1 files changed, 115 insertions, 0 deletions
diff --git a/third_party/rust/murmurhash3/src/mmh3_32.rs b/third_party/rust/murmurhash3/src/mmh3_32.rs
new file mode 100644
index 0000000000..49b7a59650
--- /dev/null
+++ b/third_party/rust/murmurhash3/src/mmh3_32.rs
@@ -0,0 +1,115 @@
+use std::mem;
+
+fn fmix32(mut h: u32) -> u32 {
+    h ^= h >> 16;
+    h = h.wrapping_mul(0x85ebca6b);
+    h ^= h >> 13;
+    h = h.wrapping_mul(0xc2b2ae35);
+    h ^= h >> 16;
+
+    return h;
+}
+
+fn get_32_block(bytes: &[u8], index: usize) -> u32 {
+    let b32: &[u32] = unsafe { mem::transmute(bytes) };
+
+    return b32[index];
+}
+
+pub fn murmurhash3_x86_32(bytes: &[u8], seed: u32) -> u32 {
+    let c1 = 0xcc9e2d51u32;
+    let c2 = 0x1b873593u32;
+    let read_size = 4;
+    let len = bytes.len() as u32;
+    let block_count = len / read_size;
+
+    let mut h1 = seed;
+
+    for i in 0..block_count as usize {
+        let mut k1 = get_32_block(bytes, i);
+
+        k1 = k1.wrapping_mul(c1);
+        k1 = k1.rotate_left(15);
+        k1 = k1.wrapping_mul(c2);
+
+        h1 ^= k1;
+        h1 = h1.rotate_left(13);
+        h1 = h1.wrapping_mul(5);
+        h1 = h1.wrapping_add(0xe6546b64)
+    }
+    let mut k1 = 0u32;
+
+    if len & 3 == 3 { k1 ^= (bytes[(block_count * read_size) as usize + 2] as u32) << 16; }
+    if len & 3 >= 2 { k1 ^= (bytes[(block_count * read_size) as usize + 1] as u32) << 8; }
+    if len & 3 >= 1 { k1 ^=  bytes[(block_count * read_size) as usize + 0] as u32;
+        k1 = k1.wrapping_mul(c1);
+        k1 = k1.rotate_left(15);
+        k1 = k1.wrapping_mul(c2);
+        h1 ^= k1;
+    }
+
+    h1 ^= bytes.len() as u32;
+    h1 = fmix32(h1);
+
+    return h1;
+}
+
+#[cfg(test)]
+mod test {
+    use super::murmurhash3_x86_32;
+
+    #[test]
+    fn test_empty_string() {
+        assert!(murmurhash3_x86_32("".as_bytes(), 0) == 0);
+    }
+
+    #[test]
+    fn test_tail_lengths() {
+        assert!(murmurhash3_x86_32("1".as_bytes(), 0)
+            == 2484513939);
+        assert!(murmurhash3_x86_32("12".as_bytes(), 0)
+            == 4191350549);
+        assert!(murmurhash3_x86_32("123".as_bytes(), 0)
+            == 2662625771);
+        assert!(murmurhash3_x86_32("1234".as_bytes(), 0)
+            == 1914461635);
+    }
+
+    #[test]
+    fn test_large_data() {
+        assert!(murmurhash3_x86_32("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Etiam at consequat massa. Cras eleifend pellentesque ex, at dignissim libero maximus ut. Sed eget nulla felis".as_bytes(), 0)
+            == 1004899618);
+    }
+
+    #[cfg(feature="nightly")]
+    mod bench {
+        extern crate rand;
+        extern crate test;
+
+        use std::iter::FromIterator;
+        use self::rand::Rng;
+        use self::test::{Bencher, black_box};
+
+        use super::super::murmurhash3_x86_32;
+
+        fn run_bench(b: &mut Bencher, size: u64) {
+            let mut data: Vec<u8> = FromIterator::from_iter((0..size).map(|_| 0u8));
+            rand::thread_rng().fill_bytes(&mut data);
+
+            b.bytes = size;
+            b.iter(|| {
+                black_box(murmurhash3_x86_32(&data, 0));
+            });
+        }
+
+        #[bench]
+        fn bench_random_256k(b: &mut Bencher) {
+            run_bench(b, 256 * 1024);
+        }
+
+        #[bench]
+        fn bench_random_16b(b: &mut Bencher) {
+            run_bench(b, 16);
+        }
+    }
+}