fb_mmap_code

fb_mmap.c

#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <dev/wscons/wsconsio.h>
#include <dev/wscons/wsksymdef.h>

int
main(int argc, char **argv)
{
	int fd;
	struct wsdisplay_fbinfo vinfo;
	int orig_mode;
	int mode;
	int wstype;
	unsigned int line_length;
	unsigned char *fb;

	if ((fd = open( "/dev/ttyE0", O_RDWR)) < 0) {
		fprintf(stderr, "Failed to open /dev/ttyE0\n") ;
		return 1;
	}

	ioctl(STDIN_FILENO, WSDISPLAYIO_GMODE, &orig_mode) ;

	mode = WSDISPLAYIO_MODE_MAPPED ;

	if (ioctl(STDIN_FILENO, WSDISPLAYIO_SMODE, &mode) == -1) {
		fprintf(stderr, "WSDISPLAYIO_SMODE failed.\n");
		return 1;
	}

	if (ioctl(fd , WSDISPLAYIO_GINFO , &vinfo) == -1) {
		fprintf(stderr, "WSDISPLAYIO_GINFO failed.\n");
		goto error;
	}

	if (ioctl(fd , WSDISPLAYIO_GTYPE , &wstype) == -1) {
		fprintf(stderr, "WSDISPLAYIO_GTYPE failed.\n");
		goto error;
	}

	if (ioctl(fd , WSDISPLAYIO_LINEBYTES , &line_length) == -1) {
		fprintf(stderr, "WSDISPLAYIO_LINEBYTES failed.\n");
		goto error;
	}

	if ((fb = mmap( NULL, line_length * vinfo.height,
			PROT_WRITE|PROT_READ, MAP_SHARED, fd , (off_t)0)) == MAP_FAILED) {
		fprintf(stderr, "mmap failed.\n");
		goto error;
	}

	fprintf(stderr, "width %d line length %d height %d depth %d mmap %p wstype %d\n" ,
		vinfo.width , line_length , vinfo.height , vinfo.depth , fb , wstype);
	memset(fb, 0xff, line_length * vinfo.height);

	sleep(2);

	ioctl(STDIN_FILENO, WSDISPLAYIO_SMODE, &orig_mode);

	return 0;

error:
	ioctl(STDIN_FILENO, WSDISPLAYIO_SMODE, &orig_mode);

	return 1;
}