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1 /*
2  * jdphuff.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) 2015-2016, 2018, D. R. Commander.
8  * For conditions of distribution and use, see the accompanying README.ijg
9  * file.
10  *
11  * This file contains Huffman entropy decoding routines for progressive JPEG.
12  *
13  * Much of the complexity here has to do with supporting input suspension.
14  * If the data source module demands suspension, we want to be able to back
15  * up to the start of the current MCU.  To do this, we copy state variables
16  * into local working storage, and update them back to the permanent
17  * storage only upon successful completion of an MCU.
18  *
19  * NOTE: All referenced figures are from
20  * Recommendation ITU-T T.81 (1992) | ISO/IEC 10918-1:1994.
21  */
22 
23 #define JPEG_INTERNALS
24 #include "jinclude.h"
25 #include "jpeglib.h"
26 #include "jdhuff.h"             /* Declarations shared with jdhuff.c */
27 #include <limits.h>
28 
29 
30 #ifdef D_PROGRESSIVE_SUPPORTED
31 
32 /*
33  * Expanded entropy decoder object for progressive Huffman decoding.
34  *
35  * The savable_state subrecord contains fields that change within an MCU,
36  * but must not be updated permanently until we complete the MCU.
37  */
38 
39 typedef struct {
40   unsigned int EOBRUN;                  /* remaining EOBs in EOBRUN */
41   int last_dc_val[MAX_COMPS_IN_SCAN];   /* last DC coef for each component */
42 } savable_state;
43 
44 /* This macro is to work around compilers with missing or broken
45  * structure assignment.  You'll need to fix this code if you have
46  * such a compiler and you change MAX_COMPS_IN_SCAN.
47  */
48 
49 #ifndef NO_STRUCT_ASSIGN
50 #define ASSIGN_STATE(dest, src)  ((dest) = (src))
51 #else
52 #if MAX_COMPS_IN_SCAN == 4
53 #define ASSIGN_STATE(dest, src) \
54   ((dest).EOBRUN = (src).EOBRUN, \
55    (dest).last_dc_val[0] = (src).last_dc_val[0], \
56    (dest).last_dc_val[1] = (src).last_dc_val[1], \
57    (dest).last_dc_val[2] = (src).last_dc_val[2], \
58    (dest).last_dc_val[3] = (src).last_dc_val[3])
59 #endif
60 #endif
61 
62 
63 typedef struct {
64   struct jpeg_entropy_decoder pub; /* public fields */
65 
66   /* These fields are loaded into local variables at start of each MCU.
67    * In case of suspension, we exit WITHOUT updating them.
68    */
69   bitread_perm_state bitstate;  /* Bit buffer at start of MCU */
70   savable_state saved;          /* Other state at start of MCU */
71 
72   /* These fields are NOT loaded into local working state. */
73   unsigned int restarts_to_go;  /* MCUs left in this restart interval */
74 
75   /* Pointers to derived tables (these workspaces have image lifespan) */
76   d_derived_tbl *derived_tbls[NUM_HUFF_TBLS];
77 
78   d_derived_tbl *ac_derived_tbl; /* active table during an AC scan */
79 } phuff_entropy_decoder;
80 
81 typedef phuff_entropy_decoder *phuff_entropy_ptr;
82 
83 /* Forward declarations */
84 METHODDEF(boolean) decode_mcu_DC_first(j_decompress_ptr cinfo,
85                                        JBLOCKROW *MCU_data);
86 METHODDEF(boolean) decode_mcu_AC_first(j_decompress_ptr cinfo,
87                                        JBLOCKROW *MCU_data);
88 METHODDEF(boolean) decode_mcu_DC_refine(j_decompress_ptr cinfo,
89                                         JBLOCKROW *MCU_data);
90 METHODDEF(boolean) decode_mcu_AC_refine(j_decompress_ptr cinfo,
91                                         JBLOCKROW *MCU_data);
92 
93 
94 /*
95  * Initialize for a Huffman-compressed scan.
