Commit | Line | Data |
---|---|---|
e1929140 RR |
1 | /* |
2 | * jcphuff.c | |
3 | * | |
4 | * Copyright (C) 1995-1997, 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 Huffman entropy encoding routines for progressive JPEG. | |
9 | * | |
10 | * We do not support output suspension in this module, since the library | |
11 | * currently does not allow multiple-scan files to be written with output | |
12 | * suspension. | |
13 | */ | |
14 | ||
15 | #define JPEG_INTERNALS | |
16 | #include "jinclude.h" | |
17 | #include "jpeglib.h" | |
18 | #include "jchuff.h" /* Declarations shared with jchuff.c */ | |
19 | ||
20 | #ifdef C_PROGRESSIVE_SUPPORTED | |
21 | ||
22 | /* Expanded entropy encoder object for progressive Huffman encoding. */ | |
23 | ||
24 | typedef struct { | |
25 | struct jpeg_entropy_encoder pub; /* public fields */ | |
26 | ||
27 | /* Mode flag: TRUE for optimization, FALSE for actual data output */ | |
28 | boolean gather_statistics; | |
29 | ||
30 | /* Bit-level coding status. | |
31 | * next_output_byte/free_in_buffer are local copies of cinfo->dest fields. | |
32 | */ | |
33 | JOCTET * next_output_byte; /* => next byte to write in buffer */ | |
34 | size_t free_in_buffer; /* # of byte spaces remaining in buffer */ | |
35 | INT32 put_buffer; /* current bit-accumulation buffer */ | |
36 | int put_bits; /* # of bits now in it */ | |
37 | j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */ | |
38 | ||
39 | /* Coding status for DC components */ | |
40 | int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */ | |
41 | ||
42 | /* Coding status for AC components */ | |
43 | int ac_tbl_no; /* the table number of the single component */ | |
44 | unsigned int EOBRUN; /* run length of EOBs */ | |
45 | unsigned int BE; /* # of buffered correction bits before MCU */ | |
46 | char * bit_buffer; /* buffer for correction bits (1 per char) */ | |
47 | /* packing correction bits tightly would save some space but cost time... */ | |
48 | ||
49 | unsigned int restarts_to_go; /* MCUs left in this restart interval */ | |
50 | int next_restart_num; /* next restart number to write (0-7) */ | |
51 | ||
52 | /* Pointers to derived tables (these workspaces have image lifespan). | |
53 | * Since any one scan codes only DC or only AC, we only need one set | |
54 | * of tables, not one for DC and one for AC. | |
55 | */ | |
56 | c_derived_tbl * derived_tbls[NUM_HUFF_TBLS]; | |
57 | ||
58 | /* Statistics tables for optimization; again, one set is enough */ | |
59 | long * count_ptrs[NUM_HUFF_TBLS]; | |
60 | } phuff_entropy_encoder; | |
61 | ||
62 | typedef phuff_entropy_encoder * phuff_entropy_ptr; | |
63 | ||
64 | /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit | |
65 | * buffer can hold. Larger sizes may slightly improve compression, but | |
66 | * 1000 is already well into the realm of overkill. | |
67 | * The minimum safe size is 64 bits. | |
68 | */ | |
69 | ||
70 | #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */ | |
71 | ||
72 | /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than INT32. | |
73 | * We assume that int right shift is unsigned if INT32 right shift is, | |
74 | * which should be safe. | |
75 | */ | |
76 | ||
77 | #ifdef RIGHT_SHIFT_IS_UNSIGNED | |
78 | #define ISHIFT_TEMPS int ishift_temp; | |
79 | #define IRIGHT_SHIFT(x,shft) \ | |
80 | ((ishift_temp = (x)) < 0 ? \ | |
81 | (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \ | |
82 | (ishift_temp >> (shft))) | |
83 | #else | |
84 | #define ISHIFT_TEMPS | |
85 | #define IRIGHT_SHIFT(x,shft) ((x) >> (shft)) | |
86 | #endif | |
87 | ||
88 | /* Forward declarations */ | |
89 | METHODDEF(boolean) encode_mcu_DC_first JPP((j_compress_ptr cinfo, | |
90 | JBLOCKROW *MCU_data)); | |
91 | METHODDEF(boolean) encode_mcu_AC_first JPP((j_compress_ptr cinfo, | |
