1 /*
2 * jddctmgr.c
3 *
4 * Copyright (C) 1994-1996, Thomas G. Lane.
5 * Modified 2002-2010 by Guido Vollbeding.
6 * This file is part of the Independent JPEG Group's software.
7 * For conditions of distribution and use, see the accompanying README file.
8 *
9 * This file contains the inverse-DCT management logic.
10 * This code selects a particular IDCT implementation to be used,
11 * and it performs related housekeeping chores. No code in this file
12 * is executed per IDCT step, only during output pass setup.
13 *
14 * Note that the IDCT routines are responsible for performing coefficient
15 * dequantization as well as the IDCT proper. This module sets up the
16 * dequantization multiplier table needed by the IDCT routine.
17 */
18
19 #define JPEG_INTERNALS
20 #include "jinclude.h"
21 #include "jpeglib.h"
22 #include "jdct.h" /* Private declarations for DCT subsystem */
23
24
25 /*
26 * The decompressor input side (jdinput.c) saves away the appropriate
27 * quantization table for each component at the start of the first scan
28 * involving that component. (This is necessary in order to correctly
29 * decode files that reuse Q-table slots.)
30 * When we are ready to make an output pass, the saved Q-table is converted
31 * to a multiplier table that will actually be used by the IDCT routine.
32 * The multiplier table contents are IDCT-method-dependent. To support
33 * application changes in IDCT method between scans, we can remake the
34 * multiplier tables if necessary.
35 * In buffered-image mode, the first output pass may occur before any data
36 * has been seen for some components, and thus before their Q-tables have
37 * been saved away. To handle this case, multiplier tables are preset
38 * to zeroes; the result of the IDCT will be a neutral gray level.
39 */
40
41
42 /* Private subobject for this module */
43
44 typedef struct {
45 struct jpeg_inverse_dct pub; /* public fields */
46
47 /* This array contains the IDCT method code that each multiplier table
48 * is currently set up for, or -1 if it's not yet set up.
49 * The actual multiplier tables are pointed to by dct_table in the
50 * per-component comp_info structures.
51 */
52 int cur_method[MAX_COMPONENTS];
53 } my_idct_controller;
54
55 typedef my_idct_controller * my_idct_ptr;
56
57
58 /* Allocated multiplier tables: big enough for any supported variant */
59
60 typedef union {
61 ISLOW_MULT_TYPE islow_array[DCTSIZE2];
62 #ifdef DCT_IFAST_SUPPORTED
63 IFAST_MULT_TYPE ifast_array[DCTSIZE2];
64 #endif
65 #ifdef DCT_FLOAT_SUPPORTED
66 FLOAT_MULT_TYPE float_array[DCTSIZE2];
67 #endif
68 } multiplier_table;
69
70
71 /* The current scaled-IDCT routines require ISLOW-style multiplier tables,
72 * so be sure to compile that code if either ISLOW or SCALING is requested.
73 */
74 #ifdef DCT_ISLOW_SUPPORTED
75 #define PROVIDE_ISLOW_TABLES
76 #else
77 #ifdef IDCT_SCALING_SUPPORTED
78 #define PROVIDE_ISLOW_TABLES
79 #endif
80 #endif
81
82
83 /*
84 * Prepare for an output pass.
85 * Here we select the proper IDCT routine for each component and build
86 * a matching multiplier table.
87 */
88
89 METHODDEF(void)
start_pass(j_decompress_ptr cinfo)90 start_pass (j_decompress_ptr cinfo)
91 {
92 my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
93 int ci, i;
94 jpeg_component_info *compptr;
95 int method = 0;
96 inverse_DCT_method_ptr method_ptr = NULL;
97 JQUANT_TBL * qtbl;
98
99 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
100 ci++, compptr++) {
101 /* Select the proper IDCT routine for this component's scaling */
102 switch ((compptr->DCT_h_scaled_size << 8) + compptr->DCT_v_scaled_size) {
103 #ifdef IDCT_SCALING_SUPPORTED
104 case ((1 << 8) + 1):
105 method_ptr = jpeg_idct_1x1;
106 method = JDCT_ISLOW; /* jidctint uses islow-style table */
107 break;
108 case ((2 << 8) + 2):
109 method_ptr = jpeg_idct_2x2;
110 method = JDCT_ISLOW; /* jidctint uses islow-style table */
111 break;
112 case ((3 << 8) + 3):
113 method_ptr = jpeg_idct_3x3;
114 method = JDCT_ISLOW; /* jidctint uses islow-style table */
115 break;
116 case ((4 << 8) + 4):
117 method_ptr = jpeg_idct_4x4;
118 method = JDCT_ISLOW; /* jidctint uses islow-style table */
119 break;
120 case ((5 << 8) + 5):
121 method_ptr = jpeg_idct_5x5;
122 method = JDCT_ISLOW; /* jidctint uses islow-style table */
