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| 1 /* | |
| 2 * jcdctmgr.c | |
| 3 * | |
| 4 * Copyright (C) 1994-1996, 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 the forward-DCT management logic. | |
| 9 * This code selects a particular DCT implementation to be used, | |
| 10 * and it performs related housekeeping chores including coefficient | |
| 11 * quantization. | |
| 12 */ | |
| 13 | |
| 14 #define JPEG_INTERNALS | |
| 15 #include "jinclude.h" | |
| 16 #include "jpeglib.h" | |
| 17 #include "jdct.h" /* Private declarations for DCT subsystem */ | |
| 18 | |
| 19 | |
| 20 /* Private subobject for this module */ | |
| 21 | |
| 22 typedef struct { | |
| 23 struct jpeg_forward_dct pub; /* public fields */ | |
| 24 | |
| 25 /* Pointer to the DCT routine actually in use */ | |
| 26 forward_DCT_method_ptr do_dct; | |
| 27 | |
| 28 /* The actual post-DCT divisors --- not identical to the quant table | |
| 29 * entries, because of scaling (especially for an unnormalized DCT). | |
| 30 * Each table is given in normal array order. | |
| 31 */ | |
| 32 DCTELEM * divisors[NUM_QUANT_TBLS]; | |
| 33 | |
| 34 #ifdef DCT_FLOAT_SUPPORTED | |
| 35 /* Same as above for the floating-point case. */ | |
| 36 float_DCT_method_ptr do_float_dct; | |
| 37 FAST_FLOAT * float_divisors[NUM_QUANT_TBLS]; | |
| 38 #endif | |
| 39 } my_fdct_controller; | |
| 40 | |
| 41 typedef my_fdct_controller * my_fdct_ptr; | |
| 42 | |
| 43 | |
| 44 /* | |
| 45 * Initialize for a processing pass. | |
| 46 * Verify that all referenced Q-tables are present, and set up | |
| 47 * the divisor table for each one. | |
| 48 * In the current implementation, DCT of all components is done during | |
| 49 * the first pass, even if only some components will be output in the | |
| 50 * first scan. Hence all components should be examined here. | |
| 51 */ | |
| 52 | |
| 53 METHODDEF(void) | |
| 54 start_pass_fdctmgr (j_compress_ptr cinfo) | |
| 55 { | |
| 56 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; | |
| 57 int ci, qtblno, i; | |
| 58 jpeg_component_info *compptr; | |
| 59 JQUANT_TBL * qtbl; | |
| 60 DCTELEM * dtbl; | |
| 61 | |
| 62 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
| 63 ci++, compptr++) { | |
| 64 qtblno = compptr->quant_tbl_no; | |
| 65 /* Make sure specified quantization table is present */ | |
| 66 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || | |
| 67 cinfo->quant_tbl_ptrs[qtblno] == NULL) | |
| 68 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); | |
| 69 qtbl = cinfo->quant_tbl_ptrs[qtblno]; | |
| 70 /* Compute divisors for this quant table */ | |
| 71 /* We may do this more than once for same table, but it's not a big deal */ | |
| 72 switch (cinfo->dct_method) { | |
| 73 #ifdef DCT_ISLOW_SUPPORTED | |
| 74 case JDCT_ISLOW: | |
| 75 /* For LL&M IDCT method, divisors are equal to raw quantization | |
| 76 * coefficients multiplied by 8 (to counteract scaling). | |
| 77 */ | |
| 78 if (fdct->divisors[qtblno] == NULL) { | |
| 79 fdct->divisors[qtblno] = (DCTELEM *) | |
| 80 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 81 DCTSIZE2 * SIZEOF(DCTELEM)); | |
| 82 } | |
| 83 dtbl = fdct->divisors[qtblno]; | |
| 84 for (i = 0; i < DCTSIZE2; i++) { | |
| 85 dtbl[i] = ((DCTELEM) qtbl->quantval[i]) << 3; | |
| 86 } | |
| 87 break; | |
| 88 #endif | |
| 89 #ifdef DCT_IFAST_SUPPORTED | |
| 90 case JDCT_IFAST: | |
| 91 { | |
| 92 /* For AA&N IDCT method, divisors are equal to quantization | |
| 93 * coefficients scaled by scalefactor[row]*scalefactor[col], where | |
| 94 * scalefactor[0] = 1 | |
| 95 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 | |
| 96 * We apply a further scale factor of 8. | |
| 97 */ | |
| 98 #define CONST_BITS 14 | |
| 99 static const INT16 aanscales[DCTSIZE2] = { | |
