Line data Source code
1 : /*
2 : * jcphuff.c
3 : *
4 : * This file was part of the Independent JPEG Group's software:
5 : * Copyright (C) 1995-1997, Thomas G. Lane.
6 : * libjpeg-turbo Modifications:
7 : * Copyright (C) 2015, D. R. Commander.
8 : * For conditions of distribution and use, see the accompanying README.ijg
9 : * file.
10 : *
11 : * This file contains Huffman entropy encoding routines for progressive JPEG.
12 : *
13 : * We do not support output suspension in this module, since the library
14 : * currently does not allow multiple-scan files to be written with output
15 : * suspension.
16 : */
17 :
18 : #define JPEG_INTERNALS
19 : #include "jinclude.h"
20 : #include "jpeglib.h"
21 : #include "jchuff.h" /* Declarations shared with jchuff.c */
22 :
23 : #ifdef C_PROGRESSIVE_SUPPORTED
24 :
25 : /* Expanded entropy encoder object for progressive Huffman encoding. */
26 :
27 : typedef struct {
28 : struct jpeg_entropy_encoder pub; /* public fields */
29 :
30 : /* Mode flag: TRUE for optimization, FALSE for actual data output */
31 : boolean gather_statistics;
32 :
33 : /* Bit-level coding status.
34 : * next_output_byte/free_in_buffer are local copies of cinfo->dest fields.
35 : */
36 : JOCTET *next_output_byte; /* => next byte to write in buffer */
37 : size_t free_in_buffer; /* # of byte spaces remaining in buffer */
38 : size_t put_buffer; /* current bit-accumulation buffer */
39 : int put_bits; /* # of bits now in it */
40 : j_compress_ptr cinfo; /* link to cinfo (needed for dump_buffer) */
41 :
42 : /* Coding status for DC components */
43 : int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
44 :
45 : /* Coding status for AC components */
46 : int ac_tbl_no; /* the table number of the single component */
47 : unsigned int EOBRUN; /* run length of EOBs */
48 : unsigned int BE; /* # of buffered correction bits before MCU */
49 : char *bit_buffer; /* buffer for correction bits (1 per char) */
50 : /* packing correction bits tightly would save some space but cost time... */
51 :
52 : unsigned int restarts_to_go; /* MCUs left in this restart interval */
53 : int next_restart_num; /* next restart number to write (0-7) */
54 :
55 : /* Pointers to derived tables (these workspaces have image lifespan).
56 : * Since any one scan codes only DC or only AC, we only need one set
57 : * of tables, not one for DC and one for AC.
58 : */
59 : c_derived_tbl *derived_tbls[NUM_HUFF_TBLS];
60 :
61 : /* Statistics tables for optimization; again, one set is enough */
62 : long *count_ptrs[NUM_HUFF_TBLS];
63 : } phuff_entropy_encoder;
64 :
65 : typedef phuff_entropy_encoder *phuff_entropy_ptr;
66 :
67 : /* MAX_CORR_BITS is the number of bits the AC refinement correction-bit
68 : * buffer can hold. Larger sizes may slightly improve compression, but
69 : * 1000 is already well into the realm of overkill.
70 : * The minimum safe size is 64 bits.
71 : */
72 :
73 : #define MAX_CORR_BITS 1000 /* Max # of correction bits I can buffer */
74 :
75 : /* IRIGHT_SHIFT is like RIGHT_SHIFT, but works on int rather than JLONG.
76 : * We assume that int right shift is unsigned if JLONG right shift is,
77 : * which should be safe.
78 : */
79 :
80 : #ifdef RIGHT_SHIFT_IS_UNSIGNED
81 : #define ISHIFT_TEMPS int ishift_temp;
82 : #define IRIGHT_SHIFT(x,shft) \
83 : ((ishift_temp = (x)) < 0 ? \
84 : (ishift_temp >> (shft)) | ((~0) << (16-(shft))) : \
85 : (ishift_temp >> (shft)))
86 : #else
87 : #define ISHIFT_TEMPS
88 : #define IRIGHT_SHIFT(x,shft) ((x) >> (shft))
89 : #endif
90 :
91 : /* Forward declarations */
92 : METHODDEF(boolean) encode_mcu_DC_first (j_compress_ptr cinfo,
93 : JBLOCKROW *MCU_data);
94 : METHODDEF(boolean) encode_mcu_AC_first (j_compress_ptr cinfo,
95 : JBLOCKROW *MCU_data);
96 : METHODDEF(boolean) encode_mcu_DC_refine (j_compress_ptr cinfo,
97 : JBLOCKROW *MCU_data);
98 : METHODDEF(boolean) encode_mcu_AC_refine (j_compress_ptr cinfo,
99 : JBLOCKROW *MCU_data);
100 : METHODDEF(void) finish_pass_phuff (j_compress_ptr cinfo);
101 : METHODDEF(void) finish_pass_gather_phuff (j_compress_ptr cinfo);
102 :
103 :
104 : /*
105 : * Initialize for a Huffman-compressed scan using progressive JPEG.
