170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * jdhuff.h 370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Copyright (C) 1991-1997, Thomas G. Lane. 570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file is part of the Independent JPEG Group's software. 670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * For conditions of distribution and use, see the accompanying README file. 770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * This file contains declarations for Huffman entropy decoding routines 970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * that are shared between the sequential decoder (jdhuff.c) and the 1070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * progressive decoder (jdphuff.c). No other modules need to see these. 1170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 1270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 1370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Short forms of external names for systems with brain-damaged linkers. */ 1470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 1570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#ifdef NEED_SHORT_EXTERNAL_NAMES 1670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define jpeg_make_d_derived_tbl jMkDDerived 1770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define jpeg_fill_bit_buffer jFilBitBuf 1870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define jpeg_huff_decode jHufDecode 1970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#endif /* NEED_SHORT_EXTERNAL_NAMES */ 2070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Derived data constructed for each Huffman table */ 2370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */ 2570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 2670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef struct { 2770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Basic tables: (element [0] of each array is unused) */ 2870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 maxcode[18]; /* largest code of length k (-1 if none) */ 2970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */ 3070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine INT32 valoffset[17]; /* huffval[] offset for codes of length k */ 3170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* valoffset[k] = huffval[] index of 1st symbol of code length k, less 3270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the smallest code of length k; so given a code of length k, the 3370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * corresponding symbol is huffval[code + valoffset[k]] 3470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 3570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Link to public Huffman table (needed only in jpeg_huff_decode) */ 3770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JHUFF_TBL *pub; 3870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 3970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Lookahead tables: indexed by the next HUFF_LOOKAHEAD bits of 4070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the input data stream. If the next Huffman code is no more 4170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * than HUFF_LOOKAHEAD bits long, we can obtain its length and 4270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * the corresponding symbol directly from these tables. 4370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 4470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int look_nbits[1<<HUFF_LOOKAHEAD]; /* # bits, or 0 if too long */ 4570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine UINT8 look_sym[1<<HUFF_LOOKAHEAD]; /* symbol, or unused */ 4670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} d_derived_tbl; 4770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 4870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Expand a Huffman table definition into the derived format */ 4970a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineEXTERN(void) jpeg_make_d_derived_tbl 5070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JPP((j_decompress_ptr cinfo, boolean isDC, int tblno, 5170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine d_derived_tbl ** pdtbl)); 5270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 5370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 5470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 5570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Fetching the next N bits from the input stream is a time-critical operation 5670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * for the Huffman decoders. We implement it with a combination of inline 5770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * macros and out-of-line subroutines. Note that N (the number of bits 5870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * demanded at one time) never exceeds 15 for JPEG use. 5970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 6070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We read source bytes into get_buffer and dole out bits as needed. 6170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * If get_buffer already contains enough bits, they are fetched in-line 6270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * by the macros CHECK_BIT_BUFFER and GET_BITS. When there aren't enough 6370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * bits, jpeg_fill_bit_buffer is called; it will attempt to fill get_buffer 6470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * as full as possible (not just to the number of bits needed; this 6570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * prefetching reduces the overhead cost of calling jpeg_fill_bit_buffer). 6670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Note that jpeg_fill_bit_buffer may return FALSE to indicate suspension. 6770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * On TRUE return, jpeg_fill_bit_buffer guarantees that get_buffer contains 6870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * at least the requested number of bits --- dummy zeroes are inserted if 6970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * necessary. 7070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 7170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 7270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef INT32 bit_buf_type; /* type of bit-extraction buffer */ 7370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BIT_BUF_SIZE 32 /* size of buffer in bits */ 7470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define LOG_TWO_BIT_BUF_SIZE 5 /* log_2(BIT_BUF_SIZE) */ 7570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 7670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* If long is > 32 bits on your machine, and shifting/masking longs is 7770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * reasonably fast, making bit_buf_type be long and setting BIT_BUF_SIZE 7870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * appropriately should be a win. Unfortunately we can't define the size 7970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * with something like #define BIT_BUF_SIZE (sizeof(bit_buf_type)*8) 8070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * because not all machines measure sizeof in 8-bit bytes. 8170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 8270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 8370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef struct { /* Bitreading state saved across MCUs */ 8470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bit_buf_type get_buffer; /* current bit-extraction buffer */ 8570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int bits_left; /* # of unused bits in it */ 8670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} bitread_perm_state; 8770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 8870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkinetypedef struct { /* Bitreading working state within an MCU */ 8970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Current data source location */ 9070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* We need a copy, rather than munging the original, in case of suspension */ 9170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine const JOCTET * next_input_byte; /* => next byte to read from source */ 9270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine size_t bytes_in_buffer; /* # of bytes remaining in source buffer */ 9370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Bit input buffer --- note these values are kept in register variables, 9470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * not in this struct, inside the inner loops. 