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/*
# (C) 2011 Hans de Goede <hdegoede@redhat.com>
# The compression algorithm has been taken from the v4l1 se401 linux kernel
# driver by Jeroen B. Vreeken (pe1rxq@amsat.org)
# 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., 51 Franklin Street, Suite 500, Boston, MA 02110-1335 USA
*/
#include "libv4lconvert-priv.h"
#include <errno.h>
/* The se401 compression algorithm uses a fixed quant factor, which
can be configured by setting the high nibble of the SE401_OPERATINGMODE
feature. This needs to exactly match what is in the SE401 driver! */
#define SE401_QUANT_FACT 8
static void wr_pixel(int p, uint8_t **dest, int pitch, int *x)
{
int i = *x;
/* First 3 pixels of each line are absolute */
if (i < 3) {
(*dest)[i] = p * SE401_QUANT_FACT;
} else {
(*dest)[i] = (*dest)[i - 3] + p * SE401_QUANT_FACT;
}
*x += 1;
if (*x == pitch) {
*x = 0;
*dest += pitch;
}
}
enum decode_state {
get_len,
sign_bit,
other_bits,
};
static int decode_JangGu(const uint8_t *data, int bits, int plen, int pixels,
uint8_t **dest, int pitch, int *x)
{
enum decode_state state = get_len;
int len = 0;
int value = 0;
int bitnr;
int bit;
while (plen) {
bitnr = 8;
while (bitnr && bits) {
bit = ((*data) >> (bitnr-1))&1;
switch (state) {
case get_len:
if (bit) {
len++;
} else {
if (!len) {
wr_pixel(0, dest, pitch, x);
if (!--pixels)
return 0;
} else {
state = sign_bit;
value = 0;
}
}
break;
case sign_bit:
if (bit)
value = 0;
else
value = -(1 << len) + 1;
state = other_bits;
/* fall through for positive number and
len == 1 handling */
case other_bits:
len--;
value += bit << len;
if (len == 0) {
/* Done write pixel and get bit len of
the next one */
state = get_len;
wr_pixel(value, dest, pitch, x);
if (!--pixels)
return 0;
}
break;
}
bitnr--;
bits--;
}
data++;
plen--;
}
return -1;
}
int v4lconvert_se401_to_rgb24(struct v4lconvert_data *data,
const unsigned char *src, int src_size,
unsigned char *dest, int width, int height)
{
int in, plen, bits, pixels, info;
int x = 0, total_pixels = 0;
if (!src || !dest)
goto error;
for (in = 0; in + 4 < src_size; in += plen) {
bits = src[in + 3] + (src[in + 2] << 8);
pixels = src[in + 1] + ((src[in + 0] & 0x3f) << 8);
info = (src[in + 0] & 0xc0) >> 6;
plen = ((bits + 47) >> 4) << 1;
/* Sanity checks */
if (plen > 1024) {
V4LCONVERT_ERR("invalid se401 packet len %d", plen);
goto error;
}
if (in + plen > src_size) {
V4LCONVERT_ERR("incomplete se401 packet");
goto error;
}
if (total_pixels + pixels > width * height) {
V4LCONVERT_ERR("se401 frame overflow");
goto error;
}
/* info: 0 inter packet, 1 eof, 2 sof, 3 not used */
if ((in == 0 && info != 2) ||
(in > 0 && in + plen < src_size && info != 0) ||
(in + plen == src_size && info != 1)) {
V4LCONVERT_ERR("invalid se401 frame info value");
goto error;
}
if (decode_JangGu(&src[in + 4], bits, plen, pixels * 3,
&dest, width * 3, &x)) {
V4LCONVERT_ERR("short se401 packet");
goto error;
}
total_pixels += pixels;
}
if (in != src_size || total_pixels != width * height) {
V4LCONVERT_ERR("se401 frame size mismatch");
goto error;
}
return 0;
error:
errno = EIO;
return -1;
}
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