106 : */
107 :
108 : METHODDEF(void)
109 0 : start_pass_phuff (j_compress_ptr cinfo, boolean gather_statistics)
110 : {
111 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
112 : boolean is_DC_band;
113 : int ci, tbl;
114 : jpeg_component_info *compptr;
115 :
116 0 : entropy->cinfo = cinfo;
117 0 : entropy->gather_statistics = gather_statistics;
118 :
119 0 : is_DC_band = (cinfo->Ss == 0);
120 :
121 : /* We assume jcmaster.c already validated the scan parameters. */
122 :
123 : /* Select execution routines */
124 0 : if (cinfo->Ah == 0) {
125 0 : if (is_DC_band)
126 0 : entropy->pub.encode_mcu = encode_mcu_DC_first;
127 : else
128 0 : entropy->pub.encode_mcu = encode_mcu_AC_first;
129 : } else {
130 0 : if (is_DC_band)
131 0 : entropy->pub.encode_mcu = encode_mcu_DC_refine;
132 : else {
133 0 : entropy->pub.encode_mcu = encode_mcu_AC_refine;
134 : /* AC refinement needs a correction bit buffer */
135 0 : if (entropy->bit_buffer == NULL)
136 0 : entropy->bit_buffer = (char *)
137 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
138 : MAX_CORR_BITS * sizeof(char));
139 : }
140 : }
141 0 : if (gather_statistics)
142 0 : entropy->pub.finish_pass = finish_pass_gather_phuff;
143 : else
144 0 : entropy->pub.finish_pass = finish_pass_phuff;
145 :
146 : /* Only DC coefficients may be interleaved, so cinfo->comps_in_scan = 1
147 : * for AC coefficients.
148 : */
149 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
150 0 : compptr = cinfo->cur_comp_info[ci];
151 : /* Initialize DC predictions to 0 */
152 0 : entropy->last_dc_val[ci] = 0;
153 : /* Get table index */
154 0 : if (is_DC_band) {
155 0 : if (cinfo->Ah != 0) /* DC refinement needs no table */
156 0 : continue;
157 0 : tbl = compptr->dc_tbl_no;
158 : } else {
159 0 : entropy->ac_tbl_no = tbl = compptr->ac_tbl_no;
160 : }
161 0 : if (gather_statistics) {
162 : /* Check for invalid table index */
163 : /* (make_c_derived_tbl does this in the other path) */
164 0 : if (tbl < 0 || tbl >= NUM_HUFF_TBLS)
165 0 : ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tbl);
166 : /* Allocate and zero the statistics tables */
167 : /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */
168 0 : if (entropy->count_ptrs[tbl] == NULL)
169 0 : entropy->count_ptrs[tbl] = (long *)
170 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
171 : 257 * sizeof(long));
172 0 : MEMZERO(entropy->count_ptrs[tbl], 257 * sizeof(long));
173 : } else {
174 : /* Compute derived values for Huffman table */
175 : /* We may do this more than once for a table, but it's not expensive */
176 0 : jpeg_make_c_derived_tbl(cinfo, is_DC_band, tbl,
177 : & entropy->derived_tbls[tbl]);
178 : }
179 : }
180 :
181 : /* Initialize AC stuff */
182 0 : entropy->EOBRUN = 0;
183 0 : entropy->BE = 0;
184 :
185 : /* Initialize bit buffer to empty */
186 0 : entropy->put_buffer = 0;
187 0 : entropy->put_bits = 0;
188 :
189 : /* Initialize restart stuff */
190 0 : entropy->restarts_to_go = cinfo->restart_interval;
191 0 : entropy->next_restart_num = 0;
192 0 : }
193 :
194 :
195 : /* Outputting bytes to the file.
