vx32

Local 9vx git repository for patches.
git clone git://r-36.net/vx32
Log | Files | Refs

jpc_t2dec.c (15905B)


      1 /*
      2  * Copyright (c) 1999-2000 Image Power, Inc. and the University of
      3  *   British Columbia.
      4  * Copyright (c) 2001-2003 Michael David Adams.
      5  * All rights reserved.
      6  */
      7 
      8 /* __START_OF_JASPER_LICENSE__
      9  * 
     10  * JasPer License Version 2.0
     11  * 
     12  * Copyright (c) 1999-2000 Image Power, Inc.
     13  * Copyright (c) 1999-2000 The University of British Columbia
     14  * Copyright (c) 2001-2003 Michael David Adams
     15  * 
     16  * All rights reserved.
     17  * 
     18  * Permission is hereby granted, free of charge, to any person (the
     19  * "User") obtaining a copy of this software and associated documentation
     20  * files (the "Software"), to deal in the Software without restriction,
     21  * including without limitation the rights to use, copy, modify, merge,
     22  * publish, distribute, and/or sell copies of the Software, and to permit
     23  * persons to whom the Software is furnished to do so, subject to the
     24  * following conditions:
     25  * 
     26  * 1.  The above copyright notices and this permission notice (which
     27  * includes the disclaimer below) shall be included in all copies or
     28  * substantial portions of the Software.
     29  * 
     30  * 2.  The name of a copyright holder shall not be used to endorse or
     31  * promote products derived from the Software without specific prior
     32  * written permission.
     33  * 
     34  * THIS DISCLAIMER OF WARRANTY CONSTITUTES AN ESSENTIAL PART OF THIS
     35  * LICENSE.  NO USE OF THE SOFTWARE IS AUTHORIZED HEREUNDER EXCEPT UNDER
     36  * THIS DISCLAIMER.  THE SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS
     37  * "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
     38  * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
     39  * PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.  IN NO
     40  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, OR ANY SPECIAL
     41  * INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES WHATSOEVER RESULTING
     42  * FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
     43  * NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     44  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.  NO ASSURANCES ARE
     45  * PROVIDED BY THE COPYRIGHT HOLDERS THAT THE SOFTWARE DOES NOT INFRINGE
     46  * THE PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OF ANY OTHER ENTITY.
     47  * EACH COPYRIGHT HOLDER DISCLAIMS ANY LIABILITY TO THE USER FOR CLAIMS
     48  * BROUGHT BY ANY OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL
     49  * PROPERTY RIGHTS OR OTHERWISE.  AS A CONDITION TO EXERCISING THE RIGHTS
     50  * GRANTED HEREUNDER, EACH USER HEREBY ASSUMES SOLE RESPONSIBILITY TO SECURE
     51  * ANY OTHER INTELLECTUAL PROPERTY RIGHTS NEEDED, IF ANY.  THE SOFTWARE
     52  * IS NOT FAULT-TOLERANT AND IS NOT INTENDED FOR USE IN MISSION-CRITICAL
     53  * SYSTEMS, SUCH AS THOSE USED IN THE OPERATION OF NUCLEAR FACILITIES,
     54  * AIRCRAFT NAVIGATION OR COMMUNICATION SYSTEMS, AIR TRAFFIC CONTROL
     55  * SYSTEMS, DIRECT LIFE SUPPORT MACHINES, OR WEAPONS SYSTEMS, IN WHICH
     56  * THE FAILURE OF THE SOFTWARE OR SYSTEM COULD LEAD DIRECTLY TO DEATH,
     57  * PERSONAL INJURY, OR SEVERE PHYSICAL OR ENVIRONMENTAL DAMAGE ("HIGH
     58  * RISK ACTIVITIES").  THE COPYRIGHT HOLDERS SPECIFICALLY DISCLAIM ANY
     59  * EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR HIGH RISK ACTIVITIES.
     60  * 
     61  * __END_OF_JASPER_LICENSE__
     62  */
     63 
     64 /*
     65  * Tier 2 Decoder
     66  *
     67  * $Id: jpc_t2dec.c 1918 2005-07-24 14:12:08Z baford $
     68  */
     69 
     70 /******************************************************************************\
     71 * Includes.
