Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jcdctmgr.c |
| 3 | * |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 4 | * Copyright (C) 1994-1995, Thomas G. Lane. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 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). |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 30 | * Each table is given in normal array order; note that this must |
| 31 | * be converted from the zigzag order of the quantization tables. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 32 | */ |
| 33 | DCTELEM * divisors[NUM_QUANT_TBLS]; |
| 34 | |
| 35 | #ifdef DCT_FLOAT_SUPPORTED |
| 36 | /* Same as above for the floating-point case. */ |
| 37 | float_DCT_method_ptr do_float_dct; |
| 38 | FAST_FLOAT * float_divisors[NUM_QUANT_TBLS]; |
| 39 | #endif |
| 40 | } my_fdct_controller; |
| 41 | |
| 42 | typedef my_fdct_controller * my_fdct_ptr; |
| 43 | |
| 44 | |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 45 | /* |
| 46 | * Initialize for a processing pass. |
| 47 | * Verify that all referenced Q-tables are present, and set up |
| 48 | * the divisor table for each one. |
| 49 | * In the current implementation, DCT of all components is done during |
| 50 | * the first pass, even if only some components will be output in the |
| 51 | * first scan. Hence all components should be examined here. |
| 52 | */ |
| 53 | |
| 54 | METHODDEF void |
| 55 | start_pass_fdctmgr (j_compress_ptr cinfo) |
| 56 | { |
| 57 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |
| 58 | int ci, qtblno, i; |
| 59 | jpeg_component_info *compptr; |
| 60 | JQUANT_TBL * qtbl; |
| 61 | DCTELEM * dtbl; |
| 62 | |
| 63 | for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; |
| 64 | ci++, compptr++) { |
| 65 | qtblno = compptr->quant_tbl_no; |
| 66 | /* Make sure specified quantization table is present */ |
| 67 | if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS || |
| 68 | cinfo->quant_tbl_ptrs[qtblno] == NULL) |
| 69 | ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno); |
| 70 | qtbl = cinfo->quant_tbl_ptrs[qtblno]; |
| 71 | /* Compute divisors for this quant table */ |
| 72 | /* We may do this more than once for same table, but it's not a big deal */ |
| 73 | switch (cinfo->dct_method) { |
| 74 | #ifdef DCT_ISLOW_SUPPORTED |
| 75 | case JDCT_ISLOW: |
| 76 | /* For LL&M IDCT method, divisors are equal to raw quantization |
| 77 | * coefficients multiplied by 8 (to counteract scaling). |
| 78 | */ |
| 79 | if (fdct->divisors[qtblno] == NULL) { |
| 80 | fdct->divisors[qtblno] = (DCTELEM *) |
| 81 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 82 | DCTSIZE2 * SIZEOF(DCTELEM)); |
| 83 | } |
| 84 | dtbl = fdct->divisors[qtblno]; |
| 85 | for (i = 0; i < DCTSIZE2; i++) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 86 | dtbl[i] = ((DCTELEM) qtbl->quantval[jpeg_zigzag_order[i]]) << 3; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 87 | } |
| 88 | break; |
| 89 | #endif |
| 90 | #ifdef DCT_IFAST_SUPPORTED |
| 91 | case JDCT_IFAST: |
| 92 | { |
| 93 | /* For AA&N IDCT method, divisors are equal to quantization |
| 94 | * coefficients scaled by scalefactor[row]*scalefactor[col], where |
| 95 | * scalefactor[0] = 1 |
| 96 | * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |
| 97 | * We apply a further scale factor of 8. |
| 98 | */ |
| 99 | #define CONST_BITS 14 |
| 100 | static const INT16 aanscales[DCTSIZE2] = { |
| 101 | /* precomputed values scaled up by 14 bits: in natural order */ |
| 102 | 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |
| 103 | 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, |
