| /* |
| * jchuff.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 encoding routines. |
| * |
| * Much of the complexity here has to do with supporting output suspension. |
| * If the data destination 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 JPEG objects only upon successful completion of an MCU. |
| */ |
| |
| /* Modifications: |
| * Copyright (C)2007 Sun Microsystems, Inc. |
| * Copyright (C)2009 D. R. Commander |
| * |
| * This library is free software and may be redistributed and/or modified under |
| * the terms of the wxWindows Library License, Version 3.1 or (at your option) |
| * any later version. The full license is in the LICENSE.txt file included |
| * with this distribution. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * wxWindows Library License for more details. |
| */ |
| |
| #define JPEG_INTERNALS |
| #include "jinclude.h" |
| #include "jpeglib.h" |
| #include "jchuff.h" /* Declarations shared with jcphuff.c */ |
| #include <limits.h> |
| |
| static unsigned char jpeg_first_bit_table[65536]; |
| int jpeg_first_bit_table_init=0; |
| |
| #ifndef min |
| #define min(a,b) ((a)<(b)?(a):(b)) |
| #endif |
| |
| /* Expanded entropy encoder object for Huffman encoding. |
| * |
| * The savable_state subrecord contains fields that change within an MCU, |
| * but must not be updated permanently until we complete the MCU. |
| */ |
| |
| typedef struct { |
| size_t put_buffer; /* current bit-accumulation buffer */ |
| int put_bits; /* # of bits now in it */ |
| 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).put_buffer = (src).put_buffer, \ |
| (dest).put_bits = (src).put_bits, \ |
| (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_encoder pub; /* public fields */ |
| |
| savable_state saved; /* Bit buffer & DC 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 */ |
| int next_restart_num; /* next restart number to write (0-7) */ |
| |
| /* Pointers to derived tables (these workspaces have image lifespan) */ |
| c_derived_tbl * dc_derived_tbls[NUM_HUFF_TBLS]; |
| c_derived_tbl * ac_derived_tbls[NUM_HUFF_TBLS]; |
| |
| #ifdef ENTROPY_OPT_SUPPORTED /* Statistics tables for optimization */ |
| long * dc_count_ptrs[NUM_HUFF_TBLS]; |
| long * ac_count_ptrs[NUM_HUFF_TBLS]; |
| #endif |
| } huff_entropy_encoder; |
| |
| typedef huff_entropy_encoder * huff_entropy_ptr; |
| |
| /* Working state while writing an MCU. |
| * This struct contains all the fields that are needed by subroutines. |
| */ |
| |
| typedef struct { |
| JOCTET * next_output_byte; /* => next byte to write in buffer */ |
| size_t free_in_buffer; /* # of byte spaces remaining in buffer */ |
| savable_state cur; /* Current bit buffer & DC state */ |
| j_compress_ptr cinfo; /* dump_buffer needs access to this */ |
| } working_state; |
| |
| |
| /* Forward declarations */ |
| METHODDEF(boolean) encode_mcu_huff JPP((j_compress_ptr cinfo, |
| JBLOCKROW *MCU_data)); |
| METHODDEF(void) finish_pass_huff JPP((j_compress_ptr cinfo)); |
| #ifdef ENTROPY_OPT_SUPPORTED |
| METHODDEF(boolean) encode_mcu_gather JPP((j_compress_ptr cinfo, |
| JBLOCKROW *MCU_data)); |
| METHODDEF(void) finish_pass_gather JPP((j_compress_ptr cinfo)); |
| #endif |
| |
| |
| /* |
| * Initialize for a Huffman-compressed scan. |
| * If gather_statistics is TRUE, we do not output anything during the scan, |
| * just count the Huffman symbols used and generate Huffman code tables. |
| */ |
| |
| METHODDEF(void) |
| start_pass_huff (j_compress_ptr cinfo, boolean gather_statistics) |
| { |
| huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| int ci, dctbl, actbl; |
| jpeg_component_info * compptr; |
| |
| if (gather_statistics) { |
| #ifdef ENTROPY_OPT_SUPPORTED |
| entropy->pub.encode_mcu = encode_mcu_gather; |
| entropy->pub.finish_pass = finish_pass_gather; |
