#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. */
{
u32 len = start_len;
-#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);
- }
+ machine_word_t v_word;
- if (sizeof(unsigned int) < sizeof(unsigned long) &&
- len + sizeof(unsigned int) <= max_len)
- {
- unsigned int x;
+ if (likely(max_len - len >= 4 * 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);
- }
+ #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; \
- 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++;
- }
- }
+ COMPARE_WORD_STEP
+ COMPARE_WORD_STEP
+ COMPARE_WORD_STEP
+ COMPARE_WORD_STEP
+ #undef COMPARE_WORD_STEP
}
- return len;
- }
-#endif /* HAVE_FAST_LZ_EXTEND */
+ 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;
+ }
- while (len < max_len && matchptr[len] == strptr[len])
- len++;
+ while (len < max_len && matchptr[len] == strptr[len])
+ len++;
+ return len;
- return len;
+ word_differs:
+ return len + (ffsw(v_word) >> 3);
+ } else {
+ while (len < max_len && matchptr[len] == strptr[len])
+ len++;
+ return len;
+ }
}
#endif /* _WIMLIB_LZ_EXTEND_H */