-/*\r
- * jdhuff.c\r
- *\r
- * Copyright (C) 1991-1995, Thomas G. Lane.\r
- * This file is part of the Independent JPEG Group's software.\r
- * For conditions of distribution and use, see the accompanying README file.\r
- *\r
- * This file contains Huffman entropy decoding routines.\r
- *\r
- * Much of the complexity here has to do with supporting input suspension.\r
- * If the data source module demands suspension, we want to be able to back\r
- * up to the start of the current MCU. To do this, we copy state variables\r
- * into local working storage, and update them back to the permanent\r
- * storage only upon successful completion of an MCU.\r
- */\r
-\r
-#define JPEG_INTERNALS\r
-#include "jinclude.h"\r
-#include "radiant_jpeglib.h"\r
-#include "jdhuff.h" /* Declarations shared with jdphuff.c */\r
-\r
-\r
-/*\r
- * Expanded entropy decoder object for Huffman decoding.\r
- *\r
- * The savable_state subrecord contains fields that change within an MCU,\r
- * but must not be updated permanently until we complete the MCU.\r
- */\r
-\r
-typedef struct {\r
- int last_dc_val[MAX_COMPS_IN_SCAN]; /* last DC coef for each component */\r
-} savable_state;\r
-\r
-/* This macro is to work around compilers with missing or broken\r
- * structure assignment. You'll need to fix this code if you have\r
- * such a compiler and you change MAX_COMPS_IN_SCAN.\r
- */\r
-\r
-#ifndef NO_STRUCT_ASSIGN\r
-#define ASSIGN_STATE(dest,src) ((dest) = (src))\r
-#else\r
-#if MAX_COMPS_IN_SCAN == 4\r
-#define ASSIGN_STATE(dest,src) \\r
- ((dest).last_dc_val[0] = (src).last_dc_val[0], \\r
- (dest).last_dc_val[1] = (src).last_dc_val[1], \\r
- (dest).last_dc_val[2] = (src).last_dc_val[2], \\r
- (dest).last_dc_val[3] = (src).last_dc_val[3])\r
-#endif\r
-#endif\r
-\r
-\r
-typedef struct {\r
- struct jpeg_entropy_decoder pub; /* public fields */\r
-\r
- /* These fields are loaded into local variables at start of each MCU.\r
- * In case of suspension, we exit WITHOUT updating them.\r
- */\r
- bitread_perm_state bitstate; /* Bit buffer at start of MCU */\r
- savable_state saved; /* Other state at start of MCU */\r
-\r
- /* These fields are NOT loaded into local working state. */\r
- unsigned int restarts_to_go; /* MCUs left in this restart interval */\r
-\r
- /* Pointers to derived tables (these workspaces have image lifespan) */\r
- d_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS];\r
- d_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS];\r
-} huff_entropy_decoder;\r
-\r
-typedef huff_entropy_decoder * huff_entropy_ptr;\r
-\r
-\r
-/*\r
- * Initialize for a Huffman-compressed scan.\r
- */\r
-\r
-METHODDEF void\r
-start_pass_huff_decoder (j_decompress_ptr cinfo)\r
-{\r
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;\r
- int ci, dctbl, actbl;\r
- jpeg_component_info * compptr;\r
-\r
- /* Check that the scan parameters Ss, Se, Ah/Al are OK for sequential JPEG.\r
- * This ought to be an error condition, but we make it a warning because\r
- * there are some baseline files out there with all zeroes in these bytes.\r
- */\r
- if (cinfo->Ss != 0 || cinfo->Se != DCTSIZE2-1 ||\r
- cinfo->Ah != 0 || cinfo->Al != 0)\r
- WARNMS(cinfo, JWRN_NOT_SEQUENTIAL);\r
-\r
- for (ci = 0; ci < cinfo->comps_in_scan; ci++) {\r
- compptr = cinfo->cur_comp_info[ci];\r
- dctbl = compptr->dc_tbl_no;\r
