1 files changed, 396 insertions, 0 deletions
diff --git a/vendor/qoi/src/decode.rs b/vendor/qoi/src/decode.rs
new file mode 100644
index 0000000..019dac2
--- /dev/null
+++ b/vendor/qoi/src/decode.rs
@@ -0,0 +1,396 @@
+#[cfg(any(feature = "std", feature = "alloc"))]
+use alloc::{vec, vec::Vec};
+#[cfg(feature = "std")]
+use std::io::Read;
+
+// TODO: can be removed once https://github.com/rust-lang/rust/issues/74985 is stable
+use bytemuck::{cast_slice_mut, Pod};
+
+use crate::consts::{
+    QOI_HEADER_SIZE, QOI_OP_DIFF, QOI_OP_INDEX, QOI_OP_LUMA, QOI_OP_RGB, QOI_OP_RGBA, QOI_OP_RUN,
+    QOI_PADDING, QOI_PADDING_SIZE,
+};
+use crate::error::{Error, Result};
+use crate::header::Header;
+use crate::pixel::{Pixel, SupportedChannels};
+use crate::types::Channels;
+use crate::utils::{cold, unlikely};
+
+const QOI_OP_INDEX_END: u8 = QOI_OP_INDEX | 0x3f;
+const QOI_OP_RUN_END: u8 = QOI_OP_RUN | 0x3d; // <- note, 0x3d (not 0x3f)
+const QOI_OP_DIFF_END: u8 = QOI_OP_DIFF | 0x3f;
+const QOI_OP_LUMA_END: u8 = QOI_OP_LUMA | 0x3f;
+
+#[inline]
+fn decode_impl_slice<const N: usize, const RGBA: bool>(data: &[u8], out: &mut [u8]) -> Result<usize>
+where
+    Pixel<N>: SupportedChannels,
+    [u8; N]: Pod,
+{
+    let mut pixels = cast_slice_mut::<_, [u8; N]>(out);
+    let data_len = data.len();
+    let mut data = data;
+
+    let mut index = [Pixel::<4>::new(); 256];
+    let mut px = Pixel::<N>::new().with_a(0xff);
+    let mut px_rgba: Pixel<4>;
+
+    while let [px_out, ptail @ ..] = pixels {
+        pixels = ptail;
+        match data {
+            [b1 @ QOI_OP_INDEX..=QOI_OP_INDEX_END, dtail @ ..] => {
+                px_rgba = index[*b1 as usize];
+                px.update(px_rgba);
+                *px_out = px.into();
+                data = dtail;
+                continue;
+            }
+            [QOI_OP_RGB, r, g, b, dtail @ ..] => {
+                px.update_rgb(*r, *g, *b);
+                data = dtail;
+            }
+            [QOI_OP_RGBA, r, g, b, a, dtail @ ..] if RGBA => {
+                px.update_rgba(*r, *g, *b, *a);
+                data = dtail;
+            }
+            [b1 @ QOI_OP_RUN..=QOI_OP_RUN_END, dtail @ ..] => {
+                *px_out = px.into();
+                let run = ((b1 & 0x3f) as usize).min(pixels.len());
+                let (phead, ptail) = pixels.split_at_mut(run); // can't panic
+                phead.fill(px.into());
+                pixels = ptail;
+                data = dtail;
+                continue;
+            }
+            [b1 @ QOI_OP_DIFF..=QOI_OP_DIFF_END, dtail @ ..] => {
+                px.update_diff(*b1);
+                data = dtail;
+            }
+            [b1 @ QOI_OP_LUMA..=QOI_OP_LUMA_END, b2, dtail @ ..] => {
+                px.update_luma(*b1, *b2);
+                data = dtail;
+            }
+            _ => {
+                cold();
+                if unlikely(data.len() < QOI_PADDING_SIZE) {
+                    return Err(Error::UnexpectedBufferEnd);
+                }
+            }
+        }
+
+        px_rgba = px.as_rgba(0xff);
+        index[px_rgba.hash_index() as usize] = px_rgba;
+        *px_out = px.into();
+    }
+
+    if unlikely(data.len() < QOI_PADDING_SIZE) {
