Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 1 | /* |
| 2 | * jdhuff.h |
| 3 | * |
DRC | a73e870 | 2012-12-31 02:52:30 +0000 | [diff] [blame] | 4 | * This file was part of the Independent JPEG Group's software: |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 5 | * Copyright (C) 1991-1997, Thomas G. Lane. |
DRC | da13af6 | 2014-05-18 17:52:06 +0000 | [diff] [blame] | 6 | * libjpeg-turbo Modifications: |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 7 | * Copyright (C) 2010-2011, 2015-2016, D. R. Commander. |
| 8 | * For conditions of distribution and use, see the accompanying README.ijg |
| 9 | * file. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 10 | * |
| 11 | * This file contains declarations for Huffman entropy decoding routines |
| 12 | * that are shared between the sequential decoder (jdhuff.c) and the |
| 13 | * progressive decoder (jdphuff.c). No other modules need to see these. |
| 14 | */ |
| 15 | |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 16 | #include "jconfigint.h" |
| 17 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 18 | |
| 19 | /* Derived data constructed for each Huffman table */ |
| 20 | |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 21 | #define HUFF_LOOKAHEAD 8 /* # of bits of lookahead */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 22 | |
| 23 | typedef struct { |
| 24 | /* Basic tables: (element [0] of each array is unused) */ |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 25 | JLONG maxcode[18]; /* largest code of length k (-1 if none) */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 26 | /* (maxcode[17] is a sentinel to ensure jpeg_huff_decode terminates) */ |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 27 | JLONG valoffset[18]; /* huffval[] offset for codes of length k */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 28 | /* valoffset[k] = huffval[] index of 1st symbol of code length k, less |
| 29 | * the smallest code of length k; so given a code of length k, the |
| 30 | * corresponding symbol is huffval[code + valoffset[k]] |
| 31 | */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 32 | |
| 33 | /* Link to public Huffman table (needed only in jpeg_huff_decode) */ |
| 34 | JHUFF_TBL *pub; |
| 35 | |
DRC | e281664 | 2009-09-28 00:33:02 +0000 | [diff] [blame] | 36 | /* Lookahead table: indexed by the next HUFF_LOOKAHEAD bits of |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 37 | * the input data stream. If the next Huffman code is no more |
| 38 | * than HUFF_LOOKAHEAD bits long, we can obtain its length and |
DRC | e281664 | 2009-09-28 00:33:02 +0000 | [diff] [blame] | 39 | * the corresponding symbol directly from this tables. |
| 40 | * |
| 41 | * The lower 8 bits of each table entry contain the number of |
| 42 | * bits in the corresponding Huffman code, or HUFF_LOOKAHEAD + 1 |
| 43 | * if too long. The next 8 bits of each entry contain the |
| 44 | * symbol. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 45 | */ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 46 | int lookup[1 << HUFF_LOOKAHEAD]; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 47 | } d_derived_tbl; |
| 48 | |
| 49 | /* Expand a Huffman table definition into the derived format */ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 50 | EXTERN(void) jpeg_make_d_derived_tbl(j_decompress_ptr cinfo, boolean isDC, |
| 51 | int tblno, d_derived_tbl **pdtbl); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 52 | |
| 53 | |
| 54 | /* |
| 55 | * Fetching the next N bits from the input stream is a time-critical operation |
| 56 | * for the Huffman decoders. We implement it with a combination of inline |
| 57 | * macros and out-of-line subroutines. Note that N (the number of bits |
| 58 | * demanded at one time) never exceeds 15 for JPEG use. |
| 59 | * |
| 60 | * We read source bytes into get_buffer and dole out bits as needed. |
