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71 lines
2.2 KiB
C
71 lines
2.2 KiB
C
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/* adler32_p.h -- Private inline functions and macros shared with
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* different computation of the Adler-32 checksum
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* of a data stream.
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* Copyright (C) 1995-2011, 2016 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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#ifndef ADLER32_P_H
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#define ADLER32_P_H
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#define BASE 65521U /* largest prime smaller than 65536 */
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#define NMAX 5552
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/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
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#define DO1(sum1, sum2, buf, i) {(sum1) += buf[(i)]; (sum2) += (sum1);}
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#define DO2(sum1, sum2, buf, i) {DO1(sum1, sum2, buf, i); DO1(sum1, sum2, buf, i+1);}
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#define DO4(sum1, sum2, buf, i) {DO2(sum1, sum2, buf, i); DO2(sum1, sum2, buf, i+2);}
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#define DO8(sum1, sum2, buf, i) {DO4(sum1, sum2, buf, i); DO4(sum1, sum2, buf, i+4);}
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#define DO16(sum1, sum2, buf) {DO8(sum1, sum2, buf, 0); DO8(sum1, sum2, buf, 8);}
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static inline uint32_t adler32_len_1(uint32_t adler, const uint8_t *buf, uint32_t sum2) {
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adler += buf[0];
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adler %= BASE;
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sum2 += adler;
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sum2 %= BASE;
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return adler | (sum2 << 16);
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}
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static inline uint32_t adler32_len_16(uint32_t adler, const uint8_t *buf, size_t len, uint32_t sum2) {
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while (len) {
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--len;
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adler += *buf++;
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sum2 += adler;
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}
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adler %= BASE;
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sum2 %= BASE; /* only added so many BASE's */
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/* return recombined sums */
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return adler | (sum2 << 16);
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}
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static inline uint32_t adler32_copy_len_16(uint32_t adler, const uint8_t *buf, uint8_t *dst, size_t len, uint32_t sum2) {
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while (len--) {
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*dst = *buf++;
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adler += *dst++;
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sum2 += adler;
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}
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adler %= BASE;
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sum2 %= BASE; /* only added so many BASE's */
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/* return recombined sums */
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return adler | (sum2 << 16);
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}
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static inline uint32_t adler32_len_64(uint32_t adler, const uint8_t *buf, size_t len, uint32_t sum2) {
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#ifdef UNROLL_MORE
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while (len >= 16) {
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len -= 16;
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DO16(adler, sum2, buf);
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buf += 16;
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#else
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while (len >= 8) {
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len -= 8;
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DO8(adler, sum2, buf, 0);
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buf += 8;
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#endif
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}
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/* Process tail (len < 16). */
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return adler32_len_16(adler, buf, len, sum2);
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}
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#endif /* ADLER32_P_H */
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