1 : /*
2 : * jdphuff.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 decoding routines for progressive JPEG.
9 : *
10 : * Much of the complexity here has to do with supporting input suspension.
11 : * If the data source module demands suspension, we want to be able to back
12 : * up to the start of the current MCU. To do this, we copy state variables
13 : * into local working storage, and update them back to the permanent
14 : * storage only upon successful completion of an MCU.
15 : */
16 :
17 : #define JPEG_INTERNALS
18 : #include "jinclude.h"
19 : #include "jpeglib.h"
20 : #include "jdhuff.h" /* Declarations shared with jdhuff.c */
21 :
22 :
23 : #ifdef D_PROGRESSIVE_SUPPORTED
24 :
25 : /*
26 : * Expanded entropy decoder object for progressive Huffman decoding.
27 : *
28 : * The savable_state subrecord contains fields that change within an MCU,
29 : * but must not be updated permanently until we complete the MCU.
30 : */
31 :
32 : typedef struct {
33 : unsigned int EOBRUN; /* remaining EOBs in EOBRUN */
34 : int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
35 : } savable_state;
36 :
37 : /* This macro is to work around compilers with missing or broken
38 : * structure assignment. You'll need to fix this code if you have
39 : * such a compiler and you change MAX_COMPS_IN_SCAN.
40 : */
41 :
42 : #ifndef NO_STRUCT_ASSIGN
43 : #define ASSIGN_STATE(dest,src) ((dest) = (src))
44 : #else
45 : #if MAX_COMPS_IN_SCAN == 4
46 : #define ASSIGN_STATE(dest,src) \
47 : ((dest).EOBRUN = (src).EOBRUN, \
48 : (dest).last_dc_val[0] = (src).last_dc_val[0], \
49 : (dest).last_dc_val[1] = (src).last_dc_val[1], \
50 : (dest).last_dc_val[2] = (src).last_dc_val[2], \
51 : (dest).last_dc_val[3] = (src).last_dc_val[3])
52 : #endif
53 : #endif
54 :
55 :
56 : typedef struct {
57 : struct jpeg_entropy_decoder pub; /* public fields */
58 :
59 : /* These fields are loaded into local variables at start of each MCU.
60 : * In case of suspension, we exit WITHOUT updating them.
61 : */
62 : bitread_perm_state bitstate; /* Bit buffer at start of MCU */
63 : savable_state saved; /* Other state at start of MCU */
64 :
65 : /* These fields are NOT loaded into local working state. */
66 : unsigned int restarts_to_go; /* MCUs left in this restart interval */
67 :
68 : /* Pointers to derived tables (these workspaces have image lifespan) */
69 : d_derived_tbl * derived_tbls[NUM_HUFF_TBLS];
70 :
71 : d_derived_tbl * ac_derived_tbl; /* active table during an AC scan */
72 : } phuff_entropy_decoder;
73 :
74 : typedef phuff_entropy_decoder * phuff_entropy_ptr;
75 :
76 : /* Forward declarations */
77 : METHODDEF(boolean) decode_mcu_DC_first JPP((j_decompress_ptr cinfo,
78 : JBLOCKROW *MCU_data));
79 : METHODDEF(boolean) decode_mcu_AC_first JPP((j_decompress_ptr cinfo,
80 : JBLOCKROW *MCU_data));
81 : METHODDEF(boolean) decode_mcu_DC_refine JPP((j_decompress_ptr cinfo,
82 : JBLOCKROW *MCU_data));
83 : METHODDEF(boolean) decode_mcu_AC_refine JPP((j_decompress_ptr cinfo,
84 : JBLOCKROW *MCU_data));
85 :
86 :
87 : /*
88 : * Initialize for a Huffman-compressed scan.
