Zlib ng

2026-05-31 00:46:46 +00:00 · 2019-06-30 18:13:46 -07:00
parent d7c110041a
commit e086f53b97
116 changed files with 30587 additions and 13 deletions
@@ -0,0 +1,77 @@
+/* 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 */
+
+/* use NO_DIVIDE if your processor does not do division in hardware --
+   try it both ways to see which is faster */
+#ifdef NO_DIVIDE
+/* note that this assumes BASE is 65521, where 65536 % 65521 == 15
+   (thank you to John Reiser for pointing this out) */
+#  define CHOP(a) \
+    do { \
+        uint32_t tmp = a >> 16; \
+        a &= 0xffff; \
+        a += (tmp << 4) - tmp; \
+    } while (0)
+#  define MOD28(a) \
+    do { \
+        CHOP(a); \
+        if (a >= BASE) a -= BASE; \
+    } while (0)
+#  define MOD(a) \
+    do { \
+        CHOP(a); \
+        MOD28(a); \
+    } while (0)
+#  define MOD63(a) \
+    do { /* this assumes a is not negative */ \
+        z_off64_t tmp = a >> 32; \
+        a &= 0xffffffffL; \
+        a += (tmp << 8) - (tmp << 5) + tmp; \
+        tmp = a >> 16; \
+        a &= 0xffffL; \
+        a += (tmp << 4) - tmp; \
+        tmp = a >> 16; \
+        a &= 0xffffL; \
+        a += (tmp << 4) - tmp; \
+        if (a >= BASE) a -= BASE; \
+    } while (0)
+#else
+#  define MOD(a) a %= BASE
+#  define MOD28(a) a %= BASE
+#  define MOD63(a) a %= BASE
+#endif
+
+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;
+    MOD28(sum2);            /* only added so many BASE's */
+    return adler | (sum2 << 16);
+}
+
+#endif /* ADLER32_P_H */