jddctmgr.c (11724B)
1 /* 2 * jddctmgr.c 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1996, Thomas G. Lane. 6 * Modified 2002-2010 by Guido Vollbeding. 7 * libjpeg-turbo Modifications: 8 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB 9 * Copyright (C) 2010, 2015, 2022, D. R. Commander. 10 * Copyright (C) 2013, MIPS Technologies, Inc., California. 11 * For conditions of distribution and use, see the accompanying README.ijg 12 * file. 13 * 14 * This file contains the inverse-DCT management logic. 15 * This code selects a particular IDCT implementation to be used, 16 * and it performs related housekeeping chores. No code in this file 17 * is executed per IDCT step, only during output pass setup. 18 * 19 * Note that the IDCT routines are responsible for performing coefficient 20 * dequantization as well as the IDCT proper. This module sets up the 21 * dequantization multiplier table needed by the IDCT routine. 22 */ 23 24 #define JPEG_INTERNALS 25 #include "jinclude.h" 26 #include "jpeglib.h" 27 #include "jdct.h" /* Private declarations for DCT subsystem */ 28 #include "jsimddct.h" 29 #include "jpegapicomp.h" 30 31 32 /* 33 * The decompressor input side (jdinput.c) saves away the appropriate 34 * quantization table for each component at the start of the first scan 35 * involving that component. (This is necessary in order to correctly 36 * decode files that reuse Q-table slots.) 37 * When we are ready to make an output pass, the saved Q-table is converted 38 * to a multiplier table that will actually be used by the IDCT routine. 39 * The multiplier table contents are IDCT-method-dependent. To support 40 * application changes in IDCT method between scans, we can remake the 41 * multiplier tables if necessary. 42 * In buffered-image mode, the first output pass may occur before any data 43 * has been seen for some components, and thus before their Q-tables have 44 * been saved away. To handle this case, multiplier tables are preset 45 * to zeroes; the result of the IDCT will be a neutral gray level. 46 */ 47 48 49 /* Private subobject for this module */ 50 51 typedef struct { 52 struct jpeg_inverse_dct pub; /* public fields */ 53 54 /* This array contains the IDCT method code that each multiplier table 55 * is currently set up for, or -1 if it's not yet set up. 56 * The actual multiplier tables are pointed to by dct_table in the 57 * per-component comp_info structures. 58 */ 59 int cur_method[MAX_COMPONENTS]; 60 } my_idct_controller; 61 62 typedef my_idct_controller *my_idct_ptr; 63 64 65 /* Allocated multiplier tables: big enough for any supported variant */ 66 67 typedef union { 68 ISLOW_MULT_TYPE islow_array[DCTSIZE2]; 69 #ifdef DCT_IFAST_SUPPORTED 70 IFAST_MULT_TYPE ifast_array[DCTSIZE2]; 71 #endif 72 #ifdef DCT_FLOAT_SUPPORTED 73 FLOAT_MULT_TYPE float_array[DCTSIZE2]; 74 #endif 75 } multiplier_table; 76 77 78 /* The current scaled-IDCT routines require ISLOW-style multiplier tables, 79 * so be sure to compile that code if either ISLOW or SCALING is requested. 80 */ 81 #ifdef DCT_ISLOW_SUPPORTED 82 #define PROVIDE_ISLOW_TABLES 83 #else 84 #ifdef IDCT_SCALING_SUPPORTED 85 #define PROVIDE_ISLOW_TABLES 86 #endif 87 #endif 88 89 90 /* 91 * Prepare for an output pass. 92 * Here we select the proper IDCT routine for each component and build 93 * a matching multiplier table. 