- actbl = compptr->ac_tbl_no;\r
- /* Make sure requested tables are present */\r
- if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS ||\r
- cinfo->dc_huff_tbl_ptrs[dctbl] == NULL)\r
- ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl);\r
- if (actbl < 0 || actbl >= NUM_HUFF_TBLS ||\r
- cinfo->ac_huff_tbl_ptrs[actbl] == NULL)\r
- ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl);\r
- /* Compute derived values for Huffman tables */\r
- /* We may do this more than once for a table, but it's not expensive */\r
- jpeg_make_d_derived_tbl(cinfo, cinfo->dc_huff_tbl_ptrs[dctbl],\r
- & entropy->dc_derived_tbls[dctbl]);\r
- jpeg_make_d_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[actbl],\r
- & entropy->ac_derived_tbls[actbl]);\r
- /* Initialize DC predictions to 0 */\r
- entropy->saved.last_dc_val[ci] = 0;\r
- }\r
-\r
- /* Initialize bitread state variables */\r
- entropy->bitstate.bits_left = 0;\r
- entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */\r
- entropy->bitstate.printed_eod = FALSE;\r
-\r
- /* Initialize restart counter */\r
- entropy->restarts_to_go = cinfo->restart_interval;\r
-}\r
-\r
-\r
-/*\r
- * Compute the derived values for a Huffman table.\r
- * Note this is also used by jdphuff.c.\r
- */\r
-\r
-GLOBAL void\r
-jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, JHUFF_TBL * htbl,\r
- d_derived_tbl ** pdtbl)\r
-{\r
- d_derived_tbl *dtbl;\r
- int p, i, l, si;\r
- int lookbits, ctr;\r
- char huffsize[257];\r
- unsigned int huffcode[257];\r
- unsigned int code;\r
-\r
- /* Allocate a workspace if we haven't already done so. */\r
- if (*pdtbl == NULL)\r
- *pdtbl = (d_derived_tbl *)\r
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,\r
- SIZEOF(d_derived_tbl));\r
- dtbl = *pdtbl;\r
- dtbl->pub = htbl; /* fill in back link */\r
- \r
- /* Figure C.1: make table of Huffman code length for each symbol */\r
- /* Note that this is in code-length order. */\r
-\r
- p = 0;\r
- for (l = 1; l <= 16; l++) {\r
- for (i = 1; i <= (int) htbl->bits[l]; i++)\r
- huffsize[p++] = (char) l;\r
- }\r
- huffsize[p] = 0;\r
- \r
- /* Figure C.2: generate the codes themselves */\r
- /* Note that this is in code-length order. */\r
- \r
- code = 0;\r
- si = huffsize[0];\r
- p = 0;\r
- while (huffsize[p]) {\r
- while (((int) huffsize[p]) == si) {\r
- huffcode[p++] = code;\r
- code++;\r
- }\r
- code <<= 1;\r
- si++;\r
- }\r
-\r
- /* Figure F.15: generate decoding tables for bit-sequential decoding */\r
-\r
- p = 0;\r
- for (l = 1; l <= 16; l++) {\r
- if (htbl->bits[l]) {\r
- dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */\r
- dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */\r
- p += htbl->bits[l];\r
- dtbl->maxcode[l] = huffcode[p-1]; /* maximum code of length l */\r
- } else {\r
- dtbl->maxcode[l] = -1; /* -1 if no codes of this length */\r
- }\r
- }\r
- dtbl->maxcode[17] = 0xFFFFFL; /* ensures jpeg_huff_decode terminates */\r
-\r
- /* Compute lookahead tables to speed up decoding.\r
- * First we set all the table entries to 0, indicating "too long";\r
- * then we iterate through the Huffman codes that are short enough and\r
- * fill in all the entries that correspond to bit sequences starting\r
- * with that code.\r
- */\r
-\r
- MEMZERO(dtbl->look_nbits, SIZEOF(dtbl->look_nbits));\r
-\r
- p = 0;\r