| 61 | * If get_buffer already contains enough bits, they are fetched in-line |
| 62 | * by the macros CHECK_BIT_BUFFER and GET_BITS. When there aren't enough |
| 63 | * bits, jpeg_fill_bit_buffer is called; it will attempt to fill get_buffer |
| 64 | * as full as possible (not just to the number of bits needed; this |
| 65 | * prefetching reduces the overhead cost of calling jpeg_fill_bit_buffer). |
| 66 | * Note that jpeg_fill_bit_buffer may return FALSE to indicate suspension. |
| 67 | * On TRUE return, jpeg_fill_bit_buffer guarantees that get_buffer contains |
| 68 | * at least the requested number of bits --- dummy zeroes are inserted if |
| 69 | * necessary. |
| 70 | */ |
| 71 | |
DRC | 3ebcc32 | 2015-05-15 19:09:44 +0000 | [diff] [blame] | 72 | #if !defined(_WIN32) && !defined(SIZEOF_SIZE_T) |
| 73 | #error Cannot determine word size |
| 74 | #endif |
| 75 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 76 | #if SIZEOF_SIZE_T == 8 || defined(_WIN64) |
DRC | 021da08 | 2009-09-28 08:19:40 +0000 | [diff] [blame] | 77 | |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 78 | typedef size_t bit_buf_type; /* type of bit-extraction buffer */ |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 79 | #define BIT_BUF_SIZE 64 /* size of buffer in bits */ |
DRC | 021da08 | 2009-09-28 08:19:40 +0000 | [diff] [blame] | 80 | |
| 81 | #else |
| 82 | |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 83 | typedef unsigned long bit_buf_type; /* type of bit-extraction buffer */ |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 84 | #define BIT_BUF_SIZE 32 /* size of buffer in bits */ |
DRC | 021da08 | 2009-09-28 08:19:40 +0000 | [diff] [blame] | 85 | |
| 86 | #endif |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 87 | |
| 88 | /* If long is > 32 bits on your machine, and shifting/masking longs is |
| 89 | * reasonably fast, making bit_buf_type be long and setting BIT_BUF_SIZE |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 90 | * appropriately should be a win. Unfortunately we can't define the size |
| 91 | * with something like #define BIT_BUF_SIZE (sizeof(bit_buf_type)*8) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 92 | * because not all machines measure sizeof in 8-bit bytes. |
| 93 | */ |
| 94 | |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 95 | typedef struct { /* Bitreading state saved across MCUs */ |
| 96 | bit_buf_type get_buffer; /* current bit-extraction buffer */ |
| 97 | int bits_left; /* # of unused bits in it */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 98 | } bitread_perm_state; |
| 99 | |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 100 | typedef struct { /* Bitreading working state within an MCU */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 101 | /* Current data source location */ |
| 102 | /* We need a copy, rather than munging the original, in case of suspension */ |
Alex Naidis | 6eb7d37 | 2016-10-16 23:10:08 +0200 | [diff] [blame] | 103 | const JOCTET *next_input_byte; /* => next byte to read from source */ |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 104 | size_t bytes_in_buffer; /* # of bytes remaining in source buffer */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 105 | /* Bit input buffer --- note these values are kept in register variables, |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 106 | * not in this struct, inside the inner loops. |
| 107 | */ |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 108 | bit_buf_type get_buffer; /* current bit-extraction buffer */ |
| 109 | int bits_left; /* # of unused bits in it */ |
Thomas G. Lane | 5ead57a | 1998-03-27 00:00:00 +0000 | [diff] [blame] | 110 | /* Pointer needed by jpeg_fill_bit_buffer. */ |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 111 | j_decompress_ptr cinfo; /* back link to decompress master record */ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 112 | } bitread_working_state; |
