drm/vkms: Compute CRC without change input data

#include "vkms_drv.h"

static u32 get_pixel_from_buffer(int x, int y, const u8 *buffer,

				 const struct vkms_composer *composer)

{

	u32 pixel;

	int src_offset = composer->offset + (y * composer->pitch)

				      + (x * composer->cpp);

	pixel = *(u32 *)&buffer[src_offset];

	return pixel;

}

/**

 * compute_crc - Compute CRC value on output frame

 *

 * @vaddr_out: address to final framebuffer

 * @vaddr: address to final framebuffer

 * @composer: framebuffer's metadata

 *

 * returns CRC value computed using crc32 on the visible portion of

 * the final framebuffer at vaddr_out

 */

static uint32_t compute_crc(void *vaddr_out, struct vkms_composer *composer)

static uint32_t compute_crc(const u8 *vaddr,

			    const struct vkms_composer *composer)

{

	int i, j, src_offset;

	int x, y;

	u32 crc = 0, pixel = 0;

	int x_src = composer->src.x1 >> 16;

	int y_src = composer->src.y1 >> 16;

	int h_src = drm_rect_height(&composer->src) >> 16;

	int w_src = drm_rect_width(&composer->src) >> 16;

	u32 crc = 0;

	for (i = y_src; i < y_src + h_src; ++i) {

		for (j = x_src; j < x_src + w_src; ++j) {

			src_offset = composer->offset

				     + (i * composer->pitch)

				     + (j * composer->cpp);

			crc = crc32_le(crc, vaddr_out + src_offset,

				       sizeof(u32));

	for (y = y_src; y < y_src + h_src; ++y) {

		for (x = x_src; x < x_src + w_src; ++x) {

			pixel = get_pixel_from_buffer(x, y, vaddr, composer);

			crc = crc32_le(crc, (void *)&pixel, sizeof(u32));

		}

	}