The following patch removes the old framebuf_size and framebuf_read_start
values from the cam structure and simplifes the read function. It also
moves the needs dummy read check into the read_frame function. cp and dd
should both still work.
Patch is against 2.5.43, but I believe should apply cleanly to
2.5.current.
--- linux-2.5.43/drivers/usb/media/vicam.c 2002-10-21 18:12:56.000000000 -0700
+++ linux-vicam/drivers/usb/media/vicam.c 2002-10-21 18:48:03.000000000 -0700
@@ -421,9 +421,6 @@
u8 bulkEndpoint;
bool needsDummyRead;
- u32 framebuf_size; // # of valid bytes in framebuf
- u32 framebuf_read_start; // position in frame buf that a read is
happening at.
-
#ifdef CONFIG_PROC_FS
struct proc_dir_entry *proc_entry;
#endif
@@ -924,6 +921,11 @@
int n;
int actual_length;
+ if (cam->needsDummyRead) {
+ cam->needsDummyRead = 0;
+ read_frame(cam, framenum);
+ }
+
memset(request, 0, 16);
request[0] = cam->gain; // 0 = 0% gain, FF = 100% gain
@@ -974,74 +976,33 @@
vicam_decode_color(cam->raw_image,
cam->framebuf +
framenum * VICAM_MAX_FRAME_SIZE );
-
- cam->framebuf_size =
- 320 * 240 * VICAM_BYTES_PER_PIXEL;
- cam->framebuf_read_start = 0;
-
- return;
-
}
static int
vicam_read( struct file *file, char *buf, size_t count, loff_t *ppos )
{
struct vicam_camera *cam = file->private_data;
- DBG("read %d bytes.\n", (int) count);
- if (!buf)
- return -EINVAL;
+ DBG("read %d bytes.\n", (int) count);
- if (!count)
- return -EINVAL;
+ down_interruptible(&cam->busy_lock);
- // This is some code that will hopefully allow us to do shell copies from
- // the /dev/videoX to a file and have it actually work.
- if (cam->framebuf_size != 0) {
- if (cam->framebuf_read_start == cam->framebuf_size) {
- cam->framebuf_size = cam->framebuf_read_start = 0;
- return 0;
- } else {
- if (cam->framebuf_read_start + count <=
- cam->framebuf_size) {
- // count does not exceed available bytes
- copy_to_user(buf,
- (cam->framebuf) +
- cam->framebuf_read_start, count);
- cam->framebuf_read_start += count;
- return count;
- } else {
- count =
- cam->framebuf_size -
- cam->framebuf_read_start;
- copy_to_user(buf,
- (cam->framebuf) +
- cam->framebuf_read_start, count);
- cam->framebuf_read_start = cam->framebuf_size;
- return count;
- }
- }
+ if (*ppos >= VICAM_MAX_FRAME_SIZE) {
+ *ppos = 0;
+ return 0;
}
- down_interruptible(&cam->busy_lock);
-
- if (cam->needsDummyRead) {
+ if (*ppos == 0) {
read_frame(cam, 0);
- cam->needsDummyRead = 0;
}
- // read_frame twice because the camera doesn't seem to take the shutter speed
for the first one.
- read_frame(cam, 0);
+ count = min_t(size_t, count, VICAM_MAX_FRAME_SIZE - *ppos);
- if (count > cam->framebuf_size)
- count = cam->framebuf_size;
-
- copy_to_user(buf, cam->framebuf, count);
-
- if (count != cam->framebuf_size)
- cam->framebuf_read_start = count;
- else
- cam->framebuf_size = 0;
+ if (copy_to_user(buf, &cam->framebuf[*ppos], count)) {
+ count = -EFAULT;
+ } else {
+ *ppos += count;
+ }
up(&cam->busy_lock);
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