+        return Err(Error::UnexpectedBufferEnd);
+    } else if unlikely(data[..QOI_PADDING_SIZE] != QOI_PADDING) {
+        return Err(Error::InvalidPadding);
+    }
+
+    Ok(data_len.saturating_sub(data.len()).saturating_sub(QOI_PADDING_SIZE))
+}
+
+#[inline]
+fn decode_impl_slice_all(
+    data: &[u8], out: &mut [u8], channels: u8, src_channels: u8,
+) -> Result<usize> {
+    match (channels, src_channels) {
+        (3, 3) => decode_impl_slice::<3, false>(data, out),
+        (3, 4) => decode_impl_slice::<3, true>(data, out),
+        (4, 3) => decode_impl_slice::<4, false>(data, out),
+        (4, 4) => decode_impl_slice::<4, true>(data, out),
+        _ => {
+            cold();
+            Err(Error::InvalidChannels { channels })
+        }
+    }
+}
+
+/// Decode the image into a pre-allocated buffer.
+///
+/// Note: the resulting number of channels will match the header. In order to change
+/// the number of channels, use [`Decoder::with_channels`].
+#[inline]
+pub fn decode_to_buf(buf: impl AsMut<[u8]>, data: impl AsRef<[u8]>) -> Result<Header> {
+    let mut decoder = Decoder::new(&data)?;
+    decoder.decode_to_buf(buf)?;
+    Ok(*decoder.header())
+}
+
+/// Decode the image into a newly allocated vector.
+///
+/// Note: the resulting number of channels will match the header. In order to change
+/// the number of channels, use [`Decoder::with_channels`].
+#[cfg(any(feature = "std", feature = "alloc"))]
+#[inline]
+pub fn decode_to_vec(data: impl AsRef<[u8]>) -> Result<(Header, Vec<u8>)> {
+    let mut decoder = Decoder::new(&data)?;
+    let out = decoder.decode_to_vec()?;
+    Ok((*decoder.header(), out))
+}
+
+/// Decode the image header from a slice of bytes.
+#[inline]
+pub fn decode_header(data: impl AsRef<[u8]>) -> Result<Header> {
+    Header::decode(data)
+}
+
+#[cfg(any(feature = "std"))]
+#[inline]
+fn decode_impl_stream<R: Read, const N: usize, const RGBA: bool>(
+    data: &mut R, out: &mut [u8],
+) -> Result<()>
+where
+    Pixel<N>: SupportedChannels,
+    [u8; N]: Pod,
+{
+    let mut pixels = cast_slice_mut::<_, [u8; N]>(out);
+
+    let mut index = [Pixel::<N>::new(); 256];
+    let mut px = Pixel::<N>::new().with_a(0xff);
+
+    while let [px_out, ptail @ ..] = pixels {
+        pixels = ptail;
+        let mut p = [0];
+        data.read_exact(&mut p)?;
+        let [b1] = p;
+        match b1 {
+            QOI_OP_INDEX..=QOI_OP_INDEX_END => {
+                px = index[b1 as usize];
+                *px_out = px.into();
+                continue;
+            }
+            QOI_OP_RGB => {
+                let mut p = [0; 3];
+                data.read_exact(&mut p)?;
+                px.update_rgb(p[0], p[1], p[2]);
+            }
+            QOI_OP_RGBA if RGBA => {
+                let mut p = [0; 4];
+                data.read_exact(&mut p)?;
+                px.update_rgba(p[0], p[1], p[2], p[3]);
+            }
+            QOI_OP_RUN..=QOI_OP_RUN_END => {
+                *px_out = px.into();
+                let run = ((b1 & 0x3f) as usize).min(pixels.len());
+                let (phead, ptail) = pixels.split_at_mut(run); // can't panic
+                phead.fill(px.into());
