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| Rev | Author | Line No. | Line |
|---|---|---|---|
| 165 | serge | 1 | /* max bits required for any lookup - change if htable changes */ |
| 2 | /* quad required 10 bit w/signs must have (MAXBITS+2) >= 10 */ |
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| 3 | #define MAXBITS 9 |
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| 4 | |||
| 5 | static unsigned int bitbuf; |
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| 6 | static int bits; |
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| 7 | static unsigned char *bs_ptr; |
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| 8 | static unsigned char *bs_ptr0; |
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| 9 | static unsigned char *bs_ptr_end; // optional for overrun test |
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| 10 | |||
| 11 | void bitget_init(unsigned char *buf) |
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| 12 | { |
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| 13 | bs_ptr0 = bs_ptr = buf; |
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| 14 | bits = 0; |
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| 15 | bitbuf = 0; |
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| 16 | } |
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| 17 | |||
| 18 | int bitget(int n) |
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| 19 | { |
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| 20 | unsigned int x; |
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| 21 | |||
| 22 | if (bits < n) |
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| 23 | { /* refill bit buf if necessary */ |
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| 24 | while (bits <= 24) |
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| 25 | { |
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| 26 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 27 | bits += 8; |
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| 28 | } |
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| 29 | } |
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| 30 | bits -= n; |
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| 31 | x = bitbuf >> bits; |
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| 32 | bitbuf -= x << bits; |
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| 33 | return x; |
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| 34 | } |
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| 35 | |||
| 36 | void bitget_skip(int n) |
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| 37 | { |
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| 38 | unsigned int k; |
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| 39 | |||
| 40 | if (bits < n) |
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| 41 | { |
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| 42 | n -= bits; |
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| 43 | k = n >> 3; |
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| 44 | /*--- bytes = n/8 --*/ |
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| 45 | bs_ptr += k; |
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| 46 | n -= k << 3; |
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| 47 | bitbuf = *bs_ptr++; |
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| 48 | bits = 8; |
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| 49 | } |
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| 50 | bits -= n; |
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| 51 | bitbuf -= (bitbuf >> bits) << bits; |
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| 52 | } |
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| 53 | |||
| 54 | void bitget_init_end(unsigned char *buf_end) |
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| 55 | { |
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| 56 | bs_ptr_end = buf_end; |
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| 57 | } |
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| 58 | |||
| 59 | /*------------- check overrun -------------*/ |
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| 60 | int bitget_overrun() |
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| 61 | { |
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| 62 | return bs_ptr > bs_ptr_end; |
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| 63 | } |
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| 64 | /*------------- get n bits from bitstream -------------*/ |
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| 65 | int bitget_bits_used() |
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| 66 | { |
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| 67 | unsigned int n; /* compute bits used from last init call */ |
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| 68 | |||
| 69 | n = ((bs_ptr - bs_ptr0) << 3) - bits; |
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| 70 | return n; |
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| 71 | } |
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| 72 | /*------------- check for n bits in bitbuf -------------*/ |
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| 73 | void bitget_check(int n) |
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| 74 | { |
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| 75 | if (bits < n) |
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| 76 | { |
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| 77 | while (bits <= 24) |
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| 78 | { |
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| 79 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 80 | bits += 8; |
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| 81 | } |
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| 82 | } |
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| 83 | } |
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| 84 | |||
| 85 | #if 0 |
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| 86 | /*------------- get 1 bit from bitstream -------------*/ |
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| 87 | int bitget_1bit() |
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| 88 | { |
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| 89 | unsigned int x; |
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| 90 | |||
| 91 | if (bits <= 0) |
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| 92 | { /* refill bit buf if necessary */ |
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| 93 | while (bits <= 24) |
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| 94 | { |
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| 95 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 96 | bits += 8; |
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| 97 | } |
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| 98 | } |
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| 99 | bits--; |
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| 100 | x = bitbuf >> bits; |
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| 101 | bitbuf -= x << bits; |
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| 102 | return x; |
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| 103 | } |
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| 104 | |||
