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 #ifdef ANDROID_ARMV6_IDCT
24 #undef ANDROID_ARMV6_IDCT
25 #ifdef __arm__
26 #include <machine/cpu-features.h>
27 #if __ARM_ARCH__ >= 6
28 #define ANDROID_ARMV6_IDCT
29 #else
30 #warning "ANDROID_ARMV6_IDCT is disabled"
31 #endif
32 #endif
33 #endif
34
35 #ifdef ANDROID_ARMV6_IDCT
36
37 /* Intentionally declare the prototype with arguments of primitive types instead
38 * of type-defined ones. This will at least generate some warnings if jmorecfg.h
39 * is changed and becomes incompatible with the assembly code.
40 */
41 extern void armv6_idct(short *coefs, int *quans, unsigned char **rows, int col);
42
jpeg_idct_armv6(j_decompress_ptr cinfo,jpeg_component_info * compptr,JCOEFPTR coef_block,JSAMPARRAY output_buf,JDIMENSION output_col)43 void jpeg_idct_armv6 (j_decompress_ptr cinfo, jpeg_component_info * compptr,
44 JCOEFPTR coef_block,
45 JSAMPARRAY output_buf, JDIMENSION output_col)
46 {
47 IFAST_MULT_TYPE *dct_table = (IFAST_MULT_TYPE *)compptr->dct_table;
48 armv6_idct(coef_block, dct_table, output_buf, output_col);
49 }
50
51 #endif
52
53 /*
54 * The decompressor input side (jdinput.c) saves away the appropriate
55 * quantization table for each component at the start of the first scan
56 * involving that component. (This is necessary in order to correctly
57 * decode files that reuse Q-table slots.)
58 * When we are ready to make an output pass, the saved Q-table is converted
59 * to a multiplier table that will actually be used by the IDCT routine.
60 * The multiplier table contents are IDCT-method-dependent. To support
61 * application changes in IDCT method between scans, we can remake the
62 * multiplier tables if necessary.
63 * In buffered-image mode, the first output pass may occur before any data
64 * has been seen for some components, and thus before their Q-tables have
65 * been saved away. To handle this case, multiplier tables are preset
66 * to zeroes; the result of the IDCT will be a neutral gray level.
67 */
68
69
70 /* Private subobject for this module */
71
72 typedef struct {
73 struct jpeg_inverse_dct pub; /* public fields */
74
75 /* This array contains the IDCT method code that each multiplier table
76 * is currently set up for, or -1 if it's not yet set up.
77 * The actual multiplier tables are pointed to by dct_table in the
78 * per-component comp_info structures.
79 */
80 int cur_method[MAX_COMPONENTS];
81 } my_idct_controller;
82
83 typedef my_idct_controller * my_idct_ptr;
84
85
86 /* Allocated multiplier tables: big enough for any supported variant */
87
88 typedef union {
89 ISLOW_MULT_TYPE islow_array[DCTSIZE2];
90 #ifdef DCT_IFAST_SUPPORTED
91 IFAST_MULT_TYPE ifast_array[DCTSIZE2];
92 #endif
93 #ifdef DCT_FLOAT_SUPPORTED
94 FLOAT_MULT_TYPE float_array[DCTSIZE2];
95 #endif
96 } multiplier_table;
97
98
99 /* The current scaled-IDCT routines require ISLOW-style multiplier tables,
100 * so be sure to compile that code if either ISLOW or SCALING is requested.
101 */
102 #ifdef DCT_ISLOW_SUPPORTED
103 #define PROVIDE_ISLOW_TABLES
104 #else
105 #ifdef IDCT_SCALING_SUPPORTED
106 #define PROVIDE_ISLOW_TABLES
107 #endif
108 #endif
109
110
111 /*
112 * Prepare for an output pass.
113 * Here we select the proper IDCT routine for each component and build
114 * a matching multiplier table.
