simple fastbuf on memory pools

[libucw.git] / lib / hashfunc.h

diff --git a/lib/hashfunc.h b/lib/hashfunc.h
index 126b8f243a897967f6bea97bc60f824f44d3e47d..5f40c3d6783eb6c7346451a813170ca442347599 100644 (file)
--- a/lib/hashfunc.h
+++ b/lib/hashfunc.h
@@ -1,14 +1,43 @@
 /*
- *     Sherlock Library -- Hash Functions
+ *     UCW Library -- Hyper-super-meta-alt-control-shift extra fast
+ *     str_len() and hash_*() routines
  *
- *     (c) 2002 Martin Mares <mj@ucw.cz>
+ *     (c) 2002, Robert Spalek <robert@ucw.cz>
+ *
+ *     This software may be freely distributed and used according to the terms
+ *     of the GNU Lesser General Public License.
  */
 
-#ifndef _SHERLOCK_HASHFUNC_H
-#define _SHERLOCK_HASHFUNC_H
+#ifndef _UCW_HASHFUNC_H
+#define _UCW_HASHFUNC_H
+
+#include "lib/lib.h"
+
+/* The following functions need str to be aligned to uns.  */
+uns str_len_aligned(const byte *str) PURE;
+uns hash_string_aligned(const byte *str) PURE;
+uns hash_block_aligned(const byte *str, uns len) PURE;
+
+#ifdef CPU_ALLOW_UNALIGNED
+#define        str_len(str)            str_len_aligned(str)
+#define        hash_string(str)        hash_string_aligned(str)
+#define        hash_block(str, len)    hash_block_aligned(str, len)
+#else
+uns str_len(const byte *str) PURE;
+uns hash_string(const byte *str) PURE;
+uns hash_block(const byte *str, uns len) PURE;
+#endif
+
+uns hash_string_nocase(const byte *str) PURE;
 
-uns hash_string(byte *x);
-uns hash_string_nocase(byte *x);
-static inline uns hash_int(uns x) { return 6442450967*x; }
+/*
+ *  We hash integers by multiplying by a reasonably large prime with
+ *  few ones in its binary form (to gave the compiler the possibility
+ *  of using shifts and adds on architectures where multiplication
+ *  instructions are slow).
+ */
+static inline uns CONST hash_u32(uns x) { return 0x01008041*x; }
+static inline uns CONST hash_u64(u64 x) { return hash_u32((uns)x ^ (uns)(x >> 32)); }
+static inline uns CONST hash_pointer(void *x) { return ((sizeof(x) <= 4) ? hash_u32((uns)(uintptr_t)x) : hash_u64((u64)(uintptr_t)x)); }
 
 #endif