- for (l = 1; l <= HUFF_LOOKAHEAD; l++) {\r
- for (i = 1; i <= (int) htbl->bits[l]; i++, p++) {\r
- /* l = current code's length, p = its index in huffcode[] & huffval[]. */\r
- /* Generate left-justified code followed by all possible bit sequences */\r
- lookbits = huffcode[p] << (HUFF_LOOKAHEAD-l);\r
- for (ctr = 1 << (HUFF_LOOKAHEAD-l); ctr > 0; ctr--) {\r
- dtbl->look_nbits[lookbits] = l;\r
- dtbl->look_sym[lookbits] = htbl->huffval[p];\r
- lookbits++;\r
- }\r
- }\r
- }\r
-}\r
-\r
-\r
-/*\r
- * Out-of-line code for bit fetching (shared with jdphuff.c).\r
- * See jdhuff.h for info about usage.\r
- * Note: current values of get_buffer and bits_left are passed as parameters,\r
- * but are returned in the corresponding fields of the state struct.\r
- *\r
- * On most machines MIN_GET_BITS should be 25 to allow the full 32-bit width\r
- * of get_buffer to be used. (On machines with wider words, an even larger\r
- * buffer could be used.) However, on some machines 32-bit shifts are\r
- * quite slow and take time proportional to the number of places shifted.\r
- * (This is true with most PC compilers, for instance.) In this case it may\r
- * be a win to set MIN_GET_BITS to the minimum value of 15. This reduces the\r
- * average shift distance at the cost of more calls to jpeg_fill_bit_buffer.\r
- */\r
-\r
-#ifdef SLOW_SHIFT_32\r
-#define MIN_GET_BITS 15 /* minimum allowable value */\r
-#else\r
-#define MIN_GET_BITS (BIT_BUF_SIZE-7)\r
-#endif\r
-\r
-\r
-GLOBAL boolean\r
-jpeg_fill_bit_buffer (bitread_working_state * state,\r
- register bit_buf_type get_buffer, register int bits_left,\r
- int nbits)\r
-/* Load up the bit buffer to a depth of at least nbits */\r
-{\r
- /* Copy heavily used state fields into locals (hopefully registers) */\r
- register const JOCTET * next_input_byte = state->next_input_byte;\r
- register size_t bytes_in_buffer = state->bytes_in_buffer;\r
- register int c;\r
-\r
- /* Attempt to load at least MIN_GET_BITS bits into get_buffer. */\r
- /* (It is assumed that no request will be for more than that many bits.) */\r
-\r
- while (bits_left < MIN_GET_BITS) {\r
- /* Attempt to read a byte */\r
- if (state->unread_marker != 0)\r
- goto no_more_data; /* can't advance past a marker */\r
-\r
- if (bytes_in_buffer == 0) {\r
- if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))\r
- return FALSE;\r
- next_input_byte = state->cinfo->src->next_input_byte;\r
- bytes_in_buffer = state->cinfo->src->bytes_in_buffer;\r
- }\r
- bytes_in_buffer--;\r
- c = GETJOCTET(*next_input_byte++);\r
-\r
- /* If it's 0xFF, check and discard stuffed zero byte */\r
- if (c == 0xFF) {\r
- do {\r
- if (bytes_in_buffer == 0) {\r
- if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))\r
- return FALSE;\r
- next_input_byte = state->cinfo->src->next_input_byte;\r
- bytes_in_buffer = state->cinfo->src->bytes_in_buffer;\r
- }\r
- bytes_in_buffer--;\r
- c = GETJOCTET(*next_input_byte++);\r
- } while (c == 0xFF);\r
-\r
- if (c == 0) {\r
- /* Found FF/00, which represents an FF data byte */\r
- c = 0xFF;\r
- } else {\r
- /* Oops, it's actually a marker indicating end of compressed data. */\r
- /* Better put it back for use later */\r
- state->unread_marker = c;\r
-\r
- no_more_data:\r
- /* There should be enough bits still left in the data segment; */\r
- /* if so, just break out of the outer while loop. */\r