| 105 | /*------------- get 1 bit from bitstream NO CHECK -------------*/ |
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| 106 | int bitget_1bit() |
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| 107 | { |
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| 108 | unsigned int x; |
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| 109 | |||
| 110 | bits--; |
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| 111 | x = bitbuf >> bits; |
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| 112 | bitbuf -= x << bits; |
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| 113 | return x; |
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| 114 | } |
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| 115 | #endif |
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| 116 | /* only huffman */ |
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| 117 | |||
| 118 | /*----- get n bits - checks for n+2 avail bits (linbits+sign) -----*/ |
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| 119 | int bitget_lb(int n) |
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| 120 | { |
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| 121 | unsigned int x; |
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| 122 | |||
| 123 | if (bits < (n + 2)) |
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| 124 | { /* refill bit buf if necessary */ |
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| 125 | while (bits <= 24) |
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| 126 | { |
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| 127 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 128 | bits += 8; |
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| 129 | } |
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| 130 | } |
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| 131 | bits -= n; |
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| 132 | x = bitbuf >> bits; |
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| 133 | bitbuf -= x << bits; |
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| 134 | return x; |
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| 135 | } |
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| 136 | |||
| 137 | /*------------- get n bits but DO NOT remove from bitstream --*/ |
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| 138 | int bitget2(int n) |
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| 139 | { |
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| 140 | unsigned int x; |
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| 141 | |||
| 142 | if (bits < (MAXBITS + 2)) |
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| 143 | { /* refill bit buf if necessary */ |
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| 144 | while (bits <= 24) |
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| 145 | { |
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| 146 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 147 | bits += 8; |
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| 148 | } |
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| 149 | } |
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| 150 | x = bitbuf >> (bits - n); |
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| 151 | return x; |
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| 152 | } |
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| 153 | |||
| 154 | /*------------- remove n bits from bitstream ---------*/ |
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| 155 | void bitget_purge(int n) |
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| 156 | { |
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| 157 | bits -= n; |
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| 158 | bitbuf -= (bitbuf >> bits) << bits; |
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| 159 | } |
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| 160 | |||
| 161 | void mac_bitget_check(int n) |
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| 162 | { |
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| 163 | if( bits < n ) { |
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| 164 | while( bits <= 24 ) { |
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| 165 | bitbuf = (bitbuf << 8) | *bs_ptr++; |
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| 166 | bits += 8; |
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| 167 | } |
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| 168 | } |
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| 169 | } |
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| 170 | |||
| 171 | int mac_bitget(int n) |
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| 172 | { |
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| 173 | unsigned int code; |
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| 174 | |||
| 175 | bits -= n; |
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| 176 | code = bitbuf >> bits; |
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| 177 | bitbuf -= code << bits; |
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| 178 | return code; |
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| 179 | } |
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| 180 | |||
| 181 | int mac_bitget2(int n) |
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| 182 | { |
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| 183 | return (bitbuf >> (bits-n)); |
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| 184 | } |
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| 185 | |||
| 186 | int mac_bitget_1bit() |
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| 187 | { |
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| 188 | unsigned int code; |
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| 189 | |||
| 190 | bits--; |
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| 191 | code = bitbuf >> bits; |
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| 192 | bitbuf -= code << bits; |
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| 193 | return code; |
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| 194 | } |
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| 195 | |||
| 196 | void mac_bitget_purge(int n) |
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| 197 | { |
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| 198 | bits -= n; |
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| 199 | bitbuf -= (bitbuf >> bits) << bits; |
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| 200 | } |
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| 201 | |||
| 202 | /* |
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| 203 | #define mac_bitget(n) ( bits -= n, \ |
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| 204 | code = bitbuf >> bits, \ |
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| 205 | bitbuf -= code << bits, \ |
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| 206 | code ) |
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| 207 | |||
| 208 | #define mac_bitget_1bit() ( bits--, \ |
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| 209 | code = bitbuf >> bits, \ |
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| 210 | bitbuf -= code << bits, \ |
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| 211 | code ) |
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| 212 | */ |