| 113 | |
| 114 | /* Macros to declare and load/save bitread local variables. */ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 115 | #define BITREAD_STATE_VARS \ |
| 116 | register bit_buf_type get_buffer; \ |
| 117 | register int bits_left; \ |
| 118 | bitread_working_state br_state |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 119 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 120 | #define BITREAD_LOAD_STATE(cinfop, permstate) \ |
| 121 | br_state.cinfo = cinfop; \ |
| 122 | br_state.next_input_byte = cinfop->src->next_input_byte; \ |
| 123 | br_state.bytes_in_buffer = cinfop->src->bytes_in_buffer; \ |
| 124 | get_buffer = permstate.get_buffer; \ |
| 125 | bits_left = permstate.bits_left; |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 126 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 127 | #define BITREAD_SAVE_STATE(cinfop, permstate) \ |
| 128 | cinfop->src->next_input_byte = br_state.next_input_byte; \ |
| 129 | cinfop->src->bytes_in_buffer = br_state.bytes_in_buffer; \ |
| 130 | permstate.get_buffer = get_buffer; \ |
| 131 | permstate.bits_left = bits_left |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 132 | |
| 133 | /* |
| 134 | * These macros provide the in-line portion of bit fetching. |
| 135 | * Use CHECK_BIT_BUFFER to ensure there are N bits in get_buffer |
| 136 | * before using GET_BITS, PEEK_BITS, or DROP_BITS. |
| 137 | * The variables get_buffer and bits_left are assumed to be locals, |
| 138 | * but the state struct might not be (jpeg_huff_decode needs this). |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 139 | * CHECK_BIT_BUFFER(state, n, action); |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 140 | * Ensure there are N bits in get_buffer; if suspend, take action. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 141 | * val = GET_BITS(n); |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 142 | * Fetch next N bits. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 143 | * val = PEEK_BITS(n); |
DRC | e5eaf37 | 2014-05-09 18:00:32 +0000 | [diff] [blame] | 144 | * Fetch next N bits without removing them from the buffer. |
| 145 | * DROP_BITS(n); |
| 146 | * Discard next N bits. |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 147 | * The value N should be a simple variable, not an expression, because it |
| 148 | * is evaluated multiple times. |
| 149 | */ |
| 150 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 151 | #define CHECK_BIT_BUFFER(state, nbits, action) { \ |
| 152 | if (bits_left < (nbits)) { \ |
| 153 | if (!jpeg_fill_bit_buffer(&(state), get_buffer, bits_left, nbits)) \ |
| 154 | { action; } \ |
| 155 | get_buffer = (state).get_buffer; bits_left = (state).bits_left; \ |
| 156 | } \ |
| 157 | } |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 158 | |
| 159 | #define GET_BITS(nbits) \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 160 | (((int)(get_buffer >> (bits_left -= (nbits)))) & ((1 << (nbits)) - 1)) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 161 | |
| 162 | #define PEEK_BITS(nbits) \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 163 | (((int)(get_buffer >> (bits_left - (nbits)))) & ((1 << (nbits)) - 1)) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 164 | |
| 165 | #define DROP_BITS(nbits) \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 166 | (bits_left -= (nbits)) |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 167 | |
| 168 | /* Load up the bit buffer to a depth of at least nbits */ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 169 | EXTERN(boolean) jpeg_fill_bit_buffer(bitread_working_state *state, |
| 170 | register bit_buf_type get_buffer, |
| 171 | register int bits_left, int nbits); |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 172 | |
| 173 | |
| 174 | /* |
