/* V4L2 video picture grabber
   Copyright (C) 2009 Mauro Carvalho Chehab <mchehab@infradead.org>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation version 2 of the License.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/mman.h>
#include <linux/videodev2.h>
#include "../../lib/include/libv4l2.h"

#define CLEAR(x) memset(&(x), 0, sizeof(x))

struct buffer {
	void   *start;
	size_t length;
};

static void xioctl(int fh, unsigned long int request, void *arg)
{
	int r;

	do {
		r = v4l2_ioctl(fh, request, arg);
	} while (r == -1 && ((errno == EINTR) || (errno == EAGAIN)));

	if (r == -1) {
		fprintf(stderr, "error %d, %s\n", errno, strerror(errno));
		exit(EXIT_FAILURE);
	}
}

int main(int argc, char **argv)
{
	struct v4l2_format		fmt;
	struct v4l2_buffer		buf;
	struct v4l2_requestbuffers	req;
	enum v4l2_buf_type		type;
	fd_set				fds;
	struct timeval			tv;
	int				r, fd = -1;
	unsigned int			i, n_buffers;
	char				*dev_name = "/dev/video0";
	char				out_name[256];
	FILE				*fout;
	struct buffer			*buffers;

	fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
	if (fd < 0) {
		perror("Cannot open device");
		exit(EXIT_FAILURE);
	}

	CLEAR(fmt);
	fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	fmt.fmt.pix.width       = 640;
	fmt.fmt.pix.height      = 480;
	fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
	fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
	xioctl(fd, VIDIOC_S_FMT, &fmt);
	if (fmt.fmt.pix.pixelformat != V4L2_PIX_FMT_RGB24) {
		printf("Libv4l didn't accept RGB24 format. Can't proceed.\n");
		exit(EXIT_FAILURE);
	}
	if ((fmt.fmt.pix.width != 640) || (fmt.fmt.pix.height != 480))
		printf("Warning: driver is sending image at %dx%d\n",
			fmt.fmt.pix.width, fmt.fmt.pix.height);

	CLEAR(req);
	req.count = 2;
	req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	req.memory = V4L2_MEMORY_MMAP;
	xioctl(fd, VIDIOC_REQBUFS, &req);

	buffers = calloc(req.count, sizeof(*buffers));
	for (n_buffers = 0; n_buffers < req.count; ++n_buffers) {
		CLEAR(buf);

		buf.type        = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.memory      = V4L2_MEMORY_MMAP;
		buf.index       = n_buffers;

		xioctl(fd, VIDIOC_QUERYBUF, &buf);

		buffers[n_buffers].length = buf.length;
		buffers[n_buffers].start = v4l2_mmap(NULL, buf.length,
			      PROT_READ | PROT_WRITE, MAP_SHARED,
			      fd, buf.m.offset);

		if (MAP_FAILED == buffers[n_buffers].start) {
			perror("mmap");
			exit(EXIT_FAILURE);
		}
	}

	for (i = 0; i < n_buffers; ++i) {
		CLEAR(buf);
		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.memory = V4L2_MEMORY_MMAP;
		buf.index = i;
		xioctl(fd, VIDIOC_QBUF, &buf);
	}
	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;

	xioctl(fd, VIDIOC_STREAMON, &type);
	for (i = 0; i < 20; i++) {
		do {
			FD_ZERO(&fds);
			FD_SET(fd, &fds);

			/* Timeout. */
			tv.tv_sec = 2;
			tv.tv_usec = 0;

			r = select(fd + 1, &fds, NULL, NULL, &tv);
		} while ((r == -1 && (errno = EINTR)));
		if (r == -1) {
			perror("select");
			return errno;
		}

		CLEAR(buf);
		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.memory = V4L2_MEMORY_MMAP;
		xioctl(fd, VIDIOC_DQBUF, &buf);

		sprintf(out_name, "out%03d.ppm", i);
		fout = fopen(out_name, "w");
		if (!fout) {
			perror("Cannot open image");
			exit(EXIT_FAILURE);
		}
		fprintf(fout, "P6\n%d %d 255\n",
			fmt.fmt.pix.width, fmt.fmt.pix.height);
		fwrite(buffers[buf.index].start, buf.bytesused, 1, fout);
		fclose(fout);

		xioctl(fd, VIDIOC_QBUF, &buf);
	}

	type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	xioctl(fd, VIDIOC_STREAMOFF, &type);
	for (i = 0; i < n_buffers; ++i)
		v4l2_munmap(buffers[i].start, buffers[i].length);
	v4l2_close(fd);

	return 0;
}
