def decode(self, file, filename):
        header = file.read(DDSURFACEDESC2.get_size())
        desc = DDSURFACEDESC2(header)
        if desc.dwMagic != 'DDS ' or desc.dwSize != 124:
            raise DDSException('Invalid DDS file (incorrect header).')

        width = desc.dwWidth
        height = desc.dwHeight
        mipmaps = 1

        if desc.dwFlags & DDSD_DEPTH:
            raise DDSException('Volume DDS files unsupported')

        if desc.dwFlags & DDSD_MIPMAPCOUNT:
            mipmaps = desc.dwMipMapCount

        if desc.ddpfPixelFormat.dwSize != 32:
            raise DDSException('Invalid DDS file (incorrect pixel format).')

        if desc.dwCaps2 & DDSCAPS2_CUBEMAP:
            raise DDSException('Cubemap DDS files unsupported')

        if not desc.ddpfPixelFormat.dwFlags & DDPF_FOURCC:
            raise DDSException('Uncompressed DDS textures not supported.')

        has_alpha = desc.ddpfPixelFormat.dwRGBAlphaBitMask != 0

        format, decoder = _compression_formats.get(
            (desc.ddpfPixelFormat.dwFourCC, has_alpha), None)
        if not format:
            raise DDSException('Unsupported texture compression %s' % \
                desc.ddpfPixelFormat.dwFourCC)

        if format == GL_COMPRESSED_RGB_S3TC_DXT1_EXT:
            block_size = 8
        else:
            block_size = 16

        datas = []
        w, h = width, height
        for i in range(mipmaps):
            if not w and not h:
                break
            if not w:
                w = 1
            if not h:
                h = 1
            size = (4 / (w + 3)) * ((h + 3) / 4) * block_size
            data = file.read(size)
            datas.append(data)
            w >>= 1
            h >>= 1

        image = CompressedImageData(width, height, format, datas[0],
            'GL_EXT_texture_compression_s3tc', decoder)
        level = 0
        for data in datas[1:]:
            level += 1
            image.set_mipmap_data(level, data)

        return image
dataset/ETHPy150Open ardekantur/pyglet/pyglet/image/codecs/dds.py/DDSImageDecoder.decode/swapped operands of `/`