Mercurial > hg > nginx-quic
annotate src/core/ngx_crc.h @ 4434:80df7b82d3c9 stable-1.0
Merge r4336:
Microoptimization of sendfile(2) usage under FreeBSD.
FreeBSD kernel checks headers/trailers pointer against NULL, not
corresponding count. Passing NULL if there are no headers/trailers
helps to avoid unneeded work in kernel, as well as unexpected 0 bytes
GIO in traces.
author | Maxim Dounin <mdounin@mdounin.ru> |
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date | Sun, 05 Feb 2012 12:42:36 +0000 |
parents | 99858705b03f |
children | d620f497c50f |
rev | line source |
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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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7 #ifndef _NGX_CRC_H_INCLUDED_ |
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8 #define _NGX_CRC_H_INCLUDED_ |
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792 | 11 #include <ngx_config.h> |
12 #include <ngx_core.h> | |
13 | |
14 | |
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15 /* 32-bit crc16 */ |
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16 |
776 | 17 static ngx_inline uint32_t |
789 | 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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22 for (sum = 0; len; len--) { |
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24 /* |
776 | 25 * gcc 2.95.2 x86 and icc 7.1.006 compile |
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_ */ |