92 | JBLOCKROW *MCU_data)); | |
93 | METHODDEF(boolean) encode_mcu_DC_refine JPP((j_compress_ptr cinfo, | |
94 | JBLOCKROW *MCU_data)); | |
95 | METHODDEF(boolean) encode_mcu_AC_refine JPP((j_compress_ptr cinfo, | |
96 | JBLOCKROW *MCU_data)); | |
97 | METHODDEF(void) finish_pass_phuff JPP((j_compress_ptr cinfo)); | |
98 | METHODDEF(void) finish_pass_gather_phuff JPP((j_compress_ptr cinfo)); | |
99 | ||
100 | ||
101 | /* | |
102 | * Initialize for a Huffman-compressed scan using progressive JPEG. | |
103 | */ | |
104 | ||
105 | METHODDEF(void) | |
106 | start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics) | |
107 | { | |
108 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
109 | boolean is_DC_band; | |
110 | int ci, tbl; | |
111 | jpeg_component_info * compptr; | |
112 | ||
113 | entropy->cinfo = cinfo; | |
114 | entropy->gather_statistics = gather_statistics; | |
115 | ||
116 | is_DC_band = (cinfo->Ss == 0); | |
117 | ||
118 | /* We assume jcmaster.c already validated the scan parameters. */ | |
119 | ||
120 | /* Select execution routines */ | |
121 | if (cinfo->Ah == 0) { | |
122 | if (is_DC_band) | |
123 | entropy->pub.encode_mcu = encode_mcu_DC_first; | |
124 | else | |
125 | entropy->pub.encode_mcu = encode_mcu_AC_first; | |
126 | } else { | |
127 | if (is_DC_band) | |
128 | entropy->pub.encode_mcu = encode_mcu_DC_refine; | |
129 | else { | |
130 | entropy->pub.encode_mcu = encode_mcu_AC_refine; | |
131 | /* AC refinement needs a correction bit buffer */ | |
132 | if (entropy->bit_buffer == NULL) | |
133 | entropy->bit_buffer = (char *) | |
134 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
135 | MAX_CORR_BITS * SIZEOF(char)); | |
136 | } | |
137 | } | |
138 | if (gather_statistics) | |
139 | entropy->pub.finish_pass = finish_pass_gather_phuff; | |
140 | else | |
141 | entropy->pub.finish_pass = finish_pass_phuff; | |
142 | ||
143 | /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1 | |
144 | * for AC coefficients. | |
145 | */ | |
146 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
147 | compptr = cinfo->cur_comp_info[ci]; | |
148 | /* Initialize DC predictions to 0 */ | |
149 | entropy->last_dc_val[ci] = 0; | |
150 | /* Get table index */ | |
151 | if (is_DC_band) { | |
152 | if (cinfo->Ah != 0) /* DC refinement needs no table */ | |
153 | continue; | |
154 | tbl = compptr->dc_tbl_no; | |
155 | } else { | |
156 | entropy->ac_tbl_no = tbl = compptr->ac_tbl_no; | |
157 | } | |
158 | if (gather_statistics) { | |
159 | /* Check for invalid table index */ | |
160 | /* (make_c_derived_tbl does this in the other path) */ | |
161 | if (tbl < 0 || tbl >= NUM_HUFF_TBLS) | |
162 | ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl); | |
163 | /* Allocate and zero the statistics tables */ | |
164 | /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ | |
165 | if (entropy->count_ptrs[tbl] == NULL) | |
166 | entropy->count_ptrs[tbl] = (long *) | |
167 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
168 | 257 * SIZEOF(long)); | |
169 | MEMZERO(entropy->count_ptrs[tbl], 257 * SIZEOF(long)); | |
170 | } else { | |
171 | /* Compute derived values for Huffman table */ | |
172 | /* We may do this more than once for a table, but it's not expensive */ | |
173 | jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl, | |
174 | & entropy->derived_tbls[tbl]); | |
175 | } | |
176 | } | |
177 | ||
178 | /* Initialize AC stuff */ | |
179 | entropy->EOBRUN = 0; | |
180 | entropy->BE = 0; | |
181 | ||
182 | /* Initialize bit buffer to empty */ | |
183 | entropy->put_buffer = 0; | |
184 | entropy->put_bits = 0; | |
185 | ||
186 | /* Initialize restart stuff */ | |
187 | entropy->restarts_to_go = cinfo->restart_interval; | |
188 | entropy->next_restart_num = 0; | |
189 | } | |
190 | ||
191 | ||
192 | /* Outputting bytes to the file. | |
