/*
* jdhuff.c
*
- * Copyright (C) 1991-1997, Thomas G. Lane.
+ * Copyright (C) 1991-1998, Thomas G. Lane.
* This file is part of the Independent JPEG Group's software.
* For conditions of distribution and use, see the accompanying README file.
*
- * This file contains Huffman entropy decoding routines.
- *
- * Much of the complexity here has to do with supporting input suspension.
- * If the data source module demands suspension, we want to be able to back
- * up to the start of the current MCU. To do this, we copy state variables
- * into local working storage, and update them back to the permanent
- * storage only upon successful completion of an MCU.
+ * This file contains Huffman entropy decoding routines which are shared
+ * by the sequential, progressive and lossless decoders.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
-#include "jdhuff.h" /* Declarations shared with jdphuff.c */
-
-
-/*
- * Expanded entropy decoder object for Huffman decoding.
- *
- * The savable_state subrecord contains fields that change within an MCU,
- * but must not be updated permanently until we complete the MCU.
- */
-
-typedef struct {
- int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */
-} savable_state;
-
-/* This macro is to work around compilers with missing or broken
- * structure assignment. You'll need to fix this code if you have
- * such a compiler and you change MAX_COMPS_IN_SCAN.
- */
-
-#ifndef NO_STRUCT_ASSIGN
-#define ASSIGN_STATE(dest,src) ((dest) = (src))
-#else
-#if MAX_COMPS_IN_SCAN == 4
-#define ASSIGN_STATE(dest,src) \
- ((dest).last_dc_val[0] = (src).last_dc_val[0], \
- (dest).last_dc_val[1] = (src).last_dc_val[1], \
- (dest).last_dc_val[2] = (src).last_dc_val[2], \
- (dest).last_dc_val[3] = (src).last_dc_val[3])
-#endif
-#endif
-
-
-typedef struct {
- struct jpeg_entropy_decoder pub; /* public fields */
-
- /* These fields are loaded into local variables at start of each MCU.
- * In case of suspension, we exit WITHOUT updating them.
- */
- bitread_perm_state bitstate; /* Bit buffer at start of MCU */
- savable_state saved; /* Other state at start of MCU */
-
- /* These fields are NOT loaded into local working state. */
- unsigned int restarts_to_go; /* MCUs left in this restart interval */
-
- /* Pointers to derived tables (these workspaces have image lifespan) */
- d_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];
- d_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];
-
- /* Precalculated info set up by start_pass for use in decode_mcu: */
-
- /* Pointers to derived tables to be used for each block within an MCU */
- d_derived_tbl * dc_cur_tbls[D_MAX_BLOCKS_IN_MCU];
- d_derived_tbl * ac_cur_tbls[D_MAX_BLOCKS_IN_MCU];
- /* Whether we care about the DC and AC coefficient values for each block */
- boolean dc_needed[D_MAX_BLOCKS_IN_MCU];
- boolean ac_needed[D_MAX_BLOCKS_IN_MCU];
-} huff_entropy_decoder;
-
-typedef huff_entropy_decoder * huff_entropy_ptr;
-
-
-/*
- * Initialize for a Huffman-compressed scan.
- */
-
-METHODDEF(void)
-start_pass_huff_decoder (j_decompress_ptr cinfo)
-{
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
- int ci, blkn, dctbl, actbl;
- jpeg_component_info * compptr;
-
- /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.
- * This ought to be an error condition, but we make it a warning because
- * there are some baseline files out there with all zeroes in these bytes.
- */
- if (cinfo->Ss != 0 || cinfo->Se != DCTSIZE2-1 ||
- cinfo->Ah != 0 || cinfo->Al != 0)
- WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);
-
- for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
- compptr = cinfo->cur_comp_info[ci];
- dctbl = compptr->dc_tbl_no;
- actbl = compptr->ac_tbl_no;
- /* Compute derived values for Huffman tables */
- /* We may do this more than once for a table, but it's not expensive */
- jpeg_make_d_derived_tbl(cinfo, TRUE, dctbl,
- & entropy->dc_derived_tbls[dctbl]);
- jpeg_make_d_derived_tbl(cinfo, FALSE, actbl,
- & entropy->ac_derived_tbls[actbl]);
- /* Initialize DC predictions to 0 */
- entropy->saved.last_dc_val[ci] = 0;
- }
-
- /* Precalculate decoding info for each block in an MCU of this scan */
- for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
- ci = cinfo->MCU_membership[blkn];
- compptr = cinfo->cur_comp_info[ci];
- /* Precalculate which table to use for each block */
- entropy->dc_cur_tbls[blkn] = entropy->dc_derived_tbls[compptr->dc_tbl_no];
- entropy->ac_cur_tbls[blkn] = entropy->ac_derived_tbls[compptr->ac_tbl_no];
- /* Decide whether we really care about the coefficient values */
- if (compptr->component_needed) {
- entropy->dc_needed[blkn] = TRUE;
- /* we don't need the ACs if producing a 1/8th-size image */
- entropy->ac_needed[blkn] = (compptr->DCT_scaled_size > 1);
- } else {
- entropy->dc_needed[blkn] = entropy->ac_needed[blkn] = FALSE;
- }
- }
-
- /* Initialize bitread state variables */
- entropy->bitstate.bits_left = 0;
- entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
- entropy->pub.insufficient_data = FALSE;
-
- /* Initialize restart counter */
- entropy->restarts_to_go = cinfo->restart_interval;
-}
+#include "jlossy.h" /* Private declarations for lossy codec */
+#include "jlossls.h" /* Private declarations for lossless codec */
+#include "jdhuff.h" /* Declarations shared with jd*huff.c */
/*
* Compute the derived values for a Huffman table.
