1/* 2 * jddctmgr.c 3 * 4 * Copyright (C) 1994-1996, Thomas G. Lane. 5 * Modified 2002-2010 by Guido Vollbeding. 6 * This file is part of the Independent JPEG Group's software. 7 * For conditions of distribution and use, see the accompanying README file. 8 * 9 * This file contains the inverse-DCT management logic. 10 * This code selects a particular IDCT implementation to be used, 11 * and it performs related housekeeping chores. No code in this file 12 * is executed per IDCT step, only during output pass setup. 13 * 14 * Note that the IDCT routines are responsible for performing coefficient 15 * dequantization as well as the IDCT proper. This module sets up the 16 * dequantization multiplier table needed by the IDCT routine. 17 */ 18 19#define JPEG_INTERNALS 20#include "jinclude.h" 21#include "jpeglib.h" 22#include "jdct.h" /* Private declarations for DCT subsystem */ 23 24 25/* 26 * The decompressor input side (jdinput.c) saves away the appropriate 27 * quantization table for each component at the start of the first scan 28 * involving that component. (This is necessary in order to correctly 29 * decode files that reuse Q-table slots.) 30 * When we are ready to make an output pass, the saved Q-table is converted 31 * to a multiplier table that will actually be used by the IDCT routine. 32 * The multiplier table contents are IDCT-method-dependent. To support 33 * application changes in IDCT method between scans, we can remake the 34 * multiplier tables if necessary. 35 * In buffered-image mode, the first output pass may occur before any data 36 * has been seen for some components, and thus before their Q-tables have 37 * been saved away. To handle this case, multiplier tables are preset 38 * to zeroes; the result of the IDCT will be a neutral gray level. 39 */ 40 41 42/* Private subobject for this module */ 43 44typedef struct { 45 struct jpeg_inverse_dct pub; /* public fields */ 46 47 /* This array contains the IDCT method code that each multiplier table 48 * is currently set up for, or -1 if it's not yet set up. 49 * The actual multiplier tables are pointed to by dct_table in the 50 * per-component comp_info structures. 51 */ 52 int cur_method[MAX_COMPONENTS]; 53} my_idct_controller; 54 55typedef my_idct_controller * my_idct_ptr; 56 57 58/* Allocated multiplier tables: big enough for any supported variant */ 59 60typedef union { 61 ISLOW_MULT_TYPE islow_array[DCTSIZE2]; 62#ifdef DCT_IFAST_SUPPORTED 63 IFAST_MULT_TYPE ifast_array[DCTSIZE2]; 64#endif 65#ifdef DCT_FLOAT_SUPPORTED 66 FLOAT_MULT_TYPE float_array[DCTSIZE2]; 67#endif 68} multiplier_table; 69 70 71/* The current scaled-IDCT routines require ISLOW-style multiplier tables, 72 * so be sure to compile that code if either ISLOW or SCALING is requested. 73 */ 74#ifdef DCT_ISLOW_SUPPORTED 75#define PROVIDE_ISLOW_TABLES 76#else 77#ifdef IDCT_SCALING_SUPPORTED 78#define PROVIDE_ISLOW_TABLES 79#endif 80#endif 81 82 83/* 84 * Prepare for an output pass. 85 * Here we select the proper IDCT routine for each component and build 86 * a matching multiplier table. 87 */ 88 89METHODDEF(void) 90start_pass (j_decompress_ptr cinfo) 91{ 92 my_idct_ptr idct = (my_idct_ptr) cinfo->idct; 93 int ci, i; 94 jpeg_component_info *compptr; 95 int method = 0; 96 inverse_DCT_method_ptr method_ptr = NULL; 97 JQUANT_TBL * qtbl; 98 99 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 100 ci++, compptr++) { 101 /* Select the proper IDCT routine for this component's scaling */ 102 switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) { 103#ifdef IDCT_SCALING_SUPPORTED 104 case ((1 << 8) + 1): 105 method_ptr = jpeg_idct_1x1; 106 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 107 break; 108 case ((2 << 8) + 2): 109 method_ptr = jpeg_idct_2x2; 110 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 111 break; 112 case ((3 << 8) + 3): 113 method_ptr = jpeg_idct_3x3; 114 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 115 break; 116 case ((4 << 8) + 4): 117 method_ptr = jpeg_idct_4x4; 118 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 119 break; 120 case ((5 << 8) + 5): 121 