     72 \******************************************************************************/
     73 
     74 #include <stdio.h>
     75 #include <stdlib.h>
     76 #include <assert.h>
     77 
     78 #include "jasper/jas_types.h"
     79 #include "jasper/jas_fix.h"
     80 #include "jasper/jas_malloc.h"
     81 #include "jasper/jas_math.h"
     82 #include "jasper/jas_stream.h"
     83 #include "jasper/jas_debug.h"
     84 
     85 #include "jpc_bs.h"
     86 #include "jpc_dec.h"
     87 #include "jpc_cs.h"
     88 #include "jpc_mqdec.h"
     89 #include "jpc_t2dec.h"
     90 #include "jpc_t1cod.h"
     91 #include "jpc_math.h"
     92 
     93 /******************************************************************************\
     94 *
     95 \******************************************************************************/
     96 
     97 long jpc_dec_lookahead(jas_stream_t *in);
     98 static int jpc_getcommacode(jpc_bitstream_t *in);
     99 static int jpc_getnumnewpasses(jpc_bitstream_t *in);
    100 static int jpc_dec_decodepkt(jpc_dec_t *dec, jas_stream_t *pkthdrstream, jas_stream_t *in, int compno, int lvlno,
    101   int prcno, int lyrno);
    102 
    103 /******************************************************************************\
    104 * Code.
    105 \******************************************************************************/
    106 
    107 static int jpc_getcommacode(jpc_bitstream_t *in)
    108 {
    109 	int n;
    110 	int v;
    111 
    112 	n = 0;
    113 	for (;;) {
    114 		if ((v = jpc_bitstream_getbit(in)) < 0) {
    115 			return -1;
    116 		}
    117 		if (jpc_bitstream_eof(in)) {
    118 			return -1;
    119 		}
    120 		if (!v) {
    121 			break;
    122 		}
    123 		++n;
    124 	}
    125 
    126 	return n;
    127 }
    128 
    129 static int jpc_getnumnewpasses(jpc_bitstream_t *in)
    130 {
    131 	int n;
    132 
    133 	if ((n = jpc_bitstream_getbit(in)) > 0) {
    134 		if ((n = jpc_bitstream_getbit(in)) > 0) {
    135 			if ((n = jpc_bitstream_getbits(in, 2)) == 3) {
    136 				if ((n = jpc_bitstream_getbits(in, 5)) == 31) {
    137 					if ((n = jpc_bitstream_getbits(in, 7)) >= 0) {
    138 						n += 36 + 1;
    139 					}
    140 				} else if (n >= 0) {
    141 					n += 5 + 1;
    142 				}
    143 			} else if (n >= 0) {
    144 				n += 2 + 1;
    145 			}
    146 		} else if (!n) {
    147 			n += 2;
    148 		}
    149 	} else if (!n) {
    150 		++n;
    151 	}
    152 
    153 	return n;
    154 }
    155 
    156 static int jpc_dec_decodepkt(jpc_dec_t *dec, jas_stream_t *pkthdrstream, jas_stream_t *in, int compno, int rlvlno,
    157   int prcno, int lyrno)
    158 {
    159 	jpc_bitstream_t *inb;
    160 	jpc_dec_tcomp_t *tcomp;
    161 	jpc_dec_rlvl_t *rlvl;
    162 	jpc_dec_band_t *band;
    163 	jpc_dec_cblk_t *cblk;
    164 	int n;
    165 	int m;
    166 	int i;
    167 	jpc_tagtreenode_t *leaf;
    168 	int included;
    169 	int ret;
    170 	int numnewpasses;
    171 	jpc_dec_seg_t *seg;
    172 	int len;
    173 	int present;
    174 	int savenumnewpasses;
    175 	int mycounter;
    176 	jpc_ms_t *ms;
    177 	jpc_dec_tile_t *tile;
    178 	jpc_dec_ccp_t *ccp;
    179 	jpc_dec_cp_t *cp;
    180 	int bandno;
    181 	jpc_dec_prc_t *prc;
    182 	int usedcblkcnt;
    183 	int cblkno;
    184 	uint_fast32_t bodylen;
    185 	bool discard;
    186 	int passno;
    187 	int maxpasses;
    188 	int hdrlen;
    189 	int hdroffstart;
    190 	int hdroffend;
    191 
    192 	/* Avoid compiler warning about possible use of uninitialized
    193 	  variable. */
    194 	bodylen = 0;
    195 
    196 	discard = (lyrno >= dec->maxlyrs);
    197 
    198 	tile = dec->curtile;
    199 	cp = tile->cp;
    200 	ccp = &cp->ccps[compno];
    201 
    202 	/*
    203 	 * Decode the packet header.
