Revert of Update Zlib to version 1.2.8

third_party/zlib/adler32.c

Index: third_party/zlib/adler32.c
diff --git a/third_party/zlib/adler32.c b/third_party/zlib/adler32.c
index a868f073d8a0e35dcb3ec812b41b1d3f0acdd84d..65ad6a5adc44c00428b35eb15ff26d16f9ef209b 100644
--- a/third_party/zlib/adler32.c
+++ b/third_party/zlib/adler32.c
@@ -1,5 +1,5 @@
 /* adler32.c -- compute the Adler-32 checksum of a data stream
- * Copyright (C) 1995-2011 Mark Adler
+ * Copyright (C) 1995-2007 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -9,9 +9,9 @@
 
 #define local static
 
-local uLong adler32_combine_ OF((uLong adler1, uLong adler2, z_off64_t len2));
+local uLong adler32_combine_(uLong adler1, uLong adler2, z_off64_t len2);
 
-#define BASE 65521      /* 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 */
 
@@ -21,44 +21,39 @@
 #define DO8(buf,i)  DO4(buf,i); DO4(buf,i+4);
 #define DO16(buf)   DO8(buf,0); DO8(buf,8);
 
-/* use NO_DIVIDE if your processor does not do division in hardware --
-   try it both ways to see which is faster */
+/* use NO_DIVIDE if your processor does not do division in hardware */
 #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) \
+#  define MOD(a) \
     do { \
-        unsigned long tmp = a >> 16; \
-        a &= 0xffffUL; \
-        a += (tmp << 4) - tmp; \
-    } while (0)
-#  define MOD28(a) \
-    do { \
-        CHOP(a); \
+        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)
-#  define MOD(a) \
+#  define MOD4(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 << 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
-#  define MOD28(a) a %= BASE
-#  define MOD63(a) a %= BASE
+#  define MOD4(a) a %= BASE
 #endif
 
 /* ========================================================================= */
@@ -97,7 +92,7 @@
         }
         if (adler >= BASE)
             adler -= BASE;
-        MOD28(sum2);            /* only added so many BASE's */
+        MOD4(sum2);             /* only added so many BASE's */
         return adler | (sum2 << 16);
     }
 
@@ -142,13 +137,8 @@
     unsigned long sum2;
     unsigned rem;
 
-    /* for negative len, return invalid adler32 as a clue for debugging */
-    if (len2 < 0)
-        return 0xffffffffUL;
-
     /* the derivation of this formula is left as an exercise for the reader */
-    MOD63(len2);                /* assumes len2 >= 0 */
-    rem = (unsigned)len2;
+    rem = (unsigned)(len2 % BASE);
     sum1 = adler1 & 0xffff;
     sum2 = rem * sum1;
     MOD(sum2);