| #else |
| ERREXIT(cinfo, JERR_NOT_COMPILED); |
| #endif |
| } else { |
| entropy->pub.encode_mcu = encode_mcu_huff; |
| entropy->pub.finish_pass = finish_pass_huff; |
| } |
| |
| 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; |
| if (gather_statistics) { |
| #ifdef ENTROPY_OPT_SUPPORTED |
| /* Check for invalid table indexes */ |
| /* (make_c_derived_tbl does this in the other path) */ |
| if (dctbl < 0 || dctbl >= NUM_HUFF_TBLS) |
| ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, dctbl); |
| if (actbl < 0 || actbl >= NUM_HUFF_TBLS) |
| ERREXIT1(cinfo, JERR_NO_HUFF_TABLE, actbl); |
| /* Allocate and zero the statistics tables */ |
| /* Note that jpeg_gen_optimal_table expects 257 entries in each table! */ |
| if (entropy->dc_count_ptrs[dctbl] == NULL) |
| entropy->dc_count_ptrs[dctbl] = (long *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 257 * SIZEOF(long)); |
| MEMZERO(entropy->dc_count_ptrs[dctbl], 257 * SIZEOF(long)); |
| if (entropy->ac_count_ptrs[actbl] == NULL) |
| entropy->ac_count_ptrs[actbl] = (long *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| 257 * SIZEOF(long)); |
| MEMZERO(entropy->ac_count_ptrs[actbl], 257 * SIZEOF(long)); |
| #endif |
| } else { |
| /* Compute derived values for Huffman tables */ |
| /* We may do this more than once for a table, but it's not expensive */ |
| jpeg_make_c_derived_tbl(cinfo, TRUE, dctbl, |
| & entropy->dc_derived_tbls[dctbl]); |
| jpeg_make_c_derived_tbl(cinfo, FALSE, actbl, |
| & entropy->ac_derived_tbls[actbl]); |
| } |
| /* Initialize DC predictions to 0 */ |
| entropy->saved.last_dc_val[ci] = 0; |
| } |
| |
| /* Initialize bit buffer to empty */ |
| |
| entropy->saved.put_buffer = 0; |
| entropy->saved.put_bits = 0; |
| |
| /* Initialize restart stuff */ |
| entropy->restarts_to_go = cinfo->restart_interval; |
| entropy->next_restart_num = 0; |
| } |
| |
| |
| /* |
| * Compute the derived values for a Huffman table. |
| * This routine also performs some validation checks on the table. |
| * |
| * Note this is also used by jcphuff.c. |
| */ |
| |
| GLOBAL(void) |
| jpeg_make_c_derived_tbl (j_compress_ptr cinfo, boolean isDC, int tblno, |
| c_derived_tbl ** pdtbl) |
| { |
| JHUFF_TBL *htbl; |
| c_derived_tbl *dtbl; |
| int p, i, l, lastp, si, maxsymbol; |
| 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 = (c_derived_tbl *) |
| (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, |
| SIZEOF(c_derived_tbl)); |
| dtbl = *pdtbl; |
| |
| /* 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; |
| lastp = 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 C.3: generate encoding tables */ |
| /* These are code and size indexed by symbol value */ |
| |
| /* Set all codeless symbols to have code length 0; |
| * this lets us detect duplicate VAL entries here, and later |
| * allows emit_bits to detect any attempt to emit such symbols. |
| */ |
| MEMZERO(dtbl->ehufsi, SIZEOF(dtbl->ehufsi)); |
| |
| /* This is also a convenient place to check for out-of-range |
| * and duplicated VAL entries. We allow 0..255 for AC symbols |
| * but only 0..15 for DC. (We could constrain them further |
| * based on data depth and mode, but this seems enough.) |
| */ |
| maxsymbol = isDC ? 15 : 255; |
| |
| for (p = 0; p < lastp; p++) { |
| i = htbl->huffval[p]; |
| if (i < 0 || i > maxsymbol || dtbl->ehufsi[i]) |
| ERREXIT(cinfo, JERR_BAD_HUFF_TABLE); |
| dtbl->ehufco[i] = huffcode[p]; |
| dtbl->ehufsi[i] = huffsize[p]; |
| } |
| |
| if(!jpeg_first_bit_table_init) { |
| for(i = 0; i < 65536; i++) { |
| int bit = 0, val = i; |
| while (val) {val >>= 1; bit++;} |
| jpeg_first_bit_table[i] = bit; |
| } |
| jpeg_first_bit_table_init = 1; |
| } |
| } |
| |
| |
| /* Outputting bytes to the file */ |
| |
| /* Emit a byte, taking 'action' if must suspend. */ |