89 : */
90 :
91 : METHODDEF(void)
92 0 : start_pass_phuff_decoder (j_decompress_ptr cinfo)
93 : {
94 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
95 : boolean is_DC_band, bad;
96 : int ci, coefi, tbl;
97 : int *coef_bit_ptr;
98 : jpeg_component_info * compptr;
99 :
100 0 : is_DC_band = (cinfo->Ss == 0);
101 :
102 : /* Validate scan parameters */
103 0 : bad = FALSE;
104 0 : if (is_DC_band) {
105 0 : if (cinfo->Se != 0)
106 0 : bad = TRUE;
107 : } else {
108 : /* need not check Ss/Se < 0 since they came from unsigned bytes */
109 0 : if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
110 0 : bad = TRUE;
111 : /* AC scans may have only one component */
112 0 : if (cinfo->comps_in_scan != 1)
113 0 : bad = TRUE;
114 : }
115 0 : if (cinfo->Ah != 0) {
116 : /* Successive approximation refinement scan: must have Al = Ah-1. */
117 0 : if (cinfo->Al != cinfo->Ah-1)
118 0 : bad = TRUE;
119 : }
120 0 : if (cinfo->Al > 13) /* need not check for < 0 */
121 0 : bad = TRUE;
122 : /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
123 : * but the spec doesn't say so, and we try to be liberal about what we
124 : * accept. Note: large Al values could result in out-of-range DC
125 : * coefficients during early scans, leading to bizarre displays due to
126 : * overflows in the IDCT math. But we won't crash.
127 : */
128 0 : if (bad)
129 0 : ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
130 : cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
131 : /* Update progression status, and verify that scan order is legal.
132 : * Note that inter-scan inconsistencies are treated as warnings
133 : * not fatal errors ... not clear if this is right way to behave.
134 : */
135 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
136 0 : int cindex = cinfo->cur_comp_info[ci]->component_index;
137 0 : coef_bit_ptr = & cinfo->coef_bits[cindex][0];
138 0 : if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
139 0 : WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
140 0 : for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
141 0 : int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
142 0 : if (cinfo->Ah != expected)
143 0 : WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
144 0 : coef_bit_ptr[coefi] = cinfo->Al;
145 : }
146 : }
147 :
148 : /* Select MCU decoding routine */
149 0 : if (cinfo->Ah == 0) {
150 0 : if (is_DC_band)
151 0 : entropy->pub.decode_mcu = decode_mcu_DC_first;
152 : else
153 0 : entropy->pub.decode_mcu = decode_mcu_AC_first;
154 : } else {
155 0 : if (is_DC_band)
156 0 : entropy->pub.decode_mcu = decode_mcu_DC_refine;
157 : else
158 0 : entropy->pub.decode_mcu = decode_mcu_AC_refine;
159 : }
160 :
161 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
162 0 : compptr = cinfo->cur_comp_info[ci];
163 : /* Make sure requested tables are present, and compute derived tables.
164 : * We may build same derived table more than once, but it's not expensive.
165 : */
166 0 : if (is_DC_band) {
167 0 : if (cinfo->Ah == 0) { /* DC refinement needs no table */
168 0 : tbl = compptr->dc_tbl_no;
169 0 : jpeg_make_d_derived_tbl(cinfo, TRUE, tbl,
170 0 : & entropy->derived_tbls[tbl]);
171 : }
172 : } else {
173 0 : tbl = compptr->ac_tbl_no;
174 0 : jpeg_make_d_derived_tbl(cinfo, FALSE, tbl,
175 0 : & entropy->derived_tbls[tbl]);
176 : /* remember the single active table */
177 0 : entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
178 : }
179 : /* Initialize DC predictions to 0 */
180 0 : entropy->saved.last_dc_val[ci] = 0;
181 : }
182 :
183 : /* Initialize bitread state variables */
184 0 : entropy->bitstate.bits_left = 0;
185 0 : entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
186 0 : entropy->pub.insufficient_data = FALSE;
187 :
188 : /* Initialize private state variables */
189 0 : entropy->saved.EOBRUN = 0;
190 :
191 : /* Initialize restart counter */
192 0 : entropy->restarts_to_go = cinfo->restart_interval;
193 0 : }
194 :
195 :
196 : /*
197 : * Figure F.12: extend sign bit.
198 : * On some machines, a shift and add will be faster than a table lookup.
199 : */
200 :
201 : #ifdef AVOID_TABLES
202 :
203 : #define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
204 :
205 : #else
206 :
207 : #define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
208 :
209 : static const int extend_test[16] = /* entry n is 2**(n-1) */
210 : { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
211 : 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
212 :
213 : static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
214 : { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
215 : ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
216 : ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
217 : ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
218 :
219 : #endif /* AVOID_TABLES */
220 :
221 :
222 : /*
223 : * Check for a restart marker & resynchronize decoder.
