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