| #define emit_byte(state,val,action) \ |
| { *(state)->next_output_byte++ = (JOCTET) (val); \ |
| if (--(state)->free_in_buffer == 0) \ |
| if (! dump_buffer(state)) \ |
| { action; } } |
| |
| |
| LOCAL(boolean) |
| dump_buffer (working_state * state) |
| /* Empty the output buffer; return TRUE if successful, FALSE if must suspend */ |
| { |
| struct jpeg_destination_mgr * dest = state->cinfo->dest; |
| |
| dest->free_in_buffer = state->free_in_buffer; |
| |
| if (! (*dest->empty_output_buffer) (state->cinfo)) |
| return FALSE; |
| /* After a successful buffer dump, must reset buffer pointers */ |
| state->next_output_byte = dest->next_output_byte; |
| state->free_in_buffer = dest->free_in_buffer; |
| return TRUE; |
| } |
| |
| |
| /* Outputting bits to the file */ |
| |
| /* Only the right 24 bits of put_buffer are used; the valid bits are |
| * left-justified in this part. At most 16 bits can be passed to emit_bits |
| * in one call, and we never retain more than 7 bits in put_buffer |
| * between calls, so 24 bits are sufficient. |
| */ |
| |
| /***************************************************************/ |
| |
| #define EMIT_BYTE() { \ |
| if (0xFF == (*buffer++ = (unsigned char)(put_buffer >> (put_bits -= 8)))) \ |
| *buffer++ = 0; \ |
| } |
| |
| /***************************************************************/ |
| |
| #define DUMP_BITS_(code, size) { \ |
| put_bits += size; \ |
| put_buffer = (put_buffer << size) | code; \ |
| if (put_bits > 7) \ |
| while(put_bits > 7) \ |
| EMIT_BYTE() \ |
| } |
| |
| /***************************************************************/ |
| |
| #define CHECKBUF15() { \ |
| if (put_bits > 15) { \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| } \ |
| } |
| |
| #define CHECKBUF47() { \ |
| if (put_bits > 47) { \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| } \ |
| } |
| |
| #define CHECKBUF31() { \ |
| if (put_bits > 31) { \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| EMIT_BYTE() \ |
| } \ |
| } |
| |
| /***************************************************************/ |
| |
| #define DUMP_BITS_NOCHECK(code, size) { \ |
| put_bits += size; \ |
| put_buffer = (put_buffer << size) | code; \ |
| } |
| |
| #if __WORDSIZE==64 || defined(_WIN64) |
| |
| #define DUMP_BITS(code, size) { \ |
| CHECKBUF47() \ |
| put_bits += size; \ |
| put_buffer = (put_buffer << size) | code; \ |
| } |
| |
| #else |
| |
| #define DUMP_BITS(code, size) { \ |
| put_bits += size; \ |
| put_buffer = (put_buffer << size) | code; \ |
| CHECKBUF15() \ |
| } |
| |
| #endif |
| |
| /***************************************************************/ |
| |
| #define DUMP_SINGLE_VALUE(ht, codevalue) { \ |
| size = ht->ehufsi[codevalue]; \ |
| code = ht->ehufco[codevalue]; \ |
| \ |
| DUMP_BITS(code, size) \ |
| } |
| |
| /***************************************************************/ |
| |
| #define DUMP_VALUE_SLOW(ht, codevalue, t, nbits) { \ |
| size = ht->ehufsi[codevalue]; \ |
| code = ht->ehufco[codevalue]; \ |
| t &= ~(-1 << nbits); \ |
| DUMP_BITS_NOCHECK(code, size) \ |
| CHECKBUF15() \ |
| DUMP_BITS_NOCHECK(t, nbits) \ |
| CHECKBUF15() \ |
| } |
| |
| int _max=0; |
| |
| #if __WORDSIZE==64 || defined(_WIN64) |
| |
| #define DUMP_VALUE(ht, codevalue, t, nbits) { \ |
| size = ht->ehufsi[codevalue]; \ |
| code = ht->ehufco[codevalue]; \ |
| t &= ~(-1 << nbits); \ |
| CHECKBUF31() \ |
| DUMP_BITS_NOCHECK(code, size) \ |
| DUMP_BITS_NOCHECK(t, nbits) \ |
| } |
| |
| #else |
| |
| #define DUMP_VALUE(ht, codevalue, t, nbits) { \ |
| size = ht->ehufsi[codevalue]; \ |
| code = ht->ehufco[codevalue]; \ |
| t &= ~(-1 << nbits); \ |
| DUMP_BITS_NOCHECK(code, size) \ |
| CHECKBUF15() \ |
| DUMP_BITS_NOCHECK(t, nbits) \ |
| CHECKBUF15() \ |
| } |
| |
| #endif |
| |
