/* *      uvc_isight.c  --  USB Video Class driver - iSight support * *	Copyright (C) 2006-2007 *		Ivan N. Zlatev <contact@i-nz.net> * *      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; either version 2 of the License, or *      (at your option) any later version. * */#include <linux/usb.h>#include <linux/kernel.h>#include <linux/mm.h>#include "uvcvideo.h"/* Built-in iSight webcams implements most of UVC 1.0 except a * different packet format. Instead of sending a header at the * beginning of each isochronous transfer payload, the webcam sends a * single header per image (on its own in a packet), followed by * packets containing data only. * * Offset   Size (bytes)	Description * ------------------------------------------------------------------ * 0x00 	1   	Header length * 0x01 	1   	Flags (UVC-compliant) * 0x02 	4   	Always equal to '11223344' * 0x06 	8   	Always equal to 'deadbeefdeadface' * 0x0e 	16  	Unknown * * The header can be prefixed by an optional, unknown-purpose byte. */static int isight_decode(struct uvc_video_queue *queue, struct uvc_buffer *buf,		const __u8 *data, unsigned int len){	static const __u8 hdr[] = {		0x11, 0x22, 0x33, 0x44,		0xde, 0xad, 0xbe, 0xef,		0xde, 0xad, 0xfa, 0xce	};	unsigned int maxlen, nbytes;	__u8 *mem;	int is_header = 0;	if (buf == NULL)		return 0;	if ((len >= 14 && memcmp(&data[2], hdr, 12) == 0) ||	    (len >= 15 && memcmp(&data[3], hdr, 12) == 0)) {		uvc_trace(UVC_TRACE_FRAME, "iSight header found\n");		is_header = 1;	}	/* Synchronize to the input stream by waiting for a header packet. */	if (buf->state != UVC_BUF_STATE_ACTIVE) {		if (!is_header) {			uvc_trace(UVC_TRACE_FRAME, "Dropping packet (out of "				  "sync).\n");			return 0;		}		buf->state = UVC_BUF_STATE_ACTIVE;	}	/* Mark the buffer as done if we're at the beginning of a new frame.	 *	 * Empty buffers (bytesused == 0) don't trigger end of frame detection	 * as it doesn't make sense to return an empty buffer.	 */	if (is_header && buf->buf.bytesused != 0) {		buf->state = UVC_BUF_STATE_DONE;		return -EAGAIN;	}	/* Copy the video data to the buffer. Skip header packets, as they	 * contain no data.	 */	if (!is_header) {		maxlen = buf->buf.length - buf->buf.bytesused;		mem = queue->mem + buf->buf.m.offset + buf->buf.bytesused;		nbytes = min(len, maxlen);		memcpy(mem, data, nbytes);		buf->buf.bytesused += nbytes;		if (len > maxlen || buf->buf.bytesused == buf->buf.length) {			uvc_trace(UVC_TRACE_FRAME, "Frame complete "				  "(overflow).\n");			buf->state = UVC_BUF_STATE_DONE;		}	}	return 0;}void uvc_video_decode_isight(struct urb *urb, struct uvc_video_device *video,		struct uvc_buffer *buf){	int ret, i;	for (i = 0; i < urb->number_of_packets; ++i) {		if (urb->iso_frame_desc[i].status < 0) {			uvc_trace(UVC_TRACE_FRAME, "USB isochronous frame "				  "lost (%d).\n",				  urb->iso_frame_desc[i].status);		}		/* Decode the payload packet.		 * uvc_video_decode is entered twice when a frame transition		 * has been detected because the end of frame can only be		 * reliably detected when the first packet of the new frame		 * is processed. The first pass detects the transition and		 * closes the previous frame's buffer, the second pass		 * processes the data of the first payload of the new frame.		 */		do {			ret = isight_decode(&video->queue, buf,					urb->transfer_buffer +					urb->iso_frame_desc[i].offset,					urb->iso_frame_desc[i].actual_length);			if (buf == NULL)				break;			if (buf->state == UVC_BUF_STATE_DONE ||			    buf->state == UVC_BUF_STATE_ERROR)				buf = uvc_queue_next_buffer(&video->queue, buf);		} while (ret == -EAGAIN);	}}