1 | /**************************************************************************
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2 | *
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3 | * bitio_m_stdio.h -- Macros for bitio to a file
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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 | * $Id: bitio_m_stdio.h 3745 2003-02-20 21:20:24Z mdewsnip $
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21 | *
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22 | **************************************************************************
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23 | *
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24 | * This file contains macros for doing bitwise input and output on a FILE*.
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25 | * With these routines you cannot mix reads and writes on the FILE,
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26 | * or multiple writes, at the same time and guarantee them to work, also you
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27 | * cannot seek to a point and do a write. The decode routine can detect when
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28 | * you run off the end of the file and will produce an approate error message.
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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_STDIO
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34 | #define H_BITIO_M_STDIO
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35 |
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36 | typedef struct stdio_bitio_state
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37 | {
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38 | FILE *File;
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39 | unsigned char Buff;
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40 | unsigned char Btg;
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41 | }
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42 | stdio_bitio_state;
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43 |
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44 |
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45 |
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46 | #ifndef DECODE_ERROR
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47 | #define DECODE_ERROR (fprintf(stderr,"Unexpected EOF in \"%s\" on line %d\n",\
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48 | __FILE__, __LINE__), exit(1))
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49 | #endif
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50 |
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51 |
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52 |
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53 | #define ENCODE_START(f) \
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54 | { \
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55 | FILE *__outfile = f; \
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56 | register unsigned char __buff = 0; \
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57 | register unsigned char __btg = sizeof(__buff)*8;
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58 |
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59 | #define ENCODE_CONTINUE(b) \
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60 | { \
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61 | FILE *__outfile = (b).File; \
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62 | register unsigned char __buff = (b).Buff; \
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63 | register unsigned char __btg = (b).Btg;
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64 |
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65 | #define ENCODE_BIT(b) \
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66 | do { \
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67 | __btg--; \
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68 | if (b) __buff |= (1 << __btg); \
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69 | if (!__btg) \
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70 | { \
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71 | putc(__buff, __outfile); \
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72 | __buff = 0; \
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73 | __btg = sizeof(__buff)*8; \
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74 | } \
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75 | } while(0)
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76 |
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77 | #define ENCODE_PAUSE(b) \
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78 | (b).File = __outfile; \
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79 | (b).Buff = __buff; \
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80 | (b).Btg = __btg; \
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81 | }
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82 |
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83 | #define ENCODE_DONE \
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84 | if (__btg != sizeof(__buff)*8) \
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85 | putc(__buff,__outfile); \
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86 | }
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87 |
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88 |
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89 | #define DECODE_START(f) \
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90 | { \
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91 | FILE *__infile = f; \
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92 | register unsigned char __buff = 0; \
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93 | register unsigned char __btg = 0;
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94 |
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95 | #define DECODE_CONTINUE(b) \
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96 | { \
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97 | FILE *__infile = (b).File; \
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98 | register unsigned char __buff = (b).Buff; \
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99 | register unsigned char __btg = (b).Btg;
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100 |
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101 | #define DECODE_ADD_FF(b) \
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102 | do { \
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103 | if (!__btg) \
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104 | { \
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105 | register int val = getc(__infile); \
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106 | __buff = val == EOF ? 0xff : val; \
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107 | __btg = sizeof(__buff)*8; \
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108 | } \
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109 | (b) += (b) + ((__buff >> --__btg) & 1); \
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110 | } while(0)
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111 |
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112 | #define DECODE_ADD_00(b) \
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113 | do { \
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114 | if (!__btg) \
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115 | { \
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116 | register int val = getc(__infile); \
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117 | __buff = val == EOF ? 0xff : val; \
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118 | __btg = sizeof(__buff)*8; \
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119 | } \
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120 | (b) += (b) + ((__buff >> --__btg) & 1); \
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121 | } while(0)
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122 |
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123 | #define DECODE_BIT (__btg ? (__buff >> --__btg) & 1 : \
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124 | (__buff = getc(__infile), (feof(__infile) ? \
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125 | (DECODE_ERROR, 0) : \
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126 | (__btg = sizeof(__buff)*8, (__buff >> --__btg) & 1))))
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127 |
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128 | #define DECODE_DONE ; \
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129 | }
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130 |
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131 | #define DECODE_PAUSE(b) \
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132 | (b).File = __infile; \
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133 | (b).Buff = __buff; \
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134 | (b).Btg = __btg; \
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135 | }
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136 |
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137 |
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138 | #define DECODE_SEEK(pos) \
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139 | do { \
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140 | register long __new_pos = (pos); \
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141 | fseek(__infile, __new_pos >> 3, 0); \
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142 | __buff = getc(__infile); \
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143 | __btg = 8 - (__new_pos&7); \
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144 | } \
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145 | while(0)
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146 |
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147 | #endif
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