224 : * Returns FALSE if must suspend.
225 : */
226 :
227 : LOCAL(boolean)
228 0 : process_restart (j_decompress_ptr cinfo)
229 : {
230 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
231 : int ci;
232 :
233 : /* Throw away any unused bits remaining in bit buffer; */
234 : /* include any full bytes in next_marker's count of discarded bytes */
235 0 : cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
236 0 : entropy->bitstate.bits_left = 0;
237 :
238 : /* Advance past the RSTn marker */
239 0 : if (! (*cinfo->marker->read_restart_marker) (cinfo))
240 0 : return FALSE;
241 :
242 : /* Re-initialize DC predictions to 0 */
243 0 : for (ci = 0; ci < cinfo->comps_in_scan; ci++)
244 0 : entropy->saved.last_dc_val[ci] = 0;
245 : /* Re-init EOB run count, too */
246 0 : entropy->saved.EOBRUN = 0;
247 :
248 : /* Reset restart counter */
249 0 : entropy->restarts_to_go = cinfo->restart_interval;
250 :
251 : /* Reset out-of-data flag, unless read_restart_marker left us smack up
252 : * against a marker. In that case we will end up treating the next data
253 : * segment as empty, and we can avoid producing bogus output pixels by
254 : * leaving the flag set.
255 : */
256 0 : if (cinfo->unread_marker == 0)
257 0 : entropy->pub.insufficient_data = FALSE;
258 :
259 0 : return TRUE;
260 : }
261 :
262 :
263 : /*
264 : * Huffman MCU decoding.
265 : * Each of these routines decodes and returns one MCU's worth of
266 : * Huffman-compressed coefficients.
267 : * The coefficients are reordered from zigzag order into natural array order,
268 : * but are not dequantized.
269 : *
270 : * The i'th block of the MCU is stored into the block pointed to by
271 : * MCU_data[i]. WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
272 : *
273 : * We return FALSE if data source requested suspension. In that case no
274 : * changes have been made to permanent state. (Exception: some output
275 : * coefficients may already have been assigned. This is harmless for
276 : * spectral selection, since we'll just re-assign them on the next call.
277 : * Successive approximation AC refinement has to be more careful, however.)
278 : */
279 :
280 : /*
281 : * MCU decoding for DC initial scan (either spectral selection,
282 : * or first pass of successive approximation).
283 : */
284 :
285 : METHODDEF(boolean)
286 0 : decode_mcu_DC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
287 : {
288 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
289 0 : int Al = cinfo->Al;
290 : register int s, r;
291 : int blkn, ci;
292 : JBLOCKROW block;
293 : BITREAD_STATE_VARS;
294 : savable_state state;
295 : d_derived_tbl * tbl;
296 : jpeg_component_info * compptr;
297 :
298 : /* Process restart marker if needed; may have to suspend */
299 0 : if (cinfo->restart_interval) {
300 0 : if (entropy->restarts_to_go == 0)
301 0 : if (! process_restart(cinfo))
302 0 : return FALSE;
303 : }
304 :
305 : /* If we've run out of data, just leave the MCU set to zeroes.
306 : * This way, we return uniform gray for the remainder of the segment.