| 104 | 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, |
| 105 | 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, |
| 106 | 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, |
| 107 | 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, |
| 108 | 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, |
| 109 | 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 |
| 110 | }; |
| 111 | SHIFT_TEMPS |
| 112 | |
| 113 | if (fdct->divisors[qtblno] == NULL) { |
| 114 | fdct->divisors[qtblno] = (DCTELEM *) |
| 115 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 116 | DCTSIZE2 * SIZEOF(DCTELEM)); |
| 117 | } |
| 118 | dtbl = fdct->divisors[qtblno]; |
| 119 | for (i = 0; i < DCTSIZE2; i++) { |
| 120 | dtbl[i] = (DCTELEM) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 121 | DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[jpeg_zigzag_order[i]], |
| 122 | (INT32) aanscales[i]), |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 123 | CONST_BITS-3); |
| 124 | } |
| 125 | } |
| 126 | break; |
| 127 | #endif |
| 128 | #ifdef DCT_FLOAT_SUPPORTED |
| 129 | case JDCT_FLOAT: |
| 130 | { |
| 131 | /* For float AA&N IDCT method, divisors are equal to quantization |
| 132 | * coefficients scaled by scalefactor[row]*scalefactor[col], where |
| 133 | * scalefactor[0] = 1 |
| 134 | * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 |
| 135 | * We apply a further scale factor of 8. |
| 136 | * What's actually stored is 1/divisor so that the inner loop can |
| 137 | * use a multiplication rather than a division. |
| 138 | */ |
| 139 | FAST_FLOAT * fdtbl; |
| 140 | int row, col; |
| 141 | static const double aanscalefactor[DCTSIZE] = { |
| 142 | 1.0, 1.387039845, 1.306562965, 1.175875602, |
| 143 | 1.0, 0.785694958, 0.541196100, 0.275899379 |
| 144 | }; |
| 145 | |
| 146 | if (fdct->float_divisors[qtblno] == NULL) { |
| 147 | fdct->float_divisors[qtblno] = (FAST_FLOAT *) |
| 148 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 149 | DCTSIZE2 * SIZEOF(FAST_FLOAT)); |
| 150 | } |
| 151 | fdtbl = fdct->float_divisors[qtblno]; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 152 | i = 0; |
| 153 | for (row = 0; row < DCTSIZE; row++) { |
| 154 | for (col = 0; col < DCTSIZE; col++) { |
| 155 | fdtbl[i] = (FAST_FLOAT) |
| 156 | (1.0 / (((double) qtbl->quantval[jpeg_zigzag_order[i]] * |
| 157 | aanscalefactor[row] * aanscalefactor[col] * 8.0))); |
| 158 | i++; |
| 159 | } |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 160 | } |
| 161 | } |
| 162 | break; |
| 163 | #endif |
| 164 | default: |
| 165 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
| 166 | break; |
| 167 | } |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | |
| 172 | /* |
| 173 | * Perform forward DCT on one or more blocks of a component. |
| 174 | * |
| 175 | * The input samples are taken from the sample_data[] array starting at |
| 176 | * position start_row/start_col, and moving to the right for any additional |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 177 | * blocks. The quantized coefficients are returned in coef_blocks[]. |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 178 | */ |
| 179 | |
| 180 | METHODDEF void |
| 181 | forward_DCT (j_compress_ptr cinfo, jpeg_component_info * compptr, |
| 182 | JSAMPARRAY sample_data, JBLOCKROW coef_blocks, |
| 183 | JDIMENSION start_row, JDIMENSION start_col, |
| 184 | JDIMENSION num_blocks) |
| 185 | /* This version is used for integer DCT implementations. */ |
| 186 | { |
| 187 | /* This routine is heavily used, so it's worth coding it tightly. */ |
| 188 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |
| 189 | forward_DCT_method_ptr do_dct = fdct->do_dct; |