    204 	 */
    205 
    206 	/* Decode the SOP marker segment if present. */
    207 	if (cp->csty & JPC_COD_SOP) {
    208 		if (jpc_dec_lookahead(in) == JPC_MS_SOP) {
    209 			if (!(ms = jpc_getms(in, dec->cstate))) {
    210 				return -1;
    211 			}
    212 			if (jpc_ms_gettype(ms) != JPC_MS_SOP) {
    213 				jpc_ms_destroy(ms);
    214 				fprintf(stderr, "missing SOP marker segment\n");
    215 				return -1;
    216 			}
    217 			jpc_ms_destroy(ms);
    218 		}
    219 	}
    220 
    221 hdroffstart = jas_stream_getrwcount(pkthdrstream);
    222 
    223 	if (!(inb = jpc_bitstream_sopen(pkthdrstream, "r"))) {
    224 		return -1;
    225 	}
    226 
    227 	if ((present = jpc_bitstream_getbit(inb)) < 0) {
    228 		return 1;
    229 	}
    230 	JAS_DBGLOG(10, ("\n", present));
    231 	JAS_DBGLOG(10, ("present=%d ", present));
    232 
    233 	/* Is the packet non-empty? */
    234 	if (present) {
    235 		/* The packet is non-empty. */
    236 		tcomp = &tile->tcomps[compno];
    237 		rlvl = &tcomp->rlvls[rlvlno];
    238 		bodylen = 0;
    239 		for (bandno = 0, band = rlvl->bands; bandno < rlvl->numbands;
    240 		  ++bandno, ++band) {
    241 			if (!band->data) {
    242 				continue;
    243 			}
    244 			prc = &band->prcs[prcno];
    245 			if (!prc->cblks) {
    246 				continue;
    247 			}
    248 			usedcblkcnt = 0;
    249 			for (cblkno = 0, cblk = prc->cblks; cblkno < prc->numcblks;
    250 			  ++cblkno, ++cblk) {
    251 				++usedcblkcnt;
    252 				if (!cblk->numpasses) {
    253 					leaf = jpc_tagtree_getleaf(prc->incltagtree, usedcblkcnt - 1);
    254 					if ((included = jpc_tagtree_decode(prc->incltagtree, leaf, lyrno + 1, inb)) < 0) {
    255 						return -1;
    256 					}
    257 				} else {
    258 					if ((included = jpc_bitstream_getbit(inb)) < 0) {
    259 						return -1;
    260 					}
    261 				}
    262 				JAS_DBGLOG(10, ("\n"));
    263 				JAS_DBGLOG(10, ("included=%d ", included));
    264 				if (!included) {
    265 					continue;
    266 				}
    267 				if (!cblk->numpasses) {
    268 					i = 1;
    269 					leaf = jpc_tagtree_getleaf(prc->numimsbstagtree, usedcblkcnt - 1);
    270 					for (;;) {
    271 						if ((ret = jpc_tagtree_decode(prc->numimsbstagtree, leaf, i, inb)) < 0) {
    272 							return -1;
    273 						}
    274 						if (ret) {
    275 							break;
    276 						}
    277 						++i;
    278 					}
    279 					cblk->numimsbs = i - 1;
    280 					cblk->firstpassno = cblk->numimsbs * 3;
    281 				}
    282 				if ((numnewpasses = jpc_getnumnewpasses(inb)) < 0) {
    283 					return -1;
    284 				}
    285 				JAS_DBGLOG(10, ("numnewpasses=%d ", numnewpasses));
    286 				seg = cblk->curseg;
    287 				savenumnewpasses = numnewpasses;
    288 				mycounter = 0;
    289 				if (numnewpasses > 0) {
    290 					if ((m = jpc_getcommacode(inb)) < 0) {
    291 						return -1;
    292 					}
    293 					cblk->numlenbits += m;
    294 					JAS_DBGLOG(10, ("increment=%d ", m));
    295 					while (numnewpasses > 0) {
    296 						passno = cblk->firstpassno + cblk->numpasses + mycounter;
    297 	/* XXX - the maxpasses is not set precisely but this doesn't matter... */