307 : */
308 0 : if (! entropy->pub.insufficient_data) {
309 :
310 : /* Load up working state */
311 0 : BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
312 0 : ASSIGN_STATE(state, entropy->saved);
313 :
314 : /* Outer loop handles each block in the MCU */
315 :
316 0 : for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
317 0 : block = MCU_data[blkn];
318 0 : ci = cinfo->MCU_membership[blkn];
319 0 : compptr = cinfo->cur_comp_info[ci];
320 0 : tbl = entropy->derived_tbls[compptr->dc_tbl_no];
321 :
322 : /* Decode a single block's worth of coefficients */
323 :
324 : /* Section F.2.2.1: decode the DC coefficient difference */
325 0 : HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
326 0 : if (s) {
327 0 : CHECK_BIT_BUFFER(br_state, s, return FALSE);
328 0 : r = GET_BITS(s);
329 0 : s = HUFF_EXTEND(r, s);
330 : }
331 :
332 : /* Convert DC difference to actual value, update last_dc_val */
333 0 : s += state.last_dc_val[ci];
334 0 : state.last_dc_val[ci] = s;
335 : /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
336 0 : (*block)[0] = (JCOEF) (s << Al);
337 : }
338 :
339 : /* Completed MCU, so update state */
340 0 : BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
341 0 : ASSIGN_STATE(entropy->saved, state);
342 : }
343 :
344 : /* Account for restart interval (no-op if not using restarts) */
345 0 : entropy->restarts_to_go--;
346 :
347 0 : return TRUE;
348 : }
349 :
350 :
351 : /*
352 : * MCU decoding for AC initial scan (either spectral selection,
353 : * or first pass of successive approximation).
354 : */
355 :
356 : METHODDEF(boolean)
357 0 : decode_mcu_AC_first (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
358 : {
359 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
360 0 : int Se = cinfo->Se;
361 0 : int Al = cinfo->Al;
362 : register int s, k, r;
363 : unsigned int EOBRUN;
364 : JBLOCKROW block;
365 : BITREAD_STATE_VARS;
366 : d_derived_tbl * tbl;
367 :
368 : /* Process restart marker if needed; may have to suspend */
369 0 : if (cinfo->restart_interval) {
370 0 : if (entropy->restarts_to_go == 0)
371 0 : if (! process_restart(cinfo))
372 0 : return FALSE;
373 : }
374 :
375 : /* If we've run out of data, just leave the MCU set to zeroes.
376 : * This way, we return uniform gray for the remainder of the segment.
377 : */
378 0 : if (! entropy->pub.insufficient_data) {
379 :
380 : /* Load up working state.
381 : * We can avoid loading/saving bitread state if in an EOB run.
382 : */
383 0 : EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
384 :
385 : /* There is always only one block per MCU */
386 :
387 0 : if (EOBRUN > 0) /* if it's a band of zeroes... */
388 0 : EOBRUN--; /* ...process it now (we do nothing) */
389 : else {
390 0 : BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
391 0 : block = MCU_data[0];
392 0 : tbl = entropy->ac_derived_tbl;
393 :
394 0 : for (k = cinfo->Ss; k <= Se; k++) {
395 0 : HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
396 0 : r = s >> 4;
397 0 : s &= 15;
398 0 : if (s) {
399 0 : k += r;
400 0 : CHECK_BIT_BUFFER(br_state, s, return FALSE);
401 0 : r = GET_BITS(s);
402 0 : s = HUFF_EXTEND(r, s);
403 : /* Scale and output coefficient in natural (dezigzagged) order */
404 0 : (*block)[jpeg_natural_order[k]] = (JCOEF) (s << Al);
405 : } else {
406 0 : if (r == 15) { /* ZRL */
407 0 : k += 15; /* skip 15 zeroes in band */
408 : } else { /* EOBr, run length is 2^r + appended bits */
409 0 : EOBRUN = 1 << r;
410 0 : if (r) { /* EOBr, r > 0 */
411 0 : CHECK_BIT_BUFFER(br_state, r, return FALSE);
412 0 : r = GET_BITS(r);
413 0 : EOBRUN += r;
414 : }
415 0 : EOBRUN--; /* this band is processed at this moment */
416 0 : break; /* force end-of-band */
417 : }
418 : }
419 : }
420 :
421 0 : BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
422 : }
423 :
424 : /* Completed MCU, so update state */
425 0 : entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
426 : }
427 :
428 : /* Account for restart interval (no-op if not using restarts) */
429 0 : entropy->restarts_to_go--;
430 :
431 0 : return TRUE;
432 : }
433 :
434 :
435 : /*
436 : * MCU decoding for DC successive approximation refinement scan.
437 : * Note: we assume such scans can be multi-component, although the spec
438 : * is not very clear on the point.