+                pixels = ptail;
+                continue;
+            }
+            QOI_OP_DIFF..=QOI_OP_DIFF_END => {
+                px.update_diff(b1);
+            }
+            QOI_OP_LUMA..=QOI_OP_LUMA_END => {
+                let mut p = [0];
+                data.read_exact(&mut p)?;
+                let [b2] = p;
+                px.update_luma(b1, b2);
+            }
+            _ => {
+                cold();
+            }
+        }
+
+        index[px.hash_index() as usize] = px;
+        *px_out = px.into();
+    }
+
+    let mut p = [0_u8; QOI_PADDING_SIZE];
+    data.read_exact(&mut p)?;
+    if unlikely(p != QOI_PADDING) {
+        return Err(Error::InvalidPadding);
+    }
+
+    Ok(())
+}
+
+#[cfg(feature = "std")]
+#[inline]
+fn decode_impl_stream_all<R: Read>(
+    data: &mut R, out: &mut [u8], channels: u8, src_channels: u8,
+) -> Result<()> {
+    match (channels, src_channels) {
+        (3, 3) => decode_impl_stream::<_, 3, false>(data, out),
+        (3, 4) => decode_impl_stream::<_, 3, true>(data, out),
+        (4, 3) => decode_impl_stream::<_, 4, false>(data, out),
+        (4, 4) => decode_impl_stream::<_, 4, true>(data, out),
+        _ => {
+            cold();
+            Err(Error::InvalidChannels { channels })
+        }
+    }
+}
+
+#[doc(hidden)]
+pub trait Reader: Sized {
+    fn decode_header(&mut self) -> Result<Header>;
+    fn decode_image(&mut self, out: &mut [u8], channels: u8, src_channels: u8) -> Result<()>;
+}
+
+pub struct Bytes<'a>(&'a [u8]);
+
+impl<'a> Bytes<'a> {
+    #[inline]
+    pub const fn new(buf: &'a [u8]) -> Self {
+        Self(buf)
+    }
+
+    #[inline]
+    pub const fn as_slice(&self) -> &[u8] {
+        self.0
+    }
+}
+
+impl<'a> Reader for Bytes<'a> {
+    #[inline]
+    fn decode_header(&mut self) -> Result<Header> {
+        let header = Header::decode(self.0)?;
+        self.0 = &self.0[QOI_HEADER_SIZE..]; // can't panic
+        Ok(header)
+    }
+
+    #[inline]
+    fn decode_image(&mut self, out: &mut [u8], channels: u8, src_channels: u8) -> Result<()> {
+        let n_read = decode_impl_slice_all(self.0, out, channels, src_channels)?;
+        self.0 = &self.0[n_read..];
+        Ok(())
+    }
+}
+
+#[cfg(feature = "std")]
+impl<R: Read> Reader for R {
+    #[inline]
+    fn decode_header(&mut self) -> Result<Header> {
+        let mut b = [0; QOI_HEADER_SIZE];
+        self.read_exact(&mut b)?;
+        Header::decode(b)
+    }
+
+    #[inline]
+    fn decode_image(&mut self, out: &mut [u8], channels: u8, src_channels: u8) -> Result<()> {
+        decode_impl_stream_all(self, out, channels, src_channels)
+    }
+}
+
+/// Decode QOI images from slices or from streams.
+#[derive(Clone)]
+pub struct Decoder<R> {
+    reader: R,
+    header: Header,
+    channels: Channels,
+}
+
+impl<'a> Decoder<Bytes<'a>> {
+    /// Creates a new decoder from a slice of bytes.
+    ///
+    /// The header will be decoded immediately upon construction.
+    ///
+    /// Note: this provides the most efficient decoding, but requires the source data to
+    /// be loaded in memory in order to decode it. In order to decode from a generic
+    /// stream, use [`Decoder::from_stream`] instead.
