1 #if !defined(_FX_JPEG_TURBO_)
2 /*
3 * jcdctmgr.c
4 *
5 * Copyright (C) 1994-1996, Thomas G. Lane.
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 forward-DCT management logic.
10 * This code selects a particular DCT implementation to be used,
11 * and it performs related housekeeping chores including coefficient
12 * quantization.
13 */
14
15 #define JPEG_INTERNALS
16 #include "jinclude.h"
17 #include "jpeglib.h"
18 #include "jdct.h" /* Private declarations for DCT subsystem */
19
20
21 /* Private subobject for this module */
22
23 typedef struct {
24 struct jpeg_forward_dct pub; /* public fields */
25
26 /* Pointer to the DCT routine actually in use */
27 forward_DCT_method_ptr do_dct;
28
29 /* The actual post-DCT divisors --- not identical to the quant table
30 * entries, because of scaling (especially for an unnormalized DCT).
31 * Each table is given in normal array order.
32 */
33 DCTELEM * divisors[NUM_QUANT_TBLS];
34
35 #ifdef DCT_FLOAT_SUPPORTED
36 /* Same as above for the floating-point case. */
37 float_DCT_method_ptr do_float_dct;
38 FAST_FLOAT * float_divisors[NUM_QUANT_TBLS];
39 #endif
40 } my_fdct_controller;
41
42 typedef my_fdct_controller * my_fdct_ptr;
43
44
45 /*
46 * Initialize for a processing pass.
47 * Verify that all referenced Q-tables are present, and set up
48 * the divisor table for each one.
49 * In the current implementation, DCT of all components is done during
50 * the first pass, even if only some components will be output in the
51 * first scan. Hence all components should be examined here.
52 */
53
54 METHODDEF(void)
start_pass_fdctmgr(j_compress_ptr cinfo)55 start_pass_fdctmgr (j_compress_ptr cinfo)
56 {
57 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
58 int ci, qtblno, i;
59 jpeg_component_info *compptr;
60 JQUANT_TBL * qtbl;
61 DCTELEM * dtbl;
62
63 for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
64 ci++, compptr++) {
65 qtblno = compptr->quant_tbl_no;
66 /* Make sure specified quantization table is present */
67 if (qtblno < 0 || qtblno >= NUM_QUANT_TBLS ||
68 cinfo->quant_tbl_ptrs[qtblno] == NULL)
69 ERREXIT1(cinfo, JERR_NO_QUANT_TABLE, qtblno);
70 qtbl = cinfo->quant_tbl_ptrs[qtblno];
71 /* Compute divisors for this quant table */
72 /* We may do this more than once for same table, but it's not a big deal */
73 switch (cinfo->dct_method) {
74 #ifdef DCT_ISLOW_SUPPORTED
75 case JDCT_ISLOW:
76 /* For LL&M IDCT method, divisors are equal to raw quantization
77 * coefficients multiplied by 8 (to counteract scaling).
78 */
79 if (fdct->divisors[qtblno] == NULL) {
80 fdct->divisors[qtblno] = (DCTELEM *)
81 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
82 DCTSIZE2 * SIZEOF(DCTELEM));
83 }
84 dtbl = fdct->divisors[qtblno];
85 for (i = 0; i < DCTSIZE2; i++) {
86 dtbl[i] = ((DCTELEM) qtbl->quantval[i]) << 3;
87 }
88 break;
89 #endif
90 #ifdef DCT_IFAST_SUPPORTED
91 case JDCT_IFAST:
92 {
93 /* For AA&N IDCT method, divisors are equal to quantization
94 * coefficients scaled by scalefactor[row]*scalefactor[col], where
95 * scalefactor[0] = 1
96 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
97 * We apply a further scale factor of 8.
98 */
99 #define CONST_BITS 14
100 static const INT16 aanscales[DCTSIZE2] = {
101 /* precomputed values scaled up by 14 bits */
102 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
103 22725, 31521, 29692, 26722, 22725, 17855, 12299, 6270,
104 21407, 29692, 27969, 25172, 21407, 16819, 11585, 5906,
105 19266, 26722, 25172, 22654, 19266, 15137, 10426, 5315,
106 16384, 22725, 21407, 19266, 16384, 12873, 8867, 4520,
107 12873, 17855, 16819, 15137, 12873, 10114, 6967, 3552,
108 8867, 12299, 11585, 10426, 8867, 6967, 4799, 2446,
109 4520, 6270, 5906, 5315, 4520, 3552, 2446, 1247
110 };
111 SHIFT_TEMPS
112
113 if (fdct->divisors[qtblno] == NULL) {
114 fdct->divisors[qtblno] = (DCTELEM *)
115 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
116 DCTSIZE2 * SIZEOF(DCTELEM));
117 }
118 dtbl = fdct->divisors[qtblno];
119 for (i = 0; i < DCTSIZE2; i++) {
120 dtbl[i] = (DCTELEM)
121 DESCALE(MULTIPLY16V16((INT32) qtbl->quantval[i],
122 (INT32) aanscales[i]),
123 CONST_BITS-3);
124 }
125 }
126 break;
127 #endif
128 #ifdef DCT_FLOAT_SUPPORTED
129 case JDCT_FLOAT:
130 {
131 /* For float AA&N IDCT method, divisors are equal to quantization
132 * coefficients scaled by scalefactor[row]*scalefactor[col], where
133 * scalefactor[0] = 1
134 * scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7
135 * We apply a further scale factor of 8.