96  */
97 
98 METHODDEF(void)
start_pass_phuff_decoder(j_decompress_ptr cinfo)99 start_pass_phuff_decoder(j_decompress_ptr cinfo)
100 {
101   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
102   boolean is_DC_band, bad;
103   int ci, coefi, tbl;
104   d_derived_tbl **pdtbl;
105   int *coef_bit_ptr;
106   jpeg_component_info *compptr;
107 
108   is_DC_band = (cinfo->Ss == 0);
109 
110   /* Validate scan parameters */
111   bad = FALSE;
112   if (is_DC_band) {
113     if (cinfo->Se != 0)
114       bad = TRUE;
115   } else {
116     /* need not check Ss/Se < 0 since they came from unsigned bytes */
117     if (cinfo->Ss > cinfo->Se || cinfo->Se >= DCTSIZE2)
118       bad = TRUE;
119     /* AC scans may have only one component */
120     if (cinfo->comps_in_scan != 1)
121       bad = TRUE;
122   }
123   if (cinfo->Ah != 0) {
124     /* Successive approximation refinement scan: must have Al = Ah-1. */
125     if (cinfo->Al != cinfo->Ah - 1)
126       bad = TRUE;
127   }
128   if (cinfo->Al > 13)           /* need not check for < 0 */
129     bad = TRUE;
130   /* Arguably the maximum Al value should be less than 13 for 8-bit precision,
131    * but the spec doesn't say so, and we try to be liberal about what we
132    * accept.  Note: large Al values could result in out-of-range DC
133    * coefficients during early scans, leading to bizarre displays due to
134    * overflows in the IDCT math.  But we won't crash.
135    */
136   if (bad)
137     ERREXIT4(cinfo, JERR_BAD_PROGRESSION,
138              cinfo->Ss, cinfo->Se, cinfo->Ah, cinfo->Al);
139   /* Update progression status, and verify that scan order is legal.
140    * Note that inter-scan inconsistencies are treated as warnings
141    * not fatal errors ... not clear if this is right way to behave.
142    */
143   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
144     int cindex = cinfo->cur_comp_info[ci]->component_index;
145     coef_bit_ptr = &cinfo->coef_bits[cindex][0];
146     if (!is_DC_band && coef_bit_ptr[0] < 0) /* AC without prior DC scan */
147       WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, 0);
148     for (coefi = cinfo->Ss; coefi <= cinfo->Se; coefi++) {
149       int expected = (coef_bit_ptr[coefi] < 0) ? 0 : coef_bit_ptr[coefi];
150       if (cinfo->Ah != expected)
151         WARNMS2(cinfo, JWRN_BOGUS_PROGRESSION, cindex, coefi);
152       coef_bit_ptr[coefi] = cinfo->Al;
153     }
154   }
155 
156   /* Select MCU decoding routine */
157   if (cinfo->Ah == 0) {
158     if (is_DC_band)
159       entropy->pub.decode_mcu = decode_mcu_DC_first;
160     else
161       entropy->pub.decode_mcu = decode_mcu_AC_first;
162   } else {
163     if (is_DC_band)
164       entropy->pub.decode_mcu = decode_mcu_DC_refine;
165     else
166       entropy->pub.decode_mcu = decode_mcu_AC_refine;
167   }
168 
169   for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
170     compptr = cinfo->cur_comp_info[ci];
171     /* Make sure requested tables are present, and compute derived tables.
172      * We may build same derived table more than once, but it's not expensive.
173      */
174     if (is_DC_band) {
175       if (cinfo->Ah == 0) {     /* DC refinement needs no table */
176         tbl = compptr->dc_tbl_no;
177         pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
178         jpeg_make_d_derived_tbl(cinfo, TRUE, tbl, pdtbl);
179       }
180     } else {
181       tbl = compptr->ac_tbl_no;
182       pdtbl = (d_derived_tbl **)(entropy->derived_tbls) + tbl;
183       jpeg_make_d_derived_tbl(cinfo, FALSE, tbl, pdtbl);
184       /* remember the single active table */
185       entropy->ac_derived_tbl = entropy->derived_tbls[tbl];
186     }
187     /* Initialize DC predictions to 0 */
188     entropy->saved.last_dc_val[ci] = 0;
189   }
190 
191   /* Initialize bitread state variables */
192   entropy->bitstate.bits_left = 0;
193   entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
194   entropy->pub.insufficient_data = FALSE;
195 
196   /* Initialize private state variables */
197   entropy->saved.EOBRUN = 0;
198 
199   /* Initialize restart counter */
200   entropy->restarts_to_go = cinfo->restart_interval;
201 }
202 
203 
204 /*
205  * Figure F.12: extend sign bit.
206  * On some machines, a shift and add will be faster than a table lookup.
