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| 1 /* | |
| 2 * jddctmgr.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 inverse-DCT management logic. | |
| 9 * This code selects a particular IDCT implementation to be used, | |
| 10 * and it performs related housekeeping chores. No code in this file | |
| 11 * is executed per IDCT step, only during output pass setup. | |
| 12 * | |
| 13 * Note that the IDCT routines are responsible for performing coefficient | |
| 14 * dequantization as well as the IDCT proper. This module sets up the | |
| 15 * dequantization multiplier table needed by the IDCT routine. | |
| 16 */ | |
| 17 | |
| 18 #define JPEG_INTERNALS | |
| 19 #include "jinclude.h" | |
| 20 #include "jpeglib.h" | |
| 21 #include "jdct.h" /* Private declarations for DCT subsystem */ | |
| 22 | |
| 23 | |
| 24 /* | |
| 25 * The decompressor input side (jdinput.c) saves away the appropriate | |
| 26 * quantization table for each component at the start of the first scan | |
| 27 * involving that component. (This is necessary in order to correctly | |
| 28 * decode files that reuse Q-table slots.) | |
| 29 * When we are ready to make an output pass, the saved Q-table is converted | |
| 30 * to a multiplier table that will actually be used by the IDCT routine. | |
| 31 * The multiplier table contents are IDCT-method-dependent. To support | |
| 32 * application changes in IDCT method between scans, we can remake the | |
| 33 * multiplier tables if necessary. | |
| 34 * In buffered-image mode, the first output pass may occur before any data | |
| 35 * has been seen for some components, and thus before their Q-tables have | |
| 36 * been saved away. To handle this case, multiplier tables are preset | |
| 37 * to zeroes; the result of the IDCT will be a neutral gray level. | |
| 38 */ | |
| 39 | |
| 40 | |
| 41 /* Private subobject for this module */ | |
| 42 | |
| 43 typedef struct { | |
| 44 struct jpeg_inverse_dct pub; /* public fields */ | |
| 45 | |
| 46 /* This array contains the IDCT method code that each multiplier table | |
| 47 * is currently set up for, or -1 if it's not yet set up. | |
| 48 * The actual multiplier tables are pointed to by dct_table in the | |
| 49 * per-component comp_info structures. | |
| 50 */ | |
| 51 int cur_method[MAX_COMPONENTS]; | |
| 52 } my_idct_controller; | |
| 53 | |
| 54 typedef my_idct_controller * my_idct_ptr; | |
| 55 | |
| 56 | |
| 57 /* Allocated multiplier tables: big enough for any supported variant */ | |
| 58 | |
| 59 typedef union { | |
| 60 ISLOW_MULT_TYPE islow_array[DCTSIZE2]; | |
| 61 #ifdef DCT_IFAST_SUPPORTED | |
| 62 IFAST_MULT_TYPE ifast_array[DCTSIZE2]; | |
| 63 #endif | |
| 64 #ifdef DCT_FLOAT_SUPPORTED | |
| 65 FLOAT_MULT_TYPE float_array[DCTSIZE2]; | |
| 66 #endif | |
| 67 } multiplier_table; | |
| 68 | |
| 69 | |
| 70 /* The current scaled-IDCT routines require ISLOW-style multiplier tables, | |
| 71 * so be sure to compile that code if either ISLOW or SCALING is requested. | |
| 72 */ | |
| 73 #ifdef DCT_ISLOW_SUPPORTED | |
| 74 #define PROVIDE_ISLOW_TABLES | |
| 75 #else | |
| 76 #ifdef IDCT_SCALING_SUPPORTED | |
| 77 #define PROVIDE_ISLOW_TABLES | |
| 78 #endif | |
| 79 #endif | |
| 80 | |
| 81 | |
| 82 /* | |
| 83 * Prepare for an output pass. | |
| 84 * Here we select the proper IDCT routine for each component and build | |
| 85 * a matching multiplier table. | |
| 86 */ | |
