Fix bug with id_pat and read_bytes_const

* Fix setting last read length, intsead of incorrectly adding

src/reader.rs

@@ -319,7 +319,7 @@ impl<'a, R: Read + Seek> Reader<'a, R> {
             }
 
             let bits_read = amt * 8;
-            self.last_bits_read_amt += bits_read;
+            self.last_bits_read_amt = bits_read;
             self.bits_read += bits_read;
 
             #[cfg(feature = "logging")]
@@ -403,7 +403,7 @@ impl<'a, R: Read + Seek> Reader<'a, R> {
                 return Err(DekuError::Io(e.kind()));
             }
 
-            self.last_bits_read_amt += N * 8;
+            self.last_bits_read_amt = N * 8;
             self.bits_read += N * 8;
 
             #[cfg(feature = "logging")]
@@ -518,4 +518,52 @@ mod tests {
         let _ = reader.read_bytes(1, &mut buf);
         assert_eq!([0xaa], buf);
     }
+
+    #[test]
+    fn test_seek_last_read_bytes() {
+        // bytes
+        let input = hex!("aa");
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let mut buf = [0; 1];
+        let _ = reader.read_bytes(1, &mut buf);
+        assert_eq!([0xaa], buf);
+        reader.seek_last_read().unwrap();
+        let _ = reader.read_bytes(1, &mut buf);
+        assert_eq!([0xaa], buf);
+
+        // 2 bytes (and const)
+        let input = hex!("aabb");
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let mut buf = [0; 2];
+        let _ = reader.read_bytes_const::<2>(&mut buf);
+        assert_eq!([0xaa, 0xbb], buf);
+        reader.seek_last_read().unwrap();
+        let _ = reader.read_bytes_const::<2>(&mut buf);
+        assert_eq!([0xaa, 0xbb], buf);
+    }
+
+    #[cfg(feature = "bits")]
+    #[test]
+    fn test_seek_last_read_bits() {
+        let input = hex!("ab");
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let bits = reader.read_bits(4).unwrap();
+        assert_eq!(bits, Some(bitvec![u8, Msb0; 1, 0, 1, 0]));
+        reader.seek_last_read().unwrap();
+        let bits = reader.read_bits(4).unwrap();
+        assert_eq!(bits, Some(bitvec![u8, Msb0; 1, 0, 1, 0]));
+
+        // more than byte
+        let input = hex!("abd0");
+        let mut cursor = Cursor::new(input);
+        let mut reader = Reader::new(&mut cursor);
+        let bits = reader.read_bits(9).unwrap();
+        assert_eq!(bits, Some(bitvec![u8, Msb0; 1, 0, 1, 0, 1, 0, 1, 1, 1]));
+        reader.seek_last_read().unwrap();
+        let bits = reader.read_bits(9).unwrap();
+        assert_eq!(bits, Some(bitvec![u8, Msb0; 1, 0, 1, 0, 1, 0, 1, 1, 1]));
+    }
 }