method_ptr = jpeg_idct_5x5; 122 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 123 break; 124 case ((6 << 8) + 6): 125 method_ptr = jpeg_idct_6x6; 126 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 127 break; 128 case ((7 << 8) + 7): 129 method_ptr = jpeg_idct_7x7; 130 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 131 break; 132 case ((9 << 8) + 9): 133 method_ptr = jpeg_idct_9x9; 134 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 135 break; 136 case ((10 << 8) + 10): 137 method_ptr = jpeg_idct_10x10; 138 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 139 break; 140 case ((11 << 8) + 11): 141 method_ptr = jpeg_idct_11x11; 142 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 143 break; 144 case ((12 << 8) + 12): 145 method_ptr = jpeg_idct_12x12; 146 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 147 break; 148 case ((13 << 8) + 13): 149 method_ptr = jpeg_idct_13x13; 150 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 151 break; 152 case ((14 << 8) + 14): 153 method_ptr = jpeg_idct_14x14; 154 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 155 break; 156 case ((15 << 8) + 15): 157 method_ptr = jpeg_idct_15x15; 158 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 159 break; 160 case ((16 << 8) + 16): 161 method_ptr = jpeg_idct_16x16; 162 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 163 break; 164 case ((16 << 8) + 8): 165 method_ptr = jpeg_idct_16x8; 166 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 167 break; 168 case ((14 << 8) + 7): 169 method_ptr = jpeg_idct_14x7; 170 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 171 break; 172 case ((12 << 8) + 6): 173 method_ptr = jpeg_idct_12x6; 174 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 175 break; 176 case ((10 << 8) + 5): 177 method_ptr = jpeg_idct_10x5; 178 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 179 break; 180 case ((8 << 8) + 4): 181 method_ptr = jpeg_idct_8x4; 182 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 183 break; 184 case ((6 << 8) + 3): 185 method_ptr = jpeg_idct_6x3; 186 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 187 break; 188 case ((4 << 8) + 2): 189 method_ptr = jpeg_idct_4x2; 190 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 191 break; 192 case ((2 << 8) + 1): 193 method_ptr = jpeg_idct_2x1; 194 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 195 break; 196 case ((8 << 8) + 16): 197 method_ptr = jpeg_idct_8x16; 198 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 199 break; 200 case ((7 << 8) + 14): 201 method_ptr = jpeg_idct_7x14; 202 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 203 break; 204 case ((6 << 8) + 12): 205 method_ptr = jpeg_idct_6x12; 206 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 207 break; 208 case ((5 << 8) + 10): 209 method_ptr = jpeg_idct_5x10; 210 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 211 break; 212 case ((4 << 8) + 8): 213 method_ptr = jpeg_idct_4x8; 214 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 215 break; 216 case ((3 << 8) + 6): 217 method_ptr = jpeg_idct_3x6; 218 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 219 break; 220 case ((2 << 8) + 4): 221 method_ptr = jpeg_idct_2x4; 222 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 223 break; 224 case ((1 << 8) + 2): 225 method_ptr = jpeg_idct_1x2; 226 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 227 break; 228#endif 229 case ((DCTSIZE << 8) + DCTSIZE): 230 switch (cinfo->dct_method) { 231#ifdef DCT_ISLOW_SUPPORTED 232 case JDCT_ISLOW: 233 method_ptr = jpeg_idct_islow; 234 method = JDCT_ISLOW; 235 break; 236#endif 237#ifdef DCT_IFAST_SUPPORTED 238 case JDCT_IFAST: 239 method_ptr = jpeg_idct_ifast; 240 method = JDCT_IFAST; 241 break; 242#endif 243#ifdef DCT_FLOAT_SUPPORTED 244 case JDCT_FLOAT: 245 method_ptr = jpeg_idct_float; 246 method = JDCT_FLOAT; 247 break; 248#endif 249 default: 250 ERREXIT(cinfo, JERR_NOT_COMPILED); 251 break; 252 } 253 break; 254 default: 255 ERREXIT2(cinfo, JERR_BAD_DCTSIZE, 256 compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size); 257 break; 258 } 259 idct->pub.inverse_DCT[ci] = method_ptr; 260 /* Create multiplier table from quant table. 