source: trunk/libjpeg/jddctmgr.c @ 283

Last change on this file since 283 was 283, checked in by rbri, 12 years ago

JPEG plugin: libjpeg updated to version 7

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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
43typedef 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
54typedef my_idct_controller * my_idct_ptr;
55
56
57/* Allocated multiplier tables: big enough for any supported variant */
58
59typedef 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
88METHODDEF(void)
89start_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_h_scaled_size << 8) + compptr->DCT_v_scaled_size) {
102#ifdef IDCT_SCALING_SUPPORTED
103    case ((1 << 8) + 1):
104      method_ptr = jpeg_idct_1x1;
105      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
106      break;
107    case ((2 << 8) + 2):
108      method_ptr = jpeg_idct_2x2;
109      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
110      break;
111    case ((3 << 8) + 3):
112      method_ptr = jpeg_idct_3x3;
113      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
114      break;
115    case ((4 << 8) + 4):
116      method_ptr = jpeg_idct_4x4;
117      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
118      break;
119    case ((5 << 8) + 5):
120      method_ptr = jpeg_idct_5x5;
121      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
122      break;
123    case ((6 << 8) + 6):
124      method_ptr = jpeg_idct_6x6;
125      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
126      break;
127    case ((7 << 8) + 7):
128      method_ptr = jpeg_idct_7x7;
129      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
130      break;
131    case ((9 << 8) + 9):
132      method_ptr = jpeg_idct_9x9;
133      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
134      break;
135    case ((10 << 8) + 10):
136      method_ptr = jpeg_idct_10x10;
137      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
138      break;
139    case ((11 << 8) + 11):
140      method_ptr = jpeg_idct_11x11;
141      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
142      break;
143    case ((12 << 8) + 12):
144      method_ptr = jpeg_idct_12x12;
145      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
146      break;
147    case ((13 << 8) + 13):
148      method_ptr = jpeg_idct_13x13;
149      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
150      break;
151    case ((14 << 8) + 14):
152      method_ptr = jpeg_idct_14x14;
153      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
154      break;
155    case ((15 << 8) + 15):
156      method_ptr = jpeg_idct_15x15;
157      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
158      break;
159    case ((16 << 8) + 16):
160      method_ptr = jpeg_idct_16x16;
161      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
162      break;
163    case ((16 << 8) + 8):
164      method_ptr = jpeg_idct_16x8;
165      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
166      break;
167    case ((14 << 8) + 7):
168      method_ptr = jpeg_idct_14x7;
169      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
170      break;
171    case ((12 << 8) + 6):
172      method_ptr = jpeg_idct_12x6;
173      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
174      break;
175    case ((10 << 8) + 5):
176      method_ptr = jpeg_idct_10x5;
177      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
178      break;
179    case ((8 << 8) + 4):
180      method_ptr = jpeg_idct_8x4;
181      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
182      break;
183    case ((6 << 8) + 3):
184      method_ptr = jpeg_idct_6x3;
185      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
186      break;
187    case ((4 << 8) + 2):
188      method_ptr = jpeg_idct_4x2;
189      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
190      break;
191    case ((2 << 8) + 1):
192      method_ptr = jpeg_idct_2x1;
193      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
194      break;
195    case ((8 << 8) + 16):
196      method_ptr = jpeg_idct_8x16;
197      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
198      break;
199    case ((7 << 8) + 14):
200      method_ptr = jpeg_idct_7x14;
201      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
202      break;
203    case ((6 << 8) + 12):
204      method_ptr = jpeg_idct_6x12;
205      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
206      break;
207    case ((5 << 8) + 10):
208      method_ptr = jpeg_idct_5x10;
209      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
210      break;
211    case ((4 << 8) + 8):
212      method_ptr = jpeg_idct_4x8;
213      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
214      break;
215    case ((3 << 8) + 6):
216      method_ptr = jpeg_idct_3x6;
217      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
218      break;
219    case ((2 << 8) + 4):
220      method_ptr = jpeg_idct_2x4;
221      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
222      break;
223    case ((1 << 8) + 2):
224      method_ptr = jpeg_idct_1x2;
225      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
226      break;
227#endif
228    case ((DCTSIZE << 8) + DCTSIZE):
229      switch (cinfo->dct_method) {
230#ifdef DCT_ISLOW_SUPPORTED
231      case JDCT_ISLOW:
232        method_ptr = jpeg_idct_islow;
233        method = JDCT_ISLOW;
234        break;
