jddctmgr.c 12.6 KB
Newer Older
wester committed
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384
/*
 * jddctmgr.c
 *
 * Copyright (C) 1994-1996, Thomas G. Lane.
 * Modified 2002-2010 by Guido Vollbeding.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains the inverse-DCT management logic.
 * This code selects a particular IDCT implementation to be used,
 * and it performs related housekeeping chores.  No code in this file
 * is executed per IDCT step, only during output pass setup.
 *
 * Note that the IDCT routines are responsible for performing coefficient
 * dequantization as well as the IDCT proper.  This module sets up the
 * dequantization multiplier table needed by the IDCT routine.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jdct.h"		/* Private declarations for DCT subsystem */


/*
 * The decompressor input side (jdinput.c) saves away the appropriate
 * quantization table for each component at the start of the first scan
 * involving that component.  (This is necessary in order to correctly
 * decode files that reuse Q-table slots.)
 * When we are ready to make an output pass, the saved Q-table is converted
 * to a multiplier table that will actually be used by the IDCT routine.
 * The multiplier table contents are IDCT-method-dependent.  To support
 * application changes in IDCT method between scans, we can remake the
 * multiplier tables if necessary.
 * In buffered-image mode, the first output pass may occur before any data
 * has been seen for some components, and thus before their Q-tables have
 * been saved away.  To handle this case, multiplier tables are preset
 * to zeroes; the result of the IDCT will be a neutral gray level.
 */


/* Private subobject for this module */

typedef struct {
  struct jpeg_inverse_dct pub;	/* public fields */

  /* This array contains the IDCT method code that each multiplier table
   * is currently set up for, or -1 if it's not yet set up.
   * The actual multiplier tables are pointed to by dct_table in the
   * per-component comp_info structures.
   */
  int cur_method[MAX_COMPONENTS];
} my_idct_controller;

typedef my_idct_controller * my_idct_ptr;


/* Allocated multiplier tables: big enough for any supported variant */

typedef union {
  ISLOW_MULT_TYPE islow_array[DCTSIZE2];
#ifdef DCT_IFAST_SUPPORTED
  IFAST_MULT_TYPE ifast_array[DCTSIZE2];
#endif
#ifdef DCT_FLOAT_SUPPORTED
  FLOAT_MULT_TYPE float_array[DCTSIZE2];
#endif
} multiplier_table;


/* The current scaled-IDCT routines require ISLOW-style multiplier tables,
 * so be sure to compile that code if either ISLOW or SCALING is requested.
 */
#ifdef DCT_ISLOW_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#else
#ifdef IDCT_SCALING_SUPPORTED
#define PROVIDE_ISLOW_TABLES
#endif
#endif


/*
 * Prepare for an output pass.
 * Here we select the proper IDCT routine for each component and build
 * a matching multiplier table.
 */