| /***************************************************************/ |
| |
| #define BUFSIZE (DCTSIZE2 * 2) |
| |
| #define LOAD_BUFFER() { \ |
| if (state->free_in_buffer < BUFSIZE) { \ |
| localbuf = 1; \ |
| buffer = _buffer; \ |
| } \ |
| else buffer = state->next_output_byte; \ |
| } |
| |
| #define STORE_BUFFER() { \ |
| if (localbuf) { \ |
| bytes = buffer - _buffer; \ |
| buffer = _buffer; \ |
| while (bytes > 0) { \ |
| bytestocopy = min(bytes, state->free_in_buffer); \ |
| MEMCOPY(state->next_output_byte, buffer, bytestocopy); \ |
| state->next_output_byte += bytestocopy; \ |
| buffer += bytestocopy; \ |
| state->free_in_buffer -= bytestocopy; \ |
| if (state->free_in_buffer == 0) \ |
| if (! dump_buffer(state)) return FALSE; \ |
| bytes -= bytestocopy; \ |
| } \ |
| } \ |
| else { \ |
| state->free_in_buffer -= (buffer - state->next_output_byte); \ |
| state->next_output_byte = buffer; \ |
| } \ |
| } |
| |
| /***************************************************************/ |
| |
| LOCAL(boolean) |
| flush_bits (working_state * state) |
| { |
| unsigned char _buffer[BUFSIZE], *buffer; |
| size_t put_buffer; int put_bits; |
| size_t bytes, bytestocopy; int localbuf = 0; |
| |
| put_buffer = state->cur.put_buffer; |
| put_bits = state->cur.put_bits; |
| LOAD_BUFFER() |
| |
| DUMP_BITS_(0x7F, 7) |
| |
| state->cur.put_buffer = 0; /* and reset bit-buffer to empty */ |
| state->cur.put_bits = 0; |
| STORE_BUFFER() |
| |
| return TRUE; |
| } |
| |
| /* Encode a single block's worth of coefficients */ |
| |
| LOCAL(boolean) |
| encode_one_block (working_state * state, JCOEFPTR block, int last_dc_val, |
| c_derived_tbl *dctbl, c_derived_tbl *actbl) |
| { |
| int temp, temp2; |
| int nbits; |
| int r, sflag, size, code; |
| unsigned char _buffer[BUFSIZE], *buffer; |
| size_t put_buffer; int put_bits; |
| int code_0xf0 = actbl->ehufco[0xf0], size_0xf0 = actbl->ehufsi[0xf0]; |
| size_t bytes, bytestocopy; int localbuf = 0; |
| |
| put_buffer = state->cur.put_buffer; |
| put_bits = state->cur.put_bits; |
| LOAD_BUFFER() |
| |
| /* Encode the DC coefficient difference per section F.1.2.1 */ |
| |
| temp = temp2 = block[0] - last_dc_val; |
| |
| sflag = temp >> 31; |
| temp -= ((temp + temp) & sflag); |
| temp2 += sflag; |
| nbits = jpeg_first_bit_table[temp]; |
| DUMP_VALUE_SLOW(dctbl, nbits, temp2, nbits) |
| |
| /* Encode the AC coefficients per section F.1.2.2 */ |
| |
| r = 0; /* r = run length of zeros */ |
| |
| #define innerloop(order) { \ |
| temp2 = *(JCOEF*)((unsigned char*)block + order); \ |
| if(temp2 == 0) r++; \ |
| else { \ |
| temp = (JCOEF)temp2; \ |
| sflag = temp >> 31; \ |
| temp = (temp ^ sflag) - sflag; \ |
| temp2 += sflag; \ |
| nbits = jpeg_first_bit_table[temp]; \ |
| for(; r > 15; r -= 16) DUMP_BITS(code_0xf0, size_0xf0) \ |
| sflag = (r << 4) + nbits; \ |
| DUMP_VALUE(actbl, sflag, temp2, nbits) \ |
| r = 0; \ |
| }} |
| |
| innerloop(2*1); innerloop(2*8); innerloop(2*16); innerloop(2*9); |
| innerloop(2*2); innerloop(2*3); innerloop(2*10); innerloop(2*17); |
| innerloop(2*24); innerloop(2*32); innerloop(2*25); innerloop(2*18); |
| innerloop(2*11); innerloop(2*4); innerloop(2*5); innerloop(2*12); |
| innerloop(2*19); innerloop(2*26); innerloop(2*33); innerloop(2*40); |
| innerloop(2*48); innerloop(2*41); innerloop(2*34); innerloop(2*27); |
| innerloop(2*20); innerloop(2*13); innerloop(2*6); innerloop(2*7); |
| innerloop(2*14); innerloop(2*21); innerloop(2*28); innerloop(2*35); |
| innerloop(2*42); innerloop(2*49); innerloop(2*56); innerloop(2*57); |
| innerloop(2*50); innerloop(2*43); innerloop(2*36); innerloop(2*29); |
| innerloop(2*22); innerloop(2*15); innerloop(2*23); innerloop(2*30); |
| innerloop(2*37); innerloop(2*44); innerloop(2*51); innerloop(2*58); |
| innerloop(2*59); innerloop(2*52); innerloop(2*45); innerloop(2*38); |
