| 1 | /**************************************************************************
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| 2 | *
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| 3 | * bitio_m_random.h -- Macros for bitio to a file (random access)
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| 4 | * Copyright (C) 1994 Neil Sharman
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| 5 | *
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| 6 | * This program is free software; you can redistribute it and/or modify
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| 7 | * it under the terms of the GNU General Public License as published by
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| 8 | * the Free Software Foundation; either version 2 of the License, or
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| 9 | * (at your option) any later version.
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| 10 | *
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| 11 | * This program is distributed in the hope that it will be useful,
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| 12 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | * GNU General Public License for more details.
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| 15 | *
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| 16 | * You should have received a copy of the GNU General Public License
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| 17 | * along with this program; if not, write to the Free Software
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| 18 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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| 19 | *
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| 20 | **************************************************************************
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| 21 | *
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| 22 | * This file contains macros for doing bitwise input and output on an array
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| 23 | * of chars. These routines are slower than the ones in "mem" files. but
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| 24 | * with these routines you can mix reads and writes, or multiple writes, on
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| 25 | * the array of chars at the same time and guarantee them to work, also you
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| 26 | * can seek to a point and do a write. The decode and encode macros cannot
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| 27 | * detect when the end off the character is reached and just continue
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| 28 | * processing.
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| 29 | *
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| 30 | *
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| 31 | **************************************************************************/
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| 32 |
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| 33 | #ifndef H_BITIO_M_RANDOM
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| 34 | #define H_BITIO_M_RANDOM
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| 35 |
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| 36 | typedef struct random_bitio_state
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| 37 | {
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| 38 | FILE *File;
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| 39 | unsigned char *Buf;
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| 40 | unsigned long Base;
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| 41 | unsigned long Used;
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| 42 | unsigned long pos;
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| 43 | unsigned long len;
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| 44 | unsigned long sft;
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| 45 | }
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| 46 | random_bitio_state;
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| 47 |
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| 48 |
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| 49 | #define ENCODE_START(f,l) \
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| 50 | { \
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| 51 | register FILE *__file = f; \
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| 52 | register unsigned char *__buf; \
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| 53 | register unsigned long __pos = 0; \
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| 54 | register unsigned long __base = 0; \
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| 55 | register unsigned long __used = 0; \
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| 56 | register unsigned long __len = (l)-1; \
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| 57 | register unsigned long __sft = 0; \
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| 58 | while (__len) { __sft++; __len >>=1; } \
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| 59 | __len = 1<<__sft; \
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| 60 | __buf = Xmalloc(__len); \
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| 61 | fseek(__file, 0, 0); \
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| 62 | fread(__buf, 1, __len, __file);
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| 63 |
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| 64 | #define ENCODE_CONTINUE(b) \
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| 65 | { \
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| 66 | register FILE *__file = (b).File; \
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| 67 | register unsigned char *__buf = (b).Buf; \
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| 68 | register unsigned long __pos = (b).pos; \
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| 69 | register unsigned long __base = (b).Base; \
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| 70 | register unsigned long __used = (b).Used; \
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| 71 | register unsigned long __len = (b).len; \
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| 72 | register unsigned long __sft = (b).sft;
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| 73 |
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| 74 | #define SEEK fprintf(stderr, "Seek to %d\n",__base)
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| 75 | #define READ fprintf(stderr, "Read of %d\n",__len)
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| 76 | #define WRITE fprintf(stderr, "Write of %d\n",__used)
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| 77 |
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| 78 | #define WRITE_READ \
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| 79 | (__used ? (fseek(__file, __base, 0), \
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| 80 | fwrite(__buf, 1, __len, __file)) : 0, \
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| 81 | __base += __len, \
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| 82 | fseek(__file, __base, 0), \
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| 83 | fread(__buf, 1, __len, __file), \
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| 84 | __pos = 0, __used = 0)
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| 85 |
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| 86 | #define ENCODE_BIT(b) \
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| 87 | do { \
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| 88 | if (b) \
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| 89 | __buf[__pos>>3] |= 0x80 >> (__pos&7); \
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| 90 | else \
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| 91 | __buf[__pos>>3] &= 0xff7f >> (__pos&7); \
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| 92 | __used = 1; \
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| 93 | __pos++; \
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| 94 | if ((__pos>>3) >= __len) \
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| 95 | (void)WRITE_READ; \
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| 96 | } while(0)
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| 97 |
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| 98 | #define ENCODE_PAUSE(b) \
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| 99 | (b).File = __file; \
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| 100 | (b).Buf = __buf; \
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| 101 | (b).pos = __pos; \
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| 102 | (b).Base = __base; \
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| 103 | (b).Used = __used; \
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| 104 | (b).len = __len; \
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| 105 | (b).sft = __sft; \
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| 106 | }
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| 107 |
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| 108 | #define ENCODE_FLUSH \
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| 109 | if (__used) \
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| 110 | { \
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| 111 | fseek(__file, __base, 0); \
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| 112 | fwrite(__buf, 1, __len, __file); \
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| 113 | __used = 0; \
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| 114 | }
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| 115 |
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| 116 |
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| 117 |
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| 118 | #define ENCODE_DONE \
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| 119 | ENCODE_FLUSH; \
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| 120 | free(__buf); \
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| 121 | }
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| 122 |
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| 123 |
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| 124 | #define DECODE_START(f,l) ENCODE_START(f,l)
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| 125 |
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| 126 | #define DECODE_CONTINUE(b) ENCODE_CONTINUE(b)
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| 127 |
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| 128 | #define DECODE_BIT \
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| 129 | (__pos++, (((__pos-1)>>3) >= __len ? WRITE_READ, __pos=1 : 0), \
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| 130 | ((__buf[(__pos-1)>>3] & (0x80 >> ((__pos-1)&7))) != 0))
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| 131 |
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| 132 | #define DECODE_ADD_FF(b) ((b) += (b) + DECODE_BIT)
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| 133 |
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| 134 | #define DECODE_ADD_00(b) DECODE_ADD_FF(b)
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| 135 |
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| 136 | #define DECODE_DONE ENCODE_DONE
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| 137 |
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| 138 | #define DECODE_PAUSE(b) ENCODE_PAUSE(b)
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| 139 |
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| 140 | #define ENCODE_SEEK(pos) \
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| 141 | do { \
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| 142 | if ((((pos)>>3) >= __base) && ((((pos)+7)>>3) < (__base+__len))) \
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| 143 | __pos = (pos)-(__base << 3); \
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| 144 | else \
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| 145 | { \
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| 146 | ENCODE_FLUSH; \
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| 147 | __base = (pos) >> 3; \
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| 148 | __base = ((pos) >> (__sft+3)) << __sft; \
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| 149 | fseek(__file, __base, 0); \
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| 150 | fread(__buf, 1, __len, __file); \
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| 151 | __pos = (pos)&7; \
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| 152 | __pos = (pos)&((8 << __sft)-1); \
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| 153 | } \
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| 154 | } while(0)
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| 155 |
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| 156 |
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| 157 | #define DECODE_SEEK(pos) ENCODE_SEEK(pos)
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| 158 |
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| 159 | #define ENCODE_TELL ((__base << 3) + __pos)
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| 160 |
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| 161 | #define DECODE_TELL ENCODE_TELL
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| 162 |
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| 163 |
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| 164 |
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| 165 |
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| 166 | #endif
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