193 | * NB: these must be called only when actually outputting, | |
194 | * that is, entropy->gather_statistics == FALSE. | |
195 | */ | |
196 | ||
197 | /* Emit a byte */ | |
198 | #define emit_byte(entropy,val) \ | |
199 | { *(entropy)->next_output_byte++ = (JOCTET) (val); \ | |
200 | if (--(entropy)->free_in_buffer == 0) \ | |
201 | dump_buffer(entropy); } | |
202 | ||
203 | ||
204 | LOCAL(void) | |
205 | dump_buffer (phuff_entropy_ptr entropy) | |
206 | /* Empty the output buffer; we do not support suspension in this module. */ | |
207 | { | |
208 | struct jpeg_destination_mgr * dest = entropy->cinfo->dest; | |
209 | ||
210 | if (! (*dest->empty_output_buffer) (entropy->cinfo)) | |
211 | ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND); | |
212 | /* After a successful buffer dump, must reset buffer pointers */ | |
213 | entropy->next_output_byte = dest->next_output_byte; | |
214 | entropy->free_in_buffer = dest->free_in_buffer; | |
215 | } | |
216 | ||
217 | ||
218 | /* Outputting bits to the file */ | |
219 | ||
220 | /* Only the right 24 bits of put_buffer are used; the valid bits are | |
221 | * left-justified in this part. At most 16 bits can be passed to emit_bits | |
222 | * in one call, and we never retain more than 7 bits in put_buffer | |
223 | * between calls, so 24 bits are sufficient. | |
224 | */ | |
225 | ||
226 | INLINE | |
227 | LOCAL(void) | |
228 | emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size) | |
229 | /* Emit some bits, unless we are in gather mode */ | |
230 | { | |
231 | /* This routine is heavily used, so it's worth coding tightly. */ | |
232 | register INT32 put_buffer = (INT32) code; | |
233 | register int put_bits = entropy->put_bits; | |
234 | ||
235 | /* if size is 0, caller used an invalid Huffman table entry */ | |
236 | if (size == 0) | |
237 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); | |
238 | ||
239 | if (entropy->gather_statistics) | |
240 | return; /* do nothing if we're only getting stats */ | |
241 | ||
242 | put_buffer &= (((INT32) 1)<<size) - 1; /* mask off any extra bits in code */ | |
243 | ||
244 | put_bits += size; /* new number of bits in buffer */ | |
245 | ||
246 | put_buffer <<= 24 - put_bits; /* align incoming bits */ | |
247 | ||
248 | put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */ | |
249 | ||
250 | while (put_bits >= 8) { | |
251 | int c = (int) ((put_buffer >> 16) & 0xFF); | |
252 | ||
253 | emit_byte(entropy, c); | |
254 | if (c == 0xFF) { /* need to stuff a zero byte? */ | |
255 | emit_byte(entropy, 0); | |
256 | } | |
257 | put_buffer <<= 8; | |
258 | put_bits -= 8; | |
259 | } | |
260 | ||
261 | entropy->put_buffer = put_buffer; /* update variables */ | |
262 | entropy->put_bits = put_bits; | |
263 | } | |
264 | ||
265 | ||
266 | LOCAL(void) | |
267 | flush_bits (phuff_entropy_ptr entropy) | |
268 | { | |
269 | emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */ | |
270 | entropy->put_buffer = 0; /* and reset bit-buffer to empty */ | |
271 | entropy->put_bits = 0; | |
272 | } | |
273 | ||
274 | ||
275 | /* | |
276 | * Emit (or just count) a Huffman symbol. | |
277 | */ | |
278 | ||
279 | INLINE | |
280 | LOCAL(void) | |
281 | emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol) | |
282 | { | |
283 | if (entropy->gather_statistics) | |
284 | entropy->count_ptrs[tbl_no][symbol]++; | |
285 | else { | |
286 | c_derived_tbl * tbl = entropy->derived_tbls[tbl_no]; | |
287 | emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]); | |
288 | } | |
289 | } | |
290 | ||
291 | ||
292 | /* | |
293 | * Emit bits from a correction bit buffer. | |
294 | */ | |
295 | ||
296 | LOCAL(void) | |
297 | emit_buffered_bits (phuff_entropy_ptr entropy, char * bufstart, | |
298 | unsigned int nbits) | |
299 | { | |
300 | if (entropy->gather_statistics) | |
