Parse SSHORT fields.

src/value.rs

@@ -48,6 +48,8 @@ pub enum Value<'a> {
     SByte(Vec<i8>),
     /// Slice of 8-bit bytes.
     Undefined(&'a [u8]),
+    /// Vector of 16-bit signed integers.  Unused in the Exif specification.
+    SShort(Vec<i16>),
     /// The type is unknown to this implementation.
     /// The associated values are the type and the count, and the
     /// offset of the "Value Offset" element.
@@ -76,6 +78,7 @@ pub fn get_type_info<'a, E>(typecode: u16)
         5 => (8, parse_rational::<E>),
         6 => (1, parse_sbyte),
         7 => (1, parse_undefined),
+        8 => (2, parse_sshort::<E>),
         _ => (0, parse_unknown),
     }
 }
@@ -140,6 +143,15 @@ fn parse_undefined<'a>(data: &'a [u8], offset: usize, count: usize)
     Value::Undefined(&data[offset .. offset + count])
 }
 
+fn parse_sshort<'a, E>(data: &'a [u8], offset: usize, count: usize)
+                       -> Value<'a> where E: Endian {
+    let mut val = Vec::with_capacity(count);
+    for i in 0..count {
+        val.push(E::loadu16(data, offset + i * 2) as i16);
+    }
+    Value::SShort(val)
+}
+
 // This is a dummy function and will never be called.
 #[allow(unused_variables)]
 fn parse_unknown<'a>(data: &'a [u8], offset: usize, count: usize)
@@ -277,4 +289,20 @@ mod tests {
             }
         }
     }
+
+    #[test]
+    fn sshort() {
+        let sets: &[(&[u8], Vec<i16>)] = &[
+            (b"x", vec![]),
+            (b"x\x01\x02\xf3\x04", vec![0x0102, -0x0cfc]),
+        ];
+        let (unitlen, parser) = get_type_info::<BigEndian>(8);
+        for &(data, ref ans) in sets {
+            assert!((data.len() - 1) % unitlen == 0);
+            match parser(data, 1, (data.len() - 1) / unitlen) {
+                Value::SShort(v) => assert_eq!(v, *ans),
+                v => panic!("wrong variant {:?}", v),
+            }
+        }
+    }
 }