From 6ca6d84a87324c29a7415343455a6cb080b6f416 Mon Sep 17 00:00:00 2001
From: Matej Kormuth <dobrakmato@gmail.com>
Date: Wed, 22 Jan 2020 02:12:31 +0100
Subject: [PATCH] fix #1292: add parentheses to fix int truncation (#1299)

---
 .../validity/copy_image_buffer.rs             | 37 +++++++++++++++++--
 1 file changed, 34 insertions(+), 3 deletions(-)

diff --git a/vulkano/src/command_buffer/validity/copy_image_buffer.rs b/vulkano/src/command_buffer/validity/copy_image_buffer.rs
index d77fb8cb..a70d02da 100644
--- a/vulkano/src/command_buffer/validity/copy_image_buffer.rs
+++ b/vulkano/src/command_buffer/validity/copy_image_buffer.rs
@@ -97,9 +97,7 @@ pub fn check_copy_buffer_image<B, I, P>(device: &Device, buffer: &B, image: &I,
     image.format().ensure_accepts()?;
 
     {
-        let (block_width, block_height) = image.format().block_dimensions();
-        let num_blocks = (image_size[0] + block_width - 1) / block_width * (image_size[1] + block_height - 1) / block_height * image_size[2] * image_num_layers;
-        let required_len = num_blocks as usize * image.format().rate() as usize;
+        let required_len = required_len_for_format(image.format(), image_size, image_num_layers);
         if required_len > buffer.len() {
             return Err(CheckCopyBufferImageError::BufferTooSmall {
                            required_len: required_len,
@@ -113,6 +111,39 @@ pub fn check_copy_buffer_image<B, I, P>(device: &Device, buffer: &B, image: &I,
     Ok(())
 }
 
+/// Computes the minimum required len in elements for buffer with image data in specified
+/// format of specified size.
+fn required_len_for_format<P>(format: Format, image_size: [u32; 3], image_num_layers: u32) -> usize
+where Format: AcceptsPixels<P>
+{
+    let (block_width, block_height) = format.block_dimensions();
+    let num_blocks = (image_size[0] + block_width - 1) / block_width * ((image_size[1] + block_height - 1) / block_height) * image_size[2] * image_num_layers;
+    let required_len = num_blocks as usize * format.rate() as usize;
+
+    return required_len;
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::format::Format;
+    use command_buffer::validity::copy_image_buffer::required_len_for_format;
+
+    #[test]
+    fn test_required_len_for_format() {
+        // issue #1292
+        assert_eq!(required_len_for_format::<u8>(Format::BC1_RGBUnormBlock, [2048, 2048, 1], 1), 2097152);
+        // other test cases
+        assert_eq!(required_len_for_format::<u8>(Format::R8G8B8A8Unorm, [2048, 2048, 1], 1), 16777216);
+        assert_eq!(required_len_for_format::<u8>(Format::R4G4UnormPack8, [512, 512, 1], 1), 262144);
+        assert_eq!(required_len_for_format::<u8>(Format::R8G8B8Uscaled, [512, 512, 1], 1), 786432);
+        assert_eq!(required_len_for_format::<u8>(Format::R32G32Uint, [512, 512, 1], 1), 2097152);
+        assert_eq!(required_len_for_format::<u32>(Format::R32G32Uint, [512, 512, 1], 1), 524288);
+        assert_eq!(required_len_for_format::<[u32; 2]>(Format::R32G32Uint, [512, 512, 1], 1), 262144);
+        assert_eq!(required_len_for_format::<u8>(Format::ASTC_8x8UnormBlock, [512, 512, 1], 1), 65536);
+        assert_eq!(required_len_for_format::<u8>(Format::ASTC_12x12SrgbBlock, [512, 512, 1], 1), 29584);
+    }
+}
+
 /// Error that can happen from `check_copy_buffer_image`.
 #[derive(Debug, Copy, Clone)]
 pub enum CheckCopyBufferImageError {