301 | return; /* no real work */ | |
302 | ||
303 | while (nbits > 0) { | |
304 | emit_bits(entropy, (unsigned int) (*bufstart), 1); | |
305 | bufstart++; | |
306 | nbits--; | |
307 | } | |
308 | } | |
309 | ||
310 | ||
311 | /* | |
312 | * Emit any pending EOBRUN symbol. | |
313 | */ | |
314 | ||
315 | LOCAL(void) | |
316 | emit_eobrun (phuff_entropy_ptr entropy) | |
317 | { | |
318 | register int temp, nbits; | |
319 | ||
320 | if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */ | |
321 | temp = entropy->EOBRUN; | |
322 | nbits = 0; | |
323 | while ((temp >>= 1)) | |
324 | nbits++; | |
325 | /* safety check: shouldn't happen given limited correction-bit buffer */ | |
326 | if (nbits > 14) | |
327 | ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE); | |
328 | ||
329 | emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4); | |
330 | if (nbits) | |
331 | emit_bits(entropy, entropy->EOBRUN, nbits); | |
332 | ||
333 | entropy->EOBRUN = 0; | |
334 | ||
335 | /* Emit any buffered correction bits */ | |
336 | emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE); | |
337 | entropy->BE = 0; | |
338 | } | |
339 | } | |
340 | ||
341 | ||
342 | /* | |
343 | * Emit a restart marker & resynchronize predictions. | |
344 | */ | |
345 | ||
346 | LOCAL(void) | |
347 | emit_restart (phuff_entropy_ptr entropy, int restart_num) | |
348 | { | |
349 | int ci; | |
350 | ||
351 | emit_eobrun(entropy); | |
352 | ||
353 | if (! entropy->gather_statistics) { | |
354 | flush_bits(entropy); | |
355 | emit_byte(entropy, 0xFF); | |
356 | emit_byte(entropy, JPEG_RST0 + restart_num); | |
357 | } | |
358 | ||
359 | if (entropy->cinfo->Ss == 0) { | |
360 | /* Re-initialize DC predictions to 0 */ | |
361 | for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++) | |
362 | entropy->last_dc_val[ci] = 0; | |
363 | } else { | |
364 | /* Re-initialize all AC-related fields to 0 */ | |
365 | entropy->EOBRUN = 0; | |
366 | entropy->BE = 0; | |
367 | } | |
368 | } | |
369 | ||
370 | ||
371 | /* | |
372 | * MCU encoding for DC initial scan (either spectral selection, | |
373 | * or first pass of successive approximation). | |
374 | */ | |
375 | ||
376 | METHODDEF(boolean) | |
377 | encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
378 | { | |
379 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
380 | register int temp, temp2; | |
381 | register int nbits; | |
382 | int blkn, ci; | |
383 | int Al = cinfo->Al; | |
384 | JBLOCKROW block; | |
385 | jpeg_component_info * compptr; | |
386 | ISHIFT_TEMPS | |
387 | ||
388 | entropy->next_output_byte = cinfo->dest->next_output_byte; | |
389 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
390 | ||
391 | /* Emit restart marker if needed */ | |
392 | if (cinfo->restart_interval) | |
393 | if (entropy->restarts_to_go == 0) | |
394 | emit_restart(entropy, entropy->next_restart_num); | |
395 | ||
396 | /* Encode the MCU data blocks */ | |
397 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
398 | block = MCU_data[blkn]; | |
399 | ci = cinfo->MCU_membership[blkn]; | |
400 | compptr = cinfo->cur_comp_info[ci]; | |
401 | ||
402 | /* Compute the DC value after the required point transform by Al. | |
403 | * This is simply an arithmetic right shift. | |
404 | */ | |
405 | temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al); | |
406 | ||
407 | /* DC differences are figured on the point-transformed values. */ | |
408 | temp = temp2 - entropy->last_dc_val[ci]; | |
409 | entropy->last_dc_val[ci] = temp2; | |
410 | ||
411 | /* Encode the DC coefficient difference per section G.1.2.1 */ | |
412 | temp2 = temp; | |
413 | if (temp < 0) { | |
414 | temp = -temp; /* temp is abs value of input */ | |
415 | /* For a negative input, want temp2 = bitwise complement of abs(input) */ | |
416 | /* This code assumes we are on a two's complement machine */ | |