261 * However, we can skip this if the component is uninteresting 262 * or if we already built the table. Also, if no quant table 263 * has yet been saved for the component, we leave the 264 * multiplier table all-zero; we'll be reading zeroes from the 265 * coefficient controller's buffer anyway. 266 */ 267 if (! compptr->component_needed || idct->cur_method[ci] == method) 268 continue; 269 qtbl = compptr->quant_table; 270 if (qtbl == NULL) /* happens if no data yet for component */ 271 continue; 272 idct->cur_method[ci] = method; 273 switch (method) { 274#ifdef PROVIDE_ISLOW_TABLES 275 case JDCT_ISLOW: 276 { 277 /* For LL&M IDCT method, multipliers are equal to raw quantization 278 * coefficients, but are stored as ints to ensure access efficiency. 279 */ 280 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table; 281 for (i = 0; i < DCTSIZE2; i++) { 282 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i]; 283 } 284 } 285 break; 286#endif 287#ifdef DCT_IFAST_SUPPORTED 288 case JDCT_IFAST: 289 { 290 /* For AA&N IDCT method, multipliers are equal to quantization 291 * coefficients scaled by scalefactor[row]*scalefactor[col], where 292 * scalefactor[0] = 1 293 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 294 * For integer operation, the multiplier table is to be scaled by 295 * IFAST_SCALE_BITS. 296 */ 297 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table; 298#define CONST_BITS 14 299 static const INT16 aanscales[DCTSIZE2] = { 300 /* precomputed values scaled up by 14 bits */ 301 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 302 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, 303 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, 304 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, 305 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 306 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, 307 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, 308 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 309 }; 310 SHIFT_TEMPS 311 312 for (i = 0; i < DCTSIZE2; i++) { 313 ifmtbl[i] = (IFAST_MULT_TYPE) 314 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], 315 (INT32) aanscales[i]), 316 CONST_BITS-IFAST_SCALE_BITS); 317 } 318 } 319 break; 320#endif 321#ifdef DCT_FLOAT_SUPPORTED 322 case JDCT_FLOAT: 323 { 324 /* For float AA&N IDCT method, multipliers are equal to quantization 325 * coefficients scaled by scalefactor[row]*scalefactor[col], where 326 * scalefactor[0] = 1 327 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 328 * We apply a further scale factor of 1/8. 329 */ 330 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table; 331 int row, col; 332 static const double aanscalefactor[DCTSIZE] = { 333 1.0, 1.387039845, 1.306562965, 1.175875602, 334 1.0, 0.785694958, 0.541196100, 0.275899379 335 }; 336 337 i = 0; 338 for (row = 0; row < DCTSIZE; row++) { 339 for (col = 0; col < DCTSIZE; col++) { 340 fmtbl[i] = (FLOAT_MULT_TYPE) 341 ((double) qtbl->quantval[i] * 342 aanscalefactor[row] * aanscalefactor[col] * 0.125); 343 i++; 344 } 345 } 346 } 347 break; 348#endif 349 default: 350 ERREXIT(cinfo, JERR_NOT_COMPILED); 351 break; 352 } 353 } 354} 355 356 357/* 358 * Initialize IDCT manager. 359 */ 360 361GLOBAL(void) 362jinit_inverse_dct (j_decompress_ptr cinfo) 363{ 364 my_idct_ptr idct; 365 int ci; 366 jpeg_component_info *compptr; 367 368 idct = (my_idct_ptr) 369 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 370 SIZEOF(my_idct_controller)); 371 cinfo->idct = (struct jpeg_inverse_dct *) idct; 372 idct->pub.start_pass = start_pass; 373 374 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 375 ci++, compptr++) { 376 /* Allocate and pre-zero a multiplier table for each component */ 377 compptr->dct_table = 378 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, 379 SIZEOF(multiplier_table)); 380 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table)); 381 /* Mark multiplier table not yet set up for any method */ 382 idct->cur_method[ci] = -1; 383 } 384} 385