pac207.c

trident tm5600的linux驱动

/*

# 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 as published by
# the Free Software Foundation; either version 2.1 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 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  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 = 0;

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 = -5;
	    len = 2;
	} else if ((i & 0xC0) == 0x80) {
	    /* code 10 */
	    val = +5;
	    len = 2;
	} else if ((i & 0xF0) == 0xC0) {
	    /* code 1100 */
	    val = -10;
	    len = 4;
	} else if ((i & 0xF0) == 0xD0) {
	    /* code 1101 */
	    val = +10;
	    len = 4;
	} else if ((i & 0xF8) == 0xE0) {
	    /* code 11100 */
	    val = -15;
	    len = 5;
	} else if ((i & 0xF8) == 0xE8) {
	    /* code 11101 */
	    val = +15;
	    len = 5;
	} else if ((i & 0xFC) == 0xF0) {
	    /* code 111100 */
	    val = -20;
	    len = 6;
	} else if ((i & 0xFC) == 0xF4) {
	    /* code 111101 */
	    val = +20;
	    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 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 += 6;
	    *outp++ = code & 0xFC;
	} else {
	    /* relative to left pixel */
	    val = outp[-2] + table[code].val;
	    *outp++ = CLIP(val);
	}
    }

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

void v4lconvert_decode_pac207(const unsigned char *inp, 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*/
    unsigned short word;
    int row;

    /* iterate over all rows */
    for (row = 0; row < height; row++) {
	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);
	    break;

	case 0x2DD2: /* prefix for "stronger" compressed lines, currently the
			kernel driver programs the cam so that we should not
			get any of these */

	default: /* corrupt frame */
	    /* FIXME add error reporting */
	    return;
	}
	outp += width;
    }

    return;
}




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	[e-mail]
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 ([e-mail]), Michel
Xhaard ([e-mail]) 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 <[e-mail]>
To: Hans de Goede <[e-mail]>
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
*/