207  */
208 
209 #define AVOID_TABLES
210 #ifdef AVOID_TABLES
211 
212 #define NEG_1  ((unsigned)-1)
213 #define HUFF_EXTEND(x, s) \
214   ((x) < (1 << ((s) - 1)) ? (x) + (((NEG_1) << (s)) + 1) : (x))
215 
216 #else
217 
218 #define HUFF_EXTEND(x, s) \
219   ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
220 
221 static const int extend_test[16] = {   /* entry n is 2**(n-1) */
222   0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
223   0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000
224 };
225 
226 static const int extend_offset[16] = { /* entry n is (-1 << n) + 1 */
227   0, ((-1) << 1) + 1, ((-1) << 2) + 1, ((-1) << 3) + 1, ((-1) << 4) + 1,
228   ((-1) << 5) + 1, ((-1) << 6) + 1, ((-1) << 7) + 1, ((-1) << 8) + 1,
229   ((-1) << 9) + 1, ((-1) << 10) + 1, ((-1) << 11) + 1, ((-1) << 12) + 1,
230   ((-1) << 13) + 1, ((-1) << 14) + 1, ((-1) << 15) + 1
231 };
232 
233 #endif /* AVOID_TABLES */
234 
235 
236 /*
237  * Check for a restart marker & resynchronize decoder.
238  * Returns FALSE if must suspend.
239  */
240 
241 LOCAL(boolean)
process_restart(j_decompress_ptr cinfo)242 process_restart(j_decompress_ptr cinfo)
243 {
244   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
245   int ci;
246 
247   /* Throw away any unused bits remaining in bit buffer; */
248   /* include any full bytes in next_marker's count of discarded bytes */
249   cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
250   entropy->bitstate.bits_left = 0;
251 
252   /* Advance past the RSTn marker */
253   if (!(*cinfo->marker->read_restart_marker) (cinfo))
254     return FALSE;
255 
256   /* Re-initialize DC predictions to 0 */
257   for (ci = 0; ci < cinfo->comps_in_scan; ci++)
258     entropy->saved.last_dc_val[ci] = 0;
259   /* Re-init EOB run count, too */
260   entropy->saved.EOBRUN = 0;
261 
262   /* Reset restart counter */
263   entropy->restarts_to_go = cinfo->restart_interval;
264 
265   /* Reset out-of-data flag, unless read_restart_marker left us smack up
266    * against a marker.  In that case we will end up treating the next data
267    * segment as empty, and we can avoid producing bogus output pixels by
268    * leaving the flag set.
269    */
270   if (cinfo->unread_marker == 0)
271     entropy->pub.insufficient_data = FALSE;
272 
273   return TRUE;
274 }
275 
276 
277 /*
278  * Huffman MCU decoding.
279  * Each of these routines decodes and returns one MCU's worth of
280  * Huffman-compressed coefficients.
281  * The coefficients are reordered from zigzag order into natural array order,
282  * but are not dequantized.
283  *
284  * The i'th block of the MCU is stored into the block pointed to by
285  * MCU_data[i].  WE ASSUME THIS AREA IS INITIALLY ZEROED BY THE CALLER.
286  *
287  * We return FALSE if data source requested suspension.  In that case no
288  * changes have been made to permanent state.  (Exception: some output
289  * coefficients may already have been assigned.  This is harmless for
290  * spectral selection, since we'll just re-assign them on the next call.
291  * Successive approximation AC refinement has to be more careful, however.)
292  */
293 
294 /*
295  * MCU decoding for DC initial scan (either spectral selection,
296  * or first pass of successive approximation).
297  */
298 
299 METHODDEF(boolean)
decode_mcu_DC_first(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)300 decode_mcu_DC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
301 {
302   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
303   int Al = cinfo->Al;
304   register int s, r;
305   int blkn, ci;
306   JBLOCKROW block;
307   BITREAD_STATE_VARS;
308   savable_state state;
309   d_derived_tbl *tbl;
310   jpeg_component_info *compptr;
311 
312   /* Process restart marker if needed; may have to suspend */
313   if (cinfo->restart_interval) {
314     if (entropy->restarts_to_go == 0)
315       if (!process_restart(cinfo))
316         return FALSE;
317   }
318 
319   /* If we've run out of data, just leave the MCU set to zeroes.
320    * This way, we return uniform gray for the remainder of the segment.