94 */ 95 96 METHODDEF(void) 97 start_pass(j_decompress_ptr cinfo) 98 { 99 my_idct_ptr idct = (my_idct_ptr)cinfo->idct; 100 int ci, i; 101 jpeg_component_info *compptr; 102 int method = 0; 103 _inverse_DCT_method_ptr method_ptr = NULL; 104 JQUANT_TBL *qtbl; 105 106 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 107 ci++, compptr++) { 108 /* Select the proper IDCT routine for this component's scaling */ 109 switch (compptr->_DCT_scaled_size) { 110 #ifdef IDCT_SCALING_SUPPORTED 111 case 1: 112 method_ptr = _jpeg_idct_1x1; 113 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 114 break; 115 case 2: 116 #ifdef WITH_SIMD 117 if (jsimd_can_idct_2x2()) 118 method_ptr = jsimd_idct_2x2; 119 else 120 #endif 121 method_ptr = _jpeg_idct_2x2; 122 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 123 break; 124 case 3: 125 method_ptr = _jpeg_idct_3x3; 126 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 127 break; 128 case 4: 129 #ifdef WITH_SIMD 130 if (jsimd_can_idct_4x4()) 131 method_ptr = jsimd_idct_4x4; 132 else 133 #endif 134 method_ptr = _jpeg_idct_4x4; 135 method = JDCT_ISLOW; /* jidctred uses islow-style table */ 136 break; 137 case 5: 138 method_ptr = _jpeg_idct_5x5; 139 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 140 break; 141 case 6: 142 #if defined(WITH_SIMD) && defined(__mips__) 143 if (jsimd_can_idct_6x6()) 144 method_ptr = jsimd_idct_6x6; 145 else 146 #endif 147 method_ptr = _jpeg_idct_6x6; 148 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 149 break; 150 case 7: 151 method_ptr = _jpeg_idct_7x7; 152 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 153 break; 154 #endif 155 case DCTSIZE: 156 switch (cinfo->dct_method) { 157 #ifdef DCT_ISLOW_SUPPORTED 158 case JDCT_ISLOW: 159 #ifdef WITH_SIMD 160 if (jsimd_can_idct_islow()) 161 method_ptr = jsimd_idct_islow; 162 else 163 #endif 164 method_ptr = _jpeg_idct_islow; 165 method = JDCT_ISLOW; 166 break; 167 #endif 168 #ifdef DCT_IFAST_SUPPORTED 169 case JDCT_IFAST: 170 #ifdef WITH_SIMD 171 if (jsimd_can_idct_ifast()) 172 method_ptr = jsimd_idct_ifast; 173 else 174 #endif 175 method_ptr = _jpeg_idct_ifast; 176 method = JDCT_IFAST; 177 break; 178 #endif 179 #ifdef DCT_FLOAT_SUPPORTED 180 case JDCT_FLOAT: 181 #ifdef WITH_SIMD 182 if (jsimd_can_idct_float()) 183 method_ptr = jsimd_idct_float; 184 else 185 #endif 186 method_ptr = _jpeg_idct_float; 187 method = JDCT_FLOAT; 188 break; 189 #endif 190 default: 191 ERREXIT(cinfo, JERR_NOT_COMPILED); 192 break; 193 } 194 break; 195 #ifdef IDCT_SCALING_SUPPORTED 196 case 9: 197 method_ptr = _jpeg_idct_9x9; 198 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 199 break; 200 case 10: 201 method_ptr = _jpeg_idct_10x10; 202 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 203 break; 204 case 11: 205 method_ptr = _jpeg_idct_11x11; 206 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 207 break; 208 case 12: 209 #if defined(WITH_SIMD) && defined(__mips__) 210 if (jsimd_can_idct_12x12()) 211 method_ptr = jsimd_idct_12x12; 212 else 213 #endif 214 method_ptr = _jpeg_idct_12x12; 215 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 216 break; 217 case 13: 218 method_ptr = _jpeg_idct_13x13; 219 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 220 break; 221 case 14: 222 method_ptr = _jpeg_idct_14x14; 223 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 224 break; 225 case 15: 226 method_ptr = _jpeg_idct_15x15; 227 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 228 break; 229 case 16: 230 method_ptr = _jpeg_idct_16x16; 231 method = JDCT_ISLOW; /* jidctint uses islow-style table */ 232 break; 233 #endif 234 default: 235 ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size); 236 break; 237 } 238 idct->pub._inverse_DCT[ci] = method_ptr; 239 /* Create multiplier table from quant table. 240 * However, we can skip this if the component is uninteresting 241 * or if we already built the table. Also, if no quant table 242 * has yet been saved for the component, we leave the 243 * multiplier table all-zero; we'll be reading zeroes from the 244 * coefficient controller's buffer anyway. 