#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <time.h>
#include <unistd.h>
#include <xf86drm.h>
#include <xf86drmMode.h>

struct buffer_object {
    
	uint32_t width;
	uint32_t height;
	uint32_t pitch;
	uint32_t handle;
	uint32_t size;
	uint32_t *vaddr;
	uint32_t fb_id;
};

struct buffer_object buf[3];

static int modeset_create_fb(int fd, struct buffer_object *bo, uint32_t color)
{
    
	struct drm_mode_create_dumb create = {
    };
 	struct drm_mode_map_dumb map = {
    };
	uint32_t i;

	create.width = bo->width;
	create.height = bo->height;
	create.bpp = 32;
	drmIoctl(fd, DRM_IOCTL_MODE_CREATE_DUMB, &create);

	bo->pitch = create.pitch;
	bo->size = create.size;
	bo->handle = create.handle;
	drmModeAddFB(fd, bo->width, bo->height, 24, 32, bo->pitch,
			   bo->handle, &bo->fb_id);

	map.handle = create.handle;
	drmIoctl(fd, DRM_IOCTL_MODE_MAP_DUMB, &map);

	bo->vaddr = mmap(0, create.size, PROT_READ | PROT_WRITE,
			MAP_SHARED, fd, map.offset);

	for (i = 0; i < (bo->size / 4); i++)
		bo->vaddr[i] = color;

	return 0;
}

static void modeset_destroy_fb(int fd, struct buffer_object *bo)
{
    
	struct drm_mode_destroy_dumb destroy = {
    };

	drmModeRmFB(fd, bo->fb_id);

	munmap(bo->vaddr, bo->size);

	destroy.handle = bo->handle;
	drmIoctl(fd, DRM_IOCTL_MODE_DESTROY_DUMB, &destroy);
}

int main(int argc, char **argv)
{
	char             *dri_card="/dev/dri/card0";
	int               fd;
	uint32_t          conn_id;
	uint32_t          crtc_id;
	drmModeConnector *conn;
	drmModeRes       *res;

	if( argc != 2 )
	{
		printf("Usage: %s /dev/dri/card0\n", argv[0]);
		return 1;
	}
	else
	{
		dri_card = argv[1];
	}

	fd = open(dri_card, O_RDWR | O_CLOEXEC);
	if( fd < 0)
	{
		printf("Open '%s' failure: %s\n", dri_card, strerror(errno));
		return 0;
	}

	res = drmModeGetResources(fd);
	if( !res )
	{
		printf("drmModeGetResources() failure\n");
		return 0;
	}

	crtc_id = res->crtcs[0];
	conn_id = res->connectors[0];

	conn = drmModeGetConnector(fd, conn_id);
	if( !conn )
	{
		printf("drmModeGetConnector() failure\n");
		return 0;
	}

	buf[0].width = conn->modes[0].hdisplay;
	buf[0].height = conn->modes[0].vdisplay;
	buf[1].width = conn->modes[0].hdisplay;
	buf[1].height = conn->modes[0].vdisplay;
	buf[2].width = conn->modes[0].hdisplay;
	buf[2].height = conn->modes[0].vdisplay;

	printf("DRM create framebuffer now.\n");
	modeset_create_fb(fd, &buf[0], 0xff0000);
	modeset_create_fb(fd, &buf[1], 0x00ff00);
	modeset_create_fb(fd, &buf[2], 0x0000ff);

	printf("Show red screen on LCD.\n");
	drmModeSetCrtc(fd, crtc_id, buf[0].fb_id, 0, 0, &conn_id, 1, &conn->modes[0]);
	getchar();

	printf("Show green screen on LCD.\n");
	drmModeSetCrtc(fd, crtc_id, buf[1].fb_id, 0, 0, &conn_id, 1, &conn->modes[0]);
	getchar();

	printf("Show blue screen on LCD.\n");
	drmModeSetCrtc(fd, crtc_id, buf[2].fb_id, 0, 0, &conn_id, 1, &conn->modes[0]);
	getchar();

	printf("DRM destroy framebuffer now.\n");
	modeset_destroy_fb(fd, &buf[0]);
	modeset_destroy_fb(fd, &buf[1]);
	modeset_destroy_fb(fd, &buf[2]);

	drmModeFreeConnector(conn);
	return 0;
	drmModeFreeResources(res);

	close(fd);

	return 0;
}