/* adler32.c -- compute the Adler-32 checksum of a data stream
- * Copyright (C) 1995-1998 Mark Adler
- * For conditions of distribution and use, see copyright notice in zlib.h
+ * Copyright (C) 1995-2003 Mark Adler
+ * For conditions of distribution and use, see copyright notice in zlib.h
*/
/* @(#) $Id$ */
+#define ZLIB_INTERNAL
#include "zlib.h"
-#define BASE 65521L /* largest prime smaller than 65536 */
+#define BASE 65521UL /* 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 DO8(buf,i) DO4(buf,i); DO4(buf,i+4);
#define DO16(buf) DO8(buf,0); DO8(buf,8);
+#ifdef NO_DIVIDE
+# define MOD(a) \
+ do { \
+ if (a >= (BASE << 16)) a -= (BASE << 16); \
+ if (a >= (BASE << 15)) a -= (BASE << 15); \
+ if (a >= (BASE << 14)) a -= (BASE << 14); \
+ if (a >= (BASE << 13)) a -= (BASE << 13); \
+ if (a >= (BASE << 12)) a -= (BASE << 12); \
+ if (a >= (BASE << 11)) a -= (BASE << 11); \
+ if (a >= (BASE << 10)) a -= (BASE << 10); \
+ if (a >= (BASE << 9)) a -= (BASE << 9); \
+ if (a >= (BASE << 8)) a -= (BASE << 8); \
+ if (a >= (BASE << 7)) a -= (BASE << 7); \
+ if (a >= (BASE << 6)) a -= (BASE << 6); \
+ if (a >= (BASE << 5)) a -= (BASE << 5); \
+ if (a >= (BASE << 4)) a -= (BASE << 4); \
+ if (a >= (BASE << 3)) a -= (BASE << 3); \
+ if (a >= (BASE << 2)) a -= (BASE << 2); \
+ if (a >= (BASE << 1)) a -= (BASE << 1); \
+ if (a >= BASE) a -= BASE; \
+ } while (0)
+#else
+# define MOD(a) a %= BASE
+#endif
+
/* ========================================================================= */
uLong ZEXPORT adler32(adler, buf, len)
uLong adler;
if (buf == Z_NULL) return 1L;
while (len > 0) {
- k = len < NMAX ? len : NMAX;
+ k = len < NMAX ? (int)len : NMAX;
len -= k;
while (k >= 16) {
DO16(buf);
- buf += 16;
+ buf += 16;
k -= 16;
}
if (k != 0) do {
s1 += *buf++;
- s2 += s1;
+ s2 += s1;
} while (--k);
- s1 %= BASE;
- s2 %= BASE;
+ MOD(s1);
+ MOD(s2);
}
return (s2 << 16) | s1;
}