115 */
116
117 METHODDEF(void)
start_pass(j_decompress_ptr cinfo)118 start_pass (j_decompress_ptr cinfo)
119 {
120 my_idct_ptr idct = (my_idct_ptr) cinfo->idct;
121 int ci, i;
122 jpeg_component_info *compptr;
123 int method = 0;
124 inverse_DCT_method_ptr method_ptr = NULL;
125 JQUANT_TBL * qtbl;
126
127 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
128 ci++, compptr++) {
129 /* Select the proper IDCT routine for this component's scaling */
130 switch (compptr->DCT_scaled_size) {
131 #ifdef IDCT_SCALING_SUPPORTED
132 case 1:
133 method_ptr = jpeg_idct_1x1;
134 method = JDCT_ISLOW; /* jidctred uses islow-style table */
135 break;
136 case 2:
137 method_ptr = jpeg_idct_2x2;
138 method = JDCT_ISLOW; /* jidctred uses islow-style table */
139 break;
140 case 4:
141 method_ptr = jpeg_idct_4x4;
142 method = JDCT_ISLOW; /* jidctred uses islow-style table */
143 break;
144 #endif
145 case DCTSIZE:
146 switch (cinfo->dct_method) {
147 #ifdef ANDROID_ARMV6_IDCT
148 case JDCT_ISLOW:
149 case JDCT_IFAST:
150 method_ptr = jpeg_idct_armv6;
151 method = JDCT_IFAST;
152 break;
153 #else /* ANDROID_ARMV6_IDCT */
154 #ifdef DCT_ISLOW_SUPPORTED
155 case JDCT_ISLOW:
156 method_ptr = jpeg_idct_islow;
157 method = JDCT_ISLOW;
158 break;
159 #endif
160 #ifdef DCT_IFAST_SUPPORTED
161 case JDCT_IFAST:
162 method_ptr = jpeg_idct_ifast;
163 method = JDCT_IFAST;
164 break;
165 #endif
166 #endif /* ANDROID_ARMV6_IDCT */
167 #ifdef DCT_FLOAT_SUPPORTED
168 case JDCT_FLOAT:
169 method_ptr = jpeg_idct_float;
170 method = JDCT_FLOAT;
171 break;
172 #endif
173 default:
174 ERREXIT(cinfo, JERR_NOT_COMPILED);
175 break;
176 }
177 break;
178 default:
179 ERREXIT1(cinfo, JERR_BAD_DCTSIZE, compptr->DCT_scaled_size);
180 break;
181 }
182 idct->pub.inverse_DCT[ci] = method_ptr;
183 /* Create multiplier table from quant table.
184 * However, we can skip this if the component is uninteresting
185 * or if we already built the table. Also, if no quant table
186 * has yet been saved for the component, we leave the
187 * multiplier table all-zero; we'll be reading zeroes from the
188 * coefficient controller's buffer anyway.
189 */
190 if (! compptr->component_needed || idct->cur_method[ci] == method)
191 continue;
192 qtbl = compptr->quant_table;
193 if (qtbl == NULL) /* happens if no data yet for component */
194 continue;
195 idct->cur_method[ci] = method;
196 switch (method) {
197 #ifdef PROVIDE_ISLOW_TABLES
198 case JDCT_ISLOW:
199 {
200 /* For LL&M IDCT method, multipliers are equal to raw quantization
201 * coefficients, but are stored as ints to ensure access efficiency.
202 */
203 ISLOW_MULT_TYPE * ismtbl = (ISLOW_MULT_TYPE *) compptr->dct_table;
204 for (i = 0; i < DCTSIZE2; i++) {
205 ismtbl[i] = (ISLOW_MULT_TYPE) qtbl->quantval[i];
206 }
207 }
208 break;
209 #endif
210 #ifdef DCT_IFAST_SUPPORTED
211 case JDCT_IFAST:
212 {
213 /* For AA&N IDCT method, multipliers are equal to quantization
214 * coefficients scaled by scalefactor[row]*scalefactor[col], where
215 * scalefactor[0] = 1
216 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
217 * For integer operation, the multiplier table is to be scaled by
218 * IFAST_SCALE_BITS.
