[ZLIB]

[reactos.git] / reactos / sdk / lib / 3rdparty / zlib / crc32.c

diff --git a/reactos/sdk/lib/3rdparty/zlib/crc32.c b/reactos/sdk/lib/3rdparty/zlib/crc32.c
index 979a719..9580440 100644 (file)
--- a/reactos/sdk/lib/3rdparty/zlib/crc32.c
+++ b/reactos/sdk/lib/3rdparty/zlib/crc32.c
@@ -1,5 +1,5 @@
 /* crc32.c -- compute the CRC-32 of a data stream
- * Copyright (C) 1995-2006, 2010, 2011, 2012 Mark Adler
+ * Copyright (C) 1995-2006, 2010, 2011, 2012, 2016 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  *
  * Thanks to Rodney Brown <rbrown64@csc.com.au> for his contribution of faster
@@ -30,17 +30,15 @@
 
 #include "zutil.h"      /* for STDC and FAR definitions */
 
-#define local static
-
 /* Definitions for doing the crc four data bytes at a time. */
 #if !defined(NOBYFOUR) && defined(Z_U4)
 #  define BYFOUR
 #endif
 #ifdef BYFOUR
    local unsigned long crc32_little OF((unsigned long,
-                        const unsigned char FAR *, unsigned));
+                        const unsigned char FAR *, z_size_t));
    local unsigned long crc32_big OF((unsigned long,
-                        const unsigned char FAR *, unsigned));
+                        const unsigned char FAR *, z_size_t));
 #  define TBLS 8
 #else
 #  define TBLS 1
@@ -201,10 +199,10 @@ const z_crc_t FAR * ZEXPORT get_crc_table()
 #define DO8 DO1; DO1; DO1; DO1; DO1; DO1; DO1; DO1
 
 /* ========================================================================= */
-unsigned long ZEXPORT crc32(crc, buf, len)
+unsigned long ZEXPORT crc32_z(crc, buf, len)
     unsigned long crc;
     const unsigned char FAR *buf;
-    uInt len;
+    z_size_t len;
 {
     if (buf == Z_NULL) return 0UL;
 
@@ -235,8 +233,29 @@ unsigned long ZEXPORT crc32(crc, buf, len)
     return crc ^ 0xffffffffUL;
 }
 
+/* ========================================================================= */
+unsigned long ZEXPORT crc32(crc, buf, len)
+    unsigned long crc;
+    const unsigned char FAR *buf;
+    uInt len;
+{
+    return crc32_z(crc, buf, len);
+}
+
 #ifdef BYFOUR
 
+/*
+   This BYFOUR code accesses the passed unsigned char * buffer with a 32-bit
+   integer pointer type. This violates the strict aliasing rule, where a
+   compiler can assume, for optimization purposes, that two pointers to
+   fundamentally different types won't ever point to the same memory. This can
+   manifest as a problem only if one of the pointers is written to. This code
+   only reads from those pointers. So long as this code remains isolated in
+   this compilation unit, there won't be a problem. For this reason, this code
+   should not be copied and pasted into a compilation unit in which other code
+   writes to the buffer that is passed to these routines.
+ */
+
 /* ========================================================================= */
 #define DOLIT4 c ^= *buf4++; \
         c = crc_table[3][c & 0xff] ^ crc_table[2][(c >> 8) & 0xff] ^ \
@@ -247,7 +266,7 @@ unsigned long ZEXPORT crc32(crc, buf, len)
 local unsigned long crc32_little(crc, buf, len)
     unsigned long crc;
     const unsigned char FAR *buf;
-    unsigned len;
+    z_size_t len;
 {
     register z_crc_t c;
     register const z_crc_t FAR *buf4;
@@ -278,7 +297,7 @@ local unsigned long crc32_little(crc, buf, len)
 }
 
 /* ========================================================================= */
-#define DOBIG4 c ^= *++buf4; \
+#define DOBIG4 c ^= *buf4++; \
         c = crc_table[4][c & 0xff] ^ crc_table[5][(c >> 8) & 0xff] ^ \
             crc_table[6][(c >> 16) & 0xff] ^ crc_table[7][c >> 24]
 #define DOBIG32 DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4; DOBIG4
@@ -287,7 +306,7 @@ local unsigned long crc32_little(crc, buf, len)
 local unsigned long crc32_big(crc, buf, len)
     unsigned long crc;
     const unsigned char FAR *buf;
-    unsigned len;
+    z_size_t len;
 {
     register z_crc_t c;
     register const z_crc_t FAR *buf4;
@@ -300,7 +319,6 @@ local unsigned long crc32_big(crc, buf, len)
     }
 
     buf4 = (const z_crc_t FAR *)(const void FAR *)buf;
-    buf4--;
     while (len >= 32) {
         DOBIG32;
         len -= 32;
@@ -309,7 +327,6 @@ local unsigned long crc32_big(crc, buf, len)
         DOBIG4;
         len -= 4;
     }
-    buf4++;
     buf = (const unsigned char FAR *)buf4;
 
     if (len) do {