    298 						maxpasses = JPC_SEGPASSCNT(passno, cblk->firstpassno, 10000, (ccp->cblkctx & JPC_COX_LAZY) != 0, (ccp->cblkctx & JPC_COX_TERMALL) != 0);
    299 						if (!discard && !seg) {
    300 							if (!(seg = jpc_seg_alloc())) {
    301 								return -1;
    302 							}
    303 							jpc_seglist_insert(&cblk->segs, cblk->segs.tail, seg);
    304 							if (!cblk->curseg) {
    305 								cblk->curseg = seg;
    306 							}
    307 							seg->passno = passno;
    308 							seg->type = JPC_SEGTYPE(seg->passno, cblk->firstpassno, (ccp->cblkctx & JPC_COX_LAZY) != 0);
    309 							seg->maxpasses = maxpasses;
    310 						}
    311 						n = JAS_MIN(numnewpasses, maxpasses);
    312 						mycounter += n;
    313 						numnewpasses -= n;
    314 						if ((len = jpc_bitstream_getbits(inb, cblk->numlenbits + jpc_floorlog2(n))) < 0) {
    315 							return -1;
    316 						}
    317 						JAS_DBGLOG(10, ("len=%d ", len));
    318 						if (!discard) {
    319 							seg->lyrno = lyrno;
    320 							seg->numpasses += n;
    321 							seg->cnt = len;
    322 							seg = seg->next;
    323 						}
    324 						bodylen += len;
    325 					}
    326 				}
    327 				cblk->numpasses += savenumnewpasses;
    328 			}
    329 		}
    330 
    331 		jpc_bitstream_inalign(inb, 0, 0);
    332 
    333 	} else {
    334 		if (jpc_bitstream_inalign(inb, 0x7f, 0)) {
    335 			fprintf(stderr, "alignment failed\n");
    336 			return -1;
    337 		}
    338 	}
    339 	jpc_bitstream_close(inb);
    340 
    341 	hdroffend = jas_stream_getrwcount(pkthdrstream);
    342 	hdrlen = hdroffend - hdroffstart;
    343 	if (jas_getdbglevel() >= 5) {
    344 		fprintf(stderr, "hdrlen=%lu bodylen=%lu \n", (unsigned long) hdrlen,
    345 		  (unsigned long) bodylen);
    346 	}
    347 
    348 	if (cp->csty & JPC_COD_EPH) {
    349 		if (jpc_dec_lookahead(pkthdrstream) == JPC_MS_EPH) {
    350 			if (!(ms = jpc_getms(pkthdrstream, dec->cstate))) {
    351 				fprintf(stderr, "cannot get (EPH) marker segment\n");
    352 				return -1;
    353 			}
    354 			if (jpc_ms_gettype(ms) != JPC_MS_EPH) {
    355 				jpc_ms_destroy(ms);
    356 				fprintf(stderr, "missing EPH marker segment\n");
    357 				return -1;
    358 			}
    359 			jpc_ms_destroy(ms);
    360 		}
    361 	}
    362 
    363 	/* decode the packet body. */
    364 
    365 	if (jas_getdbglevel() >= 1) {
    366 		fprintf(stderr, "packet body offset=%06ld\n", (long) jas_stream_getrwcount(in));
    367 	}
    368 
    369 	if (!discard) {
    370 		tcomp = &tile->tcomps[compno];
    371 		rlvl = &tcomp->rlvls[rlvlno];
    372 		for (bandno = 0, band = rlvl->bands; bandno < rlvl->numbands;
    373 		  ++bandno, ++band) {
    374 			if (!band->data) {
    375 				continue;
    376 			}
    377 			prc = &band->prcs[prcno];
    378 			if (!prc->cblks) {
    379 				continue;
    380 			}
    381 			for (cblkno = 0, cblk = prc->cblks; cblkno < prc->numcblks;
    382 			  ++cblkno, ++cblk) {
    383 				seg = cblk->curseg;
    384 				while (seg) {
    385 					if (!seg->stream) {
    386 						if (!(seg->stream = jas_stream_memopen(0, 0))) {
    387 							return -1;
    388 						}
    389 					}
