Compression updates

[wimlib] / include / wimlib / lz_repsearch.h

diff --git a/include/wimlib/lz_repsearch.h b/include/wimlib/lz_repsearch.h
index fe59558bdb46d29047d8d0657347a8b601cf6445..6883bf624a8eb66be6b5b77b6070ad1b85163a9b 100644 (file)
--- a/include/wimlib/lz_repsearch.h
+++ b/include/wimlib/lz_repsearch.h
@@ -11,45 +11,56 @@
 #define _LZ_REPSEARCH_H
 
 #include "wimlib/lz_extend.h"
-#include "wimlib/util.h"
 
 extern u32
 lz_extend_repmatch(const u8 *strptr, const u8 *matchptr, u32 max_len);
 
 /*
- * Find the longest repeat offset match.
+ * Given a pointer to the current string and a queue of 3 recent match offsets,
+ * find the longest repeat offset match.
  *
  * If no match of at least 2 bytes is found, then return 0.
  *
  * If a match of at least 2 bytes is found, then return its length and set
- * *slot_ret to the index of its offset in @queue.
- */
+ * *rep_max_idx_ret to the index of its offset in @recent_offsets.
+*/
 static inline u32
-lz_repsearch(const u8 * const strptr, const u32 bytes_remaining,
-            const u32 max_match_len, const u32 repeat_offsets[],
-            const unsigned num_repeat_offsets, unsigned *slot_ret)
+lz_repsearch3(const u8 * const strptr, const u32 max_len,
+             const u32 recent_offsets[3], unsigned *rep_max_idx_ret)
 {
-       u32 best_len = 0;
-
-       if (likely(bytes_remaining >= 2)) {
-               const u32 max_len = min(max_match_len, bytes_remaining);
-               const u16 str = *(const u16 *)strptr;
-
-               for (unsigned i = 0; i < num_repeat_offsets; i++) {
-                       const u8 * const matchptr = strptr - repeat_offsets[i];
-
-                       /* Check the first two bytes.  If they match, then
-                        * extend the match to its full length.  */
-                       if (*(const u16 *)matchptr == str) {
-                               const u32 len = lz_extend_repmatch(strptr, matchptr, max_len);
-                               if (len > best_len) {
-                                       best_len = len;
-                                       *slot_ret = i;
-                               }
-                       }
+       unsigned rep_max_idx;
+       u32 rep_len;
+       u32 rep_max_len;
+       const u16 str = *(const u16 *)strptr;
+       const u8 *matchptr;
+
+       matchptr = strptr - recent_offsets[0];
+       if (*(const u16 *)matchptr == str)
+               rep_max_len = lz_extend_repmatch(strptr, matchptr, max_len);
+       else
+               rep_max_len = 0;
+       rep_max_idx = 0;
+
+       matchptr = strptr - recent_offsets[1];
+       if (*(const u16 *)matchptr == str) {
+               rep_len = lz_extend_repmatch(strptr, matchptr, max_len);
+               if (rep_len > rep_max_len) {
+                       rep_max_len = rep_len;
+                       rep_max_idx = 1;
                }
        }
-       return best_len;
+
+       matchptr = strptr - recent_offsets[2];
+       if (*(const u16 *)matchptr == str) {
+               rep_len = lz_extend_repmatch(strptr, matchptr, max_len);
+               if (rep_len > rep_max_len) {
+                       rep_max_len = rep_len;
+                       rep_max_idx = 2;
+               }
+       }
+
+       *rep_max_idx_ret = rep_max_idx;
+       return rep_max_len;
 }
 
 #endif /* _LZ_REPSEARCH_H */