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Diffstat (limited to 'libjpegtwrp/jdhuff.c')
| -rw-r--r-- | libjpegtwrp/jdhuff.c | 894 |
1 files changed, 0 insertions, 894 deletions
diff --git a/libjpegtwrp/jdhuff.c b/libjpegtwrp/jdhuff.c deleted file mode 100644 index bc5d4fdd2..000000000 --- a/libjpegtwrp/jdhuff.c +++ /dev/null @@ -1,894 +0,0 @@ -/* - * jdhuff.c - * - * Copyright (C) 1991-1997, 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. - */ - -#define JPEG_INTERNALS -#include "jinclude.h" -#include "jpeglib.h" -#include "jdhuff.h" /* Declarations shared with jdphuff.c */ - -LOCAL(boolean) process_restart (j_decompress_ptr cinfo); - - -/* - * 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; -} - - -/* - * 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) -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) - ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); - htbl = - isDC ? cinfo->dc_huff_tbl_ptrs[tblno] : cinfo->ac_huff_tbl_ptrs[tblno]; - if (htbl == NULL) - ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, tblno); - - /* Allocate a workspace if we haven't already done so. */ - if (*pdtbl == NULL) - *pdtbl = (d_derived_tbl *) - (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, - 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 */ - 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)) - 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) - ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); - } - } -} - - -/* - * 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, - * but are returned in the corresponding fields of the state struct. - * - * On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width - * of get_buffer to be used. (On machines with wider words, an even larger - * buffer could be used.) However, on some machines 32-bit shifts are - * quite slow and take time proportional to the number of places shifted. - * (This is true with most PC compilers, for instance.) In this case it may - * be a win to set MIN_GET_BITS to the minimum value of 15. This reduces the - * average shift distance at the cost of more calls to jpeg_fill_bit_buffer. - */ - -#ifdef SLOW_SHIFT_32 -#define MIN_GET_BITS 15 /* minimum allowable value */ -#else -#define MIN_GET_BITS (BIT_BUF_SIZE-7) -#endif - - -GLOBAL(boolean) -jpeg_fill_bit_buffer (bitread_working_state * state, - register bit_buf_type get_buffer, register int bits_left, - int nbits) -/* Load up the bit buffer to a depth of at least nbits */ -{ - /* Copy heavily used state fields into locals (hopefully registers) */ - register const JOCTET * next_input_byte = state->next_input_byte; - register size_t bytes_in_buffer = state->bytes_in_buffer; - j_decompress_ptr cinfo = state->cinfo; - - /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */ - /* (It is assumed that no request will be for more than that many bits.) */ - /* We fail to do so only if we hit a marker or are forced to suspend. */ - - if (cinfo->unread_marker == 0) { /* cannot advance past a marker */ - while (bits_left < MIN_GET_BITS) { - register int c; - - /* Attempt to read a byte */ - if (bytes_in_buffer == 0) { - if (! (*cinfo->src->fill_input_buffer) (cinfo)) - return FALSE; - next_input_byte = cinfo->src->next_input_byte; - bytes_in_buffer = cinfo->src->bytes_in_buffer; - } - bytes_in_buffer--; - c = GETJOCTET(*next_input_byte++); - - /* If it's 0xFF, check and discard stuffed zero byte */ - if (c == 0xFF) { - /* Loop here to discard any padding FF's on terminating marker, - * so that we can save a valid unread_marker value. NOTE: we will - * accept multiple FF's followed by a 0 as meaning a single FF data - * byte. This data pattern is not valid according to the standard. - */ - do { - if (bytes_in_buffer == 0) { - if (! (*cinfo->src->fill_input_buffer) (cinfo)) - return FALSE; - next_input_byte = cinfo->src->next_input_byte; - bytes_in_buffer = cinfo->src->bytes_in_buffer; - } - bytes_in_buffer--; - c = GETJOCTET(*next_input_byte++); - } while (c == 0xFF); - - if (c == 0) { - /* Found FF/00, which represents an FF data byte */ - c = 0xFF; - } else { - /* Oops, it's actually a marker indicating