| 100 /* precomputed values scaled up by 14 bits */ | |
| 101 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, | |
| 102 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, | |
| 103 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, | |
| 104 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, | |
| 105 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, | |
| 106 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, | |
| 107 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, | |
| 108 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 | |
| 109 }; | |
| 110 SHIFT_TEMPS | |
| 111 | |
| 112 if (fdct->divisors[qtblno] == NULL) { | |
| 113 fdct->divisors[qtblno] = (DCTELEM *) | |
| 114 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 115 DCTSIZE2 * SIZEOF(DCTELEM)); | |
| 116 } | |
| 117 dtbl = fdct->divisors[qtblno]; | |
| 118 for (i = 0; i < DCTSIZE2; i++) { | |
| 119 dtbl[i] = (DCTELEM) | |
| 120 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], | |
| 121 (INT32) aanscales[i]), | |
| 122 CONST_BITS-3); | |
| 123 } | |
| 124 } | |
| 125 break; | |
| 126 #endif | |
| 127 #ifdef DCT_FLOAT_SUPPORTED | |
| 128 case JDCT_FLOAT: | |
| 129 { | |
| 130 /* For float AA&N IDCT method, divisors are equal to quantization | |
| 131 * coefficients scaled by scalefactor[row]*scalefactor[col], where | |
| 132 * scalefactor[0] = 1 | |
| 133 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 | |
| 134 * We apply a further scale factor of 8. | |
| 135 * What's actually stored is 1/divisor so that the inner loop can | |
| 136 * use a multiplication rather than a division. | |
| 137 */ | |
| 138 FAST_FLOAT * fdtbl; | |
| 139 int row, col; | |
| 140 static const double aanscalefactor[DCTSIZE] = { | |
| 141 1.0, 1.387039845, 1.306562965, 1.175875602, | |
| 142 1.0, 0.785694958, 0.541196100, 0.275899379 | |
| 143 }; | |
| 144 | |
| 145 if (fdct->float_divisors[qtblno] == NULL) { | |
| 146 fdct->float_divisors[qtblno] = (FAST_FLOAT *) | |
| 147 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 148 DCTSIZE2 * SIZEOF(FAST_FLOAT)); | |
| 149 } | |
| 150 fdtbl = fdct->float_divisors[qtblno]; | |
| 151 i = 0; | |
| 152 for (row = 0; row < DCTSIZE; row++) { | |
| 153 for (col = 0; col < DCTSIZE; col++) { | |
| 154 fdtbl[i] = (FAST_FLOAT) | |
| 155 (1.0 / (((double) qtbl->quantval[i] * | |
| 156 aanscalefactor[row] * aanscalefactor[col] * 8.0))); | |
| 157 i++; | |
| 158 } | |
| 159 } | |
| 160 } | |
| 161 break; | |
| 162 #endif | |
| 163 default: | |
| 164 ERREXIT(cinfo, JERR_NOT_COMPILED); | |
| 165 break; | |
| 166 } | |
| 167 } | |
| 168 } | |
| 169 | |
| 170 | |
| 171 /* | |
| 172 * Perform forward DCT on one or more blocks of a component. | |
| 173 * | |
| 174 * The input samples are taken from the sample_data[] array starting at | |
| 175 * position start_row/start_col, and moving to the right for any additional | |
| 176 * blocks. The quantized coefficients are returned in coef_blocks[]. | |
| 177 */ | |
| 178 | |
| 179 METHODDEF(void) | |
| 180 forward_DCT (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 181 JSAMPARRAY sample_data, JBLOCKROW coef_blocks, | |
| 182 JDIMENSION start_row, JDIMENSION start_col, | |
| 183 JDIMENSION num_blocks) | |
| 184 /* This version is used for integer DCT implementations. */ | |
| 185 { | |
| 186 /* This routine is heavily used, so it's worth coding it tightly. */ | |
| 187 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; | |
| 188 forward_DCT_method_ptr do_dct = fdct->do_dct; | |
| 189 DCTELEM * divisors = fdct->divisors[compptr->quant_tbl_no]; | |
| 190 DCTELEM workspace[DCTSIZE2]; /* work area for FDCT subroutine */ | |
| 191 JDIMENSION bi; | |
| 192 | |
| 193 sample_data += start_row; /* fold in the vertical offset once */ | |
