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/*
* $Id: merge_split.c,v 1.15 2010/02/05 23:50:22 simakov Exp $
*
* EPSILON - wavelet image compression library.
* Copyright (C) 2006,2007,2010 Alexander Simakov, <xander@entropyware.info>
*
* This file is part of EPSILON
*
* EPSILON 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 3 of the License, or
* (at your option) any later version.
*
* EPSILON 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 EPSILON. If not, see <http://www.gnu.org/licenses/>.
*
* http://epsilon-project.sourceforge.net
*/
#include <common.h>
#include <merge_split.h>
void merge_channels(unsigned char *channel_A, unsigned char *channel_B,
unsigned char *channel_AB, int len_A, int len_B)
{
int pkg_A, pkg_B; /* Real number of bytes in the package */
int div_A, div_B; /* Base number of bytes in the package */
int rem_A, rem_B; /* Instant reminder */
int cur_A, cur_B; /* Current savings */
int tr0_A, tr0_B; /* Lower threshold */
int tr1_A, tr1_B; /* Upper threshold */
int i, pkg, min;
/* Sanity checks. I love them! */
assert((len_A > 0) && (len_B > 0));
/* Total number of packages */
min = MIN(len_A, len_B);
/* 1-st channel setup */
div_A = len_A / min;
cur_A = len_A;
rem_A = 0;
tr0_A = div_A * min;
tr1_A = tr0_A + min;
/* 2-nd channel setup */
div_B = len_B / min;
cur_B = len_B;
rem_B = 0;
tr0_B = div_B * min;
tr1_B = tr0_B + min;
/* Loop for all packages */
for (pkg = 0; pkg < min; pkg++) {
/* Update current savings */
cur_A = len_A + rem_A;
if (cur_A >= tr1_A) {
/* Choose maximal package & update reminder */
pkg_A = div_A + 1;
rem_A = cur_A - tr1_A;
} else {
/* Choose minimal package & update reminder */
pkg_A = div_A;
rem_A = cur_A - tr0_A;
}
/* Update current savings */
cur_B = len_B + rem_B;
if (cur_B >= tr1_B) {
/* Choose maximal package & update reminder */
pkg_B = div_B + 1;
rem_B = cur_B - tr1_B;
} else {
/* Choose minimal package & update reminder */
pkg_B = div_B;
rem_B = cur_B - tr0_B;
}
/* Put bytes from the 1-st channel */
for (i = 0; i