1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
/* adler32_p.h -- Private inline functions and macros shared with
* different computation of the Adler-32 checksum
* of a data stream.
* Copyright (C) 1995-2011, 2016 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#ifndef ADLER32_P_H
#define ADLER32_P_H
#define BASE 65521U /* largest prime smaller than 65536 */
#define NMAX 5552
/* NMAX is the largest n such that 255n(n+1)/2 + (n+1)(BASE-1) <= 2^32-1 */
#define DO1(sum1, sum2, buf, i) {(sum1) += buf[(i)]; (sum2) += (sum1);}
#define DO2(sum1, sum2, buf, i) {DO1(sum1, sum2, buf, i); DO1(sum1, sum2, buf, i+1);}
#define DO4(sum1, sum2, buf, i) {DO2(sum1, sum2, buf, i); DO2(sum1, sum2, buf, i+2);}
#define DO8(sum1, sum2, buf, i) {DO4(sum1, sum2, buf, i); DO4(sum1, sum2, buf, i+4);}
#define DO16(sum1, sum2, buf) {DO8(sum1, sum2, buf, 0); DO8(sum1, sum2, buf, 8);}
static inline uint32_t adler32_len_1(uint32_t adler, const unsigned char *buf, uint32_t sum2) {
adler += buf[0];
if (adler >= BASE)
adler -= BASE;
sum2 += adler;
if (sum2 >= BASE)
sum2 -= BASE;
return adler | (sum2 << 16);
}
static inline uint32_t adler32_len_16(uint32_t adler, const unsigned char *buf, size_t len, uint32_t sum2) {
while (len) {
--len;
adler += *buf++;
sum2 += adler;
}
if (adler >= BASE)
adler -= BASE;
sum2 %= BASE; /* only added so many BASE's */
return adler | (sum2 << 16);
}
static inline uint32_t adler32_len_64(uint32_t adler, const unsigned char *buf, size_t len, uint32_t sum2) {
while (len >= 16) {
len -= 16;
DO16(adler, sum2, buf);
buf += 16;
}
/* Process tail (len < 16). */
return adler32_len_16(adler, buf, len, sum2);
}
#endif /* ADLER32_P_H */
|