| 87 | |
| 88 METHODDEF(void) | |
| 89 start_pass (j_decompress_ptr cinfo) | |
| 90 { | |
| 91 my_idct_ptr idct = (my_idct_ptr) cinfo->idct; | |
| 92 int ci, i; | |
| 93 jpeg_component_info *compptr; | |
| 94 int method = 0; | |
| 95 inverse_DCT_method_ptr method_ptr = NULL; | |
| 96 JQUANT_TBL * qtbl; | |
| 97 | |
| 98 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
| 99 ci++, compptr++) { | |
| 100 /* Select the proper IDCT routine for this component's scaling */ | |
| 101 switch (compptr->DCT_scaled_size) { | |
| 102 #ifdef IDCT_SCALING_SUPPORTED | |
| 103 case 1: | |
| 104 method_ptr = jpeg_idct_1x1; | |
| 105 method = JDCT_ISLOW; /* jidctred uses islow-style table */ | |
| 106 break; | |
| 107 case 2: | |
| 108 method_ptr = jpeg_idct_2x2; | |
| 109 method = JDCT_ISLOW; /* jidctred uses islow-style table */ | |
| 110 break; | |
| 111 case 4: | |
| 112 method_ptr = jpeg_idct_4x4; | |
| 113 method = JDCT_ISLOW; /* jidctred uses islow-style table */ | |
| 114 break; | |
| 115 #endif | |
| 116 case DCTSIZE: | |
| 117 switch (cinfo->dct_method) { | |
| 118 #ifdef DCT_ISLOW_SUPPORTED | |
| 119 case JDCT_ISLOW: | |
| 120 method_ptr = jpeg_idct_islow; | |
| 121 method = JDCT_ISLOW; | |
| 122 break; | |
| 123 #endif | |
| 124 #ifdef DCT_IFAST_SUPPORTED | |
| 125 case JDCT_IFAST: | |
| 126 method_ptr = jpeg_idct_ifast; | |
| 127 method = JDCT_IFAST; | |
| 128 break; | |
| 129 #endif | |
| 130 #ifdef DCT_FLOAT_SUPPORTED | |
| 131 case JDCT_FLOAT: | |
| 132 method_ptr = jpeg_idct_float; | |
| 133 method = JDCT_FLOAT; | |
| 134 break; | |
| 135 #endif | |
| 136 default: | |
| 137 ERREXIT(cinfo, JERR_NOT_COMPILED); | |
| 138 break; | |
| 139 } | |
| 140 break; | |
| 141 default: | |
| 142 ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size); | |
| 143 break; | |
| 144 } | |
| 145 idct->pub.inverse_DCT[ci] = method_ptr; | |
| 146 /* Create multiplier table from quant table. | |
| 147 * However, we can skip this if the component is uninteresting | |
| 148 * or if we already built the table. Also, if no quant table | |
| 149 * has yet been saved for the component, we leave the | |
| 150 * multiplier table all-zero; we'll be reading zeroes from the | |
| 151 * coefficient controller's buffer anyway. | |
| 152 */ | |
| 153 if (! compptr->component_needed || idct->cur_method[ci] == method) | |
| 154 continue; | |
| 155 qtbl = compptr->quant_table; | |
| 156 if (qtbl == NULL) /* happens if no data yet for component */ | |
| 157 continue; | |
| 158 idct->cur_method[ci] = method; | |
| 159 switch (method) { | |
| 160 #ifdef PROVIDE_ISLOW_TABLES | |
| 161 case JDCT_ISLOW: | |
| 162 { | |
| 163 /* For LL&M IDCT method, multipliers are equal to raw quantization | |
| 164 * coefficients, but are stored as ints to ensure access efficiency. | |
| 165 */ | |
| 166 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table; | |
| 167 for (i = 0; i < DCTSIZE2; i++) { | |
| 168 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i]; | |
| 169 } | |
| 170 } | |
| 171 break; | |
| 172 #endif | |
| 173 #ifdef DCT_IFAST_SUPPORTED | |
| 174 case JDCT_IFAST: | |
| 175 { | |
| 176 /* For AA&N IDCT method, multipliers are equal to quantization | |
| 177 * coefficients scaled by scalefactor[row]*scalefactor[col], where | |
| 178 * scalefactor[0] = 1 | |
| 179 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 | |
| 180 * For integer operation, the multiplier table is to be scaled by | |
