1/*
2 * jddctmgr.c
3 *
4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * Modified 2002-2010 by Guido Vollbeding.
7 * libjpeg-turbo Modifications:
8 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB
9 * Copyright (C) 2010, 2015, D. R. Commander.
10 * Copyright (C) 2013, MIPS Technologies, Inc., California.
11 * For conditions of distribution and use, see the accompanying README.ijg
12 * file.
13 *
14 * This file contains the inverse-DCT management logic.
15 * This code selects a particular IDCT implementation to be used,
16 * and it performs related housekeeping chores.  No code in this file
17 * is executed per IDCT step, only during output pass setup.
18 *
19 * Note that the IDCT routines are responsible for performing coefficient
20 * dequantization as well as the IDCT proper.  This module sets up the
21 * dequantization multiplier table needed by the IDCT routine.
22 */
23
24#define JPEG_INTERNALS
25#include "jinclude.h"
26#include "jpeglib.h"
27#include "jdct.h"               /* Private declarations for DCT subsystem */
28#include "jsimddct.h"
29#include "jpegcomp.h"
30
31
32/*
33 * The decompressor input side (jdinput.c) saves away the appropriate
34 * quantization table for each component at the start of the first scan
35 * involving that component.  (This is necessary in order to correctly
36 * decode files that reuse Q-table slots.)
37 * When we are ready to make an output pass, the saved Q-table is converted
38 * to a multiplier table that will actually be used by the IDCT routine.
39 * The multiplier table contents are IDCT-method-dependent.  To support
40 * application changes in IDCT method between scans, we can remake the
41 * multiplier tables if necessary.
42 * In buffered-image mode, the first output pass may occur before any data
43 * has been seen for some components, and thus before their Q-tables have
44 * been saved away.  To handle this case, multiplier tables are preset
45 * to zeroes; the result of the IDCT will be a neutral gray level.
46 */
47
48
49/* Private subobject for this module */
50
51typedef struct {
52  struct jpeg_inverse_dct pub;  /* public fields */
53
54  /* This array contains the IDCT method code that each multiplier table
55   * is currently set up for, or -1 if it's not yet set up.
56   * The actual multiplier tables are pointed to by dct_table in the
57   * per-component comp_info structures.
58   */
59  int cur_method[MAX_COMPONENTS];
60} my_idct_controller;
61
62typedef my_idct_controller *my_idct_ptr;
63
64
65/* Allocated multiplier tables: big enough for any supported variant */
66
67typedef union {
68  ISLOW_MULT_TYPE islow_array[DCTSIZE2];
69#ifdef DCT_IFAST_SUPPORTED
70  IFAST_MULT_TYPE ifast_array[DCTSIZE2];
71#endif
72#ifdef DCT_FLOAT_SUPPORTED
73  FLOAT_MULT_TYPE float_array[DCTSIZE2];
74#endif
75} multiplier_table;
76
77
78/* The current scaled-IDCT routines require ISLOW-style multiplier tables,
79 * so be sure to compile that code if either ISLOW or SCALING is requested.
80 */
81#ifdef DCT_ISLOW_SUPPORTED
82#define PROVIDE_ISLOW_TABLES
83#else
84#ifdef IDCT_SCALING_SUPPORTED
85#define PROVIDE_ISLOW_TABLES
86#endif
87#endif
88
89
90/*
91 * Prepare for an output pass.
92 * Here we select the proper IDCT routine for each component and build
93 * a matching multiplier table.
94 */
95
96METHODDEF(void)
97start_pass (j_decompress_ptr cinfo)
98{
99  my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
100  int ci, i;
101  jpeg_component_info *compptr;
102  int method = 0;
103  inverse_DCT_method_ptr method_ptr = NULL;
104  JQUANT_TBL *qtbl;
105
106  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
107       ci++, compptr++) {
108    /* Select the proper IDCT routine for this component's scaling */
109    switch (compptr->_DCT_scaled_size) {
110#ifdef IDCT_SCALING_SUPPORTED
111    case 1:
112      method_ptr = jpeg_idct_1x1;
113      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
114      break;
115    case 2:
116      if (jsimd_can_idct_2x2())
117        method_ptr = jsimd_idct_2x2;
118      else
119        method_ptr = jpeg_idct_2x2;
120      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
121      break;
122    case 3:
123      method_ptr = jpeg_idct_3x3;
124      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
125      break;
126    case 4:
127      if (jsimd_can_idct_4x4())
128        method_ptr = jsimd_idct_4x4;
129      else
130        method_ptr = jpeg_idct_4x4;
131      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
132      break;
133    case 5:
134      method_ptr = jpeg_idct_5x5;
135      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
136      break;
137    case 6:
138#if defined(__mips__)
139      if (jsimd_can_idct_6x6())
140        method_ptr = jsimd_idct_6x6;
141      else
142#endif
143      method_ptr = jpeg_idct_6x6;
144      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
145      break;
146    case 7:
147      method_ptr = jpeg_idct_7x7;
148      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
149      break;
150#endif
151    case DCTSIZE:
152      switch (cinfo->dct_method) {
153#ifdef DCT_ISLOW_SUPPORTED
154      case JDCT_ISLOW:
155        if (jsimd_can_idct_islow())
156          method_ptr = jsimd_idct_islow;
157        else
158          method_ptr = jpeg_idct_islow;
159        method = JDCT_ISLOW;
160        break;
161#endif
162#ifdef DCT_IFAST_SUPPORTED
163      case JDCT_IFAST:
164        if (jsimd_can_idct_ifast())
165          method_ptr = jsimd_idct_ifast;
166        else
167          method_ptr = jpeg_idct_ifast;
168        method = JDCT_IFAST;
169        break;
170#endif
171#ifdef DCT_FLOAT_SUPPORTED
172      case JDCT_FLOAT:
173        if (jsimd_can_idct_float())
174          method_ptr = jsimd_idct_float;
175        else
176          method_ptr = jpeg_idct_float;
177        method = JDCT_FLOAT;
178        break;
179#endif
180      default:
181        ERREXIT(cinfo, JERR_NOT_COMPILED);
182        break;
183      }
184      break;
185#ifdef IDCT_SCALING_SUPPORTED
186    case 9:
187      method_ptr = jpeg_idct_9x9;
188      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
189      break;
190    case 10:
191      method_ptr = jpeg_idct_10x10;
192      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
193      break;
194    case 11:
195      method_ptr = jpeg_idct_11x11;
196      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
197      break;
198    case 12:
199#if defined(__mips__)
200      if (jsimd_can_idct_12x12())
201        method_ptr = jsimd_idct_12x12;
202      else
203#endif
204      method_ptr = jpeg_idct_12x12;
205      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
206      break;
207    case 13:
208      method_ptr = jpeg_idct_13x13;
209      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
210      break;
211    case 14:
212      method_ptr = jpeg_idct_14x14;
213      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
214      break;
215    case 15:
216      method_ptr = jpeg_idct_15x15;
217      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
218      break;
219    case 16:
220      method_ptr = jpeg_idct_16x16;
221      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
222      break;
223#endif
224    default:
225      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size);
226      break;
227    }
228    idct->pub.inverse_DCT[ci] = method_ptr;
229    /* Create multiplier table from quant table.
