1 files changed, 69 insertions, 0 deletions
diff --git a/vendor/simd-adler32/src/imp/scalar.rs b/vendor/simd-adler32/src/imp/scalar.rs
new file mode 100644
index 0000000..558813e
--- /dev/null
+++ b/vendor/simd-adler32/src/imp/scalar.rs
@@ -0,0 +1,69 @@
+const MOD: u32 = 65521;
+const NMAX: usize = 5552;
+
+pub fn update(a: u16, b: u16, data: &[u8]) -> (u16, u16) {
+  let mut a = a as u32;
+  let mut b = b as u32;
+
+  let chunks = data.chunks_exact(NMAX);
+  let remainder = chunks.remainder();
+
+  for chunk in chunks {
+    for byte in chunk {
+      a = a.wrapping_add(*byte as _);
+      b = b.wrapping_add(a);
+    }
+
+    a %= MOD;
+    b %= MOD;
+  }
+
+  for byte in remainder {
+    a = a.wrapping_add(*byte as _);
+    b = b.wrapping_add(a);
+  }
+
+  a %= MOD;
+  b %= MOD;
+
+  (a as u16, b as u16)
+}
+
+#[cfg(test)]
+mod tests {
+  #[test]
+  fn zeroes() {
+    assert_eq!(adler32(&[]), 1);
+    assert_eq!(adler32(&[0]), 1 | 1 << 16);
+    assert_eq!(adler32(&[0, 0]), 1 | 2 << 16);
+    assert_eq!(adler32(&[0; 100]), 0x00640001);
+    assert_eq!(adler32(&[0; 1024]), 0x04000001);
+    assert_eq!(adler32(&[0; 1024 * 1024]), 0x00f00001);
+  }
+
+  #[test]
+  fn ones() {
+    assert_eq!(adler32(&[0xff; 1024]), 0x79a6fc2e);
+    assert_eq!(adler32(&[0xff; 1024 * 1024]), 0x8e88ef11);
+  }
+
+  #[test]
+  fn mixed() {
+    assert_eq!(adler32(&[1]), 2 | 2 << 16);
+    assert_eq!(adler32(&[40]), 41 | 41 << 16);
+
+    assert_eq!(adler32(&[0xA5; 1024 * 1024]), 0xd5009ab1);
+  }
+
+  /// Example calculation from https://en.wikipedia.org/wiki/Adler-32.
+  #[test]
+  fn wiki() {
+    assert_eq!(adler32(b"Wikipedia"), 0x11E60398);
+  }
+
+  fn adler32(data: &[u8]) -> u32 {
+    let (a, b) = super::update(1, 0, data);
+
+    u32::from(b) << 16 | u32::from(a)
+  }
+}