ibmcam.c

讲述linux的初始化过程

		/*
		 * The purpose of creating the pixel here, in one,
		 * dedicated place is that we may need to make the
		 * pixel wider and taller than it actually is. This
		 * may be used if camera generates small frames for
		 * sake of frame rate (or any other reason.)
		 *
		 * The output data consists of B, G, R bytes
		 * (in this order).
		 */
#if USES_IBMCAM_PUTPIXEL
		IBMCAM_PUTPIXEL(frame, i, frame->curline, rv, gv, bv);
#else
		*f++ = bv;
		*f++ = gv;
		*f++ = rv;
#endif
		/*
		 * Typically we do not decide within a legitimate frame
		 * that we want to end the frame. However debugging code
		 * may detect marker of new frame within the data. Then
		 * this condition activates. The 'data' pointer is already
		 * pointing at the new marker, so we'd better leave it as is.
		 */
		if (frame_done)
			break;	/* End scanning of lines */
	}
	/*
	 * Account for number of bytes that we wrote into output V4L frame.
	 * We do it here, after we are done with the scanline, because we
	 * may fill more than one output scanline if we do vertical
	 * enlargement.
	 */
	frame->curline++;
	*pcopylen += v4l_linesize;
	usb_ibmcam_align_scratch(ibmcam, data);

	if (frame_done || (frame->curline >= frame->frmheight))
		return scan_NextFrame;
	else
		return scan_Continue;
}

/*
 * usb_ibmcam_model2_parse_lines()
 *
 * This procedure deals with a weird RGB format that is produced by IBM
 * camera model 2 in modes 320x240 and above; 'x' below is 159 or 175,
 * depending on horizontal size of the picture:
 *
 * <--- 160 or 176 pairs of RA,RB bytes ----->
 * *-----------------------------------------* \
 * | RA0 | RB0 | RA1 | RB1 | ... | RAx | RBx |  \
 * |-----+-----+-----+-----+ ... +-----+-----|   *- This is pair of horizontal lines,
 * | B0  | G0  | B1  | G1  | ... | Bx  | Gx  |  /   total 240 or 288 lines (120 or 144
 * |=====+=====+=====+=====+ ... +=====+=====| /    such pairs).
 *
 * Each group of FOUR bytes (RAi, RBi, Bi, Gi) where i=0..frame_width/2-1
 * defines ONE pixel. Therefore this format yields 176x144 "decoded"
 * resolution at best. I do not know why camera sends such format - the
 * previous model just used I420 and everyone was happy.
 *
 * I do not know what is the difference between RAi and RBi bytes. Both
 * seemingly represent R component, but slightly vary in value (so that
 * the picture looks a bit colored if one or another is used). I use
 * them both as R component in attempt to at least partially recover the
 * lost resolution.
 */
static scan_state_t usb_ibmcam_model2_parse_lines(struct usb_ibmcam *ibmcam, long *pcopylen)
{
	struct ibmcam_frame *frame;
	unsigned char *data, *f, *la, *lb;
	unsigned int len;
	const int v4l_linesize = imgwidth * V4L_BYTES_PER_PIXEL;	/* V4L line offset */
	int i, j, frame_done=0, color_corr;

	color_corr = (ibmcam->vpic.colour) >> 8; /* 0..+255 */

	data = ibmcam->scratch;
	frame = &ibmcam->frame[ibmcam->curframe];

	/* Here we deal with pairs of horizontal lines */

	len = frame->frmwidth * 2; /* 2 lines */
	/*printk(KERN_DEBUG "len=%d. left=%d.\n",len,scratch_left(data));*/

	/* Make sure there's enough data for the entire line */
	if (scratch_left(data) < (len+32)) {
		/*printk(KERN_DEBUG "out of data, need %u.\n", len);*/
		return scan_Out;
	}

	/*
	 * Make sure that our writing into output buffer
	 * will not exceed the buffer. Mind that we may write
	 * not into current output scanline but in several after
	 * it as well (if we enlarge image vertically.)
	 */
	if ((frame->curline + 1) >= V4L_FRAME_HEIGHT)
		return scan_NextFrame;

	if ((frame->curline & 1) == 0) {
		la = data;
		lb = data + frame->frmwidth;
	} else {
		la = data + frame->frmwidth;
		lb = data;
	}

	/*
	 * Now we are sure that entire line (representing all 'frame->frmwidth'
	 * pixels from the camera) is available in the scratch buffer. We
	 * start copying the line left-aligned to the V4L buffer (which
	 * might be larger - not smaller, hopefully). If the camera
	 * line is shorter then we should pad the V4L buffer with something
	 * (black in this case) to complete the line.
	 */
	f = frame->data + (v4l_linesize * frame->curline);

	/* Fill the 2-line strip */
	for (i = 0; i < frame->frmwidth; i++) {
		int y, rv, gv, bv;	/* RGB components */

		j = i & (~1);