123 break;
124 case ((6 << 8) + 6):
125 method_ptr = jpeg_idct_6x6;
126 method = JDCT_ISLOW; /* jidctint uses islow-style table */
127 break;
128 case ((7 << 8) + 7):
129 method_ptr = jpeg_idct_7x7;
130 method = JDCT_ISLOW; /* jidctint uses islow-style table */
131 break;
132 case ((9 << 8) + 9):
133 method_ptr = jpeg_idct_9x9;
134 method = JDCT_ISLOW; /* jidctint uses islow-style table */
135 break;
136 case ((10 << 8) + 10):
137 method_ptr = jpeg_idct_10x10;
138 method = JDCT_ISLOW; /* jidctint uses islow-style table */
139 break;
140 case ((11 << 8) + 11):
141 method_ptr = jpeg_idct_11x11;
142 method = JDCT_ISLOW; /* jidctint uses islow-style table */
143 break;
144 case ((12 << 8) + 12):
145 method_ptr = jpeg_idct_12x12;
146 method = JDCT_ISLOW; /* jidctint uses islow-style table */
147 break;
148 case ((13 << 8) + 13):
149 method_ptr = jpeg_idct_13x13;
150 method = JDCT_ISLOW; /* jidctint uses islow-style table */
151 break;
152 case ((14 << 8) + 14):
153 method_ptr = jpeg_idct_14x14;
154 method = JDCT_ISLOW; /* jidctint uses islow-style table */
155 break;
156 case ((15 << 8) + 15):
157 method_ptr = jpeg_idct_15x15;
158 method = JDCT_ISLOW; /* jidctint uses islow-style table */
159 break;
160 case ((16 << 8) + 16):
161 method_ptr = jpeg_idct_16x16;
162 method = JDCT_ISLOW; /* jidctint uses islow-style table */
163 break;
164 case ((16 << 8) + 8):
165 method_ptr = jpeg_idct_16x8;
166 method = JDCT_ISLOW; /* jidctint uses islow-style table */
167 break;
168 case ((14 << 8) + 7):
169 method_ptr = jpeg_idct_14x7;
170 method = JDCT_ISLOW; /* jidctint uses islow-style table */
171 break;
172 case ((12 << 8) + 6):
173 method_ptr = jpeg_idct_12x6;
174 method = JDCT_ISLOW; /* jidctint uses islow-style table */
175 break;
176 case ((10 << 8) + 5):
177 method_ptr = jpeg_idct_10x5;
178 method = JDCT_ISLOW; /* jidctint uses islow-style table */
179 break;
180 case ((8 << 8) + 4):
181 method_ptr = jpeg_idct_8x4;
182 method = JDCT_ISLOW; /* jidctint uses islow-style table */
183 break;
184 case ((6 << 8) + 3):
185 method_ptr = jpeg_idct_6x3;
186 method = JDCT_ISLOW; /* jidctint uses islow-style table */
187 break;
188 case ((4 << 8) + 2):
189 method_ptr = jpeg_idct_4x2;
190 method = JDCT_ISLOW; /* jidctint uses islow-style table */
191 break;
192 case ((2 << 8) + 1):
193 method_ptr = jpeg_idct_2x1;
194 method = JDCT_ISLOW; /* jidctint uses islow-style table */
195 break;
196 case ((8 << 8) + 16):
197 method_ptr = jpeg_idct_8x16;
198 method = JDCT_ISLOW; /* jidctint uses islow-style table */
199 break;
200 case ((7 << 8) + 14):
201 method_ptr = jpeg_idct_7x14;
202 method = JDCT_ISLOW; /* jidctint uses islow-style table */
203 break;
204 case ((6 << 8) + 12):
205 method_ptr = jpeg_idct_6x12;
206 method = JDCT_ISLOW; /* jidctint uses islow-style table */
207 break;
208 case ((5 << 8) + 10):
209 method_ptr = jpeg_idct_5x10;
210 method = JDCT_ISLOW; /* jidctint uses islow-style table */
211 break;
212 case ((4 << 8) + 8):
213 method_ptr = jpeg_idct_4x8;
214 method = JDCT_ISLOW; /* jidctint uses islow-style table */
215 break;
216 case ((3 << 8) + 6):
217 method_ptr = jpeg_idct_3x6;
218 method = JDCT_ISLOW; /* jidctint uses islow-style table */
219 break;
220 case ((2 << 8) + 4):
221 method_ptr = jpeg_idct_2x4;
222 method = JDCT_ISLOW; /* jidctint uses islow-style table */
223 break;
224 case ((1 << 8) + 2):
225 method_ptr = jpeg_idct_1x2;
226 method = JDCT_ISLOW; /* jidctint uses islow-style table */
227 break;
228 #endif
229 case ((DCTSIZE << 8) + DCTSIZE):
230 switch (cinfo->dct_method) {
231 #ifdef DCT_ISLOW_SUPPORTED
232 case JDCT_ISLOW:
233 method_ptr = jpeg_idct_islow;
234 method = JDCT_ISLOW;
235 break;
236 #endif
237 #ifdef DCT_IFAST_SUPPORTED
238 case JDCT_IFAST:
239 method_ptr = jpeg_idct_ifast;
240 method = JDCT_IFAST;
241 break;
242 #endif
243 #ifdef DCT_FLOAT_SUPPORTED
244 case JDCT_FLOAT:
245 method_ptr = jpeg_idct_float;
246 method = JDCT_FLOAT;
247 break;
248 #endif
249 default:
250 ERREXIT(cinfo, JERR_NOT_COMPILED);
251 break;
252 }
253 break;
254 default:
255 ERREXIT2(cinfo, JERR_BAD_DCTSIZE,
256 compptr->DCT_h_scaled_size, compptr->DCT_v_scaled_size);
257 break;
258 }
259 idct->pub.inverse_DCT[ci] = method_ptr;
260 /* Create multiplier table from quant table.