321    */
322   if (!entropy->pub.insufficient_data) {
323 
324     /* Load up working state */
325     BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
326     ASSIGN_STATE(state, entropy->saved);
327 
328     /* Outer loop handles each block in the MCU */
329 
330     for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
331       block = MCU_data[blkn];
332       ci = cinfo->MCU_membership[blkn];
333       compptr = cinfo->cur_comp_info[ci];
334       tbl = entropy->derived_tbls[compptr->dc_tbl_no];
335 
336       /* Decode a single block's worth of coefficients */
337 
338       /* Section F.2.2.1: decode the DC coefficient difference */
339       HUFF_DECODE(s, br_state, tbl, return FALSE, label1);
340       if (s) {
341         CHECK_BIT_BUFFER(br_state, s, return FALSE);
342         r = GET_BITS(s);
343         s = HUFF_EXTEND(r, s);
344       }
345 
346       /* Convert DC difference to actual value, update last_dc_val */
347       if ((state.last_dc_val[ci] >= 0 &&
348            s > INT_MAX - state.last_dc_val[ci]) ||
349           (state.last_dc_val[ci] < 0 && s < INT_MIN - state.last_dc_val[ci]))
350         ERREXIT(cinfo, JERR_BAD_DCT_COEF);
351       s += state.last_dc_val[ci];
352       state.last_dc_val[ci] = s;
353       /* Scale and output the coefficient (assumes jpeg_natural_order[0]=0) */
354       (*block)[0] = (JCOEF)LEFT_SHIFT(s, Al);
355     }
356 
357     /* Completed MCU, so update state */
358     BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
359     ASSIGN_STATE(entropy->saved, state);
360   }
361 
362   /* Account for restart interval (no-op if not using restarts) */
363   entropy->restarts_to_go--;
364 
365   return TRUE;
366 }
367 
368 
369 /*
370  * MCU decoding for AC initial scan (either spectral selection,
371  * or first pass of successive approximation).
372  */
373 
374 METHODDEF(boolean)
decode_mcu_AC_first(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)375 decode_mcu_AC_first(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
376 {
377   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
378   int Se = cinfo->Se;
379   int Al = cinfo->Al;
380   register int s, k, r;
381   unsigned int EOBRUN;
382   JBLOCKROW block;
383   BITREAD_STATE_VARS;
384   d_derived_tbl *tbl;
385 
386   /* Process restart marker if needed; may have to suspend */
387   if (cinfo->restart_interval) {
388     if (entropy->restarts_to_go == 0)
389       if (!process_restart(cinfo))
390         return FALSE;
391   }
392 
393   /* If we've run out of data, just leave the MCU set to zeroes.
394    * This way, we return uniform gray for the remainder of the segment.
395    */
396   if (!entropy->pub.insufficient_data) {
397 
398     /* Load up working state.
399      * We can avoid loading/saving bitread state if in an EOB run.
400      */
401     EOBRUN = entropy->saved.EOBRUN;     /* only part of saved state we need */
402 
403     /* There is always only one block per MCU */
404 
405     if (EOBRUN > 0)             /* if it's a band of zeroes... */
406       EOBRUN--;                 /* ...process it now (we do nothing) */
407     else {
408       BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
409       block = MCU_data[0];
410       tbl = entropy->ac_derived_tbl;
411 
412       for (k = cinfo->Ss; k <= Se; k++) {
413         HUFF_DECODE(s, br_state, tbl, return FALSE, label2);
414         r = s >> 4;
415         s &= 15;
416         if (s) {
417           k += r;
418           CHECK_BIT_BUFFER(br_state, s, return FALSE);
419           r = GET_BITS(s);
420           s = HUFF_EXTEND(r, s);
421           /* Scale and output coefficient in natural (dezigzagged) order */
422           (*block)[jpeg_natural_order[k]] = (JCOEF)LEFT_SHIFT(s, Al);
423         } else {
424           if (r == 15) {        /* ZRL */
425             k += 15;            /* skip 15 zeroes in band */
426           } else {              /* EOBr, run length is 2^r + appended bits */
427             EOBRUN = 1 << r;
428             if (r) {            /* EOBr, r > 0 */
429               CHECK_BIT_BUFFER(br_state, r, return FALSE);
430               r = GET_BITS(r);
431               EOBRUN += r;
432             }
433             EOBRUN--;           /* this band is processed at this moment */
434             break;              /* force end-of-band */
435           }
436         }
437       }
438 
439       BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
440     }
441 
442     /* Completed MCU, so update state */
443     entropy->saved.EOBRUN = EOBRUN;     /* only part of saved state we need */
444   }
445 
446   /* Account for restart interval (no-op if not using restarts) */
447   entropy->restarts_to_go--;
448 
449   return TRUE;
450 }
451 
452 
453 /*
454  * MCU decoding for DC successive approximation refinement scan.