136 * What's actually stored is 1/divisor so that the inner loop can
137 * use a multiplication rather than a division.
138 */
139 FAST_FLOAT * fdtbl;
140 int row, col;
141 static const double aanscalefactor[DCTSIZE] = {
142 1.0, 1.387039845, 1.306562965, 1.175875602,
143 1.0, 0.785694958, 0.541196100, 0.275899379
144 };
145
146 if (fdct->float_divisors[qtblno] == NULL) {
147 fdct->float_divisors[qtblno] = (FAST_FLOAT *)
148 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
149 DCTSIZE2 * SIZEOF(FAST_FLOAT));
150 }
151 fdtbl = fdct->float_divisors[qtblno];
152 i = 0;
153 for (row = 0; row < DCTSIZE; row++) {
154 for (col = 0; col < DCTSIZE; col++) {
155 fdtbl[i] = (FAST_FLOAT)
156 (1.0 / (((double) qtbl->quantval[i] *
157 aanscalefactor[row] * aanscalefactor[col] * 8.0)));
158 i++;
159 }
160 }
161 }
162 break;
163 #endif
164 default:
165 ERREXIT(cinfo, JERR_NOT_COMPILED);
166 break;
167 }
168 }
169 }
170
171
172 /*
173 * Perform forward DCT on one or more blocks of a component.
174 *
175 * The input samples are taken from the sample_data[] array starting at
176 * position start_row/start_col, and moving to the right for any additional
177 * blocks. The quantized coefficients are returned in coef_blocks[].
178 */
179
180 METHODDEF(void)
forward_DCT(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY sample_data,JBLOCKROW coef_blocks,JDIMENSION start_row,JDIMENSION start_col,JDIMENSION num_blocks)181 forward_DCT (j_compress_ptr cinfo, jpeg_component_info * compptr,
182 JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
183 JDIMENSION start_row, JDIMENSION start_col,
184 JDIMENSION num_blocks)
185 /* This version is used for integer DCT implementations. */
186 {
187 /* This routine is heavily used, so it's worth coding it tightly. */
188 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
189 forward_DCT_method_ptr do_dct = fdct->do_dct;
190 DCTELEM * divisors = fdct->divisors[compptr->quant_tbl_no];
191 DCTELEM workspace[DCTSIZE2]; /* work area for FDCT subroutine */
192 JDIMENSION bi;
193
194 sample_data += start_row; /* fold in the vertical offset once */
195
196 for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) {
197 /* Load data into workspace, applying unsigned->signed conversion */
198 { register DCTELEM *workspaceptr;
199 register JSAMPROW elemptr;
200 register int elemr;
201
202 workspaceptr = workspace;
203 for (elemr = 0; elemr < DCTSIZE; elemr++) {
204 elemptr = sample_data[elemr] + start_col;
205 #if DCTSIZE == 8 /* unroll the inner loop */
206 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
207 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
208 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
209 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
210 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
211 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
212 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
213 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
214 #else
215 { register int elemc;
216 for (elemc = DCTSIZE; elemc > 0; elemc--) {
217 *workspaceptr++ = GETJSAMPLE(*elemptr++) - CENTERJSAMPLE;
218 }
219 }
220 #endif
221 }
222 }
223
224 /* Perform the DCT */
225 (*do_dct) (workspace);
226
227 /* Quantize/descale the coefficients, and store into coef_blocks[] */
228 { register DCTELEM temp, qval;
229 register int i;
230 register JCOEFPTR output_ptr = coef_blocks[bi];
231
232 for (i = 0; i < DCTSIZE2; i++) {
233 qval = divisors[i];
234 temp = workspace[i];
235 /* Divide the coefficient value by qval, ensuring proper rounding.
236 * Since C does not specify the direction of rounding for negative
237 * quotients, we have to force the dividend positive for portability.
238 *
239 * In most files, at least half of the output values will be zero
240 * (at default quantization settings, more like three-quarters...)
241 * so we should ensure that this case is fast. On many machines,
242 * a comparison is enough cheaper than a divide to make a special test
243 * a win. Since both inputs will be nonnegative, we need only test
244 * for a < b to discover whether a/b is 0.
245 * If your machine's division is fast enough, define FAST_DIVIDE.