| 194 | |
| 195 for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { | |
| 196 /* Load data into workspace, applying unsigned->signed conversion */ | |
| 197 { register DCTELEM *workspaceptr; | |
| 198 register JSAMPROW elemptr; | |
| 199 register int elemr; | |
| 200 | |
| 201 workspaceptr = workspace; | |
| 202 for (elemr = 0; elemr < DCTSIZE; elemr++) { | |
| 203 elemptr = sample_data[elemr] + start_col; | |
| 204 #if DCTSIZE == 8 /* unroll the inner loop */ | |
| 205 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 206 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 207 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 208 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 209 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 210 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 211 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 212 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 213 #else | |
| 214 { register int elemc; | |
| 215 for (elemc = DCTSIZE; elemc > 0; elemc--) { | |
| 216 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; | |
| 217 } | |
| 218 } | |
| 219 #endif | |
| 220 } | |
| 221 } | |
| 222 | |
| 223 /* Perform the DCT */ | |
| 224 (*do_dct) (workspace); | |
| 225 | |
| 226 /* Quantize/descale the coefficients, and store into coef_blocks[] */ | |
| 227 { register DCTELEM temp, qval; | |
| 228 register int i; | |
| 229 register JCOEFPTR output_ptr = coef_blocks[bi]; | |
| 230 | |
| 231 for (i = 0; i < DCTSIZE2; i++) { | |
| 232 qval = divisors[i]; | |
| 233 temp = workspace[i]; | |
| 234 /* Divide the coefficient value by qval, ensuring proper rounding. | |
| 235 * Since C does not specify the direction of rounding for negative | |
| 236 * quotients, we have to force the dividend positive for portability. | |
| 237 * | |
| 238 * In most files, at least half of the output values will be zero | |
| 239 * (at default quantization settings, more like three-quarters...) | |
| 240 * so we should ensure that this case is fast. On many machines, | |
| 241 * a comparison is enough cheaper than a divide to make a special test | |
| 242 * a win. Since both inputs will be nonnegative, we need only test | |
| 243 * for a < b to discover whether a/b is 0. | |
| 244 * If your machine's division is fast enough, define FAST_DIVIDE. | |
| 245 */ | |
| 246 #ifdef FAST_DIVIDE | |
| 247 #define DIVIDE_BY(a,b) a /= b | |
| 248 #else | |
| 249 #define DIVIDE_BY(a,b) if (a >= b) a /= b; else a = 0 | |
| 250 #endif | |
| 251 if (temp < 0) { | |
| 252 temp = -temp; | |
| 253 temp += qval>>1; /* for rounding */ | |
| 254 DIVIDE_BY(temp, qval); | |
| 255 temp = -temp; | |
| 256 } else { | |
| 257 temp += qval>>1; /* for rounding */ | |
| 258 DIVIDE_BY(temp, qval); | |
| 259 } | |
| 260 output_ptr[i] = (JCOEF) temp; | |
| 261 } | |
| 262 } | |
| 263 } | |
| 264 } | |
| 265 | |
| 266 | |
| 267 #ifdef DCT_FLOAT_SUPPORTED | |
| 268 | |
| 269 METHODDEF(void) | |
| 270 forward_DCT_float (j_compress_ptr cinfo, jpeg_component_info * compptr, | |
| 271 JSAMPARRAY sample_data, JBLOCKROW coef_blocks, | |
| 272 JDIMENSION start_row, JDIMENSION start_col, | |
| 273 JDIMENSION num_blocks) | |
| 274 /* This version is used for floating-point DCT implementations. */ | |
| 275 { | |
| 276 /* This routine is heavily used, so it's worth coding it tightly. */ | |
| 277 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; | |
| 278 float_DCT_method_ptr do_dct = fdct->do_float_dct; | |
| 279 FAST_FLOAT * divisors = fdct->float_divisors[compptr->quant_tbl_no]; | |
| 280 FAST_FLOAT workspace[DCTSIZE2]; /* work area for FDCT subroutine */ | |
| 281 JDIMENSION bi; | |
| 282 | |
| 283 sample_data += start_row; /* fold in the vertical offset once */ | |