    390 #if 0
    391 fprintf(stderr, "lyrno=%02d, compno=%02d, lvlno=%02d, prcno=%02d, bandno=%02d, cblkno=%02d, passno=%02d numpasses=%02d cnt=%d numbps=%d, numimsbs=%d\n", lyrno, compno, rlvlno, prcno, band - rlvl->bands, cblk - prc->cblks, seg->passno, seg->numpasses, seg->cnt, band->numbps, cblk->numimsbs);
    392 #endif
    393 					if (seg->cnt > 0) {
    394 						if (jpc_getdata(in, seg->stream, seg->cnt) < 0) {
    395 							return -1;
    396 						}
    397 						seg->cnt = 0;
    398 					}
    399 					if (seg->numpasses >= seg->maxpasses) {
    400 						cblk->curseg = seg->next;
    401 					}
    402 					seg = seg->next;
    403 				}
    404 			}
    405 		}
    406 	} else {
    407 		if (jas_stream_gobble(in, bodylen) != JAS_CAST(int, bodylen)) {
    408 			return -1;
    409 		}
    410 	}
    411 	return 0;
    412 }
    413 
    414 /********************************************************************************************/
    415 /********************************************************************************************/
    416 
    417 int jpc_dec_decodepkts(jpc_dec_t *dec, jas_stream_t *pkthdrstream, jas_stream_t *in)
    418 {
    419 	jpc_dec_tile_t *tile;
    420 	jpc_pi_t *pi;
    421 	int ret;
    422 
    423 	tile = dec->curtile;
    424 	pi = tile->pi;
    425 	for (;;) {
    426 if (!tile->pkthdrstream || jas_stream_peekc(tile->pkthdrstream) == EOF) {
    427 		switch (jpc_dec_lookahead(in)) {
    428 		case JPC_MS_EOC:
    429 		case JPC_MS_SOT:
    430 			return 0;
    431 			break;
    432 		case JPC_MS_SOP:
    433 		case JPC_MS_EPH:
    434 		case 0:
    435 			break;
    436 		default:
    437 			return -1;
    438 			break;
    439 		}
    440 }
    441 		if ((ret = jpc_pi_next(pi))) {
    442 			return ret;
    443 		}
    444 if (dec->maxpkts >= 0 && dec->numpkts >= dec->maxpkts) {
    445 	fprintf(stderr, "warning: stopping decode prematurely as requested\n");
    446 	return 0;
    447 }
    448 		if (jas_getdbglevel() >= 1) {
    449 			fprintf(stderr, "packet offset=%08ld prg=%d cmptno=%02d "
    450 			  "rlvlno=%02d prcno=%03d lyrno=%02d\n", (long)
    451 			  jas_stream_getrwcount(in), jpc_pi_prg(pi), jpc_pi_cmptno(pi),
    452 			  jpc_pi_rlvlno(pi), jpc_pi_prcno(pi), jpc_pi_lyrno(pi));
    453 		}
    454 		if (jpc_dec_decodepkt(dec, pkthdrstream, in, jpc_pi_cmptno(pi), jpc_pi_rlvlno(pi),
    455 		  jpc_pi_prcno(pi), jpc_pi_lyrno(pi))) {
    456 			return -1;
    457 		}
    458 ++dec->numpkts;
    459 	}
    460 
    461 	return 0;
    462 }
    463 
    464 jpc_pi_t *jpc_dec_pi_create(jpc_dec_t *dec, jpc_dec_tile_t *tile)
    465 {
    466 	jpc_pi_t *pi;
    467 	int compno;
    468 	jpc_picomp_t *picomp;
    469 	jpc_pirlvl_t *pirlvl;
    470 	jpc_dec_tcomp_t *tcomp;
    471 	int rlvlno;
    472 	jpc_dec_rlvl_t *rlvl;
    473 	int prcno;
    474 	int *prclyrno;
    475 	jpc_dec_cmpt_t *cmpt;
    476 
    477 	if (!(pi = jpc_pi_create0())) {
    478 		return 0;
    479 	}
    480 	pi->numcomps = dec->numcomps;
    481 	if (!(pi->picomps = jas_malloc(pi->numcomps * sizeof(jpc_picomp_t)))) {
    482 		jpc_pi_destroy(pi);
    483 		return 0;
    484 	}