439 : */
440 :
441 : METHODDEF(boolean)
442 0 : decode_mcu_DC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
443 : {
444 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
445 0 : int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
446 : int blkn;
447 : JBLOCKROW block;
448 : BITREAD_STATE_VARS;
449 :
450 : /* Process restart marker if needed; may have to suspend */
451 0 : if (cinfo->restart_interval) {
452 0 : if (entropy->restarts_to_go == 0)
453 0 : if (! process_restart(cinfo))
454 0 : return FALSE;
455 : }
456 :
457 : /* Not worth the cycles to check insufficient_data here,
458 : * since we will not change the data anyway if we read zeroes.
459 : */
460 :
461 : /* Load up working state */
462 0 : BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
463 :
464 : /* Outer loop handles each block in the MCU */
465 :
466 0 : for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
467 0 : block = MCU_data[blkn];
468 :
469 : /* Encoded data is simply the next bit of the two's-complement DC value */
470 0 : CHECK_BIT_BUFFER(br_state, 1, return FALSE);
471 0 : if (GET_BITS(1))
472 0 : (*block)[0] |= p1;
473 : /* Note: since we use |=, repeating the assignment later is safe */
474 : }
475 :
476 : /* Completed MCU, so update state */
477 0 : BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
478 :
479 : /* Account for restart interval (no-op if not using restarts) */
480 0 : entropy->restarts_to_go--;
481 :
482 0 : return TRUE;
483 : }
484 :
485 :
486 : /*
487 : * MCU decoding for AC successive approximation refinement scan.
488 : */
489 :
490 : METHODDEF(boolean)
491 0 : decode_mcu_AC_refine (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
492 : {
493 0 : phuff_entropy_ptr entropy = (phuff_entropy_ptr) cinfo->entropy;
494 0 : int Se = cinfo->Se;
495 0 : int p1 = 1 << cinfo->Al; /* 1 in the bit position being coded */
496 0 : int m1 = (-1) << cinfo->Al; /* -1 in the bit position being coded */
497 : register int s, k, r;
498 : unsigned int EOBRUN;
499 : JBLOCKROW block;
500 : JCOEFPTR thiscoef;
501 : BITREAD_STATE_VARS;
502 : d_derived_tbl * tbl;
503 : int num_newnz;
504 : int newnz_pos[DCTSIZE2];
505 :
506 : /* Process restart marker if needed; may have to suspend */
507 0 : if (cinfo->restart_interval) {
508 0 : if (entropy->restarts_to_go == 0)
509 0 : if (! process_restart(cinfo))
510 0 : return FALSE;
511 : }
512 :
513 : /* If we've run out of data, don't modify the MCU.
514 : */
515 0 : if (! entropy->pub.insufficient_data) {
516 :
517 : /* Load up working state */
518 0 : BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
519 0 : EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
520 :
521 : /* There is always only one block per MCU */
522 0 : block = MCU_data[0];
523 0 : tbl = entropy->ac_derived_tbl;
524 :
525 : /* If we are forced to suspend, we must undo the assignments to any newly
526 : * nonzero coefficients in the block, because otherwise we'd get confused
527 : * next time about which coefficients were already nonzero.
528 : * But we need not undo addition of bits to already-nonzero coefficients;
529 : * instead, we can test the current bit to see if we already did it.
530 : */
531 0 : num_newnz = 0;
532 :
533 : /* initialize coefficient loop counter to start of band */
534 0 : k = cinfo->Ss;
535 :
536 0 : if (EOBRUN == 0) {
537 0 : for (; k <= Se; k++) {
538 0 : HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
539 0 : r = s >> 4;
540 0 : s &= 15;
541 0 : if (s) {
542 0 : if (s != 1) /* size of new coef should always be 1 */
543 0 : WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
544 0 : CHECK_BIT_BUFFER(br_state, 1, goto undoit);
545 0 : if (GET_BITS(1))
546 0 : s = p1; /* newly nonzero coef is positive */
547 : else
548 0 : s = m1; /* newly nonzero coef is negative */
549 : } else {
550 0 : if (r != 15) {
551 0 : EOBRUN = 1 << r; /* EOBr, run length is 2^r + appended bits */
552 0 : if (r) {
553 0 : CHECK_BIT_BUFFER(br_state, r, goto undoit);
554 0 : r = GET_BITS(r);
555 0 : EOBRUN += r;
556 : }
557 0 : break; /* rest of block is handled by EOB logic */
558 : }
559 : /* note s = 0 for processing ZRL */
560 : }
561 : /* Advance over already-nonzero coefs and r still-zero coefs,
562 : * appending correction bits to the nonzeroes. A correction bit is 1
563 : * if the absolute value of the coefficient must be increased.
