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1
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2 /*
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3 * Copyright (C) Igor Sysoev
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4 * Copyright (C) Nginx, Inc.
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250
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5 */
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6
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7
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8 #ifndef _NGX_CRC32_H_INCLUDED_
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9 #define _NGX_CRC32_H_INCLUDED_
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10
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11
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12 #include <ngx_config.h>
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13 #include <ngx_core.h>
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14
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15
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16 extern uint32_t *ngx_crc32_table_short;
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17 extern uint32_t ngx_crc32_table256[];
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18
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19
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20 static ngx_inline uint32_t
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21 ngx_crc32_short(u_char *p, size_t len)
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22 {
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23 u_char c;
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24 uint32_t crc;
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25
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26 crc = 0xffffffff;
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27
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28 while (len--) {
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29 c = *p++;
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30 crc = ngx_crc32_table_short[(crc ^ (c & 0xf)) & 0xf] ^ (crc >> 4);
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31 crc = ngx_crc32_table_short[(crc ^ (c >> 4)) & 0xf] ^ (crc >> 4);
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32 }
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33
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34 return crc ^ 0xffffffff;
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35 }
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36
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37
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38 static ngx_inline uint32_t
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39 ngx_crc32_long(u_char *p, size_t len)
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40 {
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41 uint32_t crc;
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42
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43 crc = 0xffffffff;
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44
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45 while (len--) {
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46 crc = ngx_crc32_table256[(crc ^ *p++) & 0xff] ^ (crc >> 8);
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47 }
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48
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49 return crc ^ 0xffffffff;
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50 }
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51
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52
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53 #define ngx_crc32_init(crc) \
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54 crc = 0xffffffff
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55
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56
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57 static ngx_inline void
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58 ngx_crc32_update(uint32_t *crc, u_char *p, size_t len)
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59 {
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60 uint32_t c;
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61
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62 c = *crc;
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63
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64 while (len--) {
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65 c = ngx_crc32_table256[(c ^ *p++) & 0xff] ^ (c >> 8);
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66 }
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67
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68 *crc = c;
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69 }
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70
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71
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72 #define ngx_crc32_final(crc) \
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73 crc ^= 0xffffffff
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74
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75
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76 ngx_int_t ngx_crc32_table_init(void);
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77
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78
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79 #endif /* _NGX_CRC32_H_INCLUDED_ */
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