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