		/* Check for various visual debugging hints (colorized pixels) */
		if ((flags & FLAGS_DISPLAY_HINTS) && (ibmcam->has_hdr)) {
			if (ibmcam->has_hdr == 1) {
				bv = 0; /* Yellow marker */
				gv = 0xFF;
				rv = 0xFF;
			} else {
				bv = 0xFF; /* Cyan marker */
				gv = 0xFF;
				rv = 0;
			}
			ibmcam->has_hdr = 0;
			goto make_pixel;
		}

		/*
		 * Here I use RA and RB components, one per physical pixel.
		 * This causes fine vertical grid on the picture but may improve
		 * horizontal resolution. If you prefer replicating, use this:
		 *   rv = la[j + 0];   ... or ... rv = la[j + 1];
		 * then the pixel will be replicated.
		 */
		rv = la[i];
		gv = lb[j + 1];
		bv = lb[j + 0];

		y = (rv + gv + bv) / 3; /* Brightness (badly calculated) */

		if (flags & FLAGS_MONOCHROME) /* Use monochrome for debugging */
			rv = gv = bv = y;
		else if (color_corr != 128) {

			/* Calculate difference between color and brightness */
			rv -= y;
			gv -= y;
			bv -= y;

			/* Scale differences */
			rv = (rv * color_corr) / 128;
			gv = (gv * color_corr) / 128;
			bv = (bv * color_corr) / 128;

			/* Reapply brightness */
			rv += y;
			gv += y;
			bv += y;

			/* Watch for overflows */
			RESTRICT_TO_RANGE(rv, 0, 255);
			RESTRICT_TO_RANGE(gv, 0, 255);
			RESTRICT_TO_RANGE(bv, 0, 255);
		}

	make_pixel:
		IBMCAM_PUTPIXEL(frame, i, frame->curline, rv, gv, bv);
		IBMCAM_PUTPIXEL(frame, i, frame->curline+1, rv, gv, bv);
	}
	/*
	 * Account for number of bytes that we wrote into output V4L frame.
	 * We do it here, after we are done with the scanline, because we
	 * may fill more than one output scanline if we do vertical
	 * enlargement.
	 */
	frame->curline += 2;
	*pcopylen += v4l_linesize * 2;
	data += frame->frmwidth * 2;
	usb_ibmcam_align_scratch(ibmcam, data);

	if (frame_done || (frame->curline >= frame->frmheight))
		return scan_NextFrame;
	else
		return scan_Continue;
}

/*
 * ibmcam_parse_data()
 *
 * Generic routine to parse the scratch buffer. It employs either
 * usb_ibmcam_find_header() or usb_ibmcam_parse_lines() to do most
 * of work.
 *
 * History:
 * 1/21/00  Created.
 */
static void ibmcam_parse_data(struct usb_ibmcam *ibmcam)
{
	struct ibmcam_frame *frame;
	unsigned char *data = ibmcam->scratch;
	scan_state_t newstate;
	long copylen = 0;

	/* Grab the current frame and the previous frame */
	frame = &ibmcam->frame[ibmcam->curframe];

	/* printk(KERN_DEBUG "parsing %u.\n", ibmcam->scratchlen); */

	while (1) {

		newstate = scan_Out;
		if (scratch_left(data)) {
			if (frame->scanstate == STATE_SCANNING)
				newstate = usb_ibmcam_find_header(ibmcam);
			else if (frame->scanstate == STATE_LINES) {
				if ((ibmcam->camera_model == IBMCAM_MODEL_2) &&
				    (videosize >= VIDEOSIZE_352x288)) {
					newstate = usb_ibmcam_model2_parse_lines(ibmcam, &copylen);
				}
				else {
					newstate = usb_ibmcam_parse_lines(ibmcam, &copylen);
				}
			}
		}
		if (newstate == scan_Continue)
			continue;
		else if ((newstate == scan_NextFrame) || (newstate == scan_Out))
			break;
		else
			return; /* scan_EndParse */
	}

	if (newstate == scan_NextFrame) {
		frame->grabstate = FRAME_DONE;
		ibmcam->curframe = -1;
		ibmcam->frame_num++;

		/* Optionally display statistics on the screen */
		if (flags & FLAGS_OVERLAY_STATS)
			usb_ibmcam_overlaystats(ibmcam, frame);

		/* This will cause the process to request another frame. */
		if (waitqueue_active(&frame->wq))
			wake_up_interruptible(&frame->wq);
	}

	/* Update the frame's uncompressed length. */
	frame->scanlength += copylen;
}

/*
 * Make all of the blocks of data contiguous
 */
static int ibmcam_compress_isochronous(struct usb_ibmcam *ibmcam, urb_t *urb)
{
	unsigned char *cdata, *data, *data0;
	int i, totlen = 0;

	data = data0 = ibmcam->scratch + ibmcam->scratchlen;
	for (i = 0; i < urb->number_of_packets; i++) {
		int n = urb->iso_frame_desc[i].actual_length;
		int st = urb->iso_frame_desc[i].status;
		
		cdata = urb->transfer_buffer + urb->iso_frame_desc[i].offset;

