dbf-halloween2015

annotate libs/libjpeg/jddctmgr.c @ 3:c37fe5d8a4ed

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windows port
author John Tsiombikas <nuclear@member.fsf.org>
date Sun, 01 Nov 2015 06:04:28 +0200
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nuclear@1 1 /*
nuclear@1 2 * jddctmgr.c
nuclear@1 3 *
nuclear@1 4 * Copyright (C) 1994-1996, Thomas G. Lane.
nuclear@1 5 * This file is part of the Independent JPEG Group's software.
nuclear@1 6 * For conditions of distribution and use, see the accompanying README file.
nuclear@1 7 *
nuclear@1 8 * This file contains the inverse-DCT management logic.
nuclear@1 9 * This code selects a particular IDCT implementation to be used,
nuclear@1 10 * and it performs related housekeeping chores. No code in this file
nuclear@1 11 * is executed per IDCT step, only during output pass setup.
nuclear@1 12 *
nuclear@1 13 * Note that the IDCT routines are responsible for performing coefficient
nuclear@1 14 * dequantization as well as the IDCT proper. This module sets up the
nuclear@1 15 * dequantization multiplier table needed by the IDCT routine.
nuclear@1 16 */
nuclear@1 17
nuclear@1 18 #define JPEG_INTERNALS
nuclear@1 19 #include "jinclude.h"
nuclear@1 20 #include "jpeglib.h"
nuclear@1 21 #include "jdct.h" /* Private declarations for DCT subsystem */
nuclear@1 22
nuclear@1 23
nuclear@1 24 /*
nuclear@1 25 * The decompressor input side (jdinput.c) saves away the appropriate
nuclear@1 26 * quantization table for each component at the start of the first scan
nuclear@1 27 * involving that component. (This is necessary in order to correctly
nuclear@1 28 * decode files that reuse Q-table slots.)
nuclear@1 29 * When we are ready to make an output pass, the saved Q-table is converted
nuclear@1 30 * to a multiplier table that will actually be used by the IDCT routine.
nuclear@1 31 * The multiplier table contents are IDCT-method-dependent. To support
nuclear@1 32 * application changes in IDCT method between scans, we can remake the
nuclear@1 33 * multiplier tables if necessary.
nuclear@1 34 * In buffered-image mode, the first output pass may occur before any data
nuclear@1 35 * has been seen for some components, and thus before their Q-tables have
nuclear@1 36 * been saved away. To handle this case, multiplier tables are preset
nuclear@1 37 * to zeroes; the result of the IDCT will be a neutral gray level.
nuclear@1 38 */
nuclear@1 39
nuclear@1 40
nuclear@1 41 /* Private subobject for this module */
nuclear@1 42
nuclear@1 43 typedef struct {
nuclear@1 44 struct jpeg_inverse_dct pub; /* public fields */
nuclear@1 45
nuclear@1 46 /* This array contains the IDCT method code that each multiplier table
nuclear@1 47 * is currently set up for, or -1 if it's not yet set up.
nuclear@1 48 * The actual multiplier tables are pointed to by dct_table in the
nuclear@1 49 * per-component comp_info structures.
nuclear@1 50 */
nuclear@1 51 int cur_method[MAX_COMPONENTS];
nuclear@1 52 } my_idct_controller;
nuclear@1 53
nuclear@1 54 typedef my_idct_controller * my_idct_ptr;
nuclear@1 55
nuclear@1 56
nuclear@1 57 /* Allocated multiplier tables: big enough for any supported variant */
nuclear@1 58
nuclear@1 59 typedef union {
nuclear@1 60 ISLOW_MULT_TYPE islow_array[DCTSIZE2];
nuclear@1 61 #ifdef DCT_IFAST_SUPPORTED
nuclear@1 62 IFAST_MULT_TYPE ifast_array[DCTSIZE2];
nuclear@1 63 #endif
nuclear@1 64 #ifdef DCT_FLOAT_SUPPORTED
nuclear@1 65 FLOAT_MULT_TYPE float_array[DCTSIZE2];
nuclear@1 66 #endif
nuclear@1 67 } multiplier_table;
nuclear@1 68
nuclear@1 69
nuclear@1 70 /* The current scaled-IDCT routines require ISLOW-style multiplier tables,
nuclear@1 71 * so be sure to compile that code if either ISLOW or SCALING is requested.
nuclear@1 72 */
nuclear@1 73 #ifdef DCT_ISLOW_SUPPORTED
nuclear@1 74 #define PROVIDE_ISLOW_TABLES
nuclear@1 75 #else
nuclear@1 76 #ifdef IDCT_SCALING_SUPPORTED
nuclear@1 77 #define PROVIDE_ISLOW_TABLES
nuclear@1 78 #endif
nuclear@1 79 #endif
nuclear@1 80
nuclear@1 81
nuclear@1 82 /*
nuclear@1 83 * Prepare for an output pass.
