Initial commit

1 files changed, 33 insertions, 0 deletions

diff --git a/include/hashfuncs.h b/include/hashfuncs.h
new file mode 100755
index 0000000..da5d788
--- /dev/null
+++ b/include/hashfuncs.h
@@ -0,0 +1,33 @@
+#include <stdlib.h>
+
+/*
+ *
+ * 32 bit FNV-1a algorithm
+ * https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
+ *
+ */
+static size_t hash_key(const char *key, const size_t max_hash_value) {
+  uint32_t hash = 2166136261U; /* FNV-1a 32-bit offset basis */
+  /*
+   * We'll explicitly use unsigned chars here, since we're doing arithmetic. The
+   * C standard doesn't state whether an implementation must use signed or
+   * unsigned values for characters, so this conversion ensures we get
+   * correct behavior. If signed characters are used, we'll get overflows
+   * and other odd issues in the hash calculation.
+   */
+  const unsigned char *p = (unsigned char *) key;
+
+  while (*p) {
+    hash ^= *p++;
+    hash *= 16777619U; /* FNV-1a prime */
+  }
+
+  return hash % max_hash_value;
+}
+
+static size_t test_hash(const char *key, const size_t max_hash_value) {
+  (void) max_hash_value;
+
+  return key[0] % 3;
+}
+