417 | temp2--; | |
418 | } | |
419 | ||
420 | /* Find the number of bits needed for the magnitude of the coefficient */ | |
421 | nbits = 0; | |
422 | while (temp) { | |
423 | nbits++; | |
424 | temp >>= 1; | |
425 | } | |
426 | /* Check for out-of-range coefficient values. | |
427 | * Since we're encoding a difference, the range limit is twice as much. | |
428 | */ | |
429 | if (nbits > MAX_COEF_BITS+1) | |
430 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); | |
431 | ||
432 | /* Count/emit the Huffman-coded symbol for the number of bits */ | |
433 | emit_symbol(entropy, compptr->dc_tbl_no, nbits); | |
434 | ||
435 | /* Emit that number of bits of the value, if positive, */ | |
436 | /* or the complement of its magnitude, if negative. */ | |
437 | if (nbits) /* emit_bits rejects calls with size 0 */ | |
438 | emit_bits(entropy, (unsigned int) temp2, nbits); | |
439 | } | |
440 | ||
441 | cinfo->dest->next_output_byte = entropy->next_output_byte; | |
442 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
443 | ||
444 | /* Update restart-interval state too */ | |
445 | if (cinfo->restart_interval) { | |
446 | if (entropy->restarts_to_go == 0) { | |
447 | entropy->restarts_to_go = cinfo->restart_interval; | |
448 | entropy->next_restart_num++; | |
449 | entropy->next_restart_num &= 7; | |
450 | } | |
451 | entropy->restarts_to_go--; | |
452 | } | |
453 | ||
454 | return TRUE; | |
455 | } | |
456 | ||
457 | ||
458 | /* | |
459 | * MCU encoding for AC initial scan (either spectral selection, | |
460 | * or first pass of successive approximation). | |
461 | */ | |
462 | ||
463 | METHODDEF(boolean) | |
464 | encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
465 | { | |
466 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
467 | register int temp, temp2; | |
468 | register int nbits; | |
469 | register int r, k; | |
470 | int Se = cinfo->Se; | |
471 | int Al = cinfo->Al; | |
472 | JBLOCKROW block; | |
473 | ||
474 | entropy->next_output_byte = cinfo->dest->next_output_byte; | |
475 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
476 | ||
477 | /* Emit restart marker if needed */ | |
478 | if (cinfo->restart_interval) | |
479 | if (entropy->restarts_to_go == 0) | |
480 | emit_restart(entropy, entropy->next_restart_num); | |
481 | ||
482 | /* Encode the MCU data block */ | |
483 | block = MCU_data[0]; | |
484 | ||
485 | /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */ | |
486 | ||
487 | r = 0; /* r = run length of zeros */ | |
488 | ||
489 | for (k = cinfo->Ss; k <= Se; k++) { | |
490 | if ((temp = (*block)[jpeg_natural_order[k]]) == 0) { | |
491 | r++; | |
492 | continue; | |
493 | } | |
494 | /* We must apply the point transform by Al. For AC coefficients this | |
495 | * is an integer division with rounding towards 0. To do this portably | |
496 | * in C, we shift after obtaining the absolute value; so the code is | |
497 | * interwoven with finding the abs value (temp) and output bits (temp2). | |
498 | */ | |
499 | if (temp < 0) { | |
500 | temp = -temp; /* temp is abs value of input */ | |
501 | temp >>= Al; /* apply the point transform */ | |
502 | /* For a negative coef, want temp2 = bitwise complement of abs(coef) */ | |
503 | temp2 = ~temp; | |
504 | } else { | |
505 | temp >>= Al; /* apply the point transform */ | |
506 | temp2 = temp; | |
507 | } | |
508 | /* Watch out for case that nonzero coef is zero after point transform */ | |
509 | if (temp == 0) { | |
510 | r++; | |
511 | continue; | |
512 | } | |
513 | ||
514 | /* Emit any pending EOBRUN */ | |
515 | if (entropy->EOBRUN > 0) | |
516 | emit_eobrun(entropy); | |
517 | /* if run length > 15, must emit special run-length-16 codes (0xF0) */ | |
518 | while (r > 15) { | |
519 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); | |
