summaryrefslogtreecommitdiff
path: root/src/jpeg-8c/jddctmgr.c
blob: 0ded9d574132feb341b1fbee706be3a678e98e2a (plain)
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;
  }
}