235#endif
236#ifdef DCT_IFAST_SUPPORTED
237      case JDCT_IFAST:
238        method_ptr = jpeg_idct_ifast;
239        method = JDCT_IFAST;
240        break;
241#endif
242#ifdef DCT_FLOAT_SUPPORTED
243      case JDCT_FLOAT:
244        method_ptr = jpeg_idct_float;
245        method = JDCT_FLOAT;
246        break;
247#endif
248      default:
249        ERREXIT(cinfo, JERR_NOT_COMPILED);
250        break;
251      }
252      break;
253    default:
254      ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
255               compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size);
256      break;
257    }
258    idct->pub.inverse_DCT[ci] = method_ptr;
259    /* Create multiplier table from quant table.
260     * However, we can skip this if the component is uninteresting
261     * or if we already built the table.  Also, if no quant table
262     * has yet been saved for the component, we leave the
263     * multiplier table all-zero; we'll be reading zeroes from the
264     * coefficient controller's buffer anyway.
265     */
266    if (! compptr->component_needed || idct->cur_method[ci] == method)
267      continue;
268    qtbl = compptr->quant_table;
269    if (qtbl == NULL)           /* happens if no data yet for component */
270      continue;
271    idct->cur_method[ci] = method;
272    switch (method) {
273#ifdef PROVIDE_ISLOW_TABLES
274    case JDCT_ISLOW:
275      {
276        /* For LL&M IDCT method, multipliers are equal to raw quantization
277         * coefficients, but are stored as ints to ensure access efficiency.
278         */
279        ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
280        for (i = 0; i < DCTSIZE2; i++) {
281          ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
282        }
283      }
284      break;
285#endif
286#ifdef DCT_IFAST_SUPPORTED
287    case JDCT_IFAST:
288      {
289        /* For AA&N IDCT method, multipliers are equal to quantization
290         * coefficients scaled by scalefactor[row]*scalefactor[col], where
291         *   scalefactor[0] = 1
292         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
293         * For integer operation, the multiplier table is to be scaled by
294         * IFAST_SCALE_BITS.
295         */
296        IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
297#define CONST_BITS 14
298        static const INT16 aanscales[DCTSIZE2] = {
299          /* precomputed values scaled up by 14 bits */
300          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
301          22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
302          21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
303          19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
304          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
305          12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
306           8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
307           4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
308        };
309        SHIFT_TEMPS
310
311        for (i = 0; i < DCTSIZE2; i++) {
312          ifmtbl[i] = (IFAST_MULT_TYPE)
313            DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
314                                  (INT32) aanscales[i]),
315                    CONST_BITS-IFAST_SCALE_BITS);
316        }
317      }
318      break;
319#endif
320#ifdef DCT_FLOAT_SUPPORTED
321    case JDCT_FLOAT:
322      {
323        /* For float AA&N IDCT method, multipliers are equal to quantization
324         * coefficients scaled by scalefactor[row]*scalefactor[col], where
325         *   scalefactor[0] = 1
326         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
327         */
328        FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
329        int row, col;
330        static const double aanscalefactor[DCTSIZE] = {
331          1.0, 1.387039845, 1.306562965, 1.175875602,
332          1.0, 0.785694958, 0.541196100, 0.275899379
333        };
334
335        i = 0;
336        for (row = 0; row < DCTSIZE; row++) {
337          for (col = 0; col < DCTSIZE; col++) {
338            fmtbl[i] = (FLOAT_MULT_TYPE)
339              ((double) qtbl->quantval[i] *
340               aanscalefactor[row] * aanscalefactor[col]);
341            i++;
342          }
343        }
344      }
345      break;
346#endif
347    default:
348      ERREXIT(cinfo, JERR_NOT_COMPILED);
349      break;
350    }
351  }
352}
353
354
355/*
356 * Initialize IDCT manager.
357 */
358
359GLOBAL(void)
360jinit_inverse_dct (j_decompress_ptr cinfo)
361{
362  my_idct_ptr idct;
363  int ci;
364  jpeg_component_info *compptr;
365
366  idct = (my_idct_ptr)
367    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
368                                SIZEOF(my_idct_controller));
369  cinfo->idct = (struct jpeg_inverse_dct *) idct;
370  idct->pub.start_pass = start_pass;
371
372  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
373       ci++, compptr++) {
374    /* Allocate and pre-zero a multiplier table for each component */
375    compptr->dct_table =
376      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
377                                  SIZEOF(multiplier_table));
378    MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
379    /* Mark multiplier table not yet set up for any method */
380    idct->cur_method[ci] = -1;
381  }
382}
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