| innerloop(2*31); innerloop(2*39); innerloop(2*46); innerloop(2*53); |
| innerloop(2*60); innerloop(2*61); innerloop(2*54); innerloop(2*47); |
| innerloop(2*55); innerloop(2*62); innerloop(2*63); |
| |
| /* If the last coef(s) were zero, emit an end-of-block code */ |
| if (r > 0) DUMP_SINGLE_VALUE(actbl, 0x0) |
| |
| state->cur.put_buffer = put_buffer; |
| state->cur.put_bits = put_bits; |
| STORE_BUFFER() |
| |
| return TRUE; |
| } |
| |
| |
| /* |
| * Emit a restart marker & resynchronize predictions. |
| */ |
| |
| LOCAL(boolean) |
| emit_restart (working_state * state, int restart_num) |
| { |
| int ci; |
| |
| if (! flush_bits(state)) |
| return FALSE; |
| |
| emit_byte(state, 0xFF, return FALSE); |
| emit_byte(state, JPEG_RST0 + restart_num, return FALSE); |
| |
| /* Re-initialize DC predictions to 0 */ |
| for (ci = 0; ci < state->cinfo->comps_in_scan; ci++) |
| state->cur.last_dc_val[ci] = 0; |
| |
| /* The restart counter is not updated until we successfully write the MCU. */ |
| |
| return TRUE; |
| } |
| |
| |
| /* |
| * Encode and output one MCU's worth of Huffman-compressed coefficients. |
| */ |
| |
| METHODDEF(boolean) |
| encode_mcu_huff (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| { |
| huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| working_state state; |
| int blkn, ci; |
| jpeg_component_info * compptr; |
| |
| /* Load up working state */ |
| state.next_output_byte = cinfo->dest->next_output_byte; |
| state.free_in_buffer = cinfo->dest->free_in_buffer; |
| ASSIGN_STATE(state.cur, entropy->saved); |
| state.cinfo = cinfo; |
| |
| /* Emit restart marker if needed */ |
| if (cinfo->restart_interval) { |
| if (entropy->restarts_to_go == 0) |
| if (! emit_restart(&state, entropy->next_restart_num)) |
| return FALSE; |
| } |
| |
| /* Encode the MCU data blocks */ |
| for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| ci = cinfo->MCU_membership[blkn]; |
| compptr = cinfo->cur_comp_info[ci]; |
| if (! encode_one_block(&state, |
| MCU_data[blkn][0], state.cur.last_dc_val[ci], |
| entropy->dc_derived_tbls[compptr->dc_tbl_no], |
| entropy->ac_derived_tbls[compptr->ac_tbl_no])) |
| return FALSE; |
| /* Update last_dc_val */ |
| state.cur.last_dc_val[ci] = MCU_data[blkn][0][0]; |
| } |
| |
| /* Completed MCU, so update state */ |
| cinfo->dest->next_output_byte = state.next_output_byte; |
| cinfo->dest->free_in_buffer = state.free_in_buffer; |
| ASSIGN_STATE(entropy->saved, state.cur); |
| |
| /* Update restart-interval state too */ |
| if (cinfo->restart_interval) { |
| if (entropy->restarts_to_go == 0) { |
| entropy->restarts_to_go = cinfo->restart_interval; |
| entropy->next_restart_num++; |
| entropy->next_restart_num &= 7; |
| } |
| entropy->restarts_to_go--; |
| } |
| |
| return TRUE; |
| } |
| |
| |
| /* |
| * Finish up at the end of a Huffman-compressed scan. |
| */ |
| |
| METHODDEF(void) |
| finish_pass_huff (j_compress_ptr cinfo) |
| { |
| huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| working_state state; |
| |
| /* Load up working state ... flush_bits needs it */ |
| state.next_output_byte = cinfo->dest->next_output_byte; |
| state.free_in_buffer = cinfo->dest->free_in_buffer; |
| ASSIGN_STATE(state.cur, entropy->saved); |
| state.cinfo = cinfo; |
| |
| /* Flush out the last data */ |
| if (! flush_bits(&state)) |
| ERREXIT(cinfo, JERR_CANT_SUSPEND); |
| |
| /* Update state */ |
| cinfo->dest->next_output_byte = state.next_output_byte; |
| cinfo->dest->free_in_buffer = state.free_in_buffer; |
| ASSIGN_STATE(entropy->saved, state.cur); |
| } |
| |
| |
| /* |
| * Huffman coding optimization. |
| * |
| * We first scan the supplied data and count the number of uses of each symbol |
| * that is to be Huffman-coded. (This process MUST agree with the code above.) |
