Simple set of macros to compute the hash value for a string. The goal is

to have a very quick function.

This commit was SVN r14316.

opal/include/opal/hash_string.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2004-2007 The University of Tennessee and The University
+ *                         of Tennessee Research Foundation.  All rights
+ *                         reserved.
+ * $COPYRIGHT$
+ * 
+ * Additional copyrights may follow
+ * 
+ * $HEADER$
+ */
+
+/** @file
+ *
+ * Simple macros to quickly compute a hash value from a string.
+ *
+ */
+
+#ifndef OPAL_HASH_STRING_H
+#define OPAL_HASH_STRING_H
+
+/**
+ *  Compute the hash value and the string length simultaneously
+ *
+ *  @param str (IN)     The string which will be parsed   (char*)
+ *  @param hash (OUT)   Where the hash value will be stored (uint32_t)
+ *  @param length (OUT) The computed length of the string (uint32_t)
+ */
+#define OPAL_HASH_STRLEN( str, hash, length ) \
+    do {                                      \
+        register const char *_str = (str);    \
+        register uint32_t    _hash = 0;       \
+        register uint32_t    _len = 0;        \
+                                              \
+        while( *_str ) {                      \
+            _len++;                           \
+            _hash += *_str++;                 \
+            _hash += (_hash << 10);           \
+            _hash ^= (_hash >> 6);            \
+        }                                     \
+                                              \
+        _hash += (_hash << 3);                \
+        _hash ^= (_hash >> 11);               \
+        (hash) = (_hash + (_hash << 15));     \
+        (length)  = _len;                     \
+    } while(0)
+
+/**
+ *  Compute the hash value
+ *
+ *  @param str (IN)     The string which will be parsed   (char*)
+ *  @param hash (OUT)   Where the hash value will be stored (uint32_t)
+ */
+#define OPAL_HASH_STR( str, hash )            \
+    do {                                      \
+        register const char *_str = (str);    \
+        register uint32_t    _hash = 0;       \
+                                              \
+        while( *_str ) {                      \
+            _hash += *_str++;                 \
+            _hash += (_hash << 10);           \
+            _hash ^= (_hash >> 6);            \
+        }                                     \
+                                              \
+        _hash += (_hash << 3);                \
+        _hash ^= (_hash >> 11);               \
+        (hash) = (_hash + (_hash << 15));     \
+    } while(0)
+
+#endif  /* OPAL_HASH_STRING_H */