nuclear@1 84 * Here we select the proper IDCT routine for each component and build
nuclear@1 85 * a matching multiplier table.
nuclear@1 86 */
nuclear@1 87
nuclear@1 88 METHODDEF(void)
nuclear@1 89 start_pass (j_decompress_ptr cinfo)
nuclear@1 90 {
nuclear@1 91 my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
nuclear@1 92 int ci, i;
nuclear@1 93 jpeg_component_info *compptr;
nuclear@1 94 int method = 0;
nuclear@1 95 inverse_DCT_method_ptr method_ptr = NULL;
nuclear@1 96 JQUANT_TBL * qtbl;
nuclear@1 97
nuclear@1 98 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@1 99 ci++, compptr++) {
nuclear@1 100 /* Select the proper IDCT routine for this component's scaling */
nuclear@1 101 switch (compptr->DCT_scaled_size) {
nuclear@1 102 #ifdef IDCT_SCALING_SUPPORTED
nuclear@1 103 case 1:
nuclear@1 104 method_ptr = jpeg_idct_1x1;
nuclear@1 105 method = JDCT_ISLOW; /* jidctred uses islow-style table */
nuclear@1 106 break;
nuclear@1 107 case 2:
nuclear@1 108 method_ptr = jpeg_idct_2x2;
nuclear@1 109 method = JDCT_ISLOW; /* jidctred uses islow-style table */
nuclear@1 110 break;
nuclear@1 111 case 4:
nuclear@1 112 method_ptr = jpeg_idct_4x4;
nuclear@1 113 method = JDCT_ISLOW; /* jidctred uses islow-style table */
nuclear@1 114 break;
nuclear@1 115 #endif
nuclear@1 116 case DCTSIZE:
nuclear@1 117 switch (cinfo->dct_method) {
nuclear@1 118 #ifdef DCT_ISLOW_SUPPORTED
nuclear@1 119 case JDCT_ISLOW:
nuclear@1 120 method_ptr = jpeg_idct_islow;
nuclear@1 121 method = JDCT_ISLOW;
nuclear@1 122 break;
nuclear@1 123 #endif
nuclear@1 124 #ifdef DCT_IFAST_SUPPORTED
nuclear@1 125 case JDCT_IFAST:
nuclear@1 126 method_ptr = jpeg_idct_ifast;
nuclear@1 127 method = JDCT_IFAST;
nuclear@1 128 break;
nuclear@1 129 #endif
nuclear@1 130 #ifdef DCT_FLOAT_SUPPORTED
nuclear@1 131 case JDCT_FLOAT:
nuclear@1 132 method_ptr = jpeg_idct_float;
nuclear@1 133 method = JDCT_FLOAT;
nuclear@1 134 break;
nuclear@1 135 #endif
nuclear@1 136 default:
nuclear@1 137 ERREXIT(cinfo, JERR_NOT_COMPILED);
nuclear@1 138 break;
nuclear@1 139 }
nuclear@1 140 break;
nuclear@1 141 default:
nuclear@1 142 ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
nuclear@1 143 break;
nuclear@1 144 }
nuclear@1 145 idct->pub.inverse_DCT[ci] = method_ptr;
nuclear@1 146 /* Create multiplier table from quant table.
nuclear@1 147 * However, we can skip this if the component is uninteresting
nuclear@1 148 * or if we already built the table. Also, if no quant table
nuclear@1 149 * has yet been saved for the component, we leave the
nuclear@1 150 * multiplier table all-zero; we'll be reading zeroes from the
nuclear@1 151 * coefficient controller's buffer anyway.
nuclear@1 152 */
nuclear@1 153 if (! compptr->component_needed || idct->cur_method[ci] == method)
nuclear@1 154 continue;
nuclear@1 155 qtbl = compptr->quant_table;
nuclear@1 156 if (qtbl == NULL) /* happens if no data yet for component */
nuclear@1 157 continue;
nuclear@1 158 idct->cur_method[ci] = method;
nuclear@1 159 switch (method) {
nuclear@1 160 #ifdef PROVIDE_ISLOW_TABLES
nuclear@1 161 case JDCT_ISLOW:
nuclear@1 162 {
nuclear@1 163 /* For LL&M IDCT method, multipliers are equal to raw quantization
nuclear@1 164 * coefficients, but are stored as ints to ensure access efficiency.