- if (bits_left >= nbits)\r
- break;\r
- /* Uh-oh. Report corrupted data to user and stuff zeroes into\r
- * the data stream, so that we can produce some kind of image.\r
- * Note that this code will be repeated for each byte demanded\r
- * for the rest of the segment. We use a nonvolatile flag to ensure\r
- * that only one warning message appears.\r
- */\r
- if (! *(state->printed_eod_ptr)) {\r
- WARNMS(state->cinfo, JWRN_HIT_MARKER);\r
- *(state->printed_eod_ptr) = TRUE;\r
- }\r
- c = 0; /* insert a zero byte into bit buffer */\r
- }\r
- }\r
-\r
- /* OK, load c into get_buffer */\r
- get_buffer = (get_buffer << 8) | c;\r
- bits_left += 8;\r
- }\r
-\r
- /* Unload the local registers */\r
- state->next_input_byte = next_input_byte;\r
- state->bytes_in_buffer = bytes_in_buffer;\r
- state->get_buffer = get_buffer;\r
- state->bits_left = bits_left;\r
-\r
- return TRUE;\r
-}\r
-\r
-\r
-/*\r
- * Out-of-line code for Huffman code decoding.\r
- * See jdhuff.h for info about usage.\r
- */\r
-\r
-GLOBAL int\r
-jpeg_huff_decode (bitread_working_state * state,\r
- register bit_buf_type get_buffer, register int bits_left,\r
- d_derived_tbl * htbl, int min_bits)\r
-{\r
- register int l = min_bits;\r
- register INT32 code;\r
-\r
- /* HUFF_DECODE has determined that the code is at least min_bits */\r
- /* bits long, so fetch that many bits in one swoop. */\r
-\r
- CHECK_BIT_BUFFER(*state, l, return -1);\r
- code = GET_BITS(l);\r
-\r
- /* Collect the rest of the Huffman code one bit at a time. */\r
- /* This is per Figure F.16 in the JPEG spec. */\r
-\r
- while (code > htbl->maxcode[l]) {\r
- code <<= 1;\r
- CHECK_BIT_BUFFER(*state, 1, return -1);\r
- code |= GET_BITS(1);\r
- l++;\r
- }\r
-\r
- /* Unload the local registers */\r
- state->get_buffer = get_buffer;\r
- state->bits_left = bits_left;\r
-\r
- /* With garbage input we may reach the sentinel value l = 17. */\r
-\r
- if (l > 16) {\r
- WARNMS(state->cinfo, JWRN_HUFF_BAD_CODE);\r
- return 0; /* fake a zero as the safest result */\r
- }\r
-\r
- return htbl->pub->huffval[ htbl->valptr[l] +\r
- ((int) (code - htbl->mincode[l])) ];\r
-}\r
-\r
-\r
-/*\r
- * Figure F.12: extend sign bit.\r
- * On some machines, a shift and add will be faster than a table lookup.\r
- */\r
-\r
-#ifdef AVOID_TABLES\r
-\r
-#define HUFF_EXTEND(x,s) ((x) < (1<<((s)-1)) ? (x) + (((-1)<<(s)) + 1) : (x))\r
-\r
-#else\r
-\r
-#define HUFF_EXTEND(x,s) ((x) < extend_test[s] ? (x) + extend_offset[s] : (x))\r
-\r
-static const int extend_test[16] = /* entry n is 2**(n-1) */\r
- { 0, 0x0001, 0x0002, 0x0004, 0x0008, 0x0010, 0x0020, 0x0040, 0x0080,\r
- 0x0100, 0x0200, 0x0400, 0x0800, 0x1000, 0x2000, 0x4000 };\r
-\r
-static const int extend_offset[16] = /* entry n is (-1 << n) + 1 */\r
- { 0, ((-1)<<1) + 1, ((-1)<<2) + 1, ((-1)<<3) + 1, ((-1)<<4) + 1,\r
- ((-1)<<5) + 1, ((-1)<<6) + 1, ((-1)<<7) + 1, ((-1)<<8) + 1,\r
- ((-1)<<9) + 1, ((-1)<<10) + 1, ((-1)<<11) + 1, ((-1)<<12) + 1,\r
- ((-1)<<13) + 1, ((-1)<<14) + 1, ((-1)<<15) + 1 };\r
-\r
-#endif /* AVOID_TABLES */\r
-\r
-\r
-/*\r
- * Check for a restart marker & resynchronize decoder.\r
- * Returns FALSE if must suspend.\r
- */\r
-\r
-LOCAL boolean\r
-process_restart (j_decompress_ptr cinfo)\r
-{\r
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;\r
- int ci;\r
-\r