| 190 | DCTELEM * divisors = fdct->divisors[compptr->quant_tbl_no]; |
| 191 | DCTELEM workspace[DCTSIZE2]; /* work area for FDCT subroutine */ |
| 192 | JDIMENSION bi; |
| 193 | |
| 194 | sample_data += start_row; /* fold in the vertical offset once */ |
| 195 | |
| 196 | for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { |
| 197 | /* Load data into workspace, applying unsigned->signed conversion */ |
| 198 | { register DCTELEM *workspaceptr; |
| 199 | register JSAMPROW elemptr; |
| 200 | register int elemr; |
| 201 | |
| 202 | workspaceptr = workspace; |
| 203 | for (elemr = 0; elemr < DCTSIZE; elemr++) { |
| 204 | elemptr = sample_data[elemr] + start_col; |
| 205 | #if DCTSIZE == 8 /* unroll the inner loop */ |
| 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 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |
| 214 | #else |
| 215 | { register int elemc; |
| 216 | for (elemc = DCTSIZE; elemc > 0; elemc--) { |
| 217 | *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE; |
| 218 | } |
| 219 | } |
| 220 | #endif |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | /* Perform the DCT */ |
| 225 | (*do_dct) (workspace); |
| 226 | |
| 227 | /* Quantize/descale the coefficients, and store into coef_blocks[] */ |
| 228 | { register DCTELEM temp, qval; |
| 229 | register int i; |
| 230 | register JCOEFPTR output_ptr = coef_blocks[bi]; |
| 231 | |
| 232 | for (i = 0; i < DCTSIZE2; i++) { |
| 233 | qval = divisors[i]; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 234 | temp = workspace[i]; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 235 | /* Divide the coefficient value by qval, ensuring proper rounding. |
| 236 | * Since C does not specify the direction of rounding for negative |
| 237 | * quotients, we have to force the dividend positive for portability. |
| 238 | * |
| 239 | * In most files, at least half of the output values will be zero |
| 240 | * (at default quantization settings, more like three-quarters...) |
| 241 | * so we should ensure that this case is fast. On many machines, |
| 242 | * a comparison is enough cheaper than a divide to make a special test |
| 243 | * a win. Since both inputs will be nonnegative, we need only test |
| 244 | * for a < b to discover whether a/b is 0. |
| 245 | * If your machine's division is fast enough, define FAST_DIVIDE. |
| 246 | */ |
| 247 | #ifdef FAST_DIVIDE |
| 248 | #define DIVIDE_BY(a,b) a /= b |
| 249 | #else |
| 250 | #define DIVIDE_BY(a,b) if (a >= b) a /= b; else a = 0 |
| 251 | #endif |
| 252 | if (temp < 0) { |
| 253 | temp = -temp; |
| 254 | temp += qval>>1; /* for rounding */ |
| 255 | DIVIDE_BY(temp, qval); |
| 256 | temp = -temp; |
| 257 | } else { |
| 258 | temp += qval>>1; /* for rounding */ |
| 259 | DIVIDE_BY(temp, qval); |
| 260 | } |
| 261 | output_ptr[i] = (JCOEF) temp; |
| 262 | } |
| 263 | } |
| 264 | } |
| 265 | } |
| 266 | |
| 267 | |
| 268 | #ifdef DCT_FLOAT_SUPPORTED |
| 269 | |
| 270 | METHODDEF void |
| 271 | forward_DCT_float (j_compress_ptr cinfo, jpeg_component_info * compptr, |
| 272 | JSAMPARRAY sample_data, JBLOCKROW coef_blocks, |
| 273 | JDIMENSION start_row, JDIMENSION start_col, |
| 274 | JDIMENSION num_blocks) |
| 275 | /* This version is used for floating-point DCT implementations. */ |
| 276 | { |
| 277 | /* This routine is heavily used, so it's worth coding it tightly. */ |
| 278 | my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct; |
| 279 | float_DCT_method_ptr do_dct = fdct->do_float_dct; |
| 280 | FAST_FLOAT * divisors = fdct->float_divisors[compptr->quant_tbl_no]; |
| 281 | FAST_FLOAT workspace[DCTSIZE2]; /* work area for FDCT subroutine */ |
