From aa13e31894f69a3f5684b53af1954386e5d6fca4 Mon Sep 17 00:00:00 2001
From: HagaiHargil <hagaihargil@gmail.com>
Date: Sun, 13 Dec 2020 11:37:56 +0200
Subject: [PATCH] Initial i8 support

---
 src/bytecast.rs       |  2 +-
 src/decoder/mod.rs    | 29 ++++++++++++++++++++++++++++-
 src/decoder/stream.rs | 29 +++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+), 2 deletions(-)

diff --git a/src/bytecast.rs b/src/bytecast.rs
index 40e5fe5..0d8869f 100644
--- a/src/bytecast.rs
+++ b/src/bytecast.rs
@@ -23,7 +23,7 @@ macro_rules! integral_slice_as_bytes{($int:ty, $const:ident $(,$mut:ident)*) =>
     })*
 }}
 
-integral_slice_as_bytes!(i8, i8_as_ne_bytes);
+integral_slice_as_bytes!(i8, i8_as_ne_bytes, i8_as_ne_mut_bytes);
 integral_slice_as_bytes!(u16, u16_as_ne_bytes, u16_as_ne_mut_bytes);
 integral_slice_as_bytes!(i16, i16_as_ne_bytes, i16_as_ne_mut_bytes);
 integral_slice_as_bytes!(u32, u32_as_ne_bytes, u32_as_ne_mut_bytes);
diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index 042baba..e555fde 100644
--- a/src/decoder/mod.rs
+++ b/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),
                 )),
diff --git a/src/decoder/stream.rs b/src/decoder/stream.rs
index b371f05..862da76 100644
--- a/src/decoder/stream.rs
+++ b/src/decoder/stream.rs
@@ -48,6 +48,35 @@ pub trait EndianReader: Read {
         Ok(())
     }
 
+    /// Reads an i8
+    #[inline(always)]
+    fn read_i8(&mut self) -> Result<i8, io::Error> {
+        let mut n = [0u8; 1];
+        self.read_exact(&mut n)?;
+        Ok(match self.byte_order() {
+            ByteOrder::LittleEndian => i8::from_le_bytes(n),
+            ByteOrder::BigEndian => i8::from_be_bytes(n),
+        })
+    }
+
+    #[inline(always)]
+    fn read_i8_into(&mut self, buffer: &mut [i8]) -> Result<(), io::Error> {
+        self.read_exact(bytecast::i8_as_ne_mut_bytes(buffer))?;
+        match self.byte_order() {
+            ByteOrder::LittleEndian => {
+                for n in buffer {
+                    *n = i8::from_le(*n);
+                }
+            }
+            ByteOrder::BigEndian => {
+                for n in buffer {
+                    *n = i8::from_be(*n);
+                }
+            }
+        }
+        Ok(())
+    }
+
     /// Reads an i16
     #[inline(always)]
     fn read_i16(&mut self) -> Result<i16, io::Error> {