520 | r -= 16; | |
521 | } | |
522 | ||
523 | /* Find the number of bits needed for the magnitude of the coefficient */ | |
524 | nbits = 1; /* there must be at least one 1 bit */ | |
525 | while ((temp >>= 1)) | |
526 | nbits++; | |
527 | /* Check for out-of-range coefficient values */ | |
528 | if (nbits > MAX_COEF_BITS) | |
529 | ERREXIT(cinfo, JERR_BAD_DCT_COEF); | |
530 | ||
531 | /* Count/emit Huffman symbol for run length / number of bits */ | |
532 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits); | |
533 | ||
534 | /* Emit that number of bits of the value, if positive, */ | |
535 | /* or the complement of its magnitude, if negative. */ | |
536 | emit_bits(entropy, (unsigned int) temp2, nbits); | |
537 | ||
538 | r = 0; /* reset zero run length */ | |
539 | } | |
540 | ||
541 | if (r > 0) { /* If there are trailing zeroes, */ | |
542 | entropy->EOBRUN++; /* count an EOB */ | |
543 | if (entropy->EOBRUN == 0x7FFF) | |
544 | emit_eobrun(entropy); /* force it out to avoid overflow */ | |
545 | } | |
546 | ||
547 | cinfo->dest->next_output_byte = entropy->next_output_byte; | |
548 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
549 | ||
550 | /* Update restart-interval state too */ | |
551 | if (cinfo->restart_interval) { | |
552 | if (entropy->restarts_to_go == 0) { | |
553 | entropy->restarts_to_go = cinfo->restart_interval; | |
554 | entropy->next_restart_num++; | |
555 | entropy->next_restart_num &= 7; | |
556 | } | |
557 | entropy->restarts_to_go--; | |
558 | } | |
559 | ||
560 | return TRUE; | |
561 | } | |
562 | ||
563 | ||
564 | /* | |
565 | * MCU encoding for DC successive approximation refinement scan. | |
566 | * Note: we assume such scans can be multi-component, although the spec | |
567 | * is not very clear on the point. | |
568 | */ | |
569 | ||
570 | METHODDEF(boolean) | |
571 | encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
572 | { | |
573 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
574 | register int temp; | |
575 | int blkn; | |
576 | int Al = cinfo->Al; | |
577 | JBLOCKROW block; | |
578 | ||
579 | entropy->next_output_byte = cinfo->dest->next_output_byte; | |
580 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
581 | ||
582 | /* Emit restart marker if needed */ | |
583 | if (cinfo->restart_interval) | |
584 | if (entropy->restarts_to_go == 0) | |
585 | emit_restart(entropy, entropy->next_restart_num); | |
586 | ||
587 | /* Encode the MCU data blocks */ | |
588 | for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { | |
589 | block = MCU_data[blkn]; | |
590 | ||
591 | /* We simply emit the Al'th bit of the DC coefficient value. */ | |
592 | temp = (*block)[0]; | |
593 | emit_bits(entropy, (unsigned int) (temp >> Al), 1); | |
594 | } | |
595 | ||
596 | cinfo->dest->next_output_byte = entropy->next_output_byte; | |
597 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
598 | ||
599 | /* Update restart-interval state too */ | |
600 | if (cinfo->restart_interval) { | |
601 | if (entropy->restarts_to_go == 0) { | |
602 | entropy->restarts_to_go = cinfo->restart_interval; | |
603 | entropy->next_restart_num++; | |
604 | entropy->next_restart_num &= 7; | |
605 | } | |
606 | entropy->restarts_to_go--; | |
607 | } | |
608 | ||
609 | return TRUE; | |
610 | } | |
611 | ||
612 | ||
613 | /* | |
614 | * MCU encoding for AC successive approximation refinement scan. | |
615 | */ | |
616 | ||
617 | METHODDEF(boolean) | |
618 | encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data) | |
619 | { | |
620 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
621 | register int temp; | |
622 | register int r, k; | |
623 | int EOB; | |
624 | char *BR_buffer; | |
625 | unsigned int BR; | |
626 | int Se = cinfo->Se; | |
627 | int Al = cinfo->Al; | |
628 | JBLOCKROW block; | |
629 | int absvalues[DCTSIZE2]; | |
