v4l2_libs/libv4lconvert/pac207.c

/*

# PAC207 decoder
#               Bertrik.Sikken. Thomas Kaiser (C) 2005
#               Copyright (C) 2003 2004 2005 Michel Xhaard

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License, version 2.1,
# as published by the Free Software Foundation.
#
# 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 Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA  02110-1335  USA

# Note this code was originally licensed under the GNU GPL instead of the
# GNU LGPL, its license has been changed with permission, see the permission
# mails at the end of this file.

 */

#include <string.h>
#include "libv4lconvert-priv.h"

#define CLIP(color) (unsigned char)(((color) > 0xFF) ? 0xff : (((color) < 0) ? 0 : (color)))

/* FIXME not threadsafe */
static int decoder_initialized;

static struct {
	unsigned char is_abs;
	unsigned char len;
	signed char val;
} table[256];

static void init_pixart_decoder(void)
{
	int i;
	int is_abs, val, len;

	for (i = 0; i < 256; i++) {
		is_abs = 0;
		val = 0;
		len = 0;
		if ((i & 0xC0) == 0) {
			/* code 00 */
			val = 0;
			len = 2;
		} else if ((i & 0xC0) == 0x40) {
			/* code 01 */
			val = -1;
			len = 2;
		} else if ((i & 0xC0) == 0x80) {
			/* code 10 */
			val = 1;
			len = 2;
		} else if ((i & 0xF0) == 0xC0) {
			/* code 1100 */
			val = -2;
			len = 4;
		} else if ((i & 0xF0) == 0xD0) {
			/* code 1101 */
			val = 2;
			len = 4;
		} else if ((i & 0xF8) == 0xE0) {
			/* code 11100 */
			val = -3;
			len = 5;
		} else if ((i & 0xF8) == 0xE8) {
			/* code 11101 */
			val = 3;
			len = 5;
		} else if ((i & 0xFC) == 0xF0) {
			/* code 111100 */
			val = -4;
			len = 6;
		} else if ((i & 0xFC) == 0xF4) {
			/* code 111101 */
			val = 4;
			len = 6;
		} else if ((i & 0xF8) == 0xF8) {
			/* code 11111xxxxxx */
			is_abs = 1;
			val = 0;
			len = 5;
		}
		table[i].is_abs = is_abs;
		table[i].val = val;
		table[i].len = len;
	}
	decoder_initialized = 1;
}

static inline unsigned char getByte(const unsigned char *inp,
		unsigned int bitpos)
{
	const unsigned char *addr;

	addr = inp + (bitpos >> 3);
	return (addr[0] << (bitpos & 7)) | (addr[1] >> (8 - (bitpos & 7)));
}

static inline unsigned short getShort(const unsigned char *pt)
{
	return ((pt[0] << 8) | pt[1]);
}

static int
pac_decompress_row(const unsigned char *inp, unsigned char *outp, int width,
		int step_size, int abs_bits)
{
	int col;
	int val;
	int bitpos;
	unsigned char code;

	if (!decoder_initialized)
		init_pixart_decoder();

	/* first two pixels are stored as raw 8-bit */
	*outp++ = inp[2];
	*outp++ = inp[3];
	bitpos = 32;

	/* main decoding loop */
	for (col = 2; col < width; col++) {
		/* get bitcode */

		code = getByte(inp, bitpos);
		bitpos += table[code].len;

		/* calculate pixel value */
		if (table[code].is_abs) {
			/* absolute value: get 6 more bits */
			code = getByte(inp, bitpos);
			bitpos += abs_bits;
			*outp++ = code & ~(0xff >> abs_bits);
		} else {
			/* relative to left pixel */
			val = outp[-2] + table[code].val * step_size;
			*outp++ = CLIP(val);
		}
	}

	/* return line length, rounded up to next 16-bit word */
	return 2 * ((bitpos + 15) / 16);
}

int v4lconvert_decode_pac207(struct v4lconvert_data *data,
		const unsigned char *inp, int src_size, unsigned char *outp,
		int width, int height)
{
	/* we should received a whole frame with header and EOL marker
	   in myframe->data and return a GBRG pattern in frame->tmpbuffer
	   remove the header then copy line by line EOL is set with 0x0f 0xf0 marker
	   or 0x1e 0xe1 for compressed line*/
	const unsigned char *end = inp + src_size;
	unsigned short word;
	int row;