455  * Note: we assume such scans can be multi-component, although the spec
456  * is not very clear on the point.
457  */
458 
459 METHODDEF(boolean)
decode_mcu_DC_refine(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)460 decode_mcu_DC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
461 {
462   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
463   int p1 = 1 << cinfo->Al;      /* 1 in the bit position being coded */
464   int blkn;
465   JBLOCKROW block;
466   BITREAD_STATE_VARS;
467 
468   /* Process restart marker if needed; may have to suspend */
469   if (cinfo->restart_interval) {
470     if (entropy->restarts_to_go == 0)
471       if (!process_restart(cinfo))
472         return FALSE;
473   }
474 
475   /* Not worth the cycles to check insufficient_data here,
476    * since we will not change the data anyway if we read zeroes.
477    */
478 
479   /* Load up working state */
480   BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
481 
482   /* Outer loop handles each block in the MCU */
483 
484   for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
485     block = MCU_data[blkn];
486 
487     /* Encoded data is simply the next bit of the two's-complement DC value */
488     CHECK_BIT_BUFFER(br_state, 1, return FALSE);
489     if (GET_BITS(1))
490       (*block)[0] |= p1;
491     /* Note: since we use |=, repeating the assignment later is safe */
492   }
493 
494   /* Completed MCU, so update state */
495   BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
496 
497   /* Account for restart interval (no-op if not using restarts) */
498   entropy->restarts_to_go--;
499 
500   return TRUE;
501 }
502 
503 
504 /*
505  * MCU decoding for AC successive approximation refinement scan.
506  */
507 
508 METHODDEF(boolean)
decode_mcu_AC_refine(j_decompress_ptr cinfo,JBLOCKROW * MCU_data)509 decode_mcu_AC_refine(j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
510 {
511   phuff_entropy_ptr entropy = (phuff_entropy_ptr)cinfo->entropy;
512   int Se = cinfo->Se;
513   int p1 = 1 << cinfo->Al;        /* 1 in the bit position being coded */
514   int m1 = (NEG_1) << cinfo->Al;  /* -1 in the bit position being coded */
515   register int s, k, r;
516   unsigned int EOBRUN;
517   JBLOCKROW block;
518   JCOEFPTR thiscoef;
519   BITREAD_STATE_VARS;
520   d_derived_tbl *tbl;
521   int num_newnz;
522   int newnz_pos[DCTSIZE2];
523 
524   /* Process restart marker if needed; may have to suspend */
525   if (cinfo->restart_interval) {
526     if (entropy->restarts_to_go == 0)
527       if (!process_restart(cinfo))
528         return FALSE;
529   }
530 
531   /* If we've run out of data, don't modify the MCU.
532    */
533   if (!entropy->pub.insufficient_data) {
534 
535     /* Load up working state */
536     BITREAD_LOAD_STATE(cinfo, entropy->bitstate);
537     EOBRUN = entropy->saved.EOBRUN; /* only part of saved state we need */
538 
539     /* There is always only one block per MCU */
540     block = MCU_data[0];
541     tbl = entropy->ac_derived_tbl;
542 
543     /* If we are forced to suspend, we must undo the assignments to any newly
544      * nonzero coefficients in the block, because otherwise we'd get confused
545      * next time about which coefficients were already nonzero.
546      * But we need not undo addition of bits to already-nonzero coefficients;
547      * instead, we can test the current bit to see if we already did it.
548      */
549     num_newnz = 0;
550 
551     /* initialize coefficient loop counter to start of band */
552     k = cinfo->Ss;
553 
554     if (EOBRUN == 0) {
555       for (; k <= Se; k++) {
556         HUFF_DECODE(s, br_state, tbl, goto undoit, label3);
557         r = s >> 4;
558         s &= 15;
559         if (s) {
560           if (s != 1)           /* size of new coef should always be 1 */
561             WARNMS(cinfo, JWRN_HUFF_BAD_CODE);
562           CHECK_BIT_BUFFER(br_state, 1, goto undoit);
563           if (GET_BITS(1))
564             s = p1;             /* newly nonzero coef is positive */
565           else
566             s = m1;             /* newly nonzero coef is negative */
567         } else {
568           if (r != 15) {
569             EOBRUN = 1 << r;    /* EOBr, run length is 2^r + appended bits */
570             if (r) {
571               CHECK_BIT_BUFFER(br_state, r, goto undoit);
572               r = GET_BITS(r);
573               EOBRUN += r;
574             }
575             break;              /* rest of block is handled by EOB logic */
576           }
577           /* note s = 0 for processing ZRL */
578         }
579         /* Advance over already-nonzero coefs and r still-zero coefs,
580          * appending correction bits to the nonzeroes.  A correction bit is 1
581          * if the absolute value of the coefficient must be increased.