| 282 | JDIMENSION bi; |
| 283 | |
| 284 | sample_data += start_row; /* fold in the vertical offset once */ |
| 285 | |
| 286 | for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) { |
| 287 | /* Load data into workspace, applying unsigned->signed conversion */ |
| 288 | { register FAST_FLOAT *workspaceptr; |
| 289 | register JSAMPROW elemptr; |
| 290 | register int elemr; |
| 291 | |
| 292 | workspaceptr = workspace; |
| 293 | for (elemr = 0; elemr < DCTSIZE; elemr++) { |
| 294 | elemptr = sample_data[elemr] + start_col; |
| 295 | #if DCTSIZE == 8 /* unroll the inner loop */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 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 | *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 304 | #else |
| 305 | { register int elemc; |
| 306 | for (elemc = DCTSIZE; elemc > 0; elemc--) { |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 307 | *workspaceptr++ = (FAST_FLOAT) |
| 308 | (GETJSAMPLE(*elemptr++) - CENTERJSAMPLE); |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 309 | } |
| 310 | } |
| 311 | #endif |
| 312 | } |
| 313 | } |
| 314 | |
| 315 | /* Perform the DCT */ |
| 316 | (*do_dct) (workspace); |
| 317 | |
| 318 | /* Quantize/descale the coefficients, and store into coef_blocks[] */ |
| 319 | { register FAST_FLOAT temp; |
| 320 | register int i; |
| 321 | register JCOEFPTR output_ptr = coef_blocks[bi]; |
| 322 | |
| 323 | for (i = 0; i < DCTSIZE2; i++) { |
| 324 | /* Apply the quantization and scaling factor */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame^] | 325 | temp = workspace[i] * divisors[i]; |
Thomas G. Lane | 36a4ccc | 1994-09-24 00:00:00 +0000 | [diff] [blame] | 326 | /* Round to nearest integer. |
| 327 | * Since C does not specify the direction of rounding for negative |
| 328 | * quotients, we have to force the dividend positive for portability. |
| 329 | * The maximum coefficient size is +-16K (for 12-bit data), so this |
| 330 | * code should work for either 16-bit or 32-bit ints. |
| 331 | */ |
| 332 | output_ptr[i] = (JCOEF) ((int) (temp + (FAST_FLOAT) 16384.5) - 16384); |
| 333 | } |
| 334 | } |
| 335 | } |
| 336 | } |
| 337 | |
| 338 | #endif /* DCT_FLOAT_SUPPORTED */ |
| 339 | |
| 340 | |
| 341 | /* |
| 342 | * Initialize FDCT manager. |
| 343 | */ |
| 344 | |
| 345 | GLOBAL void |
| 346 | jinit_forward_dct (j_compress_ptr cinfo) |
| 347 | { |
| 348 | my_fdct_ptr fdct; |
| 349 | int i; |
| 350 | |
| 351 | fdct = (my_fdct_ptr) |
| 352 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 353 | SIZEOF(my_fdct_controller)); |
| 354 | cinfo->fdct = (struct jpeg_forward_dct *) fdct; |
| 355 | fdct->pub.start_pass = start_pass_fdctmgr; |
| 356 | |
| 357 | switch (cinfo->dct_method) { |
| 358 | #ifdef DCT_ISLOW_SUPPORTED |
| 359 | case JDCT_ISLOW: |
| 360 | fdct->pub.forward_DCT = forward_DCT; |
| 361 | fdct->do_dct = jpeg_fdct_islow; |
| 362 | break; |
| 363 | #endif |
| 364 | #ifdef DCT_IFAST_SUPPORTED |
| 365 | case JDCT_IFAST: |
| 366 | fdct->pub.forward_DCT = forward_DCT; |
| 367 | fdct->do_dct = jpeg_fdct_ifast; |
| 368 | break; |
| 369 | #endif |
| 370 | #ifdef DCT_FLOAT_SUPPORTED |
| 371 | case JDCT_FLOAT: |
| 372 | fdct->pub.forward_DCT = forward_DCT_float; |
| 373 | fdct->do_float_dct = jpeg_fdct_float; |
| 374 | break; |
| 375 | #endif |
| 376 | default: |
| 377 | ERREXIT(cinfo, JERR_NOT_COMPILED); |
| 378 | break; |
| 379 | } |
| 380 | |
| 381 | /* Mark divisor tables unallocated */ |
| 382 | for (i = 0; i < NUM_QUANT_TBLS; i++) { |
| 383 | fdct->divisors[i] = NULL; |
| 384 | #ifdef DCT_FLOAT_SUPPORTED |
| 385 | fdct->float_divisors[i] = NULL; |
| 386 | #endif |
| 387 | } |
| 388 | } |