drivers/media/video/pwc/pwc-uncompress.c

/* Linux driver for Philips webcam
   Decompression frontend.
   (C) 1999-2003 Nemosoft Unv.
   (C) 2004-2006 Luc Saillard (luc@saillard.org)

   NOTE: this version of pwc is an unofficial (modified) release of pwc & pcwx
   driver and thus may have bugs that are not present in the original version.
   Please send bug reports and support requests to <luc@saillard.org>.
   The decompression routines have been implemented by reverse-engineering the
   Nemosoft binary pwcx module. Caveat emptor.

   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.

   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.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

   vim: set ts=8:
*/

#include <asm/current.h>
#include <asm/types.h>

#include "pwc.h"
#include "pwc-uncompress.h"
#include "pwc-dec1.h"
#include "pwc-dec23.h"

int pwc_decompress(struct pwc_device *pdev)
{
	struct pwc_frame_buf *fbuf;
	int n, line, col, stride;
	void *yuv, *image;
	u16 *src;
	u16 *dsty, *dstu, *dstv;

	if (pdev == NULL)
		return -EFAULT;

	fbuf = pdev->read_frame;
	if (fbuf == NULL)
		return -EFAULT;
	image  = pdev->image_data;
	image += pdev->images[pdev->fill_image].offset;

	yuv = fbuf->data + pdev->frame_header_size;  /* Skip header */

	/* Raw format; that's easy... */
	if (pdev->pixfmt != V4L2_PIX_FMT_YUV420)
	{
		struct pwc_raw_frame *raw_frame = image;
		raw_frame->type = cpu_to_le16(pdev->type);
		raw_frame->vbandlength = cpu_to_le16(pdev->vbandlength);
			/* cmd_buf is always 4 bytes, but sometimes, only the
			 * first 3 bytes is filled (Nala case). We can
			 * determine this using the type of the webcam */
		memcpy(raw_frame->cmd, pdev->cmd_buf, 4);
		memcpy(raw_frame+1, yuv, pdev->frame_size);
		return 0;
	}

	if (pdev->vbandlength == 0) {
		/* Uncompressed mode.
		 * We copy the data into the output buffer, using the viewport
		 * size (which may be larger than the image size).
		 * Unfortunately we have to do a bit of byte stuffing to get
		 * the desired output format/size.
		 *
		 * We do some byte shuffling here to go from the
		 * native format to YUV420P.
		 */
		src = (u16 *)yuv;
		n = pdev->view.x * pdev->view.y;

		/* offset in Y plane */
		stride = pdev->view.x * pdev->offset.y + pdev->offset.x;
		dsty = (u16 *)(image + stride);

		/* offsets in U/V planes */
		stride = pdev->view.x * pdev->offset.y / 4 + pdev->offset.x / 2;
		dstu = (u16 *)(image + n +         stride);
		dstv = (u16 *)(image + n + n / 4 + stride);

		/* increment after each line */
		stride = (pdev->view.x - pdev->image.x) / 2; /* u16 is 2 bytes */

		for (line = 0; line < pdev->image.y; line++) {
			for (col = 0; col < pdev->image.x; col += 4) {
				*dsty++ = *src++;
				*dsty++ = *src++;
				if (line & 1)
					*dstv++ = *src++;
				else
					*dstu++ = *src++;
			}
			dsty += stride;
			if (line & 1)
				dstv += (stride >> 1);
			else
				dstu += (stride >> 1);
		}

		return 0;
	}

	/*
	 * Compressed;
	 * the decompressor routines will write the data in planar format
	 * immediately.
	 */
	if (pdev->vsize == PSZ_VGA && pdev->vframes == 5 && pdev->vsnapshot) {
		PWC_ERROR("Mode Bayer is not supported for now\n");
		/* flags |= PWCX_FLAG_BAYER; */
		return -ENXIO; /* No such device or address: missing decompressor */
	}

	if (DEVICE_USE_CODEC1(pdev->type)) {

		/* TODO & FIXME */
		PWC_ERROR("This chipset is not supported for now\n");
		return -ENXIO; /* No such device or address: missing decompressor */

	} else {
		pwc_dec23_decompress(pdev, yuv, image, PWCX_FLAG_PLANAR);
	}
	return 0;
}


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