582          */
583         do {
584           thiscoef = *block + jpeg_natural_order[k];
585           if (*thiscoef != 0) {
586             CHECK_BIT_BUFFER(br_state, 1, goto undoit);
587             if (GET_BITS(1)) {
588               if ((*thiscoef & p1) == 0) { /* do nothing if already set it */
589                 if (*thiscoef >= 0)
590                   *thiscoef += p1;
591                 else
592                   *thiscoef += m1;
593               }
594             }
595           } else {
596             if (--r < 0)
597               break;            /* reached target zero coefficient */
598           }
599           k++;
600         } while (k <= Se);
601         if (s) {
602           int pos = jpeg_natural_order[k];
603           /* Output newly nonzero coefficient */
604           (*block)[pos] = (JCOEF)s;
605           /* Remember its position in case we have to suspend */
606           newnz_pos[num_newnz++] = pos;
607         }
608       }
609     }
610 
611     if (EOBRUN > 0) {
612       /* Scan any remaining coefficient positions after the end-of-band
613        * (the last newly nonzero coefficient, if any).  Append a correction
614        * bit to each already-nonzero coefficient.  A correction bit is 1
615        * if the absolute value of the coefficient must be increased.
616        */
617       for (; k <= Se; k++) {
618         thiscoef = *block + jpeg_natural_order[k];
619         if (*thiscoef != 0) {
620           CHECK_BIT_BUFFER(br_state, 1, goto undoit);
621           if (GET_BITS(1)) {
622             if ((*thiscoef & p1) == 0) { /* do nothing if already changed it */
623               if (*thiscoef >= 0)
624                 *thiscoef += p1;
625               else
626                 *thiscoef += m1;
627             }
628           }
629         }
630       }
631       /* Count one block completed in EOB run */
632       EOBRUN--;
633     }
634 
635     /* Completed MCU, so update state */
636     BITREAD_SAVE_STATE(cinfo, entropy->bitstate);
637     entropy->saved.EOBRUN = EOBRUN; /* only part of saved state we need */
638   }
639 
640   /* Account for restart interval (no-op if not using restarts) */
641   entropy->restarts_to_go--;
642 
643   return TRUE;
644 
645 undoit:
646   /* Re-zero any output coefficients that we made newly nonzero */
647   while (num_newnz > 0)
648     (*block)[newnz_pos[--num_newnz]] = 0;
649 
650   return FALSE;
651 }
652 
653 
654 /*
655  * Module initialization routine for progressive Huffman entropy decoding.
656  */
657 
658 GLOBAL(void)
jinit_phuff_decoder(j_decompress_ptr cinfo)659 jinit_phuff_decoder(j_decompress_ptr cinfo)
660 {
661   phuff_entropy_ptr entropy;
662   int *coef_bit_ptr;
663   int ci, i;
664 
665   entropy = (phuff_entropy_ptr)
666     (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
667                                 sizeof(phuff_entropy_decoder));
668   cinfo->entropy = (struct jpeg_entropy_decoder *)entropy;
669   entropy->pub.start_pass = start_pass_phuff_decoder;
670 
671   /* Mark derived tables unallocated */
672   for (i = 0; i < NUM_HUFF_TBLS; i++) {
673     entropy->derived_tbls[i] = NULL;
674   }
675 
676   /* Create progression status table */
677   cinfo->coef_bits = (int (*)[DCTSIZE2])
678     (*cinfo->mem->alloc_small) ((j_common_ptr)cinfo, JPOOL_IMAGE,
679                                 cinfo->num_components * DCTSIZE2 *
680                                 sizeof(int));
681   coef_bit_ptr = &cinfo->coef_bits[0][0];
682   for (ci = 0; ci < cinfo->num_components; ci++)
683     for (i = 0; i < DCTSIZE2; i++)
684       *coef_bit_ptr++ = -1;
685 }
686 
687 #endif /* D_PROGRESSIVE_SUPPORTED */
688