| * Then we build a Huffman coding tree for the observed counts. |
| * Symbols which are not needed at all for the particular image are not |
| * assigned any code, which saves space in the DHT marker as well as in |
| * the compressed data. |
| */ |
| |
| #ifdef ENTROPY_OPT_SUPPORTED |
| |
| |
| /* Process a single block's worth of coefficients */ |
| |
| LOCAL(void) |
| htest_one_block (j_compress_ptr cinfo, JCOEFPTR block, int last_dc_val, |
| long dc_counts[], long ac_counts[]) |
| { |
| register int temp; |
| register int nbits; |
| register int k, r; |
| |
| /* Encode the DC coefficient difference per section F.1.2.1 */ |
| |
| temp = block[0] - last_dc_val; |
| if (temp < 0) |
| temp = -temp; |
| |
| /* Find the number of bits needed for the magnitude of the coefficient */ |
| nbits = 0; |
| while (temp) { |
| nbits++; |
| temp >>= 1; |
| } |
| /* Check for out-of-range coefficient values. |
| * Since we're encoding a difference, the range limit is twice as much. |
| */ |
| if (nbits > MAX_COEF_BITS+1) |
| ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
| |
| /* Count the Huffman symbol for the number of bits */ |
| dc_counts[nbits]++; |
| |
| /* Encode the AC coefficients per section F.1.2.2 */ |
| |
| r = 0; /* r = run length of zeros */ |
| |
| for (k = 1; k < DCTSIZE2; k++) { |
| if ((temp = block[jpeg_natural_order[k]]) == 0) { |
| r++; |
| } else { |
| /* if run length > 15, must emit special run-length-16 codes (0xF0) */ |
| while (r > 15) { |
| ac_counts[0xF0]++; |
| r -= 16; |
| } |
| |
| /* Find the number of bits needed for the magnitude of the coefficient */ |
| if (temp < 0) |
| temp = -temp; |
| |
| /* Find the number of bits needed for the magnitude of the coefficient */ |
| nbits = 1; /* there must be at least one 1 bit */ |
| while ((temp >>= 1)) |
| nbits++; |
| /* Check for out-of-range coefficient values */ |
| if (nbits > MAX_COEF_BITS) |
| ERREXIT(cinfo, JERR_BAD_DCT_COEF); |
| |
| /* Count Huffman symbol for run length / number of bits */ |
| ac_counts[(r << 4) + nbits]++; |
| |
| r = 0; |
| } |
| } |
| |
| /* If the last coef(s) were zero, emit an end-of-block code */ |
| if (r > 0) |
| ac_counts[0]++; |
| } |
| |
| |
| /* |
| * Trial-encode one MCU's worth of Huffman-compressed coefficients. |
| * No data is actually output, so no suspension return is possible. |
| */ |
| |
| METHODDEF(boolean) |
| encode_mcu_gather (j_compress_ptr cinfo, JBLOCKROW *MCU_data) |
| { |
| huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| int blkn, ci; |
| jpeg_component_info * compptr; |
| |
| /* Take care of restart intervals if needed */ |
| if (cinfo->restart_interval) { |
| if (entropy->restarts_to_go == 0) { |
| /* Re-initialize DC predictions to 0 */ |
| for (ci = 0; ci < cinfo->comps_in_scan; ci++) |
| entropy->saved.last_dc_val[ci] = 0; |
| /* Update restart state */ |
| entropy->restarts_to_go = cinfo->restart_interval; |
| } |
| entropy->restarts_to_go--; |
| } |
| |
| for (blkn = 0; blkn < cinfo->blocks_in_MCU; blkn++) { |
| ci = cinfo->MCU_membership[blkn]; |
| compptr = cinfo->cur_comp_info[ci]; |
| htest_one_block(cinfo, MCU_data[blkn][0], entropy->saved.last_dc_val[ci], |
| entropy->dc_count_ptrs[compptr->dc_tbl_no], |
| entropy->ac_count_ptrs[compptr->ac_tbl_no]); |
| entropy->saved.last_dc_val[ci] = MCU_data[blkn][0][0]; |
| } |
| |
| return TRUE; |
| } |
| |
| |
| /* |
| * Generate the best Huffman code table for the given counts, fill htbl. |
| * Note this is also used by jcphuff.c. |
| * |
| * The JPEG standard requires that no symbol be assigned a codeword of all |
| * one bits (so that padding bits added at the end of a compressed segment |
| * can't look like a valid code). Because of the canonical ordering of |
| * codewords, this just means that there must be an unused slot in the |
