1 files changed, 141 insertions, 0 deletions
diff --git a/src/common_v4l2.h b/src/common_v4l2.h
new file mode 100644
index 0000000..c3762b5
--- /dev/null
+++ b/src/common_v4l2.h
@@ -0,0 +1,141 @@
+#ifndef COMMON_V4L2_H
+#define COMMON_V4L2_H
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/time.h>
+#include <sys/types.h>
+
+#include <libv4l2.h>
+#include <linux/videodev2.h>
+
+#define COMMON_V4L2_CLEAR(x) memset(&(x), 0, sizeof(x))
+
+typedef struct {
+    void *start;
+    size_t length;
+} CommonV4l2_Buffer;
+
+typedef struct {
+    int fd;
+    CommonV4l2_Buffer *buffers;
+    struct v4l2_buffer buf;
+    unsigned int n_buffers;
+} CommonV4l2;
+
+void CommonV4l2_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);
+    }
+}
+
+void CommonV4l2_init(CommonV4l2 *this, char *dev_name, unsigned int x_res, unsigned int y_res) {
+    enum v4l2_buf_type type;
+    struct v4l2_format fmt;
+    struct v4l2_requestbuffers req;
+    unsigned int i;
+
+    this->fd = v4l2_open(dev_name, O_RDWR | O_NONBLOCK, 0);
+    if (this->fd < 0) {
+        perror("Cannot open device");
+        exit(EXIT_FAILURE);
+    }
+    COMMON_V4L2_CLEAR(fmt);
+    fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    fmt.fmt.pix.width       = x_res;
+    fmt.fmt.pix.height      = y_res;
+    fmt.fmt.pix.pixelformat = V4L2_PIX_FMT_RGB24;
+    fmt.fmt.pix.field       = V4L2_FIELD_INTERLACED;
+    CommonV4l2_xioctl(this->fd, VIDIOC_S_FMT, &fmt);
+    if ((fmt.fmt.pix.width != x_res) || (fmt.fmt.pix.height != y_res))
+        printf("Warning: driver is sending image at %dx%d\n",
+            fmt.fmt.pix.width, fmt.fmt.pix.height);
+    COMMON_V4L2_CLEAR(req);
+    req.count = 2;
+    req.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    req.memory = V4L2_MEMORY_MMAP;
+    CommonV4l2_xioctl(this->fd, VIDIOC_REQBUFS, &req);
+    this->buffers = calloc(req.count, sizeof(*this->buffers));
+    for (this->n_buffers = 0; this->n_buffers < req.count; ++this->n_buffers) {
+        COMMON_V4L2_CLEAR(this->buf);
+        this->buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        this->buf.memory = V4L2_MEMORY_MMAP;
+        this->buf.index = this->n_buffers;
+        CommonV4l2_xioctl(this->fd, VIDIOC_QUERYBUF, &this->buf);
+        this->buffers[this->n_buffers].length = this->buf.length;
+        this->buffers[this->n_buffers].start = v4l2_mmap(NULL, this->buf.length,
+            PROT_READ | PROT_WRITE, MAP_SHARED, this->fd, this->buf.m.offset);
+        if (MAP_FAILED == this->buffers[this->n_buffers].start) {
+            perror("mmap");
+            exit(EXIT_FAILURE);
+        }
+    }
+    for (i = 0; i < this->n_buffers; ++i) {
+        COMMON_V4L2_CLEAR(this->buf);
+        this->buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+        this->buf.memory = V4L2_MEMORY_MMAP;
+        this->buf.index = i;
+        CommonV4l2_xioctl(this->fd, VIDIOC_QBUF, &this->buf);
+    }
+    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    CommonV4l2_xioctl(this->fd, VIDIOC_STREAMON, &type);
+}
+
+void CommonV4l2_update_image(CommonV4l2 *this) {
+    fd_set fds;
+    int r;
+    struct timeval tv;
+
+    do {
+        FD_ZERO(&fds);
+        FD_SET(this->fd, &fds);
+
+        /* Timeout. */
+        tv.tv_sec = 2;
+        tv.tv_usec = 0;
+
+        r = select(this->fd + 1, &fds, NULL, NULL, &tv);
+    } while ((r == -1 && (errno == EINTR)));
+    if (r == -1) {
+        perror("select");
+        exit(EXIT_FAILURE);
+    }
+    COMMON_V4L2_CLEAR(this->buf);
+    this->buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    this->buf.memory = V4L2_MEMORY_MMAP;
+    CommonV4l2_xioctl(this->fd, VIDIOC_DQBUF, &this->buf);
+    CommonV4l2_xioctl(this->fd, VIDIOC_QBUF, &this->buf);
+}
+
+char * CommonV4l2_get_image(CommonV4l2 *this) {
+    return ((char *)this->buffers[this->buf.index].start);
+}
+
+size_t CommonV4l2_get_image_size(CommonV4l2 *this) {
+    return this->buffers[this->buf.index].length;
+}
+
+void CommonV4l2_deinit(CommonV4l2 *this) {
+    unsigned int i;
+    enum v4l2_buf_type type;
+
+    type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+    CommonV4l2_xioctl(this->fd, VIDIOC_STREAMOFF, &type);
+    for (i = 0; i < this->n_buffers; ++i)
+        v4l2_munmap(this->buffers[i].start, this->buffers[i].length);
+    v4l2_close(this->fd);
+    free(this->buffers);
+}
+
+#endif