9570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 9670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bit_buf_type get_buffer; /* current bit-extraction buffer */ 9770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine int bits_left; /* # of unused bits in it */ 9870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine /* Pointer needed by jpeg_fill_bit_buffer. */ 9970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine j_decompress_ptr cinfo; /* back link to decompress master record */ 10070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} bitread_working_state; 10170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Macros to declare and load/save bitread local variables. */ 10370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BITREAD_STATE_VARS \ 10470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register bit_buf_type get_buffer; \ 10570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int bits_left; \ 10670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bitread_working_state br_state 10770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 10870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BITREAD_LOAD_STATE(cinfop,permstate) \ 10970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine br_state.cinfo = cinfop; \ 11070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine br_state.next_input_byte = cinfop->src->next_input_byte; \ 11170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \ 11270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine get_buffer = permstate.get_buffer; \ 11370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine bits_left = permstate.bits_left; 11470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 11570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define BITREAD_SAVE_STATE(cinfop,permstate) \ 11670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfop->src->next_input_byte = br_state.next_input_byte; \ 11770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \ 11870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine permstate.get_buffer = get_buffer; \ 11970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine permstate.bits_left = bits_left 12070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 12170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 12270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * These macros provide the in-line portion of bit fetching. 12370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Use CHECK_BIT_BUFFER to ensure there are N bits in get_buffer 12470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * before using GET_BITS, PEEK_BITS, or DROP_BITS. 12570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The variables get_buffer and bits_left are assumed to be locals, 12670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * but the state struct might not be (jpeg_huff_decode needs this). 12770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * CHECK_BIT_BUFFER(state,n,action); 12870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Ensure there are N bits in get_buffer; if suspend, take action. 12970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * val = GET_BITS(n); 13070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Fetch next N bits. 13170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * val = PEEK_BITS(n); 13270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Fetch next N bits without removing them from the buffer. 13370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * DROP_BITS(n); 13470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Discard next N bits. 13570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * The value N should be a simple variable, not an expression, because it 13670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * is evaluated multiple times. 13770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 13870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 13970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define CHECK_BIT_BUFFER(state,nbits,action) \ 14070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine { if (bits_left < (nbits)) { \ 14170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (! jpeg_fill_bit_buffer(&(state),get_buffer,bits_left,nbits)) \ 14270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine { action; } \ 14370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine get_buffer = (state).get_buffer; bits_left = (state).bits_left; } } 14470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define GET_BITS(nbits) \ 14670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (((int) (get_buffer >> (bits_left -= (nbits)))) & ((1<<(nbits))-1)) 14770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 14870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define PEEK_BITS(nbits) \ 14970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (((int) (get_buffer >> (bits_left - (nbits)))) & ((1<<(nbits))-1)) 15070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define DROP_BITS(nbits) \ 15270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine (bits_left -= (nbits)) 15370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Load up the bit buffer to a depth of at least nbits */ 15570a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineEXTERN(boolean) jpeg_fill_bit_buffer 15670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JPP((bitread_working_state * state, register bit_buf_type get_buffer, 15770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int bits_left, int nbits)); 15870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 15970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 16070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* 16170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Code for extracting next Huffman-coded symbol from input bit stream. 16270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Again, this is time-critical and we make the main paths be macros. 16370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 16470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * We use a lookahead table to process codes of up to HUFF_LOOKAHEAD bits 16570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * without looping. Usually, more than 95% of the Huffman codes will be 8 16670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * or fewer bits long. The few overlength codes are handled with a loop, 16770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * which need not be inline code. 16870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 16970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * Notes about the HUFF_DECODE macro: 17070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 1. Near the end of the data segment, we may fail to get enough bits 17170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * for a lookahead. In that case, we do it the hard way. 17270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 2. If the lookahead table contains no entry, the next code must be 17370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * more than HUFF_LOOKAHEAD bits long. 17470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine * 3. jpeg_huff_decode returns -1 if forced to suspend. 17570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine */ 17670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 17770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine#define HUFF_DECODE(result,state,htbl,failaction,slowlabel) \ 17870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine{ register int nb, look; \ 17970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (bits_left < HUFF_LOOKAHEAD) { \ 18070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (! jpeg_fill_bit_buffer(&state,get_buffer,bits_left, 0)) {failaction;} \ 18170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine get_buffer = state.get_buffer; bits_left = state.bits_left; \ 18270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if (bits_left < HUFF_LOOKAHEAD) { \ 18370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine nb = 1; goto slowlabel; \ 18470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } \ 18570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } \ 18670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine look = PEEK_BITS(HUFF_LOOKAHEAD); \ 18770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if ((nb = htbl->look_nbits[look]) != 0) { \ 18870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine DROP_BITS(nb); \ 18970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine result = htbl->look_sym[look]; \ 19070a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } else { \ 19170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine nb = HUFF_LOOKAHEAD+1; \ 19270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkineslowlabel: \ 19370a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine if ((result=jpeg_huff_decode(&state,get_buffer,bits_left,htbl,nb)) < 0) \ 19470a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine { failaction; } \ 19570a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine get_buffer = state.get_buffer; bits_left = state.bits_left; \ 19670a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine } \ 19770a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine} 19870a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine 19970a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine/* Out-of-line case for Huffman code fetching */ 20070a18cd874a22452aca9e39e22275ed4538ed20bVladimir ChtchetkineEXTERN(int) jpeg_huff_decode 20170a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine JPP((bitread_working_state * state, register bit_buf_type get_buffer, 20270a18cd874a22452aca9e39e22275ed4538ed20bVladimir Chtchetkine register int bits_left, d_derived_tbl * htbl, int min_bits)); 203