| 28 | * to acknowledge us. | ||
| 29 | * | ||
| 30 | * Permission is NOT granted for the use of any IJG author's name or company | ||
| 31 | * name in advertising or publicity relating to this software or products | ||
| 32 | * derived from it. This software may be referred to only as "the Independent | ||
| 33 | * JPEG Group's software". | ||
| 34 | * | ||
| 35 | * We specifically permit and encourage the use of this software as the basis | ||
| 36 | * of commercial products, provided that all warranty or liability claims are | ||
| 37 | * assumed by the product vendor. | ||
| 38 | * | ||
| 39 | * This file contains a slow-but-accurate integer implementation of the | ||
| 40 | * forward DCT (Discrete Cosine Transform). | ||
| 41 | * | ||
| 42 | * A 2-D DCT can be done by 1-D DCT on each row followed by 1-D DCT | ||
| 43 | * on each column. Direct algorithms are also available, but they are | ||
| 44 | * much more complex and seem not to be any faster when reduced to code. | ||
| 45 | * | ||
| 46 | * This implementation is based on an algorithm described in | ||
| 47 | * C. Loeffler, A. Ligtenberg and G. Moschytz, "Practical Fast 1-D DCT | ||
| 48 | * Algorithms with 11 Multiplications", Proc. Int'l. Conf. on Acoustics, | ||
| 49 | * Speech, and Signal Processing 1989 (ICASSP '89), pp. 988-991. | ||
| 50 | * The primary algorithm described there uses 11 multiplies and 29 adds. | ||
| 51 | * We use their alternate method with 12 multiplies and 32 adds. | ||
| 52 | * The advantage of this method is that no data path contains more than one | ||
| 53 | * multiplication; this allows a very simple and accurate implementation in | ||
| 54 | * scaled fixed-point arithmetic, with a minimal number of shifts. | ||
| 55 | */ | ||
| 56 | |||
| 57 | /** | ||
| 58 | * @file | ||
| 59 | * Independent JPEG Group's slow & accurate dct. | ||
| 60 | */ | ||
| 61 | |||
| 62 | #include "libavutil/common.h" | ||
| 63 | #include "fdctdsp.h" | ||
| 64 | |||
| 65 | #include "bit_depth_template.c" | ||
| 66 | |||
| 67 | #define DCTSIZE 8 | ||
| 68 | #define BITS_IN_JSAMPLE BIT_DEPTH | ||
| 69 | #define GLOBAL(x) x | ||
| 70 | #define RIGHT_SHIFT(x, n) ((x) >> (n)) | ||
| 71 | #define MULTIPLY16C16(var,const) ((var)*(const)) | ||
| 72 | #define DESCALE(x,n) RIGHT_SHIFT((x) + (1 << ((n) - 1)), n) | ||
| 73 | |||
| 74 | |||
| 75 | /* | ||
| 76 | * This module is specialized to the case DCTSIZE = 8. | ||
| 77 | */ | ||
| 78 | |||
| 79 | #if DCTSIZE != 8 | ||
| 80 | #error "Sorry, this code only copes with 8x8 DCTs." | ||
| 81 | #endif | ||
| 82 | |||
| 83 | |||
| 84 | /* | ||
| 85 | * The poop on this scaling stuff is as follows: | ||
| 86 | * | ||
| 87 | * Each 1-D DCT step produces outputs which are a factor of sqrt(N) | ||
| 88 | * larger than the true DCT outputs. The final outputs are therefore | ||
| 89 | * a factor of N larger than desired; since N=8 this can be cured by | ||
| 90 | * a simple right shift at the end of the algorithm. The advantage of | ||
| 91 | * this arrangement is that we save two multiplications per 1-D DCT, | ||
| 92 | * because the y0 and y4 outputs need not be divided by sqrt(N). | ||