196 : * NB: these must be called only when actually outputting,
197 : * that is, entropy->gather_statistics == FALSE.
198 : */
199 :
200 : /* Emit a byte */
201 : #define emit_byte(entropy,val) \
202 : { *(entropy)->next_output_byte++ = (JOCTET) (val); \
203 : if (--(entropy)->free_in_buffer == 0) \
204 : dump_buffer(entropy); }
205 :
206 :
207 : LOCAL(void)
208 0 : dump_buffer (phuff_entropy_ptr entropy)
209 : /* Empty the output buffer; we do not support suspension in this module. */
210 : {
211 0 : struct jpeg_destination_mgr *dest = entropy->cinfo->dest;
212 :
213 0 : if (! (*dest->empty_output_buffer) (entropy->cinfo))
214 0 : ERREXIT(entropy->cinfo, JERR_CANT_SUSPEND);
215 : /* After a successful buffer dump, must reset buffer pointers */
216 0 : entropy->next_output_byte = dest->next_output_byte;
217 0 : entropy->free_in_buffer = dest->free_in_buffer;
218 0 : }
219 :
220 :
221 : /* Outputting bits to the file */
222 :
223 : /* Only the right 24 bits of put_buffer are used; the valid bits are
224 : * left-justified in this part. At most 16 bits can be passed to emit_bits
225 : * in one call, and we never retain more than 7 bits in put_buffer
226 : * between calls, so 24 bits are sufficient.
227 : */
228 :
229 : LOCAL(void)
230 0 : emit_bits (phuff_entropy_ptr entropy, unsigned int code, int size)
231 : /* Emit some bits, unless we are in gather mode */
232 : {
233 : /* This routine is heavily used, so it's worth coding tightly. */
234 0 : register size_t put_buffer = (size_t) code;
235 0 : register int put_bits = entropy->put_bits;
236 :
237 : /* if size is 0, caller used an invalid Huffman table entry */
238 0 : if (size == 0)
239 0 : ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
240 :
241 0 : if (entropy->gather_statistics)
242 0 : return; /* do nothing if we're only getting stats */
243 :
244 0 : put_buffer &= (((size_t) 1)<<size) - 1; /* mask off any extra bits in code */
245 :
246 0 : put_bits += size; /* new number of bits in buffer */
247 :
248 0 : put_buffer <<= 24 - put_bits; /* align incoming bits */
249 :
250 0 : put_buffer |= entropy->put_buffer; /* and merge with old buffer contents */
251 :
252 0 : while (put_bits >= 8) {
253 0 : int c = (int) ((put_buffer >> 16) & 0xFF);
254 :
255 0 : emit_byte(entropy, c);
256 0 : if (c == 0xFF) { /* need to stuff a zero byte? */
257 0 : emit_byte(entropy, 0);
258 : }
259 0 : put_buffer <<= 8;
260 0 : put_bits -= 8;
261 : }
262 :
263 0 : entropy->put_buffer = put_buffer; /* update variables */
264 0 : entropy->put_bits = put_bits;
265 : }
266 :
267 :
268 : LOCAL(void)
269 0 : flush_bits (phuff_entropy_ptr entropy)
270 : {
271 0 : emit_bits(entropy, 0x7F, 7); /* fill any partial byte with ones */
272 0 : entropy->put_buffer = 0; /* and reset bit-buffer to empty */
273 0 : entropy->put_bits = 0;
274 0 : }
275 :
276 :
277 : /*
278 : * Emit (or just count) a Huffman symbol.
279 : */
280 :
281 : LOCAL(void)
282 0 : emit_symbol (phuff_entropy_ptr entropy, int tbl_no, int symbol)
283 : {
284 0 : if (entropy->gather_statistics)
285 0 : entropy->count_ptrs[tbl_no][symbol]++;
286 : else {
287 0 : c_derived_tbl *tbl = entropy->derived_tbls[tbl_no];
288 0 : emit_bits(entropy, tbl->ehufco[symbol], tbl->ehufsi[symbol]);
289 : }
290 0 : }
291 :
292 :
293 : /*
294 : * Emit bits from a correction bit buffer.
