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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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250
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11 #include <ngx_config.h>
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12 #include <ngx_core.h>
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13
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14
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15 /* 32-bit crc16 */
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16
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248
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17 static ngx_inline uint32_t
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250
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18 ngx_crc(u_char *data, size_t len)
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19 {
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20 uint32_t sum;
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21
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22 for (sum = 0; len; len--) {
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23
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24 /*
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248
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25 * gcc 2.95.2 x86 and icc 7.1.006 compile
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26 * that operator into the single "rol" opcode,
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27 * msvc 6.0sp2 compiles it into four opcodes.
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28 */
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29 sum = sum >> 1 | sum << 31;
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30
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31 sum += *data++;
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32 }
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33
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34 return sum;
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35 }
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36
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37
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38 #endif /* _NGX_CRC_H_INCLUDED_ */
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