| 93 | * In the IJG code, this factor of 8 is removed by the quantization step | ||
| 94 | * (in jcdctmgr.c), NOT in this module. | ||
| 95 | * | ||
| 96 | * We have to do addition and subtraction of the integer inputs, which | ||
| 97 | * is no problem, and multiplication by fractional constants, which is | ||
| 98 | * a problem to do in integer arithmetic. We multiply all the constants | ||
| 99 | * by CONST_SCALE and convert them to integer constants (thus retaining | ||
| 100 | * CONST_BITS bits of precision in the constants). After doing a | ||
| 101 | * multiplication we have to divide the product by CONST_SCALE, with proper | ||
| 102 | * rounding, to produce the correct output. This division can be done | ||
| 103 | * cheaply as a right shift of CONST_BITS bits. We postpone shifting | ||
| 104 | * as long as possible so that partial sums can be added together with | ||
| 105 | * full fractional precision. | ||
| 106 | * | ||
| 107 | * The outputs of the first pass are scaled up by PASS1_BITS bits so that | ||
| 108 | * they are represented to better-than-integral precision. These outputs | ||
| 109 | * require BITS_IN_JSAMPLE + PASS1_BITS + 3 bits; this fits in a 16-bit word | ||
| 110 | * with the recommended scaling. (For 12-bit sample data, the intermediate | ||
| 111 | * array is int32_t anyway.) | ||
| 112 | * | ||
| 113 | * To avoid overflow of the 32-bit intermediate results in pass 2, we must | ||
| 114 | * have BITS_IN_JSAMPLE + CONST_BITS + PASS1_BITS <= 26. Error analysis | ||
| 115 | * shows that the values given below are the most effective. | ||
| 116 | */ | ||
| 117 | |||
| 118 | #undef CONST_BITS | ||
| 119 | #undef PASS1_BITS | ||
| 120 | #undef OUT_SHIFT | ||
| 121 | |||
| 122 | #if BITS_IN_JSAMPLE == 8 | ||
| 123 | #define CONST_BITS 13 | ||
| 124 | #define PASS1_BITS 4 /* set this to 2 if 16x16 multiplies are faster */ | ||
| 125 | #define OUT_SHIFT PASS1_BITS | ||
| 126 | #else | ||
| 127 | #define CONST_BITS 13 | ||
| 128 | #define PASS1_BITS 1 /* lose a little precision to avoid overflow */ | ||
| 129 | #define OUT_SHIFT (PASS1_BITS + 1) | ||
| 130 | #endif | ||
| 131 | |||
| 132 | /* Some C compilers fail to reduce "FIX(constant)" at compile time, thus | ||
| 133 | * causing a lot of useless floating-point operations at run time. | ||
| 134 | * To get around this we use the following pre-calculated constants. | ||
| 135 | * If you change CONST_BITS you may want to add appropriate values. | ||
| 136 | * (With a reasonable C compiler, you can just rely on the FIX() macro...) | ||
| 137 | */ | ||
| 138 | |||
| 139 | #if CONST_BITS == 13 | ||
| 140 | #define FIX_0_298631336 ((int32_t) 2446) /* FIX(0.298631336) */ | ||
| 141 | #define FIX_0_390180644 ((int32_t) 3196) /* FIX(0.390180644) */ | ||
| 142 | #define FIX_0_541196100 ((int32_t) 4433) /* FIX(0.541196100) */ | ||
| 143 | #define FIX_0_765366865 ((int32_t) 6270) /* FIX(0.765366865) */ | ||
| 144 | #define FIX_0_899976223 ((int32_t) 7373) /* FIX(0.899976223) */ | ||
| 145 | #define FIX_1_175875602 ((int32_t) 9633) /* FIX(1.175875602) */ | ||
