/*
- * Hyper-super-meta-alt-control-shift extra fast str_len() and hash_*()
- * routines
+ * UCW Library -- Hyper-super-meta-alt-control-shift extra fast
+ * str_len() and hash_*() routines
*
* (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"
-/* An equivalent of the Intel's rol instruction. */
-#define ROL(x, bits) (((x) << (bits)) | ((x) >> (sizeof(uns)*8 - (bits))))
-
/* The following functions need str to be aligned to uns. */
-uns str_len_aligned(const byte *str) CONST;
-uns hash_string_aligned(const byte *str) CONST;
-uns hash_block_aligned(const byte *str, uns len) CONST;
+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) CONST;
-uns hash_string(const byte *str) CONST;
-uns hash_block(const byte *str, uns len) CONST;
+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) CONST;
+uns hash_string_nocase(const byte *str) PURE;
-static inline uns hash_int(uns x) CONST;
-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)(addr_int_t)x) : hash_u64((u64)(addr_int_t)x)); }
#endif