function copyBufferToTexture()

in src/webgpu/web_platform/reftests/canvas_complex.html.ts [44:145]
99 lines of code
11 McCabe index (conditional complexity)

    function copyBufferToTexture(ctx: GPUCanvasContext) {
      const rows = ctx.canvas.height;
      const { bytesPerBlock: bytesPerPixel } = getBlockInfoForColorTextureFormat(format);
      const bytesPerRow = align(bytesPerPixel * ctx.canvas.width, 256);
      const componentsPerPixel = 4;

      const buffer = t.device.createBuffer({
        mappedAtCreation: true,
        size: rows * bytesPerRow,
        usage: GPUBufferUsage.COPY_SRC,
      });
      // These are run only once per test, so there are no wasted reallocations below.
      let red: Uint8Array | Uint16Array;
      let green: Uint8Array | Uint16Array;
      let blue: Uint8Array | Uint16Array;
      let yellow: Uint8Array | Uint16Array;

      const mapping = buffer.getMappedRange();
      let data: Uint8Array | Uint16Array;
      switch (format) {
        case 'bgra8unorm':
        case 'bgra8unorm-srgb':
          {
            data = new Uint8Array(mapping);
            red = new Uint8Array([0x00, 0x00, 0x66, 0xff]);
            green = new Uint8Array([0x00, 0x66, 0x00, 0xff]);
            blue = new Uint8Array([0x66, 0x00, 0x00, 0xff]);
            yellow = new Uint8Array([0x00, 0x66, 0x66, 0xff]);
          }
          break;
        case 'rgba8unorm':
        case 'rgba8unorm-srgb':
          {
            data = new Uint8Array(mapping);
            red = new Uint8Array([0x66, 0x00, 0x00, 0xff]);
            green = new Uint8Array([0x00, 0x66, 0x00, 0xff]);
            blue = new Uint8Array([0x00, 0x00, 0x66, 0xff]);
            yellow = new Uint8Array([0x66, 0x66, 0x00, 0xff]);
          }
          break;
        case 'rgba16float':
          {
            data = new Uint16Array(mapping);
            red = new Uint16Array([
              float32ToFloat16Bits(0.4),
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(1.0),
            ]);
            green = new Uint16Array([
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(0.4),
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(1.0),
            ]);
            blue = new Uint16Array([
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(0.4),
              float32ToFloat16Bits(1.0),
            ]);
            yellow = new Uint16Array([
              float32ToFloat16Bits(0.4),
              float32ToFloat16Bits(0.4),
              float32ToFloat16Bits(0.0),
              float32ToFloat16Bits(1.0),
            ]);
          }
          break;
        default:
          unreachable();
      }
      for (let i = 0; i < ctx.canvas.width; ++i)
        for (let j = 0; j < ctx.canvas.height; ++j) {
          let pixel: Uint8Array | Uint16Array;
          if (i < ctx.canvas.width / 2) {
            if (j < ctx.canvas.height / 2) {
              pixel = red;
            } else {
              pixel = blue;
            }
          } else {
            if (j < ctx.canvas.height / 2) {
              pixel = green;
            } else {
              pixel = yellow;
            }
          }
          data.set(pixel, (i + j * (bytesPerRow / bytesPerPixel)) * componentsPerPixel);
        }
      buffer.unmap();

      const encoder = t.device.createCommandEncoder({
        label: 'canvas_complex:copyBufferToTexture',
      });
      encoder.copyBufferToTexture({ buffer, bytesPerRow }, { texture: ctx.getCurrentTexture() }, [
        ctx.canvas.width,
        ctx.canvas.height,
        1,
      ]);
      t.device.queue.submit([encoder.finish()]);
    }