X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=include%2Fwimlib%2Flz_hash.h;h=f7618152b9b02377936b37d3280bb49f83ecabe8;hb=4a20aae0dd8469a352517a0b107416ffa99ccc55;hp=9a856a5b698ca7b132a2ad91c5049f6e4bb5de3f;hpb=31786dbc470c919893bf4fc5cc91a0f73cbee720;p=wimlib

diff --git a/include/wimlib/lz_hash.h b/include/wimlib/lz_hash.h
index 9a856a5b..f7618152 100644
--- a/include/wimlib/lz_hash.h
+++ b/include/wimlib/lz_hash.h
@@ -1,30 +1,39 @@
-#ifndef _WIMLIB_LZ_HASH_H
-#define _WIMLIB_LZ_HASH_H
+/*
+ * lz_hash.h - hashing for Lempel-Ziv matchfinding
+ *
+ * The following copying information applies to this specific source code file:
+ *
+ * Written in 2014-2015 by Eric Biggers <ebiggers3@gmail.com>
+ *
+ * To the extent possible under law, the author(s) have dedicated all copyright
+ * and related and neighboring rights to this software to the public domain
+ * worldwide via the Creative Commons Zero 1.0 Universal Public Domain
+ * Dedication (the "CC0").
+ *
+ * This software is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the CC0 for more details.
+ *
+ * You should have received a copy of the CC0 along with this software; if not
+ * see <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
 
-#include "wimlib/compress_common.h"
+#ifndef _LZ_HASH_H
+#define _LZ_HASH_H
 
-struct lz_params {
-	unsigned min_match;
-	unsigned max_match;
-	unsigned max_offset;
-	unsigned nice_match;
-	unsigned good_match;
-	unsigned max_chain_len;
-	unsigned max_lazy_match;
-	unsigned too_far;
-};
+#include "wimlib/types.h"
 
-typedef void (*lz_record_match_t)(unsigned len, unsigned offset, void *ctx);
-typedef void (*lz_record_literal_t)(u8 lit, void *ctx);
+/*
+ * The hash function: given a sequence prefix held in the low-order bits of a
+ * 32-bit value, multiply by a carefully-chosen large constant.  Discard any
+ * bits of the product that don't fit in a 32-bit value, but take the
+ * next-highest @num_bits bits of the product as the hash value, as those have
+ * the most randomness.
+ */
+static forceinline u32
+lz_hash(u32 seq, unsigned num_bits)
+{
+	return (u32)(seq * 0x1E35A7BD) >> (32 - num_bits);
+}
 
-extern void
-lz_analyze_block(const u8 window[restrict],
-		 u32 window_size,
-		 lz_record_match_t record_match,
-		 lz_record_literal_t record_literal,
-		 void *record_ctx,
-		 const struct lz_params *params,
-		 u32 prev_tab[restrict]);
-
-
-#endif /* _WIMLIB_LZ_HASH_H  */
+#endif /* _LZ_HASH_H */