METHODDEF(void)
start_pass (j_decompress_ptr cinfo)
{
  my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
  int ci, i;
  jpeg_component_info *compptr;
  int method = 0;
  inverse_DCT_method_ptr method_ptr = NULL;
  JQUANT_TBL * qtbl;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Select the proper IDCT routine for this component's scaling */
    switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) {
#ifdef IDCT_SCALING_SUPPORTED
    case ((1 << 8) + 1):
      method_ptr = jpeg_idct_1x1;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((2 << 8) + 2):
      method_ptr = jpeg_idct_2x2;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((3 << 8) + 3):
      method_ptr = jpeg_idct_3x3;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((4 << 8) + 4):
      method_ptr = jpeg_idct_4x4;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((5 << 8) + 5):
      method_ptr = jpeg_idct_5x5;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((6 << 8) + 6):
      method_ptr = jpeg_idct_6x6;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((7 << 8) + 7):
      method_ptr = jpeg_idct_7x7;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((9 << 8) + 9):
      method_ptr = jpeg_idct_9x9;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((10 << 8) + 10):
      method_ptr = jpeg_idct_10x10;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((11 << 8) + 11):
      method_ptr = jpeg_idct_11x11;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((12 << 8) + 12):
      method_ptr = jpeg_idct_12x12;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((13 << 8) + 13):
      method_ptr = jpeg_idct_13x13;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((14 << 8) + 14):
      method_ptr = jpeg_idct_14x14;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((15 << 8) + 15):
      method_ptr = jpeg_idct_15x15;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((16 << 8) + 16):
      method_ptr = jpeg_idct_16x16;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((16 << 8) + 8):
      method_ptr = jpeg_idct_16x8;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((14 << 8) + 7):
      method_ptr = jpeg_idct_14x7;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((12 << 8) + 6):
      method_ptr = jpeg_idct_12x6;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((10 << 8) + 5):
      method_ptr = jpeg_idct_10x5;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((8 << 8) + 4):
      method_ptr = jpeg_idct_8x4;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((6 << 8) + 3):
      method_ptr = jpeg_idct_6x3;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((4 << 8) + 2):
      method_ptr = jpeg_idct_4x2;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((2 << 8) + 1):
      method_ptr = jpeg_idct_2x1;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((8 << 8) + 16):
      method_ptr = jpeg_idct_8x16;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((7 << 8) + 14):
      method_ptr = jpeg_idct_7x14;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((6 << 8) + 12):
      method_ptr = jpeg_idct_6x12;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((5 << 8) + 10):
      method_ptr = jpeg_idct_5x10;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((4 << 8) + 8):
      method_ptr = jpeg_idct_4x8;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((3 << 8) + 6):
      method_ptr = jpeg_idct_3x6;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((2 << 8) + 4):
      method_ptr = jpeg_idct_2x4;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
    case ((1 << 8) + 2):
      method_ptr = jpeg_idct_1x2;
      method = JDCT_ISLOW;	/* jidctint uses islow-style table */
      break;
#endif
    case ((DCTSIZE << 8) + DCTSIZE):
      switch (cinfo->dct_method) {
#ifdef DCT_ISLOW_SUPPORTED
      case JDCT_ISLOW:
        method_ptr = jpeg_idct_islow;
        method = JDCT_ISLOW;
        break;
#endif
#ifdef DCT_IFAST_SUPPORTED
      case JDCT_IFAST:
        method_ptr = jpeg_idct_ifast;
        method = JDCT_IFAST;
        break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
      case JDCT_FLOAT:
        method_ptr = jpeg_idct_float;
        method = JDCT_FLOAT;
        break;
#endif
      default:
        ERREXIT(cinfo, JERR_NOT_COMPILED);
        break;
      }
      break;
    default:
      ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
               compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size);
      break;
    }
    idct->pub.inverse_DCT[ci] = method_ptr;
    /* Create multiplier table from quant table.
     * However, we can skip this if the component is uninteresting
     * or if we already built the table.  Also, if no quant table
     * has yet been saved for the component, we leave the
     * multiplier table all-zero; we'll be reading zeroes from the
     * coefficient controller's buffer anyway.
     */
    if (! compptr->component_needed || idct->cur_method[ci] == method)
      continue;
    qtbl = compptr->quant_table;
    if (qtbl == NULL)		/* happens if no data yet for component */
      continue;
    idct->cur_method[ci] = method;
    switch (method) {
#ifdef PROVIDE_ISLOW_TABLES
    case JDCT_ISLOW:
      {
        /* For LL&M IDCT method, multipliers are equal to raw quantization
         * coefficients, but are stored as ints to ensure access efficiency.
         */
        ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
        for (i = 0; i < DCTSIZE2; i++) {
          ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
        }
      }
      break;
#endif
#ifdef DCT_IFAST_SUPPORTED
    case JDCT_IFAST:
      {
        /* For AA&N IDCT method, multipliers are equal to quantization
         * coefficients scaled by scalefactor[row]*scalefactor[col], where
         *   scalefactor[0] = 1
         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
         * For integer operation, the multiplier table is to be scaled by
         * IFAST_SCALE_BITS.
         */
        IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
#define CONST_BITS 14
        static const INT16 aanscales[DCTSIZE2] = {
          /* precomputed values scaled up by 14 bits */
          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
          22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
          21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
          19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
          12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
           8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
           4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
        };
        SHIFT_TEMPS

        for (i = 0; i < DCTSIZE2; i++) {
          ifmtbl[i] = (IFAST_MULT_TYPE)
            DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
                                  (INT32) aanscales[i]),
                    CONST_BITS-IFAST_SCALE_BITS);
        }
      }
      break;
#endif
#ifdef DCT_FLOAT_SUPPORTED
    case JDCT_FLOAT:
      {
        /* For float AA&N IDCT method, multipliers are equal to quantization
         * coefficients scaled by scalefactor[row]*scalefactor[col], where
         *   scalefactor[0] = 1
         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
         * We apply a further scale factor of 1/8.
         */
        FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
        int row, col;
        static const double aanscalefactor[DCTSIZE] = {
          1.0, 1.387039845, 1.306562965, 1.175875602,
          1.0, 0.785694958, 0.541196100, 0.275899379
        };

        i = 0;
        for (row = 0; row < DCTSIZE; row++) {
          for (col = 0; col < DCTSIZE; col++) {
            fmtbl[i] = (FLOAT_MULT_TYPE)
              ((double) qtbl->quantval[i] *
               aanscalefactor[row] * aanscalefactor[col] * 0.125);
            i++;
          }
        }
      }
      break;
#endif
    default:
      ERREXIT(cinfo, JERR_NOT_COMPILED);
      break;
    }
  }
}


/*
 * Initialize IDCT manager.
 */

GLOBAL(void)
jinit_inverse_dct (j_decompress_ptr cinfo)
{
  my_idct_ptr idct;
  int ci;
  jpeg_component_info *compptr;

  idct = (my_idct_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                SIZEOF(my_idct_controller));
  cinfo->idct = (struct jpeg_inverse_dct *) idct;
  idct->pub.start_pass = start_pass;

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Allocate and pre-zero a multiplier table for each component */
    compptr->dct_table =
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                                  SIZEOF(multiplier_table));
    MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
    /* Mark multiplier table not yet set up for any method */
    idct->cur_method[ci] = -1;
  }
}