* This routine also performs some validation checks on the table.
- *
- * Note this is also used by jdphuff.c.
*/
GLOBAL(void)
}
/* code is now 1 more than the last code used for codelength si; but
* it must still fit in si bits, since no code is allowed to be all ones.
+ * BUG FIX 2001-09-03: Comparison must be >, not >=
*/
- if (((INT32) code) >= (((INT32) 1) << si))
+ if (((INT32) code) > (((INT32) 1) << si))
ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
code <<= 1;
si++;
/* Validate symbols as being reasonable.
* For AC tables, we make no check, but accept all byte values 0..255.
- * For DC tables, we require the symbols to be in range 0..15.
+ * For DC tables, we require the symbols to be in range 0..16.
* (Tighter bounds could be applied depending on the data depth and mode,
* but this is sufficient to ensure safe decoding.)
*/
if (isDC) {
for (i = 0; i < numsymbols; i++) {
int sym = htbl->huffval[i];
- if (sym < 0 || sym > 15) {
- // Now, we can read Philips MRI Images
- htbl->huffval[i]=15;
-// ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
- }
+ if (sym < 0 || sym > 16)
+/* The following is needed to be able to read certain Philips DICOM MRI images */
+#if BITS_IN_JSAMPLE == 12
+ htbl->huffval[i]=15;
+#else
+ ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);
+#endif /* BITS_IN_JSAMPLE == 12 */
}
}
}
/*
- * Out-of-line code for bit fetching (shared with jdphuff.c).
+ * Out-of-line code for bit fetching.
* See jdhuff.h for info about usage.
* Note: current values of get_buffer and bits_left are passed as parameters,
* but are returned in the corresponding fields of the state struct.
* We use a nonvolatile flag to ensure that only one warning message
* appears per data segment.
*/
- if (! cinfo->entropy->insufficient_data) {
+ huffd_common_ptr huffd;
+ if (cinfo->process == JPROC_LOSSLESS)
+ huffd = (huffd_common_ptr) ((j_lossless_d_ptr) cinfo->codec)->entropy_private;
+ else
+ huffd = (huffd_common_ptr) ((j_lossy_d_ptr) cinfo->codec)->entropy_private;
+ if (! huffd->insufficient_data) {
WARNMS(cinfo, JWRN_HIT_MARKER);
- cinfo->entropy->insufficient_data = TRUE;
+ huffd->insufficient_data = TRUE;
}
/* Fill the buffer with zero bits */
get_buffer <<= MIN_GET_BITS - bits_left;
return htbl->pub->huffval[ (int) (code + htbl->valoffset[l]) ];
}
-
-
-/*
- * Figure F.12: extend sign bit.
- * On some machines, a shift and add will be faster than a table lookup.
- */
-
-#ifdef AVOID_TABLES
-
-#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))
-
-#else
-
-#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))
-
-static const int extend_test[16] = /* entry n is 2**(n-1) */
- { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,
- 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };
-
-static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */
- { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,
- ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,
- ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,
- ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };
-
-#endif /* AVOID_TABLES */
-
-
-/*
- * Check for a restart marker & resynchronize decoder.
- * Returns FALSE if must suspend.
- */
-
-LOCAL(boolean)
-process_restart (j_decompress_ptr cinfo)
-{
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
- int ci;
-
- /* Throw away any unused bits remaining in bit buffer; */
- /* include any full bytes in next_marker's count of discarded bytes */
- cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;
- entropy->bitstate.bits_left = 0;
-
- /* Advance past the RSTn marker */
- if (! (*cinfo->marker->read_restart_marker) (cinfo))
- return FALSE;
-
- /* Re-initialize DC predictions to 0 */
- for (ci = 0; ci < cinfo->comps_in_scan; ci++)
- entropy->saved.last_dc_val[ci] = 0;
-
- /* Reset restart counter */
- entropy->restarts_to_go = cinfo->restart_interval;
-
- /* Reset out-of-data flag, unless read_restart_marker left us smack up
- * against a marker. In that case we will end up treating the next data
- * segment as empty, and we can avoid producing bogus output pixels by
- * leaving the flag set.
