X-Git-Url: https://wimlib.net/git/?p=wimlib;a=blobdiff_plain;f=include%2Fwimlib%2Flz_extend.h;h=a3780e1d54a819245b980dc36439d0ddc7d2a3ab;hp=7d7ed8b8e88b02ceb6ebdd684ed1dddd33f92a08;hb=226a6dfe2909e054568298196785c944a1b5c4fa;hpb=7e3f3761e0a9fc93341ed0b9c69f6056d9a97af9

diff --git a/include/wimlib/lz_extend.h b/include/wimlib/lz_extend.h
index 7d7ed8b8..a3780e1d 100644
--- a/include/wimlib/lz_extend.h
+++ b/include/wimlib/lz_extend.h
@@ -10,13 +10,8 @@
 #ifndef _WIMLIB_LZ_EXTEND_H
 #define _WIMLIB_LZ_EXTEND_H
 
-#include "wimlib/types.h"
-
-#if (defined(__x86_64__) || defined(__i386__)) && defined(__GNUC__)
-#  define HAVE_FAST_LZ_EXTEND 1
-#else
-#  define HAVE_FAST_LZ_EXTEND 0
-#endif
+#include "wimlib/bitops.h"
+#include "wimlib/unaligned.h"
 
 /* Return the number of bytes at @matchptr that match the bytes at @strptr, up
  * to a maximum of @max_len.  Initially, @start_len bytes are matched.  */
@@ -25,49 +20,44 @@ lz_extend(const u8 * const strptr, const u8 * const matchptr,
 	  const u32 start_len, const u32 max_len)
 {
 	u32 len = start_len;
+	machine_word_t v_word;
 
-#if HAVE_FAST_LZ_EXTEND
-
-	while (len + sizeof(unsigned long) <= max_len) {
-		unsigned long x;
+	if (UNALIGNED_ACCESS_IS_FAST) {
 
-		x = *(const unsigned long *)&matchptr[len] ^
-		    *(const unsigned long *)&strptr[len];
-		if (x != 0)
-			return len + (__builtin_ctzl(x) >> 3);
-		len += sizeof(unsigned long);
-	}
+		if (likely(max_len - len >= 4 * WORDSIZE)) {
 
-	if (sizeof(unsigned int) < sizeof(unsigned long) &&
-	    len + sizeof(unsigned int) <= max_len)
-	{
-		unsigned int x;
+		#define COMPARE_WORD_STEP					\
+			v_word = load_word_unaligned(&matchptr[len]) ^		\
+				 load_word_unaligned(&strptr[len]);		\
+			if (v_word != 0)					\
+				goto word_differs;				\
+			len += WORDSIZE;					\
 
-		x = *(const unsigned int *)&matchptr[len] ^
-		    *(const unsigned int *)&strptr[len];
-		if (x != 0)
-			return len + (__builtin_ctz(x) >> 3);
-		len += sizeof(unsigned int);
-	}
+			COMPARE_WORD_STEP
+			COMPARE_WORD_STEP
+			COMPARE_WORD_STEP
+			COMPARE_WORD_STEP
+		#undef COMPARE_WORD_STEP
+		}
 
-	if (sizeof(unsigned int) == 4) {
-		if (len < max_len && matchptr[len] == strptr[len]) {
-			len++;
-			if (len < max_len && matchptr[len] == strptr[len]) {
-				len++;
-				if (len < max_len && matchptr[len] == strptr[len]) {
-					len++;
-				}
-			}
+		while (len + WORDSIZE <= max_len) {
+			v_word = load_word_unaligned(&matchptr[len]) ^
+				 load_word_unaligned(&strptr[len]);
+			if (v_word != 0)
+				goto word_differs;
+			len += WORDSIZE;
 		}
-		return len;
 	}
 
-#endif /* HAVE_FAST_LZ_EXTEND */
-
 	while (len < max_len && matchptr[len] == strptr[len])
 		len++;
+	return len;
 
+word_differs:
+	if (CPU_IS_LITTLE_ENDIAN)
+		len += (ffsw(v_word) >> 3);
+	else
+		len += (flsw(v_word) >> 3);
 	return len;
 }