230     * However, we can skip this if the component is uninteresting
231     * or if we already built the table.  Also, if no quant table
232     * has yet been saved for the component, we leave the
233     * multiplier table all-zero; we'll be reading zeroes from the
234     * coefficient controller's buffer anyway.
235     */
236    if (! compptr->component_needed || idct->cur_method[ci] == method)
237      continue;
238    qtbl = compptr->quant_table;
239    if (qtbl == NULL)           /* happens if no data yet for component */
240      continue;
241    idct->cur_method[ci] = method;
242    switch (method) {
243#ifdef PROVIDE_ISLOW_TABLES
244    case JDCT_ISLOW:
245      {
246        /* For LL&M IDCT method, multipliers are equal to raw quantization
247         * coefficients, but are stored as ints to ensure access efficiency.
248         */
249        ISLOW_MULT_TYPE *ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
250        for (i = 0; i < DCTSIZE2; i++) {
251          ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
252        }
253      }
254      break;
255#endif
256#ifdef DCT_IFAST_SUPPORTED
257    case JDCT_IFAST:
258      {
259        /* For AA&N IDCT method, multipliers are equal to quantization
260         * coefficients scaled by scalefactor[row]*scalefactor[col], where
261         *   scalefactor[0] = 1
262         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
263         * For integer operation, the multiplier table is to be scaled by
264         * IFAST_SCALE_BITS.
265         */
266        IFAST_MULT_TYPE *ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
267#define CONST_BITS 14
268        static const INT16 aanscales[DCTSIZE2] = {
269          /* precomputed values scaled up by 14 bits */
270          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
271          22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
272          21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
273          19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
274          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
275          12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
276           8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
277           4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
278        };
279        SHIFT_TEMPS
280
281        for (i = 0; i < DCTSIZE2; i++) {
282          ifmtbl[i] = (IFAST_MULT_TYPE)
283            DESCALE(MULTIPLY16V16((JLONG) qtbl->quantval[i],
284                                  (JLONG) aanscales[i]),
285                    CONST_BITS-IFAST_SCALE_BITS);
286        }
287      }
288      break;
289#endif
290#ifdef DCT_FLOAT_SUPPORTED
291    case JDCT_FLOAT:
292      {
293        /* For float AA&N IDCT method, multipliers are equal to quantization
294         * coefficients scaled by scalefactor[row]*scalefactor[col], where
295         *   scalefactor[0] = 1
296         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
297         */
298        FLOAT_MULT_TYPE *fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
299        int row, col;
300        static const double aanscalefactor[DCTSIZE] = {
301          1.0, 1.387039845, 1.306562965, 1.175875602,
302          1.0, 0.785694958, 0.541196100, 0.275899379
303        };
304
305        i = 0;
306        for (row = 0; row < DCTSIZE; row++) {
307          for (col = 0; col < DCTSIZE; col++) {
308            fmtbl[i] = (FLOAT_MULT_TYPE)
309              ((double) qtbl->quantval[i] *
310               aanscalefactor[row] * aanscalefactor[col]);
311            i++;
312          }
313        }
314      }
315      break;
316#endif
317    default:
318      ERREXIT(cinfo, JERR_NOT_COMPILED);
319      break;
320    }
321  }
322}
323
324
325/*
326 * Initialize IDCT manager.
327 */
328
329GLOBAL(void)
330jinit_inverse_dct (j_decompress_ptr cinfo)
331{
332  my_idct_ptr idct;
333  int ci;
334  jpeg_component_info *compptr;
335
336  idct = (my_idct_ptr)
337    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
338                                sizeof(my_idct_controller));
339  cinfo->idct = (struct jpeg_inverse_dct *) idct;
340  idct->pub.start_pass = start_pass;
341
342  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
343       ci++, compptr++) {
344    /* Allocate and pre-zero a multiplier table for each component */
345    compptr->dct_table =
346      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
347                                  sizeof(multiplier_table));
348    MEMZERO(compptr->dct_table, sizeof(multiplier_table));
349    /* Mark multiplier table not yet set up for any method */
350    idct->cur_method[ci] = -1;
351  }
352}
353