| 284 | |
| 285 for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { | |
| 286 /* Load data into workspace, applying unsigned->signed conversion */ | |
| 287 { register FAST_FLOAT *workspaceptr; | |
| 288 register JSAMPROW elemptr; | |
| 289 register int elemr; | |
| 290 | |
| 291 workspaceptr = workspace; | |
| 292 for (elemr = 0; elemr < DCTSIZE; elemr++) { | |
| 293 elemptr = sample_data[elemr] + start_col; | |
| 294 #if DCTSIZE == 8 /* unroll the inner loop */ | |
| 295 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 296 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 297 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 298 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 299 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 300 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 301 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 302 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 303 #else | |
| 304 { register int elemc; | |
| 305 for (elemc = DCTSIZE; elemc > 0; elemc--) { | |
| 306 *workspaceptr++ = (FAST_FLOAT) | |
| 307 (GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); | |
| 308 } | |
| 309 } | |
| 310 #endif | |
| 311 } | |
| 312 } | |
| 313 | |
| 314 /* Perform the DCT */ | |
| 315 (*do_dct) (workspace); | |
| 316 | |
| 317 /* Quantize/descale the coefficients, and store into coef_blocks[] */ | |
| 318 { register FAST_FLOAT temp; | |
| 319 register int i; | |
| 320 register JCOEFPTR output_ptr = coef_blocks[bi]; | |
| 321 | |
| 322 for (i = 0; i < DCTSIZE2; i++) { | |
| 323 /* Apply the quantization and scaling factor */ | |
| 324 temp = workspace[i] * divisors[i]; | |
| 325 /* Round to nearest integer. | |
| 326 * Since C does not specify the direction of rounding for negative | |
| 327 * quotients, we have to force the dividend positive for portability. | |
| 328 * The maximum coefficient size is +-16K (for 12-bit data), so this | |
| 329 * code should work for either 16-bit or 32-bit ints. | |
| 330 */ | |
| 331 output_ptr[i] = (JCOEF) ((int) (temp + (FAST_FLOAT) 16384.5) - 16384); | |
| 332 } | |
| 333 } | |
| 334 } | |
| 335 } | |
| 336 | |
| 337 #endif /* DCT_FLOAT_SUPPORTED */ | |
| 338 | |
| 339 | |
| 340 /* | |
| 341 * Initialize FDCT manager. | |
| 342 */ | |
| 343 | |
| 344 GLOBAL(void) | |
| 345 jinit_forward_dct (j_compress_ptr cinfo) | |
| 346 { | |
| 347 my_fdct_ptr fdct; | |
| 348 int i; | |
| 349 | |
| 350 fdct = (my_fdct_ptr) | |
| 351 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 352 SIZEOF(my_fdct_controller)); | |
| 353 cinfo->fdct = (struct jpeg_forward_dct *) fdct; | |
| 354 fdct->pub.start_pass = start_pass_fdctmgr; | |
| 355 | |
| 356 switch (cinfo->dct_method) { | |
| 357 #ifdef DCT_ISLOW_SUPPORTED | |
| 358 case JDCT_ISLOW: | |
| 359 fdct->pub.forward_DCT = forward_DCT; | |
| 360 fdct->do_dct = jpeg_fdct_islow; | |
| 361 break; | |
| 362 #endif | |
| 363 #ifdef DCT_IFAST_SUPPORTED | |
| 364 case JDCT_IFAST: | |
| 365 fdct->pub.forward_DCT = forward_DCT; | |
| 366 fdct->do_dct = jpeg_fdct_ifast; | |
| 367 break; | |
| 368 #endif | |
| 369 #ifdef DCT_FLOAT_SUPPORTED | |
| 370 case JDCT_FLOAT: | |
| 371 fdct->pub.forward_DCT = forward_DCT_float; | |
| 372 fdct->do_float_dct = jpeg_fdct_float; | |
| 373 break; | |
| 374 #endif | |
| 375 default: | |
| 376 ERREXIT(cinfo, JERR_NOT_COMPILED); | |
| 377 break; | |
| 378 } | |
| 379 | |
| 380 /* Mark divisor tables unallocated */ | |
| 381 for (i = 0; i < NUM_QUANT_TBLS; i++) { | |
| 382 fdct->divisors[i] = NULL; | |
| 383 #ifdef DCT_FLOAT_SUPPORTED | |
| 384 fdct->float_divisors[i] = NULL; | |
| 385 #endif | |
| 386 } | |
| 387 } | |
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Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master