630 | ||
631 | entropy->next_output_byte = cinfo->dest->next_output_byte; | |
632 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
633 | ||
634 | /* Emit restart marker if needed */ | |
635 | if (cinfo->restart_interval) | |
636 | if (entropy->restarts_to_go == 0) | |
637 | emit_restart(entropy, entropy->next_restart_num); | |
638 | ||
639 | /* Encode the MCU data block */ | |
640 | block = MCU_data[0]; | |
641 | ||
642 | /* It is convenient to make a pre-pass to determine the transformed | |
643 | * coefficients' absolute values and the EOB position. | |
644 | */ | |
645 | EOB = 0; | |
646 | for (k = cinfo->Ss; k <= Se; k++) { | |
647 | temp = (*block)[jpeg_natural_order[k]]; | |
648 | /* We must apply the point transform by Al. For AC coefficients this | |
649 | * is an integer division with rounding towards 0. To do this portably | |
650 | * in C, we shift after obtaining the absolute value. | |
651 | */ | |
652 | if (temp < 0) | |
653 | temp = -temp; /* temp is abs value of input */ | |
654 | temp >>= Al; /* apply the point transform */ | |
655 | absvalues[k] = temp; /* save abs value for main pass */ | |
656 | if (temp == 1) | |
657 | EOB = k; /* EOB = index of last newly-nonzero coef */ | |
658 | } | |
659 | ||
660 | /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */ | |
661 | ||
662 | r = 0; /* r = run length of zeros */ | |
663 | BR = 0; /* BR = count of buffered bits added now */ | |
664 | BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */ | |
665 | ||
666 | for (k = cinfo->Ss; k <= Se; k++) { | |
667 | if ((temp = absvalues[k]) == 0) { | |
668 | r++; | |
669 | continue; | |
670 | } | |
671 | ||
672 | /* Emit any required ZRLs, but not if they can be folded into EOB */ | |
673 | while (r > 15 && k <= EOB) { | |
674 | /* emit any pending EOBRUN and the BE correction bits */ | |
675 | emit_eobrun(entropy); | |
676 | /* Emit ZRL */ | |
677 | emit_symbol(entropy, entropy->ac_tbl_no, 0xF0); | |
678 | r -= 16; | |
679 | /* Emit buffered correction bits that must be associated with ZRL */ | |
680 | emit_buffered_bits(entropy, BR_buffer, BR); | |
681 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ | |
682 | BR = 0; | |
683 | } | |
684 | ||
685 | /* If the coef was previously nonzero, it only needs a correction bit. | |
686 | * NOTE: a straight translation of the spec's figure G.7 would suggest | |
687 | * that we also need to test r > 15. But if r > 15, we can only get here | |
688 | * if k > EOB, which implies that this coefficient is not 1. | |
689 | */ | |
690 | if (temp > 1) { | |
691 | /* The correction bit is the next bit of the absolute value. */ | |
692 | BR_buffer[BR++] = (char) (temp & 1); | |
693 | continue; | |
694 | } | |
695 | ||
696 | /* Emit any pending EOBRUN and the BE correction bits */ | |
697 | emit_eobrun(entropy); | |
698 | ||
699 | /* Count/emit Huffman symbol for run length / number of bits */ | |
700 | emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1); | |
701 | ||
702 | /* Emit output bit for newly-nonzero coef */ | |
703 | temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1; | |
704 | emit_bits(entropy, (unsigned int) temp, 1); | |
705 | ||
706 | /* Emit buffered correction bits that must be associated with this code */ | |
707 | emit_buffered_bits(entropy, BR_buffer, BR); | |
708 | BR_buffer = entropy->bit_buffer; /* BE bits are gone now */ | |
709 | BR = 0; | |
710 | r = 0; /* reset zero run length */ | |
711 | } | |
712 | ||
713 | if (r > 0 || BR > 0) { /* If there are trailing zeroes, */ | |
714 | entropy->EOBRUN++; /* count an EOB */ | |
715 | entropy->BE += BR; /* concat my correction bits to older ones */ | |
716 | /* We force out the EOB if we risk either: | |
717 | * 1. overflow of the EOB counter; | |
718 | * 2. overflow of the correction bit buffer during the next MCU. | |