end of compressed data. - * Save the marker code for later use. - * Fine point: it might appear that we should save the marker into - * bitread working state, not straight into permanent state. But - * once we have hit a marker, we cannot need to suspend within the - * current MCU, because we will read no more bytes from the data - * source. So it is OK to update permanent state right away. - */ - cinfo->unread_marker = c; - /* See if we need to insert some fake zero bits. */ - goto no_more_bytes; - } - } - - /* OK, load c into get_buffer */ - get_buffer = (get_buffer << 8) | c; - bits_left += 8; - } /* end while */ - } else { - no_more_bytes: - /* We get here if we've read the marker that terminates the compressed - * data segment. There should be enough bits in the buffer register - * to satisfy the request; if so, no problem. - */ - if (nbits > bits_left) { - /* Uh-oh. Report corrupted data to user and stuff zeroes into - * the data stream, so that we can produce some kind of image. - * We use a nonvolatile flag to ensure that only one warning message - * appears per data segment. - */ - if (! cinfo->entropy->insufficient_data) { - WARNMS(cinfo, JWRN_HIT_MARKER); - cinfo->entropy->insufficient_data = TRUE; - } - /* Fill the buffer with zero bits */ - get_buffer <<= MIN_GET_BITS - bits_left; - bits_left = MIN_GET_BITS; - } - } - - /* Unload the local registers */ - state->next_input_byte = next_input_byte; - state->bytes_in_buffer = bytes_in_buffer; - state->get_buffer = get_buffer; - state->bits_left = bits_left; - - return TRUE; -} - - -/* - * Out-of-line code for Huffman code decoding. - * See jdhuff.h for info about usage. - */ - -GLOBAL(int) -jpeg_huff_decode (bitread_working_state * state, - register bit_buf_type get_buffer, register int bits_left, - d_derived_tbl * htbl, int min_bits) -{ - register int l = min_bits; - register INT32 code; - - /* HUFF_DECODE has determined that the code is at least min_bits */ - /* bits long, so fetch that many bits in one swoop. */ - - CHECK_BIT_BUFFER(*state, l, return -1); - code = GET_BITS(l); - - /* Collect the rest of the Huffman code one bit at a time. */ - /* This is per Figure F.16 in the JPEG spec. */ - - while (code > htbl->maxcode[l]) { - code <<= 1; - CHECK_BIT_BUFFER(*state, 1, return -1); - code |= GET_BITS(1); - l++; - } - - /* Unload the local registers */ - state->get_buffer = get_buffer; - state->bits_left = bits_left; - - /* With garbage input we may reach the sentinel value l = 17. */ - - if (l > 16) { - WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE); - return 0; /* fake a zero as the safest result */ - } - - 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; -} - -/* - * Save the current Huffman deocde position and the DC coefficients - * for each component into bitstream_offset and dc_info[], respectively. - */ -METHODDEF(void) -get_huffman_decoder_configuration(j_decompress_ptr cinfo, - huffman_offset_data *offset) -{ - huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; - short int *dc_info = offset->prev_dc; - int i; - jpeg_get_huffman_decoder_configuration(cinfo, offset); - for (i = 0; i < cinfo->comps_in_scan; i++) { - dc_info[i] = entropy->saved.last_dc_val[i]; - } -} - -/* - * Save the current Huffman decoder position and the bit buffer - * into bitstream_offset and get_buffer, respectively. - */ -GLOBAL(void) -jpeg_get_huffman_decoder_configuration(j_decompress_ptr cinfo, - huffman_offset_data *offset) -{ - huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; - - if (cinfo->restart_interval) { - // We are at the end of a data segment - if (entropy->restarts_to_go == 0) - if (! process_restart(cinfo)) - return; - } - - // Save restarts_to_go and next_restart_num - offset->restarts_to_go = (unsigned short) entropy->restarts_to_go; - offset->next_restart_num = cinfo->marker->next_restart_num; - - offset->bitstream_offset = - (jget_input_stream_position(cinfo) << LOG_TWO_BIT_BUF_SIZE) - + entropy->bitstate.bits_left; - - offset->get_buffer = entropy->bitstate.get_buffer; -} - -/* - * Configure the Huffman decoder to decode the image - * starting from the bitstream position recorded