| 146 | #define FIX_1_501321110 ((int32_t) 12299) /* FIX(1.501321110) */ | ||
| 147 | #define FIX_1_847759065 ((int32_t) 15137) /* FIX(1.847759065) */ | ||
| 148 | #define FIX_1_961570560 ((int32_t) 16069) /* FIX(1.961570560) */ | ||
| 149 | #define FIX_2_053119869 ((int32_t) 16819) /* FIX(2.053119869) */ | ||
| 150 | #define FIX_2_562915447 ((int32_t) 20995) /* FIX(2.562915447) */ | ||
| 151 | #define FIX_3_072711026 ((int32_t) 25172) /* FIX(3.072711026) */ | ||
| 152 | #else | ||
| 153 | #define FIX_0_298631336 FIX(0.298631336) | ||
| 154 | #define FIX_0_390180644 FIX(0.390180644) | ||
| 155 | #define FIX_0_541196100 FIX(0.541196100) | ||
| 156 | #define FIX_0_765366865 FIX(0.765366865) | ||
| 157 | #define FIX_0_899976223 FIX(0.899976223) | ||
| 158 | #define FIX_1_175875602 FIX(1.175875602) | ||
| 159 | #define FIX_1_501321110 FIX(1.501321110) | ||
| 160 | #define FIX_1_847759065 FIX(1.847759065) | ||
| 161 | #define FIX_1_961570560 FIX(1.961570560) | ||
| 162 | #define FIX_2_053119869 FIX(2.053119869) | ||
| 163 | #define FIX_2_562915447 FIX(2.562915447) | ||
| 164 | #define FIX_3_072711026 FIX(3.072711026) | ||
| 165 | #endif | ||
| 166 | |||
| 167 | |||
| 168 | /* Multiply an int32_t variable by an int32_t constant to yield an int32_t result. | ||
| 169 | * For 8-bit samples with the recommended scaling, all the variable | ||
| 170 | * and constant values involved are no more than 16 bits wide, so a | ||
| 171 | * 16x16->32 bit multiply can be used instead of a full 32x32 multiply. | ||
| 172 | * For 12-bit samples, a full 32-bit multiplication will be needed. | ||
| 173 | */ | ||
| 174 | |||
| 175 | #if BITS_IN_JSAMPLE == 8 && CONST_BITS<=13 && PASS1_BITS<=2 | ||
| 176 | #define MULTIPLY(var,const) MULTIPLY16C16(var,const) | ||
| 177 | #else | ||
| 178 | #define MULTIPLY(var,const) ((var) * (const)) | ||
| 179 | #endif | ||
| 180 | |||
| 181 | |||
| 182 | 54317192 | static av_always_inline void FUNC(row_fdct)(int16_t *data) | |
| 183 | { | ||
| 184 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | ||
| 185 | int tmp10, tmp11, tmp12, tmp13; | ||
| 186 | int z1, z2, z3, z4, z5; | ||
| 187 | int16_t *dataptr; | ||
| 188 | int ctr; | ||
| 189 | |||
| 190 | /* Pass 1: process rows. */ | ||
| 191 | /* Note results are scaled up by sqrt(8) compared to a true DCT; */ | ||
| 192 | /* furthermore, we scale the results by 2**PASS1_BITS. */ | ||
| 193 | |||
| 194 | 54317192 | dataptr = data; | |
| 195 |
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488854728 | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { |
| 196 | 434537536 | tmp0 = dataptr[0] + dataptr[7]; | |
| 197 | 434537536 | tmp7 = dataptr[0] - dataptr[7]; | |
| 198 | 434537536 | tmp1 = dataptr[1] + dataptr[6]; | |
| 199 | 434537536 | tmp6 = dataptr[1] - dataptr[6]; | |
| 200 | 434537536 | tmp2 = dataptr[2] + dataptr[5]; | |
| 201 | 434537536 | tmp5 = dataptr[2] - dataptr[5]; | |
| 202 | 434537536 | tmp3 = dataptr[3] + dataptr[4]; | |
| 203 | 434537536 | tmp4 = dataptr[3] - dataptr[4]; | |
| 204 | |||
| 205 | /* Even part per LL&M figure 1 --- note that published figure is faulty; | ||
| 206 | * rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | ||