719 | */ | |
720 | if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1)) | |
721 | emit_eobrun(entropy); | |
722 | } | |
723 | ||
724 | cinfo->dest->next_output_byte = entropy->next_output_byte; | |
725 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
726 | ||
727 | /* Update restart-interval state too */ | |
728 | if (cinfo->restart_interval) { | |
729 | if (entropy->restarts_to_go == 0) { | |
730 | entropy->restarts_to_go = cinfo->restart_interval; | |
731 | entropy->next_restart_num++; | |
732 | entropy->next_restart_num &= 7; | |
733 | } | |
734 | entropy->restarts_to_go--; | |
735 | } | |
736 | ||
737 | return TRUE; | |
738 | } | |
739 | ||
740 | ||
741 | /* | |
742 | * Finish up at the end of a Huffman-compressed progressive scan. | |
743 | */ | |
744 | ||
745 | METHODDEF(void) | |
746 | finish_pass_phuff (j_compress_ptr cinfo) | |
747 | { | |
748 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
749 | ||
750 | entropy->next_output_byte = cinfo->dest->next_output_byte; | |
751 | entropy->free_in_buffer = cinfo->dest->free_in_buffer; | |
752 | ||
753 | /* Flush out any buffered data */ | |
754 | emit_eobrun(entropy); | |
755 | flush_bits(entropy); | |
756 | ||
757 | cinfo->dest->next_output_byte = entropy->next_output_byte; | |
758 | cinfo->dest->free_in_buffer = entropy->free_in_buffer; | |
759 | } | |
760 | ||
761 | ||
762 | /* | |
763 | * Finish up a statistics-gathering pass and create the new Huffman tables. | |
764 | */ | |
765 | ||
766 | METHODDEF(void) | |
767 | finish_pass_gather_phuff (j_compress_ptr cinfo) | |
768 | { | |
769 | phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy; | |
770 | boolean is_DC_band; | |
771 | int ci, tbl; | |
772 | jpeg_component_info * compptr; | |
773 | JHUFF_TBL **htblptr; | |
774 | boolean did[NUM_HUFF_TBLS]; | |
775 | ||
776 | /* Flush out buffered data (all we care about is counting the EOB symbol) */ | |
777 | emit_eobrun(entropy); | |
778 | ||
779 | is_DC_band = (cinfo->Ss == 0); | |
780 | ||
781 | /* It's important not to apply jpeg_gen_optimal_table more than once | |
782 | * per table, because it clobbers the input frequency counts! | |
783 | */ | |
784 | MEMZERO(did, SIZEOF(did)); | |
785 | ||
786 | for (ci = 0; ci < cinfo->comps_in_scan; ci++) { | |
787 | compptr = cinfo->cur_comp_info[ci]; | |
788 | if (is_DC_band) { | |
789 | if (cinfo->Ah != 0) /* DC refinement needs no table */ | |
790 | continue; | |
791 | tbl = compptr->dc_tbl_no; | |
792 | } else { | |
793 | tbl = compptr->ac_tbl_no; | |
794 | } | |
795 | if (! did[tbl]) { | |
796 | if (is_DC_band) | |
797 | htblptr = & cinfo->dc_huff_tbl_ptrs[tbl]; | |
798 | else | |
799 | htblptr = & cinfo->ac_huff_tbl_ptrs[tbl]; | |
800 | if (*htblptr == NULL) | |
801 | *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); | |
802 | jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]); | |
803 | did[tbl] = TRUE; | |
804 | } | |
805 | } | |
806 | } | |
807 | ||
808 | ||
809 | /* | |
810 | * Module initialization routine for progressive Huffman entropy encoding. | |
811 | */ | |
812 | ||
813 | GLOBAL(void) | |
814 | jinit_phuff_encoder (j_compress_ptr cinfo) | |
815 | { | |
816 | phuff_entropy_ptr entropy; | |
817 | int i; | |
818 | ||
819 | entropy = (phuff_entropy_ptr) | |
820 | (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, | |
821 | SIZEOF(phuff_entropy_encoder)); | |
822 | cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; | |
823 | entropy->pub.start_pass = start_pass_phuff; | |
824 | ||
825 | /* Mark tables unallocated */ | |
826 | for (i = 0; i < NUM_HUFF_TBLS; i++) { | |
827 | entropy->derived_tbls[i] = NULL; | |
828 | entropy->count_ptrs[i] = NULL; | |
829 | } | |
830 | entropy->bit_buffer = NULL; /* needed only in AC refinement scan */ | |
831 | } | |
832 | ||
833 | #endif /* C_PROGRESSIVE_SUPPORTED */ |