		/* Detect and ignore errored packets */
		if (st < 0) {
			if (debug >= 1) {
				printk(KERN_ERR "ibmcam data error: [%d] len=%d, status=%X\n",
				       i, n, st);
			}
			ibmcam->iso_err_count++;
			continue;
		}

		/* Detect and ignore empty packets */
		if (n <= 0) {
			ibmcam->iso_skip_count++;
			continue;
		}

		/*
		 * If camera continues to feed us with data but there is no
		 * consumption (if, for example, V4L client fell asleep) we
		 * may overflow the buffer. We have to move old data over to
		 * free room for new data. This is bad for old data. If we
		 * just drop new data then it's bad for new data... choose
		 * your favorite evil here.
		 */
		if ((ibmcam->scratchlen + n) > scratchbufsize) {
#if 0
			ibmcam->scratch_ovf_count++;
			if (debug >= 3)
				printk(KERN_ERR "ibmcam: scratch buf overflow! "
				       "scr_len: %d, n: %d\n", ibmcam->scratchlen, n );
			return totlen;
#else
			int mv;

			ibmcam->scratch_ovf_count++;
			if (debug >= 3) {
				printk(KERN_ERR "ibmcam: scratch buf overflow! "
				       "scr_len: %d, n: %d\n", ibmcam->scratchlen, n );
			}
			mv  = (ibmcam->scratchlen + n) - scratchbufsize;
			if (ibmcam->scratchlen >= mv) {
				int newslen = ibmcam->scratchlen - mv;
				memmove(ibmcam->scratch, ibmcam->scratch + mv, newslen);
				ibmcam->scratchlen = newslen;
				data = data0 = ibmcam->scratch + ibmcam->scratchlen;
			} else {
				printk(KERN_ERR "ibmcam: scratch buf too small\n");
				return totlen;
			}
#endif
		}

		/* Now we know that there is enough room in scratch buffer */
		memmove(data, cdata, n);
		data += n;
		totlen += n;
		ibmcam->scratchlen += n;
	}
#if 0
	if (totlen > 0) {
		static int foo=0;
		if (foo < 1) {
			printk(KERN_DEBUG "+%d.\n", totlen);
			ibmcam_hexdump(data0, (totlen > 64) ? 64:totlen);
			++foo;
		}
	}
#endif
	return totlen;
}

static void ibmcam_isoc_irq(struct urb *urb)
{
	int len;
	struct usb_ibmcam *ibmcam = urb->context;
	struct ibmcam_sbuf *sbuf;
	int i;

	/* We don't want to do anything if we are about to be removed! */
	if (!IBMCAM_IS_OPERATIONAL(ibmcam))
		return;

#if 0
	if (urb->actual_length > 0) {
		printk(KERN_DEBUG "ibmcam_isoc_irq: %p status %d, "
		       " errcount = %d, length = %d\n", urb, urb->status,
		       urb->error_count, urb->actual_length);
	} else {
		static int c = 0;
		if (c++ % 100 == 0)
			printk(KERN_DEBUG "ibmcam_isoc_irq: no data\n");
	}
#endif

	if (!ibmcam->streaming) {
		if (debug >= 1)
			printk(KERN_DEBUG "ibmcam: oops, not streaming, but interrupt\n");
		return;
	}
	
	sbuf = &ibmcam->sbuf[ibmcam->cursbuf];

	/* Copy the data received into our scratch buffer */
	len = ibmcam_compress_isochronous(ibmcam, urb);

	ibmcam->urb_count++;
	ibmcam->urb_length = len;
	ibmcam->data_count += len;

#if 0   /* This code prints few initial bytes of ISO data: used to decode markers */
	if (ibmcam->urb_count % 64 == 1) {
		if (ibmcam->urb_count == 1) {
			ibmcam_hexdump(ibmcam->scratch,
				       (ibmcam->scratchlen > 32) ? 32 : ibmcam->scratchlen);
		}
	}
#endif

	/* If we collected enough data let's parse! */
	if (ibmcam->scratchlen) {
		/* If we don't have a frame we're current working on, complain */
		if (ibmcam->curframe >= 0)
			ibmcam_parse_data(ibmcam);
		else {
			if (debug >= 1)
				printk(KERN_DEBUG "ibmcam: received data, but no frame available\n");
		}
	}

	for (i = 0; i < FRAMES_PER_DESC; i++) {
		sbuf->urb->iso_frame_desc[i].status = 0;
		sbuf->urb->iso_frame_desc[i].actual_length = 0;
	}

	/* Move to the next sbuf */
	ibmcam->cursbuf = (ibmcam->cursbuf + 1) % IBMCAM_NUMSBUF;

	return;
}

/*
 * usb_ibmcam_veio()
 *
 * History:
 * 1/27/00  Added check for dev == NULL; this happens if camera is unplugged.
 */
static int usb_ibmcam_veio(
	struct usb_ibmcam *ibmcam,
	unsigned char req,
	unsigned short value,
	unsigned short index)
{
	static const char proc[] = "usb_ibmcam_veio";