| 207 | */ | ||
| 208 | |||
| 209 | 434537536 | tmp10 = tmp0 + tmp3; | |
| 210 | 434537536 | tmp13 = tmp0 - tmp3; | |
| 211 | 434537536 | tmp11 = tmp1 + tmp2; | |
| 212 | 434537536 | tmp12 = tmp1 - tmp2; | |
| 213 | |||
| 214 | 434537536 | dataptr[0] = (int16_t) ((tmp10 + tmp11) * (1 << PASS1_BITS)); | |
| 215 | 434537536 | dataptr[4] = (int16_t) ((tmp10 - tmp11) * (1 << PASS1_BITS)); | |
| 216 | |||
| 217 | 434537536 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
| 218 | 434537536 | dataptr[2] = (int16_t) DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
| 219 | CONST_BITS-PASS1_BITS); | ||
| 220 | 434537536 | dataptr[6] = (int16_t) DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
| 221 | CONST_BITS-PASS1_BITS); | ||
| 222 | |||
| 223 | /* Odd part per figure 8 --- note paper omits factor of sqrt(2). | ||
| 224 | * cK represents cos(K*pi/16). | ||
| 225 | * i0..i3 in the paper are tmp4..tmp7 here. | ||
| 226 | */ | ||
| 227 | |||
| 228 | 434537536 | z1 = tmp4 + tmp7; | |
| 229 | 434537536 | z2 = tmp5 + tmp6; | |
| 230 | 434537536 | z3 = tmp4 + tmp6; | |
| 231 | 434537536 | z4 = tmp5 + tmp7; | |
| 232 | 434537536 | z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |
| 233 | |||
| 234 | 434537536 | tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |
| 235 | 434537536 | tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |
| 236 | 434537536 | tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |
| 237 | 434537536 | tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ | |
| 238 | 434537536 | z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ | |
| 239 | 434537536 | z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ | |
| 240 | 434537536 | z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ | |
| 241 | 434537536 | z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ | |
| 242 | |||
| 243 | 434537536 | z3 += z5; | |
| 244 | 434537536 | z4 += z5; | |
| 245 | |||
| 246 | 434537536 | dataptr[7] = (int16_t) DESCALE(tmp4 + z1 + z3, CONST_BITS-PASS1_BITS); | |
| 247 | 434537536 | dataptr[5] = (int16_t) DESCALE(tmp5 + z2 + z4, CONST_BITS-PASS1_BITS); | |
| 248 | 434537536 | dataptr[3] = (int16_t) DESCALE(tmp6 + z2 + z3, CONST_BITS-PASS1_BITS); | |
| 249 | 434537536 | dataptr[1] = (int16_t) DESCALE(tmp7 + z1 + z4, CONST_BITS-PASS1_BITS); | |
| 250 | |||
| 251 | 434537536 | dataptr += DCTSIZE; /* advance pointer to next row */ | |
| 252 | } | ||
| 253 | 54317192 | } | |
| 254 | |||
| 255 | /* | ||
| 256 | * Perform the forward DCT on one block of samples. | ||
| 257 | */ | ||
| 258 | |||
| 259 | GLOBAL(void) | ||
| 260 | 54317192 | FUNC(ff_jpeg_fdct_islow)(int16_t *data) | |
| 261 | { | ||
| 262 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | ||
| 263 | int tmp10, tmp11, tmp12, tmp13; | ||
| 264 | int z1, z2, z3, z4, z5; | ||
| 265 | int16_t *dataptr; | ||
| 266 | int ctr; | ||
| 267 | |||
| 268 | 54317192 | FUNC(row_fdct)(data); | |
| 269 | |||
| 270 | /* Pass 2: process columns. | ||
| 271 | * We remove the PASS1_BITS scaling, but leave the results scaled up | ||
| 272 | * by an overall factor of 8. | ||
| 273 | */ | ||
