cache: switch to wyhash for cache tables

This is dramatically faster on files with large drawings.

2 files changed, 8 insertions, 18 deletions

diff --git a/libass/ass_cache.c b/libass/ass_cache.c
index 83b9588..2306008 100644
--- a/libass/ass_cache.c
+++ b/libass/ass_cache.c
@@ -30,26 +30,16 @@
 #include "ass_outline.h"
 #include "ass_cache.h"
 
-#define ASS_HASH_INIT 0x811c9dc5U
-#define FNV1_32A_PRIME 16777619U
+// Always enable native-endian mode, since we don't care about cross-platform consistency of the hash
+#define WYHASH_LITTLE_ENDIAN 1
+#include "wyhash.h"
+
+// With wyhash any arbitrary 64 bit value will suffice
+#define ASS_HASH_INIT 0xb3e46a540bd36cd4ULL
 
 static inline ass_hashcode ass_hash_buf(const void *buf, size_t len, ass_hashcode hval)
 {
-    if (!len)
-        return hval;
-
-    const uint8_t *bp = buf;
-    size_t n = (len + 3) / 4;
-
-    switch (len % 4) {
-    case 0: do { hval ^= *bp++; hval *= FNV1_32A_PRIME; //-fallthrough
-    case 3:      hval ^= *bp++; hval *= FNV1_32A_PRIME; //-fallthrough
-    case 2:      hval ^= *bp++; hval *= FNV1_32A_PRIME; //-fallthrough
-    case 1:      hval ^= *bp++; hval *= FNV1_32A_PRIME;
-               } while (--n > 0);
-    }
-
-    return hval;
+    return wyhash(buf, len, hval, _wyp);
 }
 
 // type-specific functions
diff --git a/libass/ass_cache.h b/libass/ass_cache.h
index e96956c..6af2e79 100644
--- a/libass/ass_cache.h
+++ b/libass/ass_cache.h
@@ -26,7 +26,7 @@
 #include "ass_bitmap.h"
 
 typedef struct cache Cache;
-typedef uint32_t ass_hashcode;
+typedef uint64_t ass_hashcode;
 
 // cache values