From 5105c699551b511db93d9a65f2e51964f24ee271 Mon Sep 17 00:00:00 2001 From: Oliver Schinagl Date: Thu, 2 Jun 2005 12:26:08 +0000 Subject: 2 weird errors, appears to be working sofar. --- src/d_huffman.c | 455 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 455 insertions(+) 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; +} -- cgit v0.12