- /* Throw away any unused bits remaining in bit buffer; */\r
- /* include any full bytes in next_marker's count of discarded bytes */\r
- cinfo->marker->discarded_bytes += entropy->bitstate.bits_left / 8;\r
- entropy->bitstate.bits_left = 0;\r
-\r
- /* Advance past the RSTn marker */\r
- if (! (*cinfo->marker->read_restart_marker) (cinfo))\r
- return FALSE;\r
-\r
- /* Re-initialize DC predictions to 0 */\r
- for (ci = 0; ci < cinfo->comps_in_scan; ci++)\r
- entropy->saved.last_dc_val[ci] = 0;\r
-\r
- /* Reset restart counter */\r
- entropy->restarts_to_go = cinfo->restart_interval;\r
-\r
- /* Next segment can get another out-of-data warning */\r
- entropy->bitstate.printed_eod = FALSE;\r
-\r
- return TRUE;\r
-}\r
-\r
-\r
-/*\r
- * Decode and return one MCU's worth of Huffman-compressed coefficients.\r
- * The coefficients are reordered from zigzag order into natural array order,\r
- * but are not dequantized.\r
- *\r
- * The i'th block of the MCU is stored into the block pointed to by\r
- * MCU_data[i]. WE ASSUME THIS AREA HAS BEEN ZEROED BY THE CALLER.\r
- * (Wholesale zeroing is usually a little faster than retail...)\r
- *\r
- * Returns FALSE if data source requested suspension. In that case no\r
- * changes have been made to permanent state. (Exception: some output\r
- * coefficients may already have been assigned. This is harmless for\r
- * this module, since we'll just re-assign them on the next call.)\r
- */\r
-\r
-METHODDEF boolean\r
-decode_mcu (j_decompress_ptr cinfo, JBLOCKROW *MCU_data)\r
-{\r
- huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy;\r
- register int s, k, r;\r
- int blkn, ci;\r
- JBLOCKROW block;\r
- BITREAD_STATE_VARS;\r
- savable_state state;\r
- d_derived_tbl * dctbl;\r
- d_derived_tbl * actbl;\r
- jpeg_component_info * compptr;\r
-\r
- /* Process restart marker if needed; may have to suspend */\r
- if (cinfo->restart_interval) {\r
- if (entropy->restarts_to_go == 0)\r
- if (! process_restart(cinfo))\r
- return FALSE;\r
- }\r
-\r
- /* Load up working state */\r
- BITREAD_LOAD_STATE(cinfo,entropy->bitstate);\r
- ASSIGN_STATE(state, entropy->saved);\r
-\r
- /* Outer loop handles each block in the MCU */\r
-\r
- for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) {\r
- block = MCU_data[blkn];\r
- ci = cinfo->MCU_membership[blkn];\r
- compptr = cinfo->cur_comp_info[ci];\r
- dctbl = entropy->dc_derived_tbls[compptr->dc_tbl_no];\r
- actbl = entropy->ac_derived_tbls[compptr->ac_tbl_no];\r
-\r
- /* Decode a single block's worth of coefficients */\r
-\r
- /* Section F.2.2.1: decode the DC coefficient difference */\r
- HUFF_DECODE(s, br_state, dctbl, return FALSE, label1);\r
- if (s) {\r
- CHECK_BIT_BUFFER(br_state, s, return FALSE);\r
- r = GET_BITS(s);\r
- s = HUFF_EXTEND(r, s);\r
- }\r
-\r
- /* Shortcut if component's values are not interesting */\r
- if (! compptr->component_needed)\r
- goto skip_ACs;\r
-\r
- /* Convert DC difference to actual value, update last_dc_val */\r
- s += state.last_dc_val[ci];\r
- state.last_dc_val[ci] = s;\r
- /* Output the DC coefficient (assumes jpeg_natural_order[0] = 0) */\r
- (*block)[0] = (JCOEF) s;\r
-\r
- /* Do we need to decode the AC coefficients for this component? */\r
- if (compptr->DCT_scaled_size > 1) {\r
-\r
- /* Section F.2.2.2: decode the AC coefficients */\r