in offset. - */ -METHODDEF(void) -configure_huffman_decoder(j_decompress_ptr cinfo, huffman_offset_data offset) -{ - huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; - short int *dc_info = offset.prev_dc; - int i; - jpeg_configure_huffman_decoder(cinfo, offset); - for (i = 0; i < cinfo->comps_in_scan; i++) { - entropy->saved.last_dc_val[i] = dc_info[i]; - } -} - -/* - * Configure the Huffman decoder reader position and bit buffer. - */ -GLOBAL(void) -jpeg_configure_huffman_decoder(j_decompress_ptr cinfo, - huffman_offset_data offset) -{ - huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; - - // Restore restarts_to_go and next_restart_num - cinfo->unread_marker = 0; - entropy->restarts_to_go = offset.restarts_to_go; - cinfo->marker->next_restart_num = offset.next_restart_num; - - unsigned int bitstream_offset = offset.bitstream_offset; - int blkn, i; - - unsigned int byte_offset = bitstream_offset >> LOG_TWO_BIT_BUF_SIZE; - unsigned int bit_in_bit_buffer = - bitstream_offset & ((1 << LOG_TWO_BIT_BUF_SIZE) - 1); - - jset_input_stream_position_bit(cinfo, byte_offset, - bit_in_bit_buffer, offset.get_buffer); -} - -/* - * 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; -} - -/* - * Decode one MCU's worth of Huffman-compressed coefficients. - * The propose of this method is to calculate the - * data length of one MCU in Huffman-coded format. - * Therefore, all coefficients are discarded. - */ - -METHODDEF(boolean) -decode_mcu_discard_coef (j_decompress_ptr cinfo) -{ - 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 (! 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++) { - 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); - } - - /* discard all coefficients */ - 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; - } - 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; - entropy->pub.decode_mcu_discard_coef = decode_mcu_discard_coef; - entropy->pub.configure_huffman_decoder = configure_huffman_decoder; - entropy->pub.get_huffman_decoder_configuration = - get_huffman_decoder_configuration; - entropy->pub.index = NULL; - - /* Mark tables unallocated */ - for (i = 0; i < NUM_HUFF_TBLS; i++) { - entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL; - } -} - -/* - * Call after jpeg_read_header - */ -GLOBAL(void) -jpeg_create_huffman_index(j_decompress_ptr cinfo, huffman_index *index) -{ - int i, s; - index->scan_count = 1; - index->total_iMCU_rows = cinfo->total_iMCU_rows; - index->scan = (huffman_scan_header*)malloc(index->scan_count - * sizeof(huffman_scan_header)); - index->scan[0].offset = (huffman_offset_data**)malloc(cinfo->total_iMCU_rows - * sizeof(huffman_offset_data*)); - index->scan[0].prev_MCU_offset.bitstream_offset = 0; - index->MCU_sample_size = DEFAULT_MCU_SAMPLE_SIZE; - - index->mem_used = sizeof(huffman_scan_header) - + cinfo->total_iMCU_rows * sizeof(huffman_offset_data*); -} - -GLOBAL(void) -jpeg_destroy_huffman_index(huffman_index *index) -{ - int i, j; - for (i = 0; i < index->scan_count; i++) { - for(j = 0; j < index->total_iMCU_rows; j++) { - free(index->scan[i].offset[j]); - } - free(index->scan[i].offset); - } - free(index->scan); -} - -/* - * Set the reader byte position to offset - */ -GLOBAL(void) -jset_input_stream_position(j_decompress_ptr cinfo, int offset) -{ - if (cinfo->src->seek_input_data) { - cinfo->src->seek_input_data(cinfo, offset); - } else { - cinfo->src->bytes_in_buffer = cinfo->src->current_offset - offset; - cinfo->src->next_input_byte = cinfo->src->start_input_byte + offset; - } -} - -/* - * Set the reader byte position to offset and bit position to bit_left - * with bit buffer set to buf. - */ -GLOBAL(void) -jset_input_stream_position_bit(j_decompress_ptr cinfo, - int byte_offset, int bit_left, INT32 buf) -{ - huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; - - entropy->bitstate.bits_left = bit_left; - entropy->bitstate.get_buffer = buf; - - jset_input_stream_position(cinfo, byte_offset); -} - -/* - * Get the current reader byte position. - */ -GLOBAL(int) -jget_input_stream_position(j_decompress_ptr cinfo) -{ - return cinfo->src->current_offset - cinfo->src->bytes_in_buffer; -} |