nuclear@1 165 */
nuclear@1 166 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
nuclear@1 167 for (i = 0; i < DCTSIZE2; i++) {
nuclear@1 168 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
nuclear@1 169 }
nuclear@1 170 }
nuclear@1 171 break;
nuclear@1 172 #endif
nuclear@1 173 #ifdef DCT_IFAST_SUPPORTED
nuclear@1 174 case JDCT_IFAST:
nuclear@1 175 {
nuclear@1 176 /* For AA&N IDCT method, multipliers are equal to quantization
nuclear@1 177 * coefficients scaled by scalefactor[row]*scalefactor[col], where
nuclear@1 178 * scalefactor[0] = 1
nuclear@1 179 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
nuclear@1 180 * For integer operation, the multiplier table is to be scaled by
nuclear@1 181 * IFAST_SCALE_BITS.
nuclear@1 182 */
nuclear@1 183 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
nuclear@1 184 #define CONST_BITS 14
nuclear@1 185 static const INT16 aanscales[DCTSIZE2] = {
nuclear@1 186 /* precomputed values scaled up by 14 bits */
nuclear@1 187 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
nuclear@1 188 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
nuclear@1 189 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
nuclear@1 190 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
nuclear@1 191 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
nuclear@1 192 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
nuclear@1 193 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
nuclear@1 194 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
nuclear@1 195 };
nuclear@1 196 SHIFT_TEMPS
nuclear@1 197
nuclear@1 198 for (i = 0; i < DCTSIZE2; i++) {
nuclear@1 199 ifmtbl[i] = (IFAST_MULT_TYPE)
nuclear@1 200 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
nuclear@1 201 (INT32) aanscales[i]),
nuclear@1 202 CONST_BITS-IFAST_SCALE_BITS);
nuclear@1 203 }
nuclear@1 204 }
nuclear@1 205 break;
nuclear@1 206 #endif
nuclear@1 207 #ifdef DCT_FLOAT_SUPPORTED
nuclear@1 208 case JDCT_FLOAT:
nuclear@1 209 {
nuclear@1 210 /* For float AA&N IDCT method, multipliers are equal to quantization
nuclear@1 211 * coefficients scaled by scalefactor[row]*scalefactor[col], where
nuclear@1 212 * scalefactor[0] = 1
nuclear@1 213 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
nuclear@1 214 */
nuclear@1 215 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
nuclear@1 216 int row, col;
nuclear@1 217 static const double aanscalefactor[DCTSIZE] = {
nuclear@1 218 1.0, 1.387039845, 1.306562965, 1.175875602,
nuclear@1 219 1.0, 0.785694958, 0.541196100, 0.275899379
nuclear@1 220 };
nuclear@1 221
nuclear@1 222 i = 0;
nuclear@1 223 for (row = 0; row < DCTSIZE; row++) {
nuclear@1 224 for (col = 0; col < DCTSIZE; col++) {
nuclear@1 225 fmtbl[i] = (FLOAT_MULT_TYPE)
nuclear@1 226 ((double) qtbl->quantval[i] *
nuclear@1 227 aanscalefactor[row] * aanscalefactor[col]);
nuclear@1 228 i++;
nuclear@1 229 }
nuclear@1 230 }
nuclear@1 231 }
nuclear@1 232 break;
nuclear@1 233 #endif
nuclear@1 234 default:
nuclear@1 235 ERREXIT(cinfo, JERR_NOT_COMPILED);
nuclear@1 236 break;
nuclear@1 237 }
nuclear@1 238 }
nuclear@1 239 }
nuclear@1 240
nuclear@1 241
nuclear@1 242 /*
nuclear@1 243 * Initialize IDCT manager.
nuclear@1 244 */
nuclear@1 245
nuclear@1 246 GLOBAL(void)
nuclear@1 247 jinit_inverse_dct (j_decompress_ptr cinfo)
nuclear@1 248 {
nuclear@1 249 my_idct_ptr idct;
nuclear@1 250 int ci;
nuclear@1 251 jpeg_component_info *compptr;
nuclear@1 252
nuclear@1 253 idct = (my_idct_ptr)
nuclear@1 254 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 255 SIZEOF(my_idct_controller));
nuclear@1 256 cinfo->idct = (struct jpeg_inverse_dct *) idct;
nuclear@1 257 idct->pub.start_pass = start_pass;
nuclear@1 258
nuclear@1 259 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
nuclear@1 260 ci++, compptr++) {
nuclear@1 261 /* Allocate and pre-zero a multiplier table for each component */
nuclear@1 262 compptr->dct_table =
nuclear@1 263 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
nuclear@1 264 SIZEOF(multiplier_table));
nuclear@1 265 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
nuclear@1 266 /* Mark multiplier table not yet set up for any method */
nuclear@1 267 idct->cur_method[ci] = -1;
nuclear@1 268 }
nuclear@1 269 }