295 : */
296 :
297 : LOCAL(void)
298 0 : emit_buffered_bits (phuff_entropy_ptr entropy, char *bufstart,
299 : unsigned int nbits)
300 : {
301 0 : if (entropy->gather_statistics)
302 0 : return; /* no real work */
303 :
304 0 : while (nbits > 0) {
305 0 : emit_bits(entropy, (unsigned int) (*bufstart), 1);
306 0 : bufstart++;
307 0 : nbits--;
308 : }
309 : }
310 :
311 :
312 : /*
313 : * Emit any pending EOBRUN symbol.
314 : */
315 :
316 : LOCAL(void)
317 0 : emit_eobrun (phuff_entropy_ptr entropy)
318 : {
319 : register int temp, nbits;
320 :
321 0 : if (entropy->EOBRUN > 0) { /* if there is any pending EOBRUN */
322 0 : temp = entropy->EOBRUN;
323 0 : nbits = 0;
324 0 : while ((temp >>= 1))
325 0 : nbits++;
326 : /* safety check: shouldn't happen given limited correction-bit buffer */
327 0 : if (nbits > 14)
328 0 : ERREXIT(entropy->cinfo, JERR_HUFF_MISSING_CODE);
329 :
330 0 : emit_symbol(entropy, entropy->ac_tbl_no, nbits << 4);
331 0 : if (nbits)
332 0 : emit_bits(entropy, entropy->EOBRUN, nbits);
333 :
334 0 : entropy->EOBRUN = 0;
335 :
336 : /* Emit any buffered correction bits */
337 0 : emit_buffered_bits(entropy, entropy->bit_buffer, entropy->BE);
338 0 : entropy->BE = 0;
339 : }
340 0 : }
341 :
342 :
343 : /*
344 : * Emit a restart marker & resynchronize predictions.
345 : */
346 :
347 : LOCAL(void)
348 0 : emit_restart (phuff_entropy_ptr entropy, int restart_num)
349 : {
350 : int ci;
351 :
352 0 : emit_eobrun(entropy);
353 :
354 0 : if (! entropy->gather_statistics) {
355 0 : flush_bits(entropy);
356 0 : emit_byte(entropy, 0xFF);
357 0 : emit_byte(entropy, JPEG_RST0 + restart_num);
358 : }
359 :
360 0 : if (entropy->cinfo->Ss == 0) {
361 : /* Re-initialize DC predictions to 0 */
362 0 : for (ci = 0; ci < entropy->cinfo->comps_in_scan; ci++)
363 0 : entropy->last_dc_val[ci] = 0;
364 : } else {
365 : /* Re-initialize all AC-related fields to 0 */
366 0 : entropy->EOBRUN = 0;
367 0 : entropy->BE = 0;
368 : }
369 0 : }
370 :
371 :
372 : /*
373 : * MCU encoding for DC initial scan (either spectral selection,
374 : * or first pass of successive approximation).
375 : */
376 :
377 : METHODDEF(boolean)
378 0 : encode_mcu_DC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
379 : {
380 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
381 : register int temp, temp2;
382 : register int nbits;
383 : int blkn, ci;
384 0 : int Al = cinfo->Al;
385 : JBLOCKROW block;
386 : jpeg_component_info *compptr;
387 : ISHIFT_TEMPS
388 :
389 0 : entropy->next_output_byte = cinfo->dest->next_output_byte;
390 0 : entropy->free_in_buffer = cinfo->dest->free_in_buffer;
391 :
392 : /* Emit restart marker if needed */
393 0 : if (cinfo->restart_interval)
394 0 : if (entropy->restarts_to_go == 0)
395 0 : emit_restart(entropy, entropy->next_restart_num);
396 :
397 : /* Encode the MCU data blocks */
398 0 : for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
399 0 : block = MCU_data[blkn];
400 0 : ci = cinfo->MCU_membership[blkn];
401 0 : compptr = cinfo->cur_comp_info[ci];
402 :
403 : /* Compute the DC value after the required point transform by Al.
404 : * This is simply an arithmetic right shift.
