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, D. R. Commander.
10 * Copyright (C) 2013, MIPS Technologies, Inc., California
11 * For conditions of distribution and use, see the accompanying README file.
12 *
13 * This file contains the inverse-DCT management logic.
14 * This code selects a particular IDCT implementation to be used,
15 * and it performs related housekeeping chores.  No code in this file
16 * is executed per IDCT step, only during output pass setup.
17 *
18 * Note that the IDCT routines are responsible for performing coefficient
19 * dequantization as well as the IDCT proper.  This module sets up the
20 * dequantization multiplier table needed by the IDCT routine.
21 */
22
23#define JPEG_INTERNALS
24#include "jinclude.h"
25#include "jpeglib.h"
26#include "jdct.h"               /* Private declarations for DCT subsystem */
27#include "jsimddct.h"
28#include "jpegcomp.h"
29
30
31/*
32 * The decompressor input side (jdinput.c) saves away the appropriate
33 * quantization table for each component at the start of the first scan
34 * involving that component.  (This is necessary in order to correctly
35 * decode files that reuse Q-table slots.)
36 * When we are ready to make an output pass, the saved Q-table is converted
37 * to a multiplier table that will actually be used by the IDCT routine.
38 * The multiplier table contents are IDCT-method-dependent.  To support
39 * application changes in IDCT method between scans, we can remake the
40 * multiplier tables if necessary.
41 * In buffered-image mode, the first output pass may occur before any data
42 * has been seen for some components, and thus before their Q-tables have
43 * been saved away.  To handle this case, multiplier tables are preset
44 * to zeroes; the result of the IDCT will be a neutral gray level.
45 */
46
47
48/* Private subobject for this module */
49
50typedef struct {
51  struct jpeg_inverse_dct pub;  /* public fields */
52
53  /* This array contains the IDCT method code that each multiplier table
54   * is currently set up for, or -1 if it's not yet set up.
55   * The actual multiplier tables are pointed to by dct_table in the
56   * per-component comp_info structures.
57   */
58  int cur_method[MAX_COMPONENTS];
59} my_idct_controller;
60
61typedef my_idct_controller * my_idct_ptr;
62
63
64/* Allocated multiplier tables: big enough for any supported variant */
65
66typedef union {
67  ISLOW_MULT_TYPE islow_array[DCTSIZE2];
68#ifdef DCT_IFAST_SUPPORTED
69  IFAST_MULT_TYPE ifast_array[DCTSIZE2];
70#endif
71#ifdef DCT_FLOAT_SUPPORTED
72  FLOAT_MULT_TYPE float_array[DCTSIZE2];
73#endif
74} multiplier_table;
75
76
77/* The current scaled-IDCT routines require ISLOW-style multiplier tables,
78 * so be sure to compile that code if either ISLOW or SCALING is requested.
79 */
80#ifdef DCT_ISLOW_SUPPORTED
81#define PROVIDE_ISLOW_TABLES
82#else
83#ifdef IDCT_SCALING_SUPPORTED
84#define PROVIDE_ISLOW_TABLES
85#endif
86#endif
87
88
89/*
90 * Prepare for an output pass.
91 * Here we select the proper IDCT routine for each component and build
92 * a matching multiplier table.