| * longest codeword length category. Section K.2 of the JPEG spec suggests |
| * reserving such a slot by pretending that symbol 256 is a valid symbol |
| * with count 1. In theory that's not optimal; giving it count zero but |
| * including it in the symbol set anyway should give a better Huffman code. |
| * But the theoretically better code actually seems to come out worse in |
| * practice, because it produces more all-ones bytes (which incur stuffed |
| * zero bytes in the final file). In any case the difference is tiny. |
| * |
| * The JPEG standard requires Huffman codes to be no more than 16 bits long. |
| * If some symbols have a very small but nonzero probability, the Huffman tree |
| * must be adjusted to meet the code length restriction. We currently use |
| * the adjustment method suggested in JPEG section K.2. This method is *not* |
| * optimal; it may not choose the best possible limited-length code. But |
| * typically only very-low-frequency symbols will be given less-than-optimal |
| * lengths, so the code is almost optimal. Experimental comparisons against |
| * an optimal limited-length-code algorithm indicate that the difference is |
| * microscopic --- usually less than a hundredth of a percent of total size. |
| * So the extra complexity of an optimal algorithm doesn't seem worthwhile. |
| */ |
| |
| GLOBAL(void) |
| jpeg_gen_optimal_table (j_compress_ptr cinfo, JHUFF_TBL * htbl, long freq[]) |
| { |
| #define MAX_CLEN 32 /* assumed maximum initial code length */ |
| UINT8 bits[MAX_CLEN+1]; /* bits[k] = # of symbols with code length k */ |
| int codesize[257]; /* codesize[k] = code length of symbol k */ |
| int others[257]; /* next symbol in current branch of tree */ |
| int c1, c2; |
| int p, i, j; |
| long v; |
| |
| /* This algorithm is explained in section K.2 of the JPEG standard */ |
| |
| MEMZERO(bits, SIZEOF(bits)); |
| MEMZERO(codesize, SIZEOF(codesize)); |
| for (i = 0; i < 257; i++) |
| others[i] = -1; /* init links to empty */ |
| |
| freq[256] = 1; /* make sure 256 has a nonzero count */ |
| /* Including the pseudo-symbol 256 in the Huffman procedure guarantees |
| * that no real symbol is given code-value of all ones, because 256 |
| * will be placed last in the largest codeword category. |
| */ |
| |
| /* Huffman's basic algorithm to assign optimal code lengths to symbols */ |
| |
| for (;;) { |
| /* Find the smallest nonzero frequency, set c1 = its symbol */ |
| /* In case of ties, take the larger symbol number */ |
| c1 = -1; |
| v = 1000000000L; |
| for (i = 0; i <= 256; i++) { |
| if (freq[i] && freq[i] <= v) { |
| v = freq[i]; |
| c1 = i; |
| } |
| } |
| |
| /* Find the next smallest nonzero frequency, set c2 = its symbol */ |
| /* In case of ties, take the larger symbol number */ |
| c2 = -1; |
| v = 1000000000L; |
| for (i = 0; i <= 256; i++) { |
| if (freq[i] && freq[i] <= v && i != c1) { |
| v = freq[i]; |
| c2 = i; |
| } |
| } |
| |
| /* Done if we've merged everything into one frequency */ |
| if (c2 < 0) |
| break; |
| |
| /* Else merge the two counts/trees */ |
| freq[c1] += freq[c2]; |
| freq[c2] = 0; |
| |
| /* Increment the codesize of everything in c1's tree branch */ |
| codesize[c1]++; |
| while (others[c1] >= 0) { |
| c1 = others[c1]; |
| codesize[c1]++; |
| } |
| |
| others[c1] = c2; /* chain c2 onto c1's tree branch */ |
| |
| /* Increment the codesize of everything in c2's tree branch */ |
| codesize[c2]++; |
| while (others[c2] >= 0) { |
| c2 = others[c2]; |
| codesize[c2]++; |
| } |
| } |
| |
| /* Now count the number of symbols of each code length */ |
| for (i = 0; i <= 256; i++) { |
| if (codesize[i]) { |
| /* The JPEG standard seems to think that this can't happen, */ |
| /* but I'm paranoid... */ |
| if (codesize[i] > MAX_CLEN) |