405 : */
406 0 : temp2 = IRIGHT_SHIFT((int) ((*block)[0]), Al);
407 :
408 : /* DC differences are figured on the point-transformed values. */
409 0 : temp = temp2 - entropy->last_dc_val[ci];
410 0 : entropy->last_dc_val[ci] = temp2;
411 :
412 : /* Encode the DC coefficient difference per section G.1.2.1 */
413 0 : temp2 = temp;
414 0 : if (temp < 0) {
415 0 : temp = -temp; /* temp is abs value of input */
416 : /* For a negative input, want temp2 = bitwise complement of abs(input) */
417 : /* This code assumes we are on a two's complement machine */
418 0 : temp2--;
419 : }
420 :
421 : /* Find the number of bits needed for the magnitude of the coefficient */
422 0 : nbits = 0;
423 0 : while (temp) {
424 0 : nbits++;
425 0 : temp >>= 1;
426 : }
427 : /* Check for out-of-range coefficient values.
428 : * Since we're encoding a difference, the range limit is twice as much.
429 : */
430 0 : if (nbits > MAX_COEF_BITS+1)
431 0 : ERREXIT(cinfo, JERR_BAD_DCT_COEF);
432 :
433 : /* Count/emit the Huffman-coded symbol for the number of bits */
434 0 : emit_symbol(entropy, compptr->dc_tbl_no, nbits);
435 :
436 : /* Emit that number of bits of the value, if positive, */
437 : /* or the complement of its magnitude, if negative. */
438 0 : if (nbits) /* emit_bits rejects calls with size 0 */
439 0 : emit_bits(entropy, (unsigned int) temp2, nbits);
440 : }
441 :
442 0 : cinfo->dest->next_output_byte = entropy->next_output_byte;
443 0 : cinfo->dest->free_in_buffer = entropy->free_in_buffer;
444 :
445 : /* Update restart-interval state too */
446 0 : if (cinfo->restart_interval) {
447 0 : if (entropy->restarts_to_go == 0) {
448 0 : entropy->restarts_to_go = cinfo->restart_interval;
449 0 : entropy->next_restart_num++;
450 0 : entropy->next_restart_num &= 7;
451 : }
452 0 : entropy->restarts_to_go--;
453 : }
454 :
455 0 : return TRUE;
456 : }
457 :
458 :
459 : /*
460 : * MCU encoding for AC initial scan (either spectral selection,
461 : * or first pass of successive approximation).
462 : */
463 :
464 : METHODDEF(boolean)
465 0 : encode_mcu_AC_first (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
466 : {
467 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
468 : register int temp, temp2;
469 : register int nbits;
470 : register int r, k;
471 0 : int Se = cinfo->Se;
472 0 : int Al = cinfo->Al;
473 : JBLOCKROW block;
474 :
475 0 : entropy->next_output_byte = cinfo->dest->next_output_byte;
476 0 : entropy->free_in_buffer = cinfo->dest->free_in_buffer;
477 :
478 : /* Emit restart marker if needed */
479 0 : if (cinfo->restart_interval)
480 0 : if (entropy->restarts_to_go == 0)
481 0 : emit_restart(entropy, entropy->next_restart_num);
482 :
483 : /* Encode the MCU data block */
484 0 : block = MCU_data[0];
485 :
486 : /* Encode the AC coefficients per section G.1.2.2, fig. G.3 */
487 :
488 0 : r = 0; /* r = run length of zeros */
489 :
490 0 : for (k = cinfo->Ss; k <= Se; k++) {
491 0 : if ((temp = (*block)[jpeg_natural_order[k]]) == 0) {
492 0 : r++;
493 0 : continue;
494 : }
495 : /* We must apply the point transform by Al. For AC coefficients this
496 : * is an integer division with rounding towards 0. To do this portably
497 : * in C, we shift after obtaining the absolute value; so the code is
498 : * interwoven with finding the abs value (temp) and output bits (temp2).
