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authorOliver Schinagl <oliver@schinagl.nl>2005-06-02 12:26:08 (GMT)
committerOliver Schinagl <oliver@schinagl.nl>2005-06-02 12:26:08 (GMT)
commit5105c699551b511db93d9a65f2e51964f24ee271 (patch)
tree39e98b1f68b49b7a51ead9691163b3bc535b9b2d
parent1c7e7214d5b8ebc3acecba3c67a90985bca8046b (diff)
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2 weird errors, appears to be working sofar.
-rw-r--r--src/d_huffman.c455
1 files changed, 455 insertions, 0 deletions
diff --git a/src/d_huffman.c b/src/d_huffman.c
index 7431f98..38962ac 100644
--- a/src/d_huffman.c
+++ b/src/d_huffman.c
@@ -11,6 +11,112 @@
/*
+ * 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.
+ */
+
+#define ASSIGN_STATE(dest,src) ((dest) = (src))
+
+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.
+ */
+
+static 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)
+ perror("Invalid SOS parameters for sequential JPEG");
+ /*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;
+}
+
+
+/*
* Out-of-line code for bit fetching (shared with jdphuff.c).
* See jdhuff.h for info about usage.
* Note: current values of get_buffer and bits_left are passed as parameters,
@@ -132,6 +238,139 @@ boolean jpeg_fill_bit_buffer(bitread_working_state *state, register bit_buf_type
/*
+ * 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.
+ */
+
+void jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, boolean isDC, int tblno, d_derived_tbl ** pdtbl) {
+ JHUFF_TBL *htbl;
+ d_derived_tbl *dtbl;
+ int p, i, l, si, numsymbols;
+ int lookbits, ctr;
+ char huffsize[257];
+ unsigned int huffcode[257];
+ unsigned int code;
+
+ /* Note that huffsize[] and huffcode[] are filled in code-length order,
+ * paralleling the order of the symbols themselves in htbl->huffval[].
+ */
+
+ /* Find the input Huffman table */
+ if (tblno < 0 || tblno >= NUM_HUFF_TBLS)
+ perror("Huffman table 0x%%02x was not defined");
+ exit(1);
+ /*ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);*/
+ htbl =
+ isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno];
+ if (htbl == NULL)
+ perror("Huffman table 0x%%02x was not defined");
+ exit(1);
+ /*ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno);*/
+
+ /* Allocate a workspace if we haven't already done so. */
+ if (*pdtbl == NULL)
+ *pdtbl = (d_derived_tbl *) malloc((size_t) sizeof(d_derived_tbl));
+ dtbl = *pdtbl;
+ dtbl->pub = htbl; /* fill in back link */
+
+ /* Figure C.1: make table of Huffman code length for each symbol */
+
+ p = 0;
+ for (l = 1; l <= 16; l++) {
+ i = (int) htbl->bits[l];
+ if (i < 0 || p + i > 256) /* protect against table overrun */
+ perror("Bogus Huffman table definition");
+ exit(0);
+ /*ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);*/
+ while (i--)
+ huffsize[p++] = (char) l;
+ }
+ huffsize[p] = 0;
+ numsymbols = p;
+
+ /* Figure C.2: generate the codes themselves */
+ /* We also validate that the counts represent a legal Huffman code tree. */
+
+ code = 0;
+ si = huffsize[0];
+ p = 0;
+ while (huffsize[p]) {
+ while (((int) huffsize[p]) == si) {
+ huffcode[p++] = code;
+ code++;
+ }
+ /* 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.
+ */
+ if (((INT32) code) >= (((INT32) 1) << si))
+ perror("Bogus Huffman table definition");
+ exit(0);
+ /*ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);*/
+ code <<= 1;
+ si++;
+ }
+
+ /* Figure F.15: generate decoding tables for bit-sequential decoding */
+
+ p = 0;
+ for (l = 1; l <= 16; l++) {
+ if (htbl->bits[l]) {
+ /* valoffset[l] = huffval[] index of 1st symbol of code length l,
+ * minus the minimum code of length l
+ */
+ dtbl->valoffset[l] = (INT32) p - (INT32) huffcode[p];
+ p += htbl->bits[l];
+ dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */
+ } else {
+ dtbl->maxcode[l] = -1; /* -1 if no codes of this length */
+ }
+ }
+ dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */
+
+ /* Compute lookahead tables to speed up decoding.
+ * First we set all the table entries to 0, indicating "too long";
+ * then we iterate through the Huffman codes that are short enough and
+ * fill in all the entries that correspond to bit sequences starting
+ * with that code.
+ */
+
+ MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));
+
+ p = 0;
+ for (l = 1; l <= HUFF_LOOKAHEAD; l++) {
+ for (i = 1; i <= (int) htbl->bits[l]; i++, p++) {
+ /* l = current code's length, p = its index in huffcode[] & huffval[]. */
+ /* Generate left-justified code followed by all possible bit sequences */
+ lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);
+ for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {
+ dtbl->look_nbits[lookbits] = l;
+ dtbl->look_sym[lookbits] = htbl->huffval[p];
+ lookbits++;
+ }
+ }
+ }
+
+ /* 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.
+ * (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)
+ perror("Bogus Huffman table definition");
+ exit(0);
+ /*ERREXIT(cinfo, JERR_BAD_HUFF_TABLE);*/
+ }
+ }
+}
+
+
+/*
* Out-of-line code for Huffman code decoding.
* See jdhuff.h for info about usage.
*/
@@ -170,3 +409,219 @@ int jpeg_huff_decode(bitread_working_state *state, register bit_buf_type get_buf
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.
+ */
+
+static 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.)
+ */
+
+static 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.
+ */
+
+void jinit_huff_decoder (j_decompress_ptr cinfo) {
+ huff_entropy_ptr entropy;
+ int i;
+
+ entropy = (huff_entropy_ptr) malloc((size_t) 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;
+ }
+}
+
+int main(void) {
+ jinit_huff_decoder(NULL);
+
+
+ return 0;
+}