+    #[inline]
+    pub fn new(data: &'a (impl AsRef<[u8]> + ?Sized)) -> Result<Self> {
+        Self::new_impl(Bytes::new(data.as_ref()))
+    }
+
+    /// Returns the undecoded tail of the input slice of bytes.
+    #[inline]
+    pub const fn data(&self) -> &[u8] {
+        self.reader.as_slice()
+    }
+}
+
+#[cfg(feature = "std")]
+impl<R: Read> Decoder<R> {
+    /// Creates a new decoder from a generic reader that implements [`Read`](std::io::Read).
+    ///
+    /// The header will be decoded immediately upon construction.
+    ///
+    /// Note: while it's possible to pass a `&[u8]` slice here since it implements `Read`, it
+    /// would be more efficient to use a specialized constructor instead: [`Decoder::new`].
+    #[inline]
+    pub fn from_stream(reader: R) -> Result<Self> {
+        Self::new_impl(reader)
+    }
+
+    /// Returns an immutable reference to the underlying reader.
+    #[inline]
+    pub const fn reader(&self) -> &R {
+        &self.reader
+    }
+
+    /// Consumes the decoder and returns the underlying reader back.
+    #[inline]
+    #[allow(clippy::missing_const_for_fn)]
+    pub fn into_reader(self) -> R {
+        self.reader
+    }
+}
+
+impl<R: Reader> Decoder<R> {
+    #[inline]
+    fn new_impl(mut reader: R) -> Result<Self> {
+        let header = reader.decode_header()?;
+        Ok(Self { reader, header, channels: header.channels })
+    }
+
+    /// Returns a new decoder with modified number of channels.
+    ///
+    /// By default, the number of channels in the decoded image will be equal
+    /// to whatever is specified in the header. However, it is also possible
+    /// to decode RGB into RGBA (in which case the alpha channel will be set
+    /// to 255), and vice versa (in which case the alpha channel will be ignored).
+    #[inline]
+    pub const fn with_channels(mut self, channels: Channels) -> Self {
+        self.channels = channels;
+        self
+    }
+
+    /// Returns the number of channels in the decoded image.
+    ///
+    /// Note: this may differ from the number of channels specified in the header.
+    #[inline]
+    pub const fn channels(&self) -> Channels {
+        self.channels
+    }
+
+    /// Returns the decoded image header.
+    #[inline]
+    pub const fn header(&self) -> &Header {
+        &self.header
+    }
+
+    /// The number of bytes the decoded image will take.
+    ///
+    /// Can be used to pre-allocate the buffer to decode the image into.
+    #[inline]
+    pub const fn required_buf_len(&self) -> usize {
+        self.header.n_pixels().saturating_mul(self.channels.as_u8() as usize)
+    }
+
+    /// Decodes the image to a pre-allocated buffer and returns the number of bytes written.
+    ///
+    /// The minimum size of the buffer can be found via [`Decoder::required_buf_len`].
+    #[inline]
+    pub fn decode_to_buf(&mut self, mut buf: impl AsMut<[u8]>) -> Result<usize> {
+        let buf = buf.as_mut();
+        let size = self.required_buf_len();
+        if unlikely(buf.len() < size) {
+            return Err(Error::OutputBufferTooSmall { size: buf.len(), required: size });
+        }
+        self.reader.decode_image(buf, self.channels.as_u8(), self.header.channels.as_u8())?;
+        Ok(size)
+    }
+
+    /// Decodes the image into a newly allocated vector of bytes and returns it.
+    #[cfg(any(feature = "std", feature = "alloc"))]
+    #[inline]
+    pub fn decode_to_vec(&mut self) -> Result<Vec<u8>> {
+        let mut out = vec![0; self.header.n_pixels() * self.channels.as_u8() as usize];
+        let _ = self.decode_to_buf(&mut out)?;
+        Ok(out)
+    }
+}