use memchr for alligned string reads

Cargo.toml

@@ -14,6 +14,7 @@ travis-ci = { repository = "icewind1991/bitstream_reader" }
 num-traits = "0.2"
 bitstream_reader_derive = { version = "0.6", path = "bitstream_reader_derive" }
 bytecount = "0.5"
+memchr = "2.2"
 
 [dev-dependencies]
 maplit = "1.0.1"

src/buffer.rs

@@ -431,12 +431,8 @@ where
 
     #[inline]
     fn find_null_byte(&self, byte_index: usize) -> usize {
-        self.bytes
-            .iter()
-            .enumerate()
-            .skip(byte_index)
-            .find(|(_, byte)| **byte == 0)
-            .map(|(i, _)| i)
+        memchr::memchr(0, &self.bytes[byte_index..])
+            .map(|index| index + byte_index)
             .unwrap_or(self.byte_len())
     }