246 */
247 #ifdef FAST_DIVIDE
248 #define DIVIDE_BY(a,b) a /= b
249 #else
250 #define DIVIDE_BY(a,b) if (a >= b) a /= b; else a = 0
251 #endif
252 if (temp < 0) {
253 temp = -temp;
254 temp += qval>>1; /* for rounding */
255 DIVIDE_BY(temp, qval);
256 temp = -temp;
257 } else {
258 temp += qval>>1; /* for rounding */
259 DIVIDE_BY(temp, qval);
260 }
261 output_ptr[i] = (JCOEF) temp;
262 }
263 }
264 }
265 }
266
267
268 #ifdef DCT_FLOAT_SUPPORTED
269
270 METHODDEF(void)
forward_DCT_float(j_compress_ptr cinfo,jpeg_component_info * compptr,JSAMPARRAY sample_data,JBLOCKROW coef_blocks,JDIMENSION start_row,JDIMENSION start_col,JDIMENSION num_blocks)271 forward_DCT_float (j_compress_ptr cinfo, jpeg_component_info * compptr,
272 JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
273 JDIMENSION start_row, JDIMENSION start_col,
274 JDIMENSION num_blocks)
275 /* This version is used for floating-point DCT implementations. */
276 {
277 /* This routine is heavily used, so it's worth coding it tightly. */
278 my_fdct_ptr fdct = (my_fdct_ptr) cinfo->fdct;
279 float_DCT_method_ptr do_dct = fdct->do_float_dct;
280 FAST_FLOAT * divisors = fdct->float_divisors[compptr->quant_tbl_no];
281 FAST_FLOAT workspace[DCTSIZE2]; /* work area for FDCT subroutine */
282 JDIMENSION bi;
283
284 sample_data += start_row; /* fold in the vertical offset once */
285
286 for (bi = 0; bi < num_blocks; bi++, start_col += DCTSIZE) {
287 /* Load data into workspace, applying unsigned->signed conversion */
288 { register FAST_FLOAT *workspaceptr;
289 register JSAMPROW elemptr;
290 register int elemr;
291
292 workspaceptr = workspace;
293 for (elemr = 0; elemr < DCTSIZE; elemr++) {
294 elemptr = sample_data[elemr] + start_col;
295 #if DCTSIZE == 8 /* unroll the inner loop */
296 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
297 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
298 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
299 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
300 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
301 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
302 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
303 *workspaceptr++ = (FAST_FLOAT)(GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
304 #else
305 { register int elemc;
306 for (elemc = DCTSIZE; elemc > 0; elemc--) {
307 *workspaceptr++ = (FAST_FLOAT)
308 (GETJSAMPLE(*elemptr++) - CENTERJSAMPLE);
309 }
310 }
311 #endif
312 }
313 }
314
315 /* Perform the DCT */
316 (*do_dct) (workspace);
317
318 /* Quantize/descale the coefficients, and store into coef_blocks[] */
319 { register FAST_FLOAT temp;
320 register int i;
321 register JCOEFPTR output_ptr = coef_blocks[bi];
322
323 for (i = 0; i < DCTSIZE2; i++) {
324 /* Apply the quantization and scaling factor */
325 temp = workspace[i] * divisors[i];
326 /* Round to nearest integer.
327 * Since C does not specify the direction of rounding for negative
328 * quotients, we have to force the dividend positive for portability.
329 * The maximum coefficient size is +-16K (for 12-bit data), so this
330 * code should work for either 16-bit or 32-bit ints.
331 */
332 output_ptr[i] = (JCOEF) ((int) (temp + (FAST_FLOAT) 16384.5) - 16384);
333 }
334 }
335 }
336 }
337
338 #endif /* DCT_FLOAT_SUPPORTED */
339
340
341 /*
342 * Initialize FDCT manager.
343 */
344
345 GLOBAL(void)
jinit_forward_dct(j_compress_ptr cinfo)346 jinit_forward_dct (j_compress_ptr cinfo)
347 {
348 my_fdct_ptr fdct;
349 int i;
350
351 fdct = (my_fdct_ptr)
352 (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
353 SIZEOF(my_fdct_controller));
354 cinfo->fdct = (struct jpeg_forward_dct *) fdct;
355 fdct->pub.start_pass = start_pass_fdctmgr;
356
357 switch (cinfo->dct_method) {
358 #ifdef DCT_ISLOW_SUPPORTED
359 case JDCT_ISLOW:
360 fdct->pub.forward_DCT = forward_DCT;
361 fdct->do_dct = jpeg_fdct_islow;
362 break;
363 #endif
364 #ifdef DCT_IFAST_SUPPORTED
365 case JDCT_IFAST:
366 fdct->pub.forward_DCT = forward_DCT;
367 fdct->do_dct = jpeg_fdct_ifast;
368 break;
369 #endif
370 #ifdef DCT_FLOAT_SUPPORTED
371 case JDCT_FLOAT:
372 fdct->pub.forward_DCT = forward_DCT_float;
373 fdct->do_float_dct = jpeg_fdct_float;
374 break;
375 #endif
376 default:
377 ERREXIT(cinfo, JERR_NOT_COMPILED);
378 break;
379 }
380
381 /* Mark divisor tables unallocated */
382 for (i = 0; i < NUM_QUANT_TBLS; i++) {
383 fdct->divisors[i] = NULL;
384 #ifdef DCT_FLOAT_SUPPORTED
385 fdct->float_divisors[i] = NULL;
386 #endif
387 }
388 }
389
390 #endif //_FX_JPEG_TURBO_
391