#include <sys/types.h>
#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

static void bail(int cond, const char *msg)
{
	if (cond) {
		perror(msg);
		exit(1);
	}
}

int main(void)
{
	unsigned *addr;
	char buf[4096];
	unsigned data[2] = { 0xdeadbeef, 0xcafeabab };
	int fd, i;

	fd = open("/dev/fb0", O_RDWR);
	bail(fd < 0, "/dev/fb0");

	for (i = 0; i < sizeof(buf); i+=sizeof(data))
		memcpy(buf + i, data, sizeof(data));

	addr = mmap(NULL, sizeof(buf), PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	bail(addr == MAP_FAILED, "mmap");
	printf("Mapped /dev/fb0 at %p\n", addr);

	memcpy(addr, buf, sizeof(buf));
//	write(fd, buf, sizeof(buf));

	sleep(10);

	close(fd);

	return 0;
}