workbench/libs/jpeg/jddctmgr.c

   1 /*
   2  * jddctmgr.c
   3  *
   4  * Copyright (C) 1994-1996, Thomas G. Lane.
   5  * Modified 2002-2013 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
  44 typedef 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
  55 typedef my_idct_controller * my_idct_ptr;
  56
  57
  58 /* Allocated multiplier tables: big enough for any supported variant */
  59
  60 typedef 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
  89 METHODDEF(void)
  90 start_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
 361 GLOBAL(void)
 362 jinit_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 = &idct->pub;
 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 }