1 files changed, 61 insertions, 0 deletions
diff --git a/src/hash.h b/src/hash.h
new file mode 100644
index 0000000..f2534e9
--- /dev/null
+++ b/src/hash.h
@@ -0,0 +1,61 @@
+/*
+ * hash.h
+ * generic hash functions
+ */
+
+#ifndef HASH_H
+#define HASH_H
+
+#include "pooltypes.h"
+
+/* value of a hash */
+typedef unsigned int Hashval;
+/* mask for hash, used as modulo operator to ensure 'wrapping' of hash
+   values -> hash table */
+typedef unsigned int Hashmask;
+
+/* inside the hash table, Ids are stored. Hash maps: string -> hash -> Id */
+typedef Id *Hashtable;
+
+/* hash chain */
+#define HASHCHAIN_START 7
+#define HASHCHAIN_NEXT(h, hh, mask) (((h) + (hh)++) & (mask))
+
+/* very simple hash function
+ * string -> hash
+ */
+static inline Hashval
+strhash(const char *str)
+{
+  Hashval r = 0;
+  unsigned int c;
+  while ((c = *(const unsigned char *)str++) != 0)
+    r += (r << 3) + c;
+  return r;
+}
+
+/* hash for rel
+ * rel -> hash
+ */
+static inline Hashval
+relhash(Id name, Id evr, int flags)
+{
+  return name + 7 * evr + 13 * flags;
+}
+
+
+/* compute bitmask for value
+ * returns smallest (2^n-1) > num
+ * 
+ * used for Hashtable 'modulo' operation
+ */ 
+static inline Hashmask
+mkmask(unsigned int num)
+{
+  num *= 2;
+  while (num & (num - 1))
+    num &= num - 1;
+  return num * 2 - 1;
+}
+
+#endif /* HASH_H */