499 : */
500 0 : if (temp < 0) {
501 0 : temp = -temp; /* temp is abs value of input */
502 0 : temp >>= Al; /* apply the point transform */
503 : /* For a negative coef, want temp2 = bitwise complement of abs(coef) */
504 0 : temp2 = ~temp;
505 : } else {
506 0 : temp >>= Al; /* apply the point transform */
507 0 : temp2 = temp;
508 : }
509 : /* Watch out for case that nonzero coef is zero after point transform */
510 0 : if (temp == 0) {
511 0 : r++;
512 0 : continue;
513 : }
514 :
515 : /* Emit any pending EOBRUN */
516 0 : if (entropy->EOBRUN > 0)
517 0 : emit_eobrun(entropy);
518 : /* if run length > 15, must emit special run-length-16 codes (0xF0) */
519 0 : while (r > 15) {
520 0 : emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
521 0 : r -= 16;
522 : }
523 :
524 : /* Find the number of bits needed for the magnitude of the coefficient */
525 0 : nbits = 1; /* there must be at least one 1 bit */
526 0 : while ((temp >>= 1))
527 0 : nbits++;
528 : /* Check for out-of-range coefficient values */
529 0 : if (nbits > MAX_COEF_BITS)
530 0 : ERREXIT(cinfo, JERR_BAD_DCT_COEF);
531 :
532 : /* Count/emit Huffman symbol for run length / number of bits */
533 0 : emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + nbits);
534 :
535 : /* Emit that number of bits of the value, if positive, */
536 : /* or the complement of its magnitude, if negative. */
537 0 : emit_bits(entropy, (unsigned int) temp2, nbits);
538 :
539 0 : r = 0; /* reset zero run length */
540 : }
541 :
542 0 : if (r > 0) { /* If there are trailing zeroes, */
543 0 : entropy->EOBRUN++; /* count an EOB */
544 0 : if (entropy->EOBRUN == 0x7FFF)
545 0 : emit_eobrun(entropy); /* force it out to avoid overflow */
546 : }
547 :
548 0 : cinfo->dest->next_output_byte = entropy->next_output_byte;
549 0 : cinfo->dest->free_in_buffer = entropy->free_in_buffer;
550 :
551 : /* Update restart-interval state too */
552 0 : if (cinfo->restart_interval) {
553 0 : if (entropy->restarts_to_go == 0) {
554 0 : entropy->restarts_to_go = cinfo->restart_interval;
555 0 : entropy->next_restart_num++;
556 0 : entropy->next_restart_num &= 7;
557 : }
558 0 : entropy->restarts_to_go--;
559 : }
560 :
561 0 : return TRUE;
562 : }
563 :
564 :
565 : /*
566 : * MCU encoding for DC successive approximation refinement scan.
567 : * Note: we assume such scans can be multi-component, although the spec
568 : * is not very clear on the point.
569 : */
570 :
571 : METHODDEF(boolean)
572 0 : encode_mcu_DC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
573 : {
574 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
575 : register int temp;
576 : int blkn;
577 0 : int Al = cinfo->Al;
578 : JBLOCKROW block;
579 :
580 0 : entropy->next_output_byte = cinfo->dest->next_output_byte;
581 0 : entropy->free_in_buffer = cinfo->dest->free_in_buffer;
582 :
583 : /* Emit restart marker if needed */
584 0 : if (cinfo->restart_interval)
585 0 : if (entropy->restarts_to_go == 0)
586 0 : emit_restart(entropy, entropy->next_restart_num);
587 :
588 : /* Encode the MCU data blocks */
589 0 : for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
590 0 : block = MCU_data[blkn];
591 :
592 : /* We simply emit the Al'th bit of the DC coefficient value. */
593 0 : temp = (*block)[0];
594 0 : emit_bits(entropy, (unsigned int) (temp >> Al), 1);
595 : }
596 :
597 0 : cinfo->dest->next_output_byte = entropy->next_output_byte;
598 0 : cinfo->dest->free_in_buffer = entropy->free_in_buffer;
599 :
600 : /* Update restart-interval state too */
601 0 : if (cinfo->restart_interval) {
602 0 : if (entropy->restarts_to_go == 0) {
603 0 : entropy->restarts_to_go = cinfo->restart_interval;
604 0 : entropy->next_restart_num++;
605 0 : entropy->next_restart_num &= 7;
606 : }
607 0 : entropy->restarts_to_go--;
608 : }
609 :
610 0 : return TRUE;
611 : }
612 :
613 :
614 : /*
615 : * MCU encoding for AC successive approximation refinement scan.
616 : */
617 :
618 : METHODDEF(boolean)
619 0 : encode_mcu_AC_refine (j_compress_ptr cinfo, JBLOCKROW *MCU_data)
620 : {
621 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
622 : register int temp;
623 : register int r, k;
624 : int EOB;
625 : char *BR_buffer;
626 : unsigned int BR;
627 0 : int Se = cinfo->Se;
628 0 : int Al = cinfo->Al;
629 : JBLOCKROW block;
630 : int absvalues[DCTSIZE2];
631 :
632 0 : entropy->next_output_byte = cinfo->dest->next_output_byte;
633 0 : entropy->free_in_buffer = cinfo->dest->free_in_buffer;
634 :
635 : /* Emit restart marker if needed */
636 0 : if (cinfo->restart_interval)
637 0 : if (entropy->restarts_to_go == 0)
638 0 : emit_restart(entropy, entropy->next_restart_num);
639 :
640 : /* Encode the MCU data block */
641 0 : block = MCU_data[0];
642 :
643 : /* It is convenient to make a pre-pass to determine the transformed
644 : * coefficients' absolute values and the EOB position.