- /* Since zeroes are skipped, output area must be cleared beforehand */\r
- for (k = 1; k < DCTSIZE2; k++) {\r
- HUFF_DECODE(s, br_state, actbl, return FALSE, label2);\r
- \r
- r = s >> 4;\r
- s &= 15;\r
- \r
- if (s) {\r
- k += r;\r
- CHECK_BIT_BUFFER(br_state, s, return FALSE);\r
- r = GET_BITS(s);\r
- s = HUFF_EXTEND(r, s);\r
- /* Output coefficient in natural (dezigzagged) order.\r
- * Note: the extra entries in jpeg_natural_order[] will save us\r
- * if k >= DCTSIZE2, which could happen if the data is corrupted.\r
- */\r
- (*block)[jpeg_natural_order[k]] = (JCOEF) s;\r
- } else {\r
- if (r != 15)\r
- break;\r
- k += 15;\r
- }\r
- }\r
-\r
- } else {\r
-skip_ACs:\r
-\r
- /* Section F.2.2.2: decode the AC coefficients */\r
- /* In this path we just discard the values */\r
- for (k = 1; k < DCTSIZE2; k++) {\r
- HUFF_DECODE(s, br_state, actbl, return FALSE, label3);\r
- \r
- r = s >> 4;\r
- s &= 15;\r
- \r
- if (s) {\r
- k += r;\r
- CHECK_BIT_BUFFER(br_state, s, return FALSE);\r
- DROP_BITS(s);\r
- } else {\r
- if (r != 15)\r
- break;\r
- k += 15;\r
- }\r
- }\r
-\r
- }\r
- }\r
-\r
- /* Completed MCU, so update state */\r
- BITREAD_SAVE_STATE(cinfo,entropy->bitstate);\r
- ASSIGN_STATE(entropy->saved, state);\r
-\r
- /* Account for restart interval (no-op if not using restarts) */\r
- entropy->restarts_to_go--;\r
-\r
- return TRUE;\r
-}\r
-\r
-\r
-/*\r
- * Module initialization routine for Huffman entropy decoding.\r
- */\r
-\r
-GLOBAL void\r
-jinit_huff_decoder (j_decompress_ptr cinfo)\r
-{\r
- huff_entropy_ptr entropy;\r
- int i;\r
-\r
- entropy = (huff_entropy_ptr)\r
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,\r
- SIZEOF(huff_entropy_decoder));\r
- cinfo->entropy = (struct jpeg_entropy_decoder *) entropy;\r
- entropy->pub.start_pass = start_pass_huff_decoder;\r
- entropy->pub.decode_mcu = decode_mcu;\r
-\r
- /* Mark tables unallocated */\r
- for (i = 0; i < NUM_HUFF_TBLS; i++) {\r
- entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL;\r
- }\r
-}\r
+/*
+ * jdhuff.c
+ *
+ * Copyright (C) 1991-1995, 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 "radiant_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];
+} 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, 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;
+ /* Make sure requested tables are present */
+ if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS ||
+ cinfo->dc_huff_tbl_ptrs[dctbl] == NULL)
+ ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl);
+ if (actbl < 0 || actbl >= NUM_HUFF_TBLS ||
+ cinfo->ac_huff_tbl_ptrs[actbl] == NULL)
+ ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl);
+ /* 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, cinfo->dc_huff_tbl_ptrs[dctbl],
+ & entropy->dc_derived_tbls[dctbl]);
+ jpeg_make_d_derived_tbl(cinfo, cinfo->ac_huff_tbl_ptrs[actbl],
+ & entropy->ac_derived_tbls[actbl]);
+ /* Initialize DC predictions to 0 */
+ entropy->saved.last_dc_val[ci] = 0;
+ }
+
+ /* Initialize bitread state variables */
+ entropy->bitstate.bits_left = 0;
+ entropy->bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
+ entropy->bitstate.printed_eod = FALSE;
+
+ /* Initialize restart counter */
+ entropy->restarts_to_go = cinfo->restart_interval;
+}
+
+
+/*
+ * Compute the derived values for a Huffman table.
+ * Note this is also used by jdphuff.c.
