now version controlled.

1 files changed, 85 insertions, 0 deletions

diff --git a/hashing.c b/hashing.c
new file mode 100644
index 0000000..32e550f
--- /dev/null
+++ b/hashing.c
@@ -0,0 +1,85 @@
+#include <u.h>
+#include <libc.h>
+
+enum {
+	MULT = 31,
+	NHASH = 37,
+};
+
+uint
+hash(char *s)
+{
+	uint h;
+
+	h = 0;
+	while(*s != 0)
+		h = MULT * h + (uchar)*s++;
+	return h % NHASH;
+}
+
+uint
+djb2(char *s)
+{
+	uint h;
+
+	h = 5381;
+	while(*s != 0)
+		h = ((h << 5) + h) + (uchar)*s++;
+	return h % NHASH;
+}
+
+uint
+djb2a(char *s)
+{
+	uint h;
+
+	h = 5381;
+	while(*s != 0)
+		h = ((h << 5) + h) ^ (uchar)*s++;
+	return h % NHASH;
+}
+
+uint
+fnv1(char *s)
+{
+	uint h;
+
+	h = 0x811c9dc5;
+	while(*s != 0)
+		h = (h*0x1000193) ^ (uchar)*s++;
+	return h % NHASH;
+}
+
+uint
+fnv1a(char *s)
+{
+	uint h;
+
+	h = 0x811c9dc5;
+	while(*s != 0)
+		h = (h^(uchar)*s++) * 0x1000193;
+	return h % NHASH;
+}
+
+void
+usage(void)
+{
+	fprint(2, "usage: %s word\n", argv0);
+	exits("usage");
+}
+
+void
+main(int argc, char *argv[])
+{
+	ARGBEGIN{
+	default: usage();
+	}ARGEND;
+	if(argc != 1)
+		usage();
+	print("tpop:\t%ud\n", hash(*argv));
+	print("djb2:\t%ud\n", djb2(*argv));
+	print("djb2a:\t%ud\n", djb2a(*argv));
+	print("fnv1:\t%ud\n", fnv1(*argv));
+	print("fnv1a:\t%ud\n", fnv1a(*argv));
+	exits(0);
+}