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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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4 */
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5
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6
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7 #ifndef _NGX_CRC_H_INCLUDED_
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8 #define _NGX_CRC_H_INCLUDED_
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9
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10
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11 /* 32-bit crc16 */
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12
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13 ngx_inline static uint32_t ngx_crc(char *data, size_t len)
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14 {
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15 uint32_t sum;
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16
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17 for (sum = 0; len; len--) {
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18
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19 /*
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20 * gcc 2.95.2 x86 and icc 7.1.006 compile that operator
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21 * into the single "rol" opcode.
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22 * msvc 6.0sp2 compiles it into four opcodes.
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23 */
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24 sum = sum >> 1 | sum << 31;
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25
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26 sum += *data++;
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27 }
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28
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29 return sum;
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30 }
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31
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32
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33 #endif /* _NGX_CRC_H_INCLUDED_ */
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