219 */
220 IFAST_MULT_TYPE * ifmtbl = (IFAST_MULT_TYPE *) compptr->dct_table;
221 #ifdef ANDROID_ARMV6_IDCT
222 /* Precomputed values scaled up by 15 bits. */
223 static const unsigned short scales[DCTSIZE2] = {
224 32768, 45451, 42813, 38531, 32768, 25746, 17734, 9041,
225 45451, 63042, 59384, 53444, 45451, 35710, 24598, 12540,
226 42813, 59384, 55938, 50343, 42813, 33638, 23170, 11812,
227 38531, 53444, 50343, 45308, 38531, 30274, 20853, 10631,
228 32768, 45451, 42813, 38531, 32768, 25746, 17734, 9041,
229 25746, 35710, 33638, 30274, 25746, 20228, 13933, 7103,
230 17734, 24598, 23170, 20853, 17734, 13933, 9598, 4893,
231 9041, 12540, 11812, 10631, 9041, 7103, 4893, 2494,
232 };
233 /* Inverse map of [7, 5, 1, 3, 0, 2, 4, 6]. */
234 static const char orders[DCTSIZE] = {4, 2, 5, 3, 6, 1, 7, 0};
235 /* Reorder the columns after transposing. */
236 for (i = 0; i < DCTSIZE2; ++i) {
237 int j = ((i & 7) << 3) + orders[i >> 3];
238 ifmtbl[j] = (qtbl->quantval[i] * scales[i] + 2) >> 2;
239 }
240 #else /* ANDROID_ARMV6_IDCT */
241
242 #define CONST_BITS 14
243 static const INT16 aanscales[DCTSIZE2] = {
244 /* precomputed values scaled up by 14 bits */
245 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
246 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
247 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
248 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
249 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
250 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
251 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
252 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
253 };
254 SHIFT_TEMPS
255
256 for (i = 0; i < DCTSIZE2; i++) {
257 ifmtbl[i] = (IFAST_MULT_TYPE)
258 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
259 (INT32) aanscales[i]),
260 CONST_BITS-IFAST_SCALE_BITS);
261 }
262 #endif /* ANDROID_ARMV6_IDCT */
263 }
264 break;
265 #endif
266 #ifdef DCT_FLOAT_SUPPORTED
267 case JDCT_FLOAT:
268 {
269 /* For float AA&N IDCT method, multipliers are equal to quantization
270 * coefficients scaled by scalefactor[row]*scalefactor[col], where
271 * scalefactor[0] = 1
272 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
273 */
274 FLOAT_MULT_TYPE * fmtbl = (FLOAT_MULT_TYPE *) compptr->dct_table;
275 int row, col;
276 static const double aanscalefactor[DCTSIZE] = {
277 1.0, 1.387039845, 1.306562965, 1.175875602,
278 1.0, 0.785694958, 0.541196100, 0.275899379
279 };
280
281 i = 0;
282 for (row = 0; row < DCTSIZE; row++) {
283 for (col = 0; col < DCTSIZE; col++) {
284 fmtbl[i] = (FLOAT_MULT_TYPE)
285 ((double) qtbl->quantval[i] *
286 aanscalefactor[row] * aanscalefactor[col]);
287 i++;
288 }
289 }
290 }
291 break;
292 #endif
293 default:
294 ERREXIT(cinfo, JERR_NOT_COMPILED);
295 break;
296 }
297 }
298 }
299
300
301 /*
302 * Initialize IDCT manager.
303 */
304
305 GLOBAL(void)
jinit_inverse_dct(j_decompress_ptr cinfo)306 jinit_inverse_dct (j_decompress_ptr cinfo)
307 {
308 my_idct_ptr idct;
309 int ci;
310 jpeg_component_info *compptr;
311
312 idct = (my_idct_ptr)
313 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
314 SIZEOF(my_idct_controller));
315 cinfo->idct = (struct jpeg_inverse_dct *) idct;
316 idct->pub.start_pass = start_pass;
317
318 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
319 ci++, compptr++) {
320 /* Allocate and pre-zero a multiplier table for each component */
321 compptr->dct_table =
322 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
323 SIZEOF(multiplier_table));
324 MEMZERO(compptr->dct_table, SIZEOF(multiplier_table));
325 /* Mark multiplier table not yet set up for any method */
326 idct->cur_method[ci] = -1;
327 }
328 }
329