Function astcenc_decompress_image

Source/astcenc_entry.cpp:1274–1390

See header for documentation. */

/* See header for documentation. */
astcenc_error astcenc_decompress_image(
	astcenc_context* ctxo,
	const uint8_t* data,
	size_t data_len,
	astcenc_image* image_outp,
	const astcenc_swizzle* swizzle,
	unsigned int thread_index
) {
	astcenc_error status;
	astcenc_image& image_out = *image_outp;
	astcenc_contexti* ctx = &ctxo->context;

	// Today this doesn't matter (working set on stack) but might in future ...
	if (thread_index >= ctx->thread_count)
	{
		return ASTCENC_ERR_BAD_PARAM;
	}

	status = validate_decompression_swizzle(*swizzle);
	if (status != ASTCENC_SUCCESS)
	{
		return status;
	}

	size_t dim_x = image_out.dim_x;
	size_t dim_y = image_out.dim_y;
	size_t dim_z = image_out.dim_z;

	size_t texel_count = get_texels_count(dim_x, dim_y, dim_z);
	// Cumulative texel sizes would overflow a size_t
	if (texel_count == 0)
	{
		return ASTCENC_ERR_BAD_PARAM;
	}

	size_t block_x = ctx->config.block_x;
	size_t block_y = ctx->config.block_y;
	size_t block_z = ctx->config.block_z;

	size_t blocks_x = astc::get_block_count_safe(dim_x, block_x);
	size_t blocks_y = astc::get_block_count_safe(dim_y, block_y);
	size_t blocks_z = astc::get_block_count_safe(dim_z, block_z);

	size_t block_count = get_blocks_count(blocks_x, blocks_y, blocks_z);
	// Cumulative block sizes would overflow a size_t
	if (block_count == 0)
	{
		return ASTCENC_ERR_BAD_PARAM;
	}

	// Check we have enough output space, size_needed calc cannot overflow as
	// get_blocks_count() already validated that a byte count would fit
	size_t size_needed = block_count * 16;
	if (data_len < size_needed)
	{
		return ASTCENC_ERR_OUT_OF_MEM;
	}