1 files changed, 87 insertions, 0 deletions
diff --git a/siphash.c b/siphash.c
new file mode 100644
index 0000000..7a5c8d4
--- /dev/null
+++ b/siphash.c
@@ -0,0 +1,87 @@
+// Code taken from https://github.com/floodyberry/siphash with some edits.
+//
+// To the extent possible under law, the author(s) have dedicated all copyright
+// and related and neighboring rights to this software to the public domain
+// worldwide. This software is distributed without any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication along
+// with this software. If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+#include "siphash.h"
+
+inline static uint64_t
+u8to64_le (const unsigned char *p)
+{
+	return
+		(uint64_t) p[0]       |
+		(uint64_t) p[1] <<  8 |
+		(uint64_t) p[2] << 16 |
+		(uint64_t) p[3] << 24 |
+		(uint64_t) p[4] << 32 |
+		(uint64_t) p[5] << 40 |
+		(uint64_t) p[6] << 48 |
+		(uint64_t) p[7] << 56 ;
+}
+
+uint64_t
+siphash (const unsigned char key[16], const unsigned char *m, size_t len)
+{
+	uint64_t v0, v1, v2, v3;
+	uint64_t mi, k0, k1;
+	uint64_t last7;
+	size_t i, blocks;
+
+	k0 = u8to64_le (key + 0);
+	k1 = u8to64_le (key + 8);
+	v0 = k0 ^ 0x736f6d6570736575ull;
+	v1 = k1 ^ 0x646f72616e646f6dull;
+	v2 = k0 ^ 0x6c7967656e657261ull;
+	v3 = k1 ^ 0x7465646279746573ull;
+
+	last7 = (uint64_t) (len & 0xff) << 56;
+
+#define ROTL64(a,b) (((a)<<(b))|((a)>>(64-b)))
+
+#define COMPRESS                              \
+	v0 += v1; v2 += v3;                       \
+	v1 = ROTL64 (v1,13); v3 = ROTL64 (v3,16); \
+	v1 ^= v0; v3 ^= v2;                       \
+	v0 = ROTL64 (v0,32);                      \
+	v2 += v1; v0 += v3;                       \
+	v1 = ROTL64 (v1,17); v3 = ROTL64 (v3,21); \
+	v1 ^= v2; v3 ^= v0;                       \
+	v2 = ROTL64(v2,32);
+
+	for (i = 0, blocks = (len & ~(size_t) 7); i < blocks; i += 8)
+	{
+		mi = u8to64_le (m + i);
+		v3 ^= mi;
+		COMPRESS
+		COMPRESS
+		v0 ^= mi;
+	}
+
+	switch (len - blocks)
+	{
+	case 7: last7 |= (uint64_t) m[i + 6] << 48;
+	case 6: last7 |= (uint64_t) m[i + 5] << 40;
+	case 5: last7 |= (uint64_t) m[i + 4] << 32;
+	case 4: last7 |= (uint64_t) m[i + 3] << 24;
+	case 3: last7 |= (uint64_t) m[i + 2] << 16;
+	case 2: last7 |= (uint64_t) m[i + 1] <<  8;
+	case 1: last7 |= (uint64_t) m[i + 0]      ;
+	default:;
+	};
+	v3 ^= last7;
+	COMPRESS
+	COMPRESS
+	v0 ^= last7;
+	v2 ^= 0xff;
+	COMPRESS
+	COMPRESS
+	COMPRESS
+	COMPRESS
+
+	return v0 ^ v1 ^ v2 ^ v3;
+}
+