    485 	for (compno = 0, picomp = pi->picomps; compno < pi->numcomps; ++compno,
    486 	  ++picomp) {
    487 		picomp->pirlvls = 0;
    488 	}
    489 
    490 	for (compno = 0, tcomp = tile->tcomps, picomp = pi->picomps;
    491 	  compno < pi->numcomps; ++compno, ++tcomp, ++picomp) {
    492 		picomp->numrlvls = tcomp->numrlvls;
    493 		if (!(picomp->pirlvls = jas_malloc(picomp->numrlvls *
    494 		  sizeof(jpc_pirlvl_t)))) {
    495 			jpc_pi_destroy(pi);
    496 			return 0;
    497 		}
    498 		for (rlvlno = 0, pirlvl = picomp->pirlvls; rlvlno <
    499 		  picomp->numrlvls; ++rlvlno, ++pirlvl) {
    500 			pirlvl->prclyrnos = 0;
    501 		}
    502 		for (rlvlno = 0, pirlvl = picomp->pirlvls, rlvl = tcomp->rlvls;
    503 		  rlvlno < picomp->numrlvls; ++rlvlno, ++pirlvl, ++rlvl) {
    504 /* XXX sizeof(long) should be sizeof different type */
    505 			pirlvl->numprcs = rlvl->numprcs;
    506 			if (!(pirlvl->prclyrnos = jas_malloc(pirlvl->numprcs *
    507 			  sizeof(long)))) {
    508 				jpc_pi_destroy(pi);
    509 				return 0;
    510 			}
    511 		}
    512 	}
    513 
    514 	pi->maxrlvls = 0;
    515 	for (compno = 0, tcomp = tile->tcomps, picomp = pi->picomps, cmpt =
    516 	  dec->cmpts; compno < pi->numcomps; ++compno, ++tcomp, ++picomp,
    517 	  ++cmpt) {
    518 		picomp->hsamp = cmpt->hstep;
    519 		picomp->vsamp = cmpt->vstep;
    520 		for (rlvlno = 0, pirlvl = picomp->pirlvls, rlvl = tcomp->rlvls;
    521 		  rlvlno < picomp->numrlvls; ++rlvlno, ++pirlvl, ++rlvl) {
    522 			pirlvl->prcwidthexpn = rlvl->prcwidthexpn;
    523 			pirlvl->prcheightexpn = rlvl->prcheightexpn;
    524 			for (prcno = 0, prclyrno = pirlvl->prclyrnos;
    525 			  prcno < pirlvl->numprcs; ++prcno, ++prclyrno) {
    526 				*prclyrno = 0;
    527 			}
    528 			pirlvl->numhprcs = rlvl->numhprcs;
    529 		}
    530 		if (pi->maxrlvls < tcomp->numrlvls) {
    531 			pi->maxrlvls = tcomp->numrlvls;
    532 		}
    533 	}
    534 
    535 	pi->numlyrs = tile->cp->numlyrs;
    536 	pi->xstart = tile->xstart;
    537 	pi->ystart = tile->ystart;
    538 	pi->xend = tile->xend;
    539 	pi->yend = tile->yend;
    540 
    541 	pi->picomp = 0;
    542 	pi->pirlvl = 0;
    543 	pi->x = 0;
    544 	pi->y = 0;
    545 	pi->compno = 0;
    546 	pi->rlvlno = 0;
    547 	pi->prcno = 0;
    548 	pi->lyrno = 0;
    549 	pi->xstep = 0;
    550 	pi->ystep = 0;
    551 
    552 	pi->pchgno = -1;
    553 
    554 	pi->defaultpchg.prgord = tile->cp->prgord;
    555 	pi->defaultpchg.compnostart = 0;
    556 	pi->defaultpchg.compnoend = pi->numcomps;
    557 	pi->defaultpchg.rlvlnostart = 0;
    558 	pi->defaultpchg.rlvlnoend = pi->maxrlvls;
    559 	pi->defaultpchg.lyrnoend = pi->numlyrs;
    560 	pi->pchg = 0;
    561 
    562 	pi->valid = 0;
    563 
    564 	return pi;
    565 }
    566 
    567 long jpc_dec_lookahead(jas_stream_t *in)
    568 {
    569 	uint_fast16_t x;
    570 	if (jpc_getuint16(in, &x)) {
    571 		return -1;
    572 	}
    573 	if (jas_stream_ungetc(in, x & 0xff) == EOF ||
    574 	  jas_stream_ungetc(in, x >> 8) == EOF) {
    575 		return -1;
    576 	}
    577 	if (x >= JPC_MS_INMIN && x <= JPC_MS_INMAX) {
    578 		return x;
    579 	}
    580 	return 0;
    581 }