	/* iterate over all rows */
	for (row = 0; row < height; row++) {
		if ((inp + 2) > end) {
			V4LCONVERT_ERR("incomplete pac207 frame\n");
			return -1;
		}
		word = getShort(inp);
		switch (word) {
		case 0x0FF0:
			memcpy(outp, inp + 2, width);
			inp += (2 + width);
			break;
		case 0x1EE1:
			inp += pac_decompress_row(inp, outp, width, 5, 6);
			break;

		case 0x2DD2:
			inp += pac_decompress_row(inp, outp, width, 9, 5);
			break;

		case 0x3CC3:
			inp += pac_decompress_row(inp, outp, width, 17, 4);
			break;

		case 0x4BB4:
			/* skip or copy line? */
			memcpy(outp, outp - 2 * width, width);
			inp += 2;
			break;

		default: /* corrupt frame */
			V4LCONVERT_ERR("unknown pac207 row header: 0x%04x\n", (int)word);
			return -1;
		}
		outp += width;
	}

	return 0;
}




/*
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Date: Thu, 26 Jun 2008 01:17:37 +0200
From: Thomas Kaiser <thomas@kaiser-linux.li>
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To: Hans de Goede <j.w.r.degoede@hhs.nl>
CC: Thomas Kaiser <spca5xx@kaiser-linux.li>, bertrik@zonnet.nl,
mxhaard@magic.fr
Subject: Re: pac207 bayer decompression algorithm license question
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Hello Hans

Hans de Goede wrote:
> Hi,
>
> As you may have seen on the mailinglist, I've created a userspace
> library to handle cam specific format handling in userspace where it
> belongs, see:
> http://hansdegoede.livejournal.com/
Yes, I saw it on the mail list and I think it is a good idea :-)
>
> I would like to also add support for decompressing the pac207's
> compressed bayer to this lib (and remove it from the kernel driver)
> for this I need permission to relicense the decompress code under the
> LGPL (version 2 or later).
Actually, this was done by Bertrik Sikken (bertrik@zonnet.nl), Michel
Xhaard (mxhaard@magic.fr) and me. But Bertrik was the one who found out
how to decode the lines :-)
>
> Can you give me permission for this, or if the code is not yours put
> me in contact with someone who can?
For me it's no problem to release it with LGPL. Maybe you have to ask
the other one's also.
>
> Thanks & Regards,
>
> Hans

Rgeards, Thomas
*/

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   From: Michel Xhaard <mxhaard@magic.fr>
   To: Hans de Goede <j.w.r.degoede@hhs.nl>
   Subject: Re: pac207 bayer decompression algorithm license question
   Date: Thu, 26 Jun 2008 11:15:32 +0200
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   Le jeudi 26 juin 2008 09:02, Hans de Goede a =E9crit=A0:
   > Hi,
   >
   > As you may have seen on the mailinglist, I've created a userspace library
   > to handle cam specific format handling in userspace, see:
   > http://hansdegoede.livejournal.com/
   >
   > I would like to also add support for decompressing the pac207's compressed
   > bayer to this lib (and remove it from the kernel driver) and I've heard
   > from Thomas Kaiser that you are a co-author of the decompression code. In
   > order to add support for decompressing pac207 compressed bayer to libv4l I
   > need permission to relicense the decompression code under the LGPL (versi=
   on
   > 2 or later).
   >
   > Can you give me permission for this?
   >
   > Thanks & Regards,
   >
   > Hans
   >
   >
   >
   > p.s.
>
> Thomas has already given permission.

=46or me it is ok and a good idea for all free world familly ;-).
Bests regards
=2D-=20
Michel Xhaard
http://mxhaard.free.fr
*/

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   Hallo Hans,

   Hans de Goede wrote:
   > Hi,
   >
   > As you may have seen on the mailinglist, I've created a userspace
   > library to
   > handle cam specific format handling in userspace, see:
   > http://hansdegoede.livejournal.com/

   O leuk, zoiets is naar mijn idee precies wat er nodig is voor webcam
   support onder linux. Ik ben een jaar of 3 geleden heel actief geweest
   met een aantal webcams, maar doe er tegenwoordig helemaal niets meer
   aan.

   > I would like to also add support for decompressing the pac207's compressed
   > bayer to this lib (and remove it from the kernel driver) and I've heard
   > from Thomas Kaiser that you are a co-author of the decompression code.
   > In order to add support for decompressing pac207 compressed bayer to
   > libv4l I need
   > permission to relicense the decompression code under the LGPL (version 2
   > or later).
   >
   > Can you give me permission for this?

   Ja, vind ik goed.

   Vriendelijke groet,
   Bertrik
 */