| ERREXIT(cinfo, JERR_HUFF_CLEN_OVERFLOW); |
| |
| bits[codesize[i]]++; |
| } |
| } |
| |
| /* JPEG doesn't allow symbols with code lengths over 16 bits, so if the pure |
| * Huffman procedure assigned any such lengths, we must adjust the coding. |
| * Here is what the JPEG spec says about how this next bit works: |
| * Since symbols are paired for the longest Huffman code, the symbols are |
| * removed from this length category two at a time. The prefix for the pair |
| * (which is one bit shorter) is allocated to one of the pair; then, |
| * skipping the BITS entry for that prefix length, a code word from the next |
| * shortest nonzero BITS entry is converted into a prefix for two code words |
| * one bit longer. |
| */ |
| |
| for (i = MAX_CLEN; i > 16; i--) { |
| while (bits[i] > 0) { |
| j = i - 2; /* find length of new prefix to be used */ |
| while (bits[j] == 0) |
| j--; |
| |
| bits[i] -= 2; /* remove two symbols */ |
| bits[i-1]++; /* one goes in this length */ |
| bits[j+1] += 2; /* two new symbols in this length */ |
| bits[j]--; /* symbol of this length is now a prefix */ |
| } |
| } |
| |
| /* Remove the count for the pseudo-symbol 256 from the largest codelength */ |
| while (bits[i] == 0) /* find largest codelength still in use */ |
| i--; |
| bits[i]--; |
| |
| /* Return final symbol counts (only for lengths 0..16) */ |
| MEMCOPY(htbl->bits, bits, SIZEOF(htbl->bits)); |
| |
| /* Return a list of the symbols sorted by code length */ |
| /* It's not real clear to me why we don't need to consider the codelength |
| * changes made above, but the JPEG spec seems to think this works. |
| */ |
| p = 0; |
| for (i = 1; i <= MAX_CLEN; i++) { |
| for (j = 0; j <= 255; j++) { |
| if (codesize[j] == i) { |
| htbl->huffval[p] = (UINT8) j; |
| p++; |
| } |
| } |
| } |
| |
| /* Set sent_table FALSE so updated table will be written to JPEG file. */ |
| htbl->sent_table = FALSE; |
| } |
| |
| |
| /* |
| * Finish up a statistics-gathering pass and create the new Huffman tables. |
| */ |
| |
| METHODDEF(void) |
| finish_pass_gather (j_compress_ptr cinfo) |
| { |
| huff_entropy_ptr entropy = (huff_entropy_ptr) cinfo->entropy; |
| int ci, dctbl, actbl; |
| jpeg_component_info * compptr; |
| JHUFF_TBL **htblptr; |
| boolean did_dc[NUM_HUFF_TBLS]; |
| boolean did_ac[NUM_HUFF_TBLS]; |
| |
| /* It's important not to apply jpeg_gen_optimal_table more than once |
| * per table, because it clobbers the input frequency counts! |
| */ |
| MEMZERO(did_dc, SIZEOF(did_dc)); |
| MEMZERO(did_ac, SIZEOF(did_ac)); |
| |
| 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; |
| if (! did_dc[dctbl]) { |
| htblptr = & cinfo->dc_huff_tbl_ptrs[dctbl]; |
| if (*htblptr == NULL) |
| *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
| jpeg_gen_optimal_table(cinfo, *htblptr, entropy->dc_count_ptrs[dctbl]); |
| did_dc[dctbl] = TRUE; |
| } |
| if (! did_ac[actbl]) { |
| htblptr = & cinfo->ac_huff_tbl_ptrs[actbl]; |
| if (*htblptr == NULL) |
| *htblptr = jpeg_alloc_huff_table((j_common_ptr) cinfo); |
| jpeg_gen_optimal_table(cinfo, *htblptr, entropy->ac_count_ptrs[actbl]); |
| did_ac[actbl] = TRUE; |
| } |
| } |
| } |
| |
| |
| #endif /* ENTROPY_OPT_SUPPORTED */ |
| |
| |
| /* |
| * Module initialization routine for Huffman entropy encoding. |
| */ |
| |
| GLOBAL(void) |
| jinit_huff_encoder (j_compress_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_encoder)); |
| cinfo->entropy = (struct jpeg_entropy_encoder *) entropy; |
| entropy->pub.start_pass = start_pass_huff; |
| |
| /* Mark tables unallocated */ |
| for (i = 0; i < NUM_HUFF_TBLS; i++) { |
| entropy->dc_derived_tbls[i] = entropy->ac_derived_tbls[i] = NULL; |
| #ifdef ENTROPY_OPT_SUPPORTED |
| entropy->dc_count_ptrs[i] = entropy->ac_count_ptrs[i] = NULL; |
| #endif |
| } |
| } |