645 : */
646 0 : EOB = 0;
647 0 : for (k = cinfo->Ss; k <= Se; k++) {
648 0 : temp = (*block)[jpeg_natural_order[k]];
649 : /* We must apply the point transform by Al. For AC coefficients this
650 : * is an integer division with rounding towards 0. To do this portably
651 : * in C, we shift after obtaining the absolute value.
652 : */
653 0 : if (temp < 0)
654 0 : temp = -temp; /* temp is abs value of input */
655 0 : temp >>= Al; /* apply the point transform */
656 0 : absvalues[k] = temp; /* save abs value for main pass */
657 0 : if (temp == 1)
658 0 : EOB = k; /* EOB = index of last newly-nonzero coef */
659 : }
660 :
661 : /* Encode the AC coefficients per section G.1.2.3, fig. G.7 */
662 :
663 0 : r = 0; /* r = run length of zeros */
664 0 : BR = 0; /* BR = count of buffered bits added now */
665 0 : BR_buffer = entropy->bit_buffer + entropy->BE; /* Append bits to buffer */
666 :
667 0 : for (k = cinfo->Ss; k <= Se; k++) {
668 0 : if ((temp = absvalues[k]) == 0) {
669 0 : r++;
670 0 : continue;
671 : }
672 :
673 : /* Emit any required ZRLs, but not if they can be folded into EOB */
674 0 : while (r > 15 && k <= EOB) {
675 : /* emit any pending EOBRUN and the BE correction bits */
676 0 : emit_eobrun(entropy);
677 : /* Emit ZRL */
678 0 : emit_symbol(entropy, entropy->ac_tbl_no, 0xF0);
679 0 : r -= 16;
680 : /* Emit buffered correction bits that must be associated with ZRL */
681 0 : emit_buffered_bits(entropy, BR_buffer, BR);
682 0 : BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
683 0 : BR = 0;
684 : }
685 :
686 : /* If the coef was previously nonzero, it only needs a correction bit.
687 : * NOTE: a straight translation of the spec's figure G.7 would suggest
688 : * that we also need to test r > 15. But if r > 15, we can only get here
689 : * if k > EOB, which implies that this coefficient is not 1.
690 : */
691 0 : if (temp > 1) {
692 : /* The correction bit is the next bit of the absolute value. */
693 0 : BR_buffer[BR++] = (char) (temp & 1);
694 0 : continue;
695 : }
696 :
697 : /* Emit any pending EOBRUN and the BE correction bits */
698 0 : emit_eobrun(entropy);
699 :
700 : /* Count/emit Huffman symbol for run length / number of bits */
701 0 : emit_symbol(entropy, entropy->ac_tbl_no, (r << 4) + 1);
702 :
703 : /* Emit output bit for newly-nonzero coef */
704 0 : temp = ((*block)[jpeg_natural_order[k]] < 0) ? 0 : 1;
705 0 : emit_bits(entropy, (unsigned int) temp, 1);
706 :
707 : /* Emit buffered correction bits that must be associated with this code */
708 0 : emit_buffered_bits(entropy, BR_buffer, BR);
709 0 : BR_buffer = entropy->bit_buffer; /* BE bits are gone now */
710 0 : BR = 0;
711 0 : r = 0; /* reset zero run length */
712 : }
713 :
714 0 : if (r > 0 || BR > 0) { /* If there are trailing zeroes, */
715 0 : entropy->EOBRUN++; /* count an EOB */
716 0 : entropy->BE += BR; /* concat my correction bits to older ones */
717 : /* We force out the EOB if we risk either:
718 : * 1. overflow of the EOB counter;
719 : * 2. overflow of the correction bit buffer during the next MCU.