93 */
94
95METHODDEF(void)
96start_pass (j_decompress_ptr cinfo)
97{
98  my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
99  int ci, i;
100  jpeg_component_info *compptr;
101  int method = 0;
102  inverse_DCT_method_ptr method_ptr = NULL;
103  JQUANT_TBL * qtbl;
104
105  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
106       ci++, compptr++) {
107    /* Select the proper IDCT routine for this component's scaling */
108    switch (compptr->_DCT_scaled_size) {
109#ifdef IDCT_SCALING_SUPPORTED
110    case 1:
111      method_ptr = jpeg_idct_1x1;
112      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
113      break;
114    case 2:
115      if (jsimd_can_idct_2x2())
116        method_ptr = jsimd_idct_2x2;
117      else
118        method_ptr = jpeg_idct_2x2;
119      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
120      break;
121    case 3:
122      method_ptr = jpeg_idct_3x3;
123      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
124      break;
125    case 4:
126      if (jsimd_can_idct_4x4())
127        method_ptr = jsimd_idct_4x4;
128      else
129        method_ptr = jpeg_idct_4x4;
130      method = JDCT_ISLOW;      /* jidctred uses islow-style table */
131      break;
132    case 5:
133      method_ptr = jpeg_idct_5x5;
134      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
135      break;
136    case 6:
137#if defined(__mips__)
138      if (jsimd_can_idct_6x6())
139        method_ptr = jsimd_idct_6x6;
140      else
141#endif
142      method_ptr = jpeg_idct_6x6;
143      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
144      break;
145    case 7:
146      method_ptr = jpeg_idct_7x7;
147      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
148      break;
149#endif
150    case DCTSIZE:
151      switch (cinfo->dct_method) {
152#ifdef DCT_ISLOW_SUPPORTED
153      case JDCT_ISLOW:
154        if (jsimd_can_idct_islow())
155          method_ptr = jsimd_idct_islow;
156        else
157          method_ptr = jpeg_idct_islow;
158        method = JDCT_ISLOW;
159        break;
160#endif
161#ifdef DCT_IFAST_SUPPORTED
162      case JDCT_IFAST:
163        if (jsimd_can_idct_ifast())
164          method_ptr = jsimd_idct_ifast;
165        else
166          method_ptr = jpeg_idct_ifast;
167        method = JDCT_IFAST;
168        break;
169#endif
170#ifdef DCT_FLOAT_SUPPORTED
171      case JDCT_FLOAT:
172        if (jsimd_can_idct_float())
173          method_ptr = jsimd_idct_float;
174        else
175          method_ptr = jpeg_idct_float;
176        method = JDCT_FLOAT;
177        break;
178#endif
179      default:
180        ERREXIT(cinfo, JERR_NOT_COMPILED);
181        break;
182      }
183      break;
184#ifdef IDCT_SCALING_SUPPORTED
185    case 9:
186      method_ptr = jpeg_idct_9x9;
187      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
188      break;
189    case 10:
190      method_ptr = jpeg_idct_10x10;
191      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
192      break;
193    case 11:
194      method_ptr = jpeg_idct_11x11;
195      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
196      break;
197    case 12:
198#if defined(__mips__)
199      if (jsimd_can_idct_12x12())
200        method_ptr = jsimd_idct_12x12;
201      else
202#endif
203      method_ptr = jpeg_idct_12x12;
204      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
205      break;
206    case 13:
207      method_ptr = jpeg_idct_13x13;
208      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
209      break;
210    case 14:
211      method_ptr = jpeg_idct_14x14;
212      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
213      break;
214    case 15:
215      method_ptr = jpeg_idct_15x15;
216      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
217      break;
218    case 16:
219      method_ptr = jpeg_idct_16x16;
220      method = JDCT_ISLOW;      /* jidctint uses islow-style table */
221      break;
222#endif
223    default:
224      ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->_DCT_scaled_size);
225      break;
226    }
227    idct->pub.inverse_DCT[ci] = method_ptr;
228    /* Create multiplier table from quant table.
229     * However, we can skip this if the component is uninteresting
230     * or if we already built the table.  Also, if no quant table
231     * has yet been saved for the component, we leave the
232     * multiplier table all-zero; we'll be reading zeroes from the
233     * coefficient controller's buffer anyway.
234     */
235    if (! compptr->component_needed || idct->cur_method[ci] == method)
236      continue;
237    qtbl = compptr->quant_table;
238    if (qtbl == NULL)           /* happens if no data yet for component */
239      continue;
240    idct->cur_method[ci] = method;
241    switch (method) {
242#ifdef PROVIDE_ISLOW_TABLES
243    case JDCT_ISLOW:
244      {
245        /* For LL&M IDCT method, multipliers are equal to raw quantization
246         * coefficients, but are stored as ints to ensure access efficiency.