| 274 | |||
| 275 | 54317192 | dataptr = data; | |
| 276 |
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488854728 | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { |
| 277 | 434537536 | tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*7]; | |
| 278 | 434537536 | tmp7 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*7]; | |
| 279 | 434537536 | tmp1 = dataptr[DCTSIZE*1] + dataptr[DCTSIZE*6]; | |
| 280 | 434537536 | tmp6 = dataptr[DCTSIZE*1] - dataptr[DCTSIZE*6]; | |
| 281 | 434537536 | tmp2 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*5]; | |
| 282 | 434537536 | tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*5]; | |
| 283 | 434537536 | tmp3 = dataptr[DCTSIZE*3] + dataptr[DCTSIZE*4]; | |
| 284 | 434537536 | tmp4 = dataptr[DCTSIZE*3] - dataptr[DCTSIZE*4]; | |
| 285 | |||
| 286 | /* Even part per LL&M figure 1 --- note that published figure is faulty; | ||
| 287 | * rotator "sqrt(2)*c1" should be "sqrt(2)*c6". | ||
| 288 | */ | ||
| 289 | |||
| 290 | 434537536 | tmp10 = tmp0 + tmp3; | |
| 291 | 434537536 | tmp13 = tmp0 - tmp3; | |
| 292 | 434537536 | tmp11 = tmp1 + tmp2; | |
| 293 | 434537536 | tmp12 = tmp1 - tmp2; | |
| 294 | |||
| 295 | 434537536 | dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
| 296 | 434537536 | dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
| 297 | |||
| 298 | 434537536 | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
| 299 | 434537536 | dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
| 300 | CONST_BITS + OUT_SHIFT); | ||
| 301 | 434537536 | dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
| 302 | CONST_BITS + OUT_SHIFT); | ||
| 303 | |||
| 304 | /* Odd part per figure 8 --- note paper omits factor of sqrt(2). | ||
| 305 | * cK represents cos(K*pi/16). | ||
| 306 | * i0..i3 in the paper are tmp4..tmp7 here. | ||
| 307 | */ | ||
| 308 | |||
| 309 | 434537536 | z1 = tmp4 + tmp7; | |
| 310 | 434537536 | z2 = tmp5 + tmp6; | |
| 311 | 434537536 | z3 = tmp4 + tmp6; | |
| 312 | 434537536 | z4 = tmp5 + tmp7; | |
| 313 | 434537536 | z5 = MULTIPLY(z3 + z4, FIX_1_175875602); /* sqrt(2) * c3 */ | |
| 314 | |||
| 315 | 434537536 | tmp4 = MULTIPLY(tmp4, FIX_0_298631336); /* sqrt(2) * (-c1+c3+c5-c7) */ | |
| 316 | 434537536 | tmp5 = MULTIPLY(tmp5, FIX_2_053119869); /* sqrt(2) * ( c1+c3-c5+c7) */ | |
| 317 | 434537536 | tmp6 = MULTIPLY(tmp6, FIX_3_072711026); /* sqrt(2) * ( c1+c3+c5-c7) */ | |
| 318 | 434537536 | tmp7 = MULTIPLY(tmp7, FIX_1_501321110); /* sqrt(2) * ( c1+c3-c5-c7) */ | |
| 319 | 434537536 | z1 = MULTIPLY(z1, - FIX_0_899976223); /* sqrt(2) * (c7-c3) */ | |
| 320 | 434537536 | z2 = MULTIPLY(z2, - FIX_2_562915447); /* sqrt(2) * (-c1-c3) */ | |
| 321 | 434537536 | z3 = MULTIPLY(z3, - FIX_1_961570560); /* sqrt(2) * (-c3-c5) */ | |
| 322 | 434537536 | z4 = MULTIPLY(z4, - FIX_0_390180644); /* sqrt(2) * (c5-c3) */ | |
| 323 | |||
| 324 | 434537536 | z3 += z5; | |
| 325 | 434537536 | z4 += z5; | |
| 326 | |||
| 327 | 434537536 | dataptr[DCTSIZE*7] = DESCALE(tmp4 + z1 + z3, CONST_BITS + OUT_SHIFT); | |
| 328 | 434537536 | dataptr[DCTSIZE*5] = DESCALE(tmp5 + z2 + z4, CONST_BITS + OUT_SHIFT); | |