564 : */
565 : do {
566 0 : thiscoef = *block + jpeg_natural_order[k];
567 0 : if (*thiscoef != 0) {
568 0 : CHECK_BIT_BUFFER(br_state, 1, goto undoit);
569 0 : if (GET_BITS(1)) {
570 0 : if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
571 0 : if (*thiscoef >= 0)
572 0 : *thiscoef += p1;
573 : else
574 0 : *thiscoef += m1;
575 : }
576 : }
577 : } else {
578 0 : if (--r < 0)
579 0 : break; /* reached target zero coefficient */
580 : }
581 0 : k++;
582 0 : } while (k <= Se);
583 0 : if (s) {
584 0 : int pos = jpeg_natural_order[k];
585 : /* Output newly nonzero coefficient */
586 0 : (*block)[pos] = (JCOEF) s;
587 : /* Remember its position in case we have to suspend */
588 0 : newnz_pos[num_newnz++] = pos;
589 : }
590 : }
591 : }
592 :
593 0 : if (EOBRUN > 0) {
594 : /* Scan any remaining coefficient positions after the end-of-band
595 : * (the last newly nonzero coefficient, if any). Append a correction
596 : * bit to each already-nonzero coefficient. A correction bit is 1
597 : * if the absolute value of the coefficient must be increased.
598 : */
599 0 : for (; k <= Se; k++) {
600 0 : thiscoef = *block + jpeg_natural_order[k];
601 0 : if (*thiscoef != 0) {
602 0 : CHECK_BIT_BUFFER(br_state, 1, goto undoit);
603 0 : if (GET_BITS(1)) {
604 0 : if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
605 0 : if (*thiscoef >= 0)
606 0 : *thiscoef += p1;
607 : else
608 0 : *thiscoef += m1;
609 : }
610 : }
611 : }
612 : }
613 : /* Count one block completed in EOB run */
614 0 : EOBRUN--;
615 : }
616 :
617 : /* Completed MCU, so update state */
618 0 : BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
619 0 : entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
620 : }
621 :
622 : /* Account for restart interval (no-op if not using restarts) */
623 0 : entropy->restarts_to_go--;
624 :
625 0 : return TRUE;
626 :
627 : undoit:
628 : /* Re-zero any output coefficients that we made newly nonzero */
629 0 : while (num_newnz > 0)
630 0 : (*block)[newnz_pos[--num_newnz]] = 0;
631 :
632 0 : return FALSE;
633 : }
634 :
635 :
636 : /*
637 : * Module initialization routine for progressive Huffman entropy decoding.
638 : */
639 :
640 : GLOBAL(void)
641 0 : jinit_phuff_decoder (j_decompress_ptr cinfo)
642 : {
643 : phuff_entropy_ptr entropy;
644 : int *coef_bit_ptr;
645 : int ci, i;
646 :
647 0 : entropy = (phuff_entropy_ptr)
648 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
649 : SIZEOF(phuff_entropy_decoder));
650 0 : cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
651 0 : entropy->pub.start_pass = start_pass_phuff_decoder;
652 :
653 : /* Mark derived tables unallocated */
654 0 : for (i = 0; i < NUM_HUFF_TBLS; i++) {
655 0 : entropy->derived_tbls[i] = NULL;
656 : }
657 :
658 : /* Create progression status table */
659 0 : cinfo->coef_bits = (int (*)[DCTSIZE2])
660 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
661 0 : cinfo->num_components*DCTSIZE2*SIZEOF(int));
662 0 : coef_bit_ptr = & cinfo->coef_bits[0][0];
663 0 : for (ci = 0; ci < cinfo->num_components; ci++)
664 0 : for (i = 0; i < DCTSIZE2; i++)
665 0 : *coef_bit_ptr++ = -1;
666 0 : }
667 :
668 : #endif /* D_PROGRESSIVE_SUPPORTED */
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