247         */
248        ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
249        for (i = 0; i < DCTSIZE2; i++) {
250          ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
251        }
252      }
253      break;
254#endif
255#ifdef DCT_IFAST_SUPPORTED
256    case JDCT_IFAST:
257      {
258        /* For AA&N IDCT method, multipliers are equal to quantization
259         * coefficients scaled by scalefactor[row]*scalefactor[col], where
260         *   scalefactor[0] = 1
261         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
262         * For integer operation, the multiplier table is to be scaled by
263         * IFAST_SCALE_BITS.
264         */
265        IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
266#define CONST_BITS 14
267        static const INT16 aanscales[DCTSIZE2] = {
268          /* precomputed values scaled up by 14 bits */
269          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
270          22725, 31521, 29692, 26722, 22725, 17855, 12299,  6270,
271          21407, 29692, 27969, 25172, 21407, 16819, 11585,  5906,
272          19266, 26722, 25172, 22654, 19266, 15137, 10426,  5315,
273          16384, 22725, 21407, 19266, 16384, 12873,  8867,  4520,
274          12873, 17855, 16819, 15137, 12873, 10114,  6967,  3552,
275           8867, 12299, 11585, 10426,  8867,  6967,  4799,  2446,
276           4520,  6270,  5906,  5315,  4520,  3552,  2446,  1247
277        };
278        SHIFT_TEMPS
279
280        for (i = 0; i < DCTSIZE2; i++) {
281          ifmtbl[i] = (IFAST_MULT_TYPE)
282            DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
283                                  (INT32) aanscales[i]),
284                    CONST_BITS-IFAST_SCALE_BITS);
285        }
286      }
287      break;
288#endif
289#ifdef DCT_FLOAT_SUPPORTED
290    case JDCT_FLOAT:
291      {
292        /* For float AA&N IDCT method, multipliers are equal to quantization
293         * coefficients scaled by scalefactor[row]*scalefactor[col], where
294         *   scalefactor[0] = 1
295         *   scalefactor[k] = cos(k*PI/16) * sqrt(2)    for k=1..7
296         */
297        FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
298        int row, col;
299        static const double aanscalefactor[DCTSIZE] = {
300          1.0, 1.387039845, 1.306562965, 1.175875602,
301          1.0, 0.785694958, 0.541196100, 0.275899379
302        };
303
304        i = 0;
305        for (row = 0; row < DCTSIZE; row++) {
306          for (col = 0; col < DCTSIZE; col++) {
307            fmtbl[i] = (FLOAT_MULT_TYPE)
308              ((double) qtbl->quantval[i] *
309               aanscalefactor[row] * aanscalefactor[col]);
310            i++;
311          }
312        }
313      }
314      break;
315#endif
316    default:
317      ERREXIT(cinfo, JERR_NOT_COMPILED);
318      break;
319    }
320  }
321}
322
323
324/*
325 * Initialize IDCT manager.
326 */
327
328GLOBAL(void)
329jinit_inverse_dct (j_decompress_ptr cinfo)
330{
331  my_idct_ptr idct;
332  int ci;
333  jpeg_component_info *compptr;
334
335  idct = (my_idct_ptr)
336    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
337                                sizeof(my_idct_controller));
338  cinfo->idct = (struct jpeg_inverse_dct *) idct;
339  idct->pub.start_pass = start_pass;
340
341  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
342       ci++, compptr++) {
343    /* Allocate and pre-zero a multiplier table for each component */
344    compptr->dct_table =
345      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
346                                  sizeof(multiplier_table));
347    MEMZERO(compptr->dct_table, sizeof(multiplier_table));
348    /* Mark multiplier table not yet set up for any method */
349    idct->cur_method[ci] = -1;
350  }
351}
352