C implementation of hash function.

base/modules/aux/hashval.c

@@ -0,0 +1,49 @@
+#include <stdint.h>
+/*
+   This is based on the djb2 hashing algorithm
+   see e.g. http://www.cse.yorku.ca/~oz/hash.html
+*/  
+
+#define IVAL     5381
+#define H32MASK  0x7FFFFFFF
+#define H64MASK  0x7FFFFFFFFFFFFFFF
+#define BMASK    0xFF
+
+int32_t psb_chashval_32(int32_t inkey)
+{
+  uint32_t key, val, i;
+  key = inkey;
+  val = IVAL;
+  for (i=0; i<4; i++) {
+    val = ((val<<5)+val)+(key & BMASK);
+    key >>= 8;
+  }
+  val &= H32MASK;
+  return(val);
+}
+
+int64_t psb_chashval_64(int64_t inkey)
+{
+  uint64_t key, val, i;
+  key = inkey;
+  val = IVAL;
+  for (i=0; i<8; i++) {
+    val = ((val<<5)+val)+(key & BMASK);
+    key >>= 8;
+  }
+  val &= H64MASK;
+  return(val);
+}
+
+int32_t psb_chashval_64_32(int64_t inkey)
+{
+  uint32_t key, val, i;
+  key = inkey;
+  val = IVAL;
+  for (i=0; i<8; i++) {
+    val = ((val<<5)+val)+(key & BMASK);
+    key >>= 8;
+  }
+  val &= H32MASK;
+  return(val);
+}