- */
- if (cinfo->unread_marker == 0)
- entropy->pub.insufficient_data = FALSE;
-
- return TRUE;
-}
-
-
-/*
- * Decode and return one MCU's worth of Huffman-compressed coefficients.
- * The coefficients are reordered from zigzag order into natural array order,
- * but are not dequantized.
- *
- * The i'th block of the MCU is stored into the block pointed to by
- * MCU_data[i]. WE ASSUME THIS AREA HAS BEEN ZEROED BY THE CALLER.
- * (Wholesale zeroing is usually a little faster than retail...)
- *
- * Returns FALSE if data source requested suspension. In that case no
- * changes have been made to permanent state. (Exception: some output
- * coefficients may already have been assigned. This is harmless for
- * this module, since we'll just re-assign them on the next call.)
- */
-
-METHODDEF(boolean)
-decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)
-{
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;
- int blkn;
- BITREAD_STATE_VARS;
- savable_state state;
-
- /* Process restart marker if needed; may have to suspend */
- if (cinfo->restart_interval) {
- if (entropy->restarts_to_go == 0)
- if (! process_restart(cinfo))
- return FALSE;
- }
-
- /* If we've run out of data, just leave the MCU set to zeroes.
- * This way, we return uniform gray for the remainder of the segment.
- */
- if (! entropy->pub.insufficient_data) {
-
- /* Load up working state */
- BITREAD_LOAD_STATE(cinfo,entropy->bitstate);
- ASSIGN_STATE(state, entropy->saved);
-
- /* Outer loop handles each block in the MCU */
-
- for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {
- JBLOCKROW block = MCU_data[blkn];
- d_derived_tbl * dctbl = entropy->dc_cur_tbls[blkn];
- d_derived_tbl * actbl = entropy->ac_cur_tbls[blkn];
- register int s, k, r;
-
- /* Decode a single block's worth of coefficients */
-
- /* Section F.2.2.1: decode the DC coefficient difference */
- HUFF_DECODE(s, br_state, dctbl, return FALSE, label1);
- if (s) {
- CHECK_BIT_BUFFER(br_state, s, return FALSE);
- r = GET_BITS(s);
- s = HUFF_EXTEND(r, s);
- }
-
- if (entropy->dc_needed[blkn]) {
- /* Convert DC difference to actual value, update last_dc_val */
- int ci = cinfo->MCU_membership[blkn];
- s += state.last_dc_val[ci];
- state.last_dc_val[ci] = s;
- /* Output the DC coefficient (assumes jpeg_natural_order[0] = 0) */
- (*block)[0] = (JCOEF) s;
- }
-
- if (entropy->ac_needed[blkn]) {
-
- /* Section F.2.2.2: decode the AC coefficients */
- /* Since zeroes are skipped, output area must be cleared beforehand */
- for (k = 1; k < DCTSIZE2; k++) {
- HUFF_DECODE(s, br_state, actbl, return FALSE, label2);
-
- r = s >> 4;
- s &= 15;
-
- if (s) {
- k += r;
- CHECK_BIT_BUFFER(br_state, s, return FALSE);
- r = GET_BITS(s);
- s = HUFF_EXTEND(r, s);
- /* Output coefficient in natural (dezigzagged) order.
- * Note: the extra entries in jpeg_natural_order[] will save us
- * if k >= DCTSIZE2, which could happen if the data is corrupted.
- */
- (*block)[jpeg_natural_order[k]] = (JCOEF) s;
- } else {
- if (r != 15)
- break;
- k += 15;
- }
- }
-
- } else {
-
- /* Section F.2.2.2: decode the AC coefficients */
- /* In this path we just discard the values */
- for (k = 1; k < DCTSIZE2; k++) {
- HUFF_DECODE(s, br_state, actbl, return FALSE, label3);
-
- r = s >> 4;
- s &= 15;
-
- if (s) {
- k += r;
- CHECK_BIT_BUFFER(br_state, s, return FALSE);
- DROP_BITS(s);
- } else {
- if (r != 15)
- break;
- k += 15;
- }
- }
-
- }
- }
-
- /* Completed MCU, so update state */
- BITREAD_SAVE_STATE(cinfo,entropy->bitstate);
- ASSIGN_STATE(entropy->saved, state);
- }
-
- /* Account for restart interval (no-op if not using restarts) */
- entropy->restarts_to_go--;
-
- return TRUE;
-}
-
-
-/*
- * Module initialization routine for Huffman entropy decoding.
- */
-
-GLOBAL(void)
-jinit_huff_decoder (j_decompress_ptr cinfo)
-{
- huff_entropy_ptr entropy;
- int i;
-
- entropy = (huff_entropy_ptr)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(huff_entropy_decoder));
- cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;
- entropy->pub.start_pass = start_pass_huff_decoder;
- entropy->pub.decode_mcu = decode_mcu;
-
- /* Mark tables unallocated */
- for (i = 0; i < NUM_HUFF_TBLS; i++) {
- entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;
- }
-}
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