| 329 | 434537536 | dataptr[DCTSIZE*3] = DESCALE(tmp6 + z2 + z3, CONST_BITS + OUT_SHIFT); | |
| 330 | 434537536 | dataptr[DCTSIZE*1] = DESCALE(tmp7 + z1 + z4, CONST_BITS + OUT_SHIFT); | |
| 331 | |||
| 332 | 434537536 | dataptr++; /* advance pointer to next column */ | |
| 333 | } | ||
| 334 | 54317192 | } | |
| 335 | |||
| 336 | /* | ||
| 337 | * The secret of DCT2-4-8 is really simple -- you do the usual 1-DCT | ||
| 338 | * on the rows and then, instead of doing even and odd, part on the columns | ||
| 339 | * you do even part two times. | ||
| 340 | */ | ||
| 341 | GLOBAL(void) | ||
| 342 | ✗ | FUNC(ff_fdct248_islow)(int16_t *data) | |
| 343 | { | ||
| 344 | int tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; | ||
| 345 | int tmp10, tmp11, tmp12, tmp13; | ||
| 346 | int z1; | ||
| 347 | int16_t *dataptr; | ||
| 348 | int ctr; | ||
| 349 | |||
| 350 | ✗ | FUNC(row_fdct)(data); | |
| 351 | |||
| 352 | /* Pass 2: process columns. | ||
| 353 | * We remove the PASS1_BITS scaling, but leave the results scaled up | ||
| 354 | * by an overall factor of 8. | ||
| 355 | */ | ||
| 356 | |||
| 357 | ✗ | dataptr = data; | |
| 358 | ✗ | for (ctr = DCTSIZE-1; ctr >= 0; ctr--) { | |
| 359 | ✗ | tmp0 = dataptr[DCTSIZE*0] + dataptr[DCTSIZE*1]; | |
| 360 | ✗ | tmp1 = dataptr[DCTSIZE*2] + dataptr[DCTSIZE*3]; | |
| 361 | ✗ | tmp2 = dataptr[DCTSIZE*4] + dataptr[DCTSIZE*5]; | |
| 362 | ✗ | tmp3 = dataptr[DCTSIZE*6] + dataptr[DCTSIZE*7]; | |
| 363 | ✗ | tmp4 = dataptr[DCTSIZE*0] - dataptr[DCTSIZE*1]; | |
| 364 | ✗ | tmp5 = dataptr[DCTSIZE*2] - dataptr[DCTSIZE*3]; | |
| 365 | ✗ | tmp6 = dataptr[DCTSIZE*4] - dataptr[DCTSIZE*5]; | |
| 366 | ✗ | tmp7 = dataptr[DCTSIZE*6] - dataptr[DCTSIZE*7]; | |
| 367 | |||
| 368 | ✗ | tmp10 = tmp0 + tmp3; | |
| 369 | ✗ | tmp11 = tmp1 + tmp2; | |
| 370 | ✗ | tmp12 = tmp1 - tmp2; | |
| 371 | ✗ | tmp13 = tmp0 - tmp3; | |
| 372 | |||
| 373 | ✗ | dataptr[DCTSIZE*0] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
| 374 | ✗ | dataptr[DCTSIZE*4] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
| 375 | |||
| 376 | ✗ | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
| 377 | ✗ | dataptr[DCTSIZE*2] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
| 378 | CONST_BITS+OUT_SHIFT); | ||
| 379 | ✗ | dataptr[DCTSIZE*6] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
| 380 | CONST_BITS+OUT_SHIFT); | ||
| 381 | |||
| 382 | ✗ | tmp10 = tmp4 + tmp7; | |
| 383 | ✗ | tmp11 = tmp5 + tmp6; | |
| 384 | ✗ | tmp12 = tmp5 - tmp6; | |
| 385 | ✗ | tmp13 = tmp4 - tmp7; | |
| 386 | |||
| 387 | ✗ | dataptr[DCTSIZE*1] = DESCALE(tmp10 + tmp11, OUT_SHIFT); | |
| 388 | ✗ | dataptr[DCTSIZE*5] = DESCALE(tmp10 - tmp11, OUT_SHIFT); | |
| 389 | |||
| 390 | ✗ | z1 = MULTIPLY(tmp12 + tmp13, FIX_0_541196100); | |
| 391 | ✗ | dataptr[DCTSIZE*3] = DESCALE(z1 + MULTIPLY(tmp13, FIX_0_765366865), | |
| 392 | CONST_BITS + OUT_SHIFT); | ||
| 393 | ✗ | dataptr[DCTSIZE*7] = DESCALE(z1 + MULTIPLY(tmp12, - FIX_1_847759065), | |
| 394 | CONST_BITS + OUT_SHIFT); | ||
| 395 | |||
| 396 | ✗ | dataptr++; /* advance pointer to next column */ | |
| 397 | } | ||
| 398 | ✗ | } | |
| 399 |