261 * However, we can skip this if the component is uninteresting
262 * or if we already built the table. Also, if no quant table
263 * has yet been saved for the component, we leave the
264 * multiplier table all-zero; we'll be reading zeroes from the
265 * coefficient controller's buffer anyway.
266 */
267 if (! compptr->component_needed || idct->cur_method[ci] == method)
268 continue;
269 qtbl = compptr->quant_table;
270 if (qtbl == NULL) /* happens if no data yet for component */
271 continue;
272 idct->cur_method[ci] = method;
273 switch (method) {
274 #ifdef PROVIDE_ISLOW_TABLES
275 case JDCT_ISLOW:
276 {
277 /* For LL&M IDCT method, multipliers are equal to raw quantization
278 * coefficients, but are stored as ints to ensure access efficiency.
279 */
280 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
281 for (i = 0; i < DCTSIZE2; i++) {
282 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
283 }
284 }
285 break;
286 #endif
287 #ifdef DCT_IFAST_SUPPORTED
288 case JDCT_IFAST:
289 {
290 /* For AA&N IDCT method, multipliers are equal to quantization
291 * coefficients scaled by scalefactor[row]*scalefactor[col], where
292 * scalefactor[0] = 1
293 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
294 * For integer operation, the multiplier table is to be scaled by
295 * IFAST_SCALE_BITS.
296 */
297 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
298 #define CONST_BITS 14
299 static const INT16 aanscales[DCTSIZE2] = {
300 /* precomputed values scaled up by 14 bits */
301 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
302 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
303 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
304 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
305 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
306 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
307 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
308 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
309 };
310 SHIFT_TEMPS
311
312 for (i = 0; i < DCTSIZE2; i++) {
313 ifmtbl[i] = (IFAST_MULT_TYPE)
314 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
315 (INT32) aanscales[i]),
316 CONST_BITS-IFAST_SCALE_BITS);
317 }
318 }
319 break;
320 #endif
321 #ifdef DCT_FLOAT_SUPPORTED
322 case JDCT_FLOAT:
323 {
324 /* For float AA&N IDCT method, multipliers are equal to quantization
325 * coefficients scaled by scalefactor[row]*scalefactor[col], where
326 * scalefactor[0] = 1
327 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
328 * We apply a further scale factor of 1/8.
329 */
330 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
331 int row, col;
332 static const double aanscalefactor[DCTSIZE] = {
333 1.0, 1.387039845, 1.306562965, 1.175875602,
334 1.0, 0.785694958, 0.541196100, 0.275899379
335 };
336
337 i = 0;
338 for (row = 0; row < DCTSIZE; row++) {
339 for (col = 0; col < DCTSIZE; col++) {
340 fmtbl[i] = (FLOAT_MULT_TYPE)
341 ((double) qtbl->quantval[i] *
342 aanscalefactor[row] * aanscalefactor[col] * 0.125);
343 i++;
344 }
345 }
346 }
347 break;
348 #endif
349 default:
350 ERREXIT(cinfo, JERR_NOT_COMPILED);
351 break;
352 }
353 }
354 }
355
356
357 /*
358 * Initialize IDCT manager.
359 */
360
361 GLOBAL(void)
jinit_inverse_dct(j_decompress_ptr cinfo)362 jinit_inverse_dct (j_decompress_ptr cinfo)
363 {
364 my_idct_ptr idct;
365 int ci;
366 jpeg_component_info *compptr;
367
368 idct = (my_idct_ptr)
369 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
370 SIZEOF(my_idct_controller));
371 cinfo->idct = (struct jpeg_inverse_dct *) idct;
372 idct->pub.start_pass = start_pass;
373
374 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
375 ci++, compptr++) {
376 /* Allocate and pre-zero a multiplier table for each component */
377 compptr->dct_table =
378 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
379 SIZEOF(multiplier_table));
380 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
381 /* Mark multiplier table not yet set up for any method */
382 idct->cur_method[ci] = -1;
383 }
384 }
385