720 : */
721 0 : if (entropy->EOBRUN == 0x7FFF || entropy->BE > (MAX_CORR_BITS-DCTSIZE2+1))
722 0 : emit_eobrun(entropy);
723 : }
724 :
725 0 : cinfo->dest->next_output_byte = entropy->next_output_byte;
726 0 : cinfo->dest->free_in_buffer = entropy->free_in_buffer;
727 :
728 : /* Update restart-interval state too */
729 0 : if (cinfo->restart_interval) {
730 0 : if (entropy->restarts_to_go == 0) {
731 0 : entropy->restarts_to_go = cinfo->restart_interval;
732 0 : entropy->next_restart_num++;
733 0 : entropy->next_restart_num &= 7;
734 : }
735 0 : entropy->restarts_to_go--;
736 : }
737 :
738 0 : return TRUE;
739 : }
740 :
741 :
742 : /*
743 : * Finish up at the end of a Huffman-compressed progressive scan.
744 : */
745 :
746 : METHODDEF(void)
747 0 : finish_pass_phuff (j_compress_ptr cinfo)
748 : {
749 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
750 :
751 0 : entropy->next_output_byte = cinfo->dest->next_output_byte;
752 0 : entropy->free_in_buffer = cinfo->dest->free_in_buffer;
753 :
754 : /* Flush out any buffered data */
755 0 : emit_eobrun(entropy);
756 0 : flush_bits(entropy);
757 :
758 0 : cinfo->dest->next_output_byte = entropy->next_output_byte;
759 0 : cinfo->dest->free_in_buffer = entropy->free_in_buffer;
760 0 : }
761 :
762 :
763 : /*
764 : * Finish up a statistics-gathering pass and create the new Huffman tables.
765 : */
766 :
767 : METHODDEF(void)
768 0 : finish_pass_gather_phuff (j_compress_ptr cinfo)
769 : {
770 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
771 : boolean is_DC_band;
772 : int ci, tbl;
773 : jpeg_component_info *compptr;
774 : JHUFF_TBL **htblptr;
775 : boolean did[NUM_HUFF_TBLS];
776 :
777 : /* Flush out buffered data (all we care about is counting the EOB symbol) */
778 0 : emit_eobrun(entropy);
779 :
780 0 : is_DC_band = (cinfo->Ss == 0);
781 :
782 : /* It's important not to apply jpeg_gen_optimal_table more than once
783 : * per table, because it clobbers the input frequency counts!
784 : */
785 0 : MEMZERO(did, sizeof(did));
786 :
787 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
788 0 : compptr = cinfo->cur_comp_info[ci];
789 0 : if (is_DC_band) {
790 0 : if (cinfo->Ah != 0) /* DC refinement needs no table */
791 0 : continue;
792 0 : tbl = compptr->dc_tbl_no;
793 : } else {
794 0 : tbl = compptr->ac_tbl_no;
795 : }
796 0 : if (! did[tbl]) {
797 0 : if (is_DC_band)
798 0 : htblptr = & cinfo->dc_huff_tbl_ptrs[tbl];
799 : else
800 0 : htblptr = & cinfo->ac_huff_tbl_ptrs[tbl];
801 0 : if (*htblptr == NULL)
802 0 : *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo);
803 0 : jpeg_gen_optimal_table(cinfo, *htblptr, entropy->count_ptrs[tbl]);
804 0 : did[tbl] = TRUE;
805 : }
806 : }
807 0 : }
808 :
809 :
810 : /*
811 : * Module initialization routine for progressive Huffman entropy encoding.
812 : */
813 :
814 : GLOBAL(void)
815 0 : jinit_phuff_encoder (j_compress_ptr cinfo)
816 : {
817 : phuff_entropy_ptr entropy;
818 : int i;
819 :
820 0 : entropy = (phuff_entropy_ptr)
821 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
822 : sizeof(phuff_entropy_encoder));
823 0 : cinfo->entropy = (struct jpeg_entropy_encoder *) entropy;
824 0 : entropy->pub.start_pass = start_pass_phuff;
825 :
826 : /* Mark tables unallocated */
827 0 : for (i = 0; i < NUM_HUFF_TBLS; i++) {
828 0 : entropy->derived_tbls[i] = NULL;
829 0 : entropy->count_ptrs[i] = NULL;
830 : }
831 0 : entropy->bit_buffer = NULL; /* needed only in AC refinement scan */
832 0 : }
833 :
834 : #endif /* C_PROGRESSIVE_SUPPORTED */
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