245 */ 246 if (!compptr->component_needed || idct->cur_method[ci] == method) 247 continue; 248 qtbl = compptr->quant_table; 249 if (qtbl == NULL) /* happens if no data yet for component */ 250 continue; 251 idct->cur_method[ci] = method; 252 switch (method) { 253 #ifdef PROVIDE_ISLOW_TABLES 254 case JDCT_ISLOW: 255 { 256 /* For LL&M IDCT method, multipliers are equal to raw quantization 257 * coefficients, but are stored as ints to ensure access efficiency. 258 */ 259 ISLOW_MULT_TYPE *ismtbl = (ISLOW_MULT_TYPE *)compptr->dct_table; 260 for (i = 0; i < DCTSIZE2; i++) { 261 ismtbl[i] = (ISLOW_MULT_TYPE)qtbl->quantval[i]; 262 } 263 } 264 break; 265 #endif 266 #ifdef DCT_IFAST_SUPPORTED 267 case JDCT_IFAST: 268 { 269 /* For AA&N IDCT method, multipliers are equal to quantization 270 * coefficients scaled by scalefactor[row]*scalefactor[col], where 271 * scalefactor[0] = 1 272 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 273 * For integer operation, the multiplier table is to be scaled by 274 * IFAST_SCALE_BITS. 275 */ 276 IFAST_MULT_TYPE *ifmtbl = (IFAST_MULT_TYPE *)compptr->dct_table; 277 #define CONST_BITS 14 278 static const INT16 aanscales[DCTSIZE2] = { 279 /* precomputed values scaled up by 14 bits */ 280 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 281 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, 282 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, 283 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, 284 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, 285 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, 286 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, 287 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 288 }; 289 SHIFT_TEMPS 290 291 for (i = 0; i < DCTSIZE2; i++) { 292 ifmtbl[i] = (IFAST_MULT_TYPE) 293 DESCALE(MULTIPLY16V16((JLONG)qtbl->quantval[i], 294 (JLONG)aanscales[i]), 295 CONST_BITS - IFAST_SCALE_BITS); 296 } 297 } 298 break; 299 #endif 300 #ifdef DCT_FLOAT_SUPPORTED 301 case JDCT_FLOAT: 302 { 303 /* For float AA&N IDCT method, multipliers are equal to quantization 304 * coefficients scaled by scalefactor[row]*scalefactor[col], where 305 * scalefactor[0] = 1 306 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 307 */ 308 FLOAT_MULT_TYPE *fmtbl = (FLOAT_MULT_TYPE *)compptr->dct_table; 309 int row, col; 310 static const double aanscalefactor[DCTSIZE] = { 311 1.0, 1.387039845, 1.306562965, 1.175875602, 312 1.0, 0.785694958, 0.541196100, 0.275899379 313 }; 314 315 i = 0; 316 for (row = 0; row < DCTSIZE; row++) { 317 for (col = 0; col < DCTSIZE; col++) { 318 fmtbl[i] = (FLOAT_MULT_TYPE) 319 ((double)qtbl->quantval[i] * 320 aanscalefactor[row] * aanscalefactor[col]); 321 i++; 322 } 323 } 324 } 325 break; 326 #endif 327 default: 328 ERREXIT(cinfo, JERR_NOT_COMPILED); 329 break; 330 } 331 } 332 } 333 334 335 /* 336 * Initialize IDCT manager. 337 */ 338 339 GLOBAL(void) 340 _jinit_inverse_dct(j_decompress_ptr cinfo) 341 { 342 my_idct_ptr idct; 343 int ci; 344 jpeg_component_info *compptr; 345 346 if (cinfo->data_precision != BITS_IN_JSAMPLE) 347 ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision); 348 349 idct = (my_idct_ptr) 350 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 351 sizeof(my_idct_controller)); 352 cinfo->idct = (struct jpeg_inverse_dct *)idct; 353 idct->pub.start_pass = start_pass; 354 355 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; 356 ci++, compptr++) { 357 /* Allocate and pre-zero a multiplier table for each component */ 358 compptr->dct_table = 359 (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE, 360 sizeof(multiplier_table)); 361 memset(compptr->dct_table, 0, sizeof(multiplier_table)); 362 /* Mark multiplier table not yet set up for any method */ 363 idct->cur_method[ci] = -1; 364 } 365 }