| 181 * IFAST_SCALE_BITS. | |
| 182 */ | |
| 183 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table; | |
| 184 #define CONST_BITS 14 | |
| 185 static const INT16 aanscales[DCTSIZE2] = { | |
| 186 /* precomputed values scaled up by 14 bits */ | |
| 187 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, | |
| 188 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270, | |
| 189 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906, | |
| 190 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315, | |
| 191 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520, | |
| 192 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552, | |
| 193 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446, | |
| 194 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247 | |
| 195 }; | |
| 196 SHIFT_TEMPS | |
| 197 | |
| 198 for (i = 0; i < DCTSIZE2; i++) { | |
| 199 ifmtbl[i] = (IFAST_MULT_TYPE) | |
| 200 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i], | |
| 201 (INT32) aanscales[i]), | |
| 202 CONST_BITS-IFAST_SCALE_BITS); | |
| 203 } | |
| 204 } | |
| 205 break; | |
| 206 #endif | |
| 207 #ifdef DCT_FLOAT_SUPPORTED | |
| 208 case JDCT_FLOAT: | |
| 209 { | |
| 210 /* For float AA&N IDCT method, multipliers are equal to quantization | |
| 211 * coefficients scaled by scalefactor[row]*scalefactor[col], where | |
| 212 * scalefactor[0] = 1 | |
| 213 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 | |
| 214 */ | |
| 215 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table; | |
| 216 int row, col; | |
| 217 static const double aanscalefactor[DCTSIZE] = { | |
| 218 1.0, 1.387039845, 1.306562965, 1.175875602, | |
| 219 1.0, 0.785694958, 0.541196100, 0.275899379 | |
| 220 }; | |
| 221 | |
| 222 i = 0; | |
| 223 for (row = 0; row < DCTSIZE; row++) { | |
| 224 for (col = 0; col < DCTSIZE; col++) { | |
| 225 fmtbl[i] = (FLOAT_MULT_TYPE) | |
| 226 ((double) qtbl->quantval[i] * | |
| 227 aanscalefactor[row] * aanscalefactor[col]); | |
| 228 i++; | |
| 229 } | |
| 230 } | |
| 231 } | |
| 232 break; | |
| 233 #endif | |
| 234 default: | |
| 235 ERREXIT(cinfo, JERR_NOT_COMPILED); | |
| 236 break; | |
| 237 } | |
| 238 } | |
| 239 } | |
| 240 | |
| 241 | |
| 242 /* | |
| 243 * Initialize IDCT manager. | |
| 244 */ | |
| 245 | |
| 246 GLOBAL(void) | |
| 247 jinit_inverse_dct (j_decompress_ptr cinfo) | |
| 248 { | |
| 249 my_idct_ptr idct; | |
| 250 int ci; | |
| 251 jpeg_component_info *compptr; | |
| 252 | |
| 253 idct = (my_idct_ptr) | |
| 254 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 255 SIZEOF(my_idct_controller)); | |
| 256 cinfo->idct = (struct jpeg_inverse_dct *) idct; | |
| 257 idct->pub.start_pass = start_pass; | |
| 258 | |
| 259 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; | |
| 260 ci++, compptr++) { | |
| 261 /* Allocate and pre-zero a multiplier table for each component */ | |
| 262 compptr->dct_table = | |
| 263 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
| 264 SIZEOF(multiplier_table)); | |
| 265 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table)); | |
| 266 /* Mark multiplier table not yet set up for any method */ | |
| 267 idct->cur_method[ci] = -1; | |
| 268 } | |
| 269 } | |
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Chromium Code Reviews
Issue 1705523002:
Remove libjpeg and libjpeg_turbo. (Closed)
Base URL: https://github.com/domokit/mojo.git@master