Initial i8 support

src/decoder/mod.rs

@@ -32,6 +32,8 @@ pub enum DecodingResult {
     F32(Vec<f32>),
     /// A vector of 64 bit IEEE floats
     F64(Vec<f64>),
+    /// A vector of 8 bit signed ints
+    I8(Vec<i8>),
     /// A vector of 16 bit signed ints
     I16(Vec<i16>),
 }
@@ -85,6 +87,14 @@ impl DecodingResult {
         }
     }
 
+    fn new_i8(size: usize, limits: &Limits) -> TiffResult<DecodingResult> {
+        if size > limits.decoding_buffer_size / std::mem::size_of::<i8>() {
+            Err(TiffError::LimitsExceeded)
+        } else {
+            Ok(DecodingResult::I8(vec![0; size]))
+        }
+    }
+
     fn new_i16(size: usize, limits: &Limits) -> TiffResult<DecodingResult> {
         if size > limits.decoding_buffer_size / 2 {
             Err(TiffError::LimitsExceeded)
@@ -101,6 +111,7 @@ impl DecodingResult {
             DecodingResult::U64(ref mut buf) => DecodingBuffer::U64(&mut buf[start..]),
             DecodingResult::F32(ref mut buf) => DecodingBuffer::F32(&mut buf[start..]),
             DecodingResult::F64(ref mut buf) => DecodingBuffer::F64(&mut buf[start..]),
+            DecodingResult::I8(ref mut buf) => DecodingBuffer::I8(&mut buf[start..]),
             DecodingResult::I16(ref mut buf) => DecodingBuffer::I16(&mut buf[start..]),
         }
     }
@@ -120,6 +131,8 @@ pub enum DecodingBuffer<'a> {
     F32(&'a mut [f32]),
     /// A slice of 64 bit IEEE floats
     F64(&'a mut [f64]),
+    /// A slice of 8 bits signed ints
+    I8(&'a mut [i8]),
     /// A slice of 16 bits signed ints
     I16(&'a mut [i16]),
 }
@@ -133,6 +146,7 @@ impl<'a> DecodingBuffer<'a> {
             DecodingBuffer::U64(ref buf) => buf.len(),
             DecodingBuffer::F32(ref buf) => buf.len(),
             DecodingBuffer::F64(ref buf) => buf.len(),
+            DecodingBuffer::I8(ref buf) => buf.len(),
             DecodingBuffer::I16(ref buf) => buf.len(),
         }
     }
@@ -145,6 +159,7 @@ impl<'a> DecodingBuffer<'a> {
             DecodingBuffer::U64(_) => 8,
             DecodingBuffer::F32(_) => 4,
             DecodingBuffer::F64(_) => 8,
+            DecodingBuffer::I8(_) => 1,
             DecodingBuffer::I16(_) => 2,
         }
     }
@@ -160,6 +175,7 @@ impl<'a> DecodingBuffer<'a> {
             DecodingBuffer::U64(ref mut buf) => DecodingBuffer::U64(buf),
             DecodingBuffer::F32(ref mut buf) => DecodingBuffer::F32(buf),
             DecodingBuffer::F64(ref mut buf) => DecodingBuffer::F64(buf),
+            DecodingBuffer::I8(ref mut buf) => DecodingBuffer::I8(buf),
             DecodingBuffer::I16(ref mut buf) => DecodingBuffer::I16(buf),
         }
     }
@@ -273,6 +289,13 @@ impl Wrapping for u64 {
     }
 }
 
+
+impl Wrapping for i8 {
+    fn wrapping_add(&self, other: Self) -> Self {
+        i8::wrapping_add(*self, other)
+    }
+}
+
 impl Wrapping for i16 {
     fn wrapping_add(&self, other: Self) -> Self {
         i16::wrapping_add(*self, other)
@@ -342,6 +365,9 @@ fn rev_hpredict(image: DecodingBuffer, size: (u32, u32), color_type: ColorType)
                 TiffUnsupportedError::HorizontalPredictor(color_type),
             ));
         }
+        DecodingBuffer::I8(buf) => {
+            rev_hpredict_nsamp(buf, size, samples)?;
+        }
         DecodingBuffer::I16(buf) => {
             rev_hpredict_nsamp(buf, size, samples)?;
         }
@@ -1152,7 +1178,8 @@ impl<R: Read + Seek> Decoder<R> {
                 )),
             },
             SampleFormat::Int => match max_sample_bits {
-                n if n <= 16 => DecodingResult::new_i16(buffer_size, &self.limits),
+                n if n <= 8 => DecodingResult::new_i8(buffer_size, &self.limits),
+                n if (n > 8) & (n <= 16) => DecodingResult::new_i16(buffer_size, &self.limits),
                 n => Err(TiffError::UnsupportedError(
                     TiffUnsupportedError::UnsupportedBitsPerChannel(n),
                 )),