+ */
+
+GLOBAL void
+jpeg_make_d_derived_tbl (j_decompress_ptr cinfo, JHUFF_TBL * htbl,
+ d_derived_tbl ** pdtbl)
+{
+ d_derived_tbl *dtbl;
+ int p, i, l, si;
+ int lookbits, ctr;
+ char huffsize[257];
+ unsigned int huffcode[257];
+ unsigned int code;
+
+ /* 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 */
+ /* Note that this is in code-length order. */
+
+ p = 0;
+ for (l = 1; l <= 16; l++) {
+ for (i = 1; i <= (int) htbl->bits[l]; i++)
+ huffsize[p++] = (char) l;
+ }
+ huffsize[p] = 0;
+
+ /* Figure C.2: generate the codes themselves */
+ /* Note that this is in code-length order. */
+
+ code = 0;
+ si = huffsize[0];
+ p = 0;
+ while (huffsize[p]) {
+ while (((int) huffsize[p]) == si) {
+ huffcode[p++] = code;
+ code++;
+ }
+ 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]) {
+ dtbl->valptr[l] = p; /* huffval[] index of 1st symbol of code length l */
+ dtbl->mincode[l] = huffcode[p]; /* minimum code of length l */
+ 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++;
+ }
+ }
+ }
+}
+
+
+/*
+ * 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;
+ register int c;
+
+ /* 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.) */
+
+ while (bits_left < MIN_GET_BITS) {
+ /* Attempt to read a byte */
+ if (state->unread_marker != 0)
+ goto no_more_data; /* can't advance past a marker */
+
+ if (bytes_in_buffer == 0) {
+ if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))
+ return FALSE;
+ next_input_byte = state->cinfo->src->next_input_byte;
+ bytes_in_buffer = state->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) {
+ do {
+ if (bytes_in_buffer == 0) {
+ if (! (*state->cinfo->src->fill_input_buffer) (state->cinfo))
+ return FALSE;
+ next_input_byte = state->cinfo->src->next_input_byte;
+ bytes_in_buffer = state->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. */
+ /* Better put it back for use later */
+ state->unread_marker = c;
+
+ no_more_data:
+ /* There should be enough bits still left in the data segment; */
+ /* if so, just break out of the outer while loop. */
+ if (bits_left >= nbits)
+ break;
+ /* Uh-oh. Report corrupted data to user and stuff zeroes into
+ * the data stream, so that we can produce some kind of image.
+ * Note that this code will be repeated for each byte demanded
+ * for the rest of the segment. We use a nonvolatile flag to ensure
+ * that only one warning message appears.
+ */
+ if (! *(state->printed_eod_ptr)) {
+ WARNMS(state->cinfo, JWRN_HIT_MARKER);
+ *(state->printed_eod_ptr) = TRUE;
+ }
+ c = 0; /* insert a zero byte into bit buffer */
+ }
+ }
+
+ /* OK, load c into get_buffer */
+ get_buffer = (get_buffer << 8) | c;
+ bits_left += 8;
+ }
+
+ /* 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[ htbl->valptr[l] +
+ ((int) (code - htbl->mincode[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;
+
+ /* Next segment can get another out-of-data warning */
+ entropy->bitstate.printed_eod = 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;
+ register int s, k, r;
+ int blkn, ci;
+ JBLOCKROW block;
+ BITREAD_STATE_VARS;
+ savable_state state;
+ d_derived_tbl * dctbl;
+ d_derived_tbl * actbl;
+ jpeg_component_info * compptr;
+
+ /* 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;
+ }
+
+ /* 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++) {
+ block = MCU_data[blkn];
+ ci = cinfo->MCU_membership[blkn];
+ compptr = cinfo->cur_comp_info[ci];
+ dctbl = entropy->dc_derived_tbls[compptr->dc_tbl_no];
+ actbl = entropy->ac_derived_tbls[compptr->ac_tbl_no];
+
+ /* 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);
+ }
+
+ /* Shortcut if component's values are not interesting */
+ if (! compptr->component_needed)
+ goto skip_ACs;
+
+ /* Convert DC difference to actual value, update last_dc_val */
+ 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;
+
+ /* Do we need to decode the AC coefficients for this component? */
+ if (compptr->DCT_scaled_size > 1) {
+
+ /* 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 {
+skip_ACs:
+
+ /* 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;
+ }
+}
projects / xonotic / netradiant.git / blobdiff