1 files changed, 94 insertions, 0 deletions
diff --git a/third_party/rust/crc32fast/src/baseline.rs b/third_party/rust/crc32fast/src/baseline.rs
new file mode 100644
index 0000000000..fbc4136bae
--- /dev/null
+++ b/third_party/rust/crc32fast/src/baseline.rs
@@ -0,0 +1,94 @@
+use table::CRC32_TABLE;
+
+#[derive(Clone)]
+pub struct State {
+    state: u32,
+}
+
+impl State {
+    pub fn new(state: u32) -> Self {
+        State { state }
+    }
+
+    pub fn update(&mut self, buf: &[u8]) {
+        self.state = update_fast_16(self.state, buf);
+    }
+
+    pub fn finalize(self) -> u32 {
+        self.state
+    }
+
+    pub fn reset(&mut self) {
+        self.state = 0;
+    }
+
+    pub fn combine(&mut self, other: u32, amount: u64) {
+        self.state = ::combine::combine(self.state, other, amount);
+    }
+}
+
+pub(crate) fn update_fast_16(prev: u32, mut buf: &[u8]) -> u32 {
+    const UNROLL: usize = 4;
+    const BYTES_AT_ONCE: usize = 16 * UNROLL;
+
+    let mut crc = !prev;
+
+    while buf.len() >= BYTES_AT_ONCE {
+        for _ in 0..UNROLL {
+            crc = CRC32_TABLE[0x0][buf[0xf] as usize]
+                ^ CRC32_TABLE[0x1][buf[0xe] as usize]
+                ^ CRC32_TABLE[0x2][buf[0xd] as usize]
+                ^ CRC32_TABLE[0x3][buf[0xc] as usize]
+                ^ CRC32_TABLE[0x4][buf[0xb] as usize]
+                ^ CRC32_TABLE[0x5][buf[0xa] as usize]
+                ^ CRC32_TABLE[0x6][buf[0x9] as usize]
+                ^ CRC32_TABLE[0x7][buf[0x8] as usize]
+                ^ CRC32_TABLE[0x8][buf[0x7] as usize]
+                ^ CRC32_TABLE[0x9][buf[0x6] as usize]
+                ^ CRC32_TABLE[0xa][buf[0x5] as usize]
+                ^ CRC32_TABLE[0xb][buf[0x4] as usize]
+                ^ CRC32_TABLE[0xc][buf[0x3] as usize ^ ((crc >> 0x18) & 0xFF) as usize]
+                ^ CRC32_TABLE[0xd][buf[0x2] as usize ^ ((crc >> 0x10) & 0xFF) as usize]
+                ^ CRC32_TABLE[0xe][buf[0x1] as usize ^ ((crc >> 0x08) & 0xFF) as usize]
+                ^ CRC32_TABLE[0xf][buf[0x0] as usize ^ ((crc >> 0x00) & 0xFF) as usize];
+            buf = &buf[16..];
+        }
+    }
+
+    update_slow(!crc, buf)
+}
+
+pub(crate) fn update_slow(prev: u32, buf: &[u8]) -> u32 {
+    let mut crc = !prev;
+
+    for &byte in buf.iter() {
+        crc = CRC32_TABLE[0][((crc as u8) ^ byte) as usize] ^ (crc >> 8);
+    }
+
+    !crc
+}
+
+#[cfg(test)]
+mod test {
+    #[test]
+    fn slow() {
+        assert_eq!(super::update_slow(0, b""), 0);
+
+        // test vectors from the iPXE project (input and output are bitwise negated)
+        assert_eq!(super::update_slow(!0x12345678, b""), !0x12345678);
+        assert_eq!(super::update_slow(!0xffffffff, b"hello world"), !0xf2b5ee7a);
+        assert_eq!(super::update_slow(!0xffffffff, b"hello"), !0xc9ef5979);
+        assert_eq!(super::update_slow(!0xc9ef5979, b" world"), !0xf2b5ee7a);
+
+        // Some vectors found on Rosetta code
+        assert_eq!(super::update_slow(0, b"\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00"), 0x190A55AD);
+        assert_eq!(super::update_slow(0, b"\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF"), 0xFF6CAB0B);
+        assert_eq!(super::update_slow(0, b"\x00\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0A\x0B\x0C\x0D\x0E\x0F\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1A\x1B\x1C\x1D\x1E\x1F"), 0x91267E8A);
+    }
+
+    quickcheck! {
+        fn fast_16_is_the_same_as_slow(crc: u32, bytes: Vec<u8>) -> bool {
+            super::update_fast_16(crc, &bytes) == super::update_slow(crc, &bytes)
+        }
+    }
+}