| 175 | * Code for extracting next Huffman-coded symbol from input bit stream. |
| 176 | * Again, this is time-critical and we make the main paths be macros. |
| 177 | * |
| 178 | * We use a lookahead table to process codes of up to HUFF_LOOKAHEAD bits |
| 179 | * without looping. Usually, more than 95% of the Huffman codes will be 8 |
| 180 | * or fewer bits long. The few overlength codes are handled with a loop, |
| 181 | * which need not be inline code. |
| 182 | * |
| 183 | * Notes about the HUFF_DECODE macro: |
| 184 | * 1. Near the end of the data segment, we may fail to get enough bits |
| 185 | * for a lookahead. In that case, we do it the hard way. |
| 186 | * 2. If the lookahead table contains no entry, the next code must be |
| 187 | * more than HUFF_LOOKAHEAD bits long. |
| 188 | * 3. jpeg_huff_decode returns -1 if forced to suspend. |
| 189 | */ |
| 190 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 191 | #define HUFF_DECODE(result, state, htbl, failaction, slowlabel) { \ |
| 192 | register int nb, look; \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 193 | if (bits_left < HUFF_LOOKAHEAD) { \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 194 | if (!jpeg_fill_bit_buffer(&state, get_buffer, bits_left, 0)) \ |
| 195 | { failaction; } \ |
| 196 | get_buffer = state.get_buffer; bits_left = state.bits_left; \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 197 | if (bits_left < HUFF_LOOKAHEAD) { \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 198 | nb = 1; goto slowlabel; \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 199 | } \ |
| 200 | } \ |
| 201 | look = PEEK_BITS(HUFF_LOOKAHEAD); \ |
DRC | e281664 | 2009-09-28 00:33:02 +0000 | [diff] [blame] | 202 | if ((nb = (htbl->lookup[look] >> HUFF_LOOKAHEAD)) <= HUFF_LOOKAHEAD) { \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 203 | DROP_BITS(nb); \ |
DRC | e281664 | 2009-09-28 00:33:02 +0000 | [diff] [blame] | 204 | result = htbl->lookup[look] & ((1 << HUFF_LOOKAHEAD) - 1); \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 205 | } else { \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 206 | slowlabel: \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 207 | if ((result = \ |
| 208 | jpeg_huff_decode(&state, get_buffer, bits_left, htbl, nb)) < 0) \ |
| 209 | { failaction; } \ |
| 210 | get_buffer = state.get_buffer; bits_left = state.bits_left; \ |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 211 | } \ |
| 212 | } |
| 213 | |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 214 | #define HUFF_DECODE_FAST(s, nb, htbl) \ |
DRC | bc51580 | 2011-04-18 06:52:07 +0000 | [diff] [blame] | 215 | FILL_BIT_BUFFER_FAST; \ |
| 216 | s = PEEK_BITS(HUFF_LOOKAHEAD); \ |
| 217 | s = htbl->lookup[s]; \ |
| 218 | nb = s >> HUFF_LOOKAHEAD; \ |
| 219 | /* Pre-execute the common case of nb <= HUFF_LOOKAHEAD */ \ |
| 220 | DROP_BITS(nb); \ |
| 221 | s = s & ((1 << HUFF_LOOKAHEAD) - 1); \ |
| 222 | if (nb > HUFF_LOOKAHEAD) { \ |
| 223 | /* Equivalent of jpeg_huff_decode() */ \ |
| 224 | /* Don't use GET_BITS() here because we don't want to modify bits_left */ \ |
| 225 | s = (get_buffer >> bits_left) & ((1 << (nb)) - 1); \ |
| 226 | while (s > htbl->maxcode[nb]) { \ |
| 227 | s <<= 1; \ |
| 228 | s |= GET_BITS(1); \ |
| 229 | nb++; \ |
| 230 | } \ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 231 | s = htbl->pub->huffval[(int)(s + htbl->valoffset[nb]) & 0xFF]; \ |
DRC | bc51580 | 2011-04-18 06:52:07 +0000 | [diff] [blame] | 232 | } |
| 233 | |
Thomas G. Lane | bc79e06 | 1995-08-02 00:00:00 +0000 | [diff] [blame] | 234 | /* Out-of-line case for Huffman code fetching */ |
Leon Scroggins III | 3993b37 | 2018-07-16 10:43:45 -0400 | [diff] [blame] | 235 | EXTERN(int) jpeg_huff_decode(bitread_working_state *state, |
| 236 | register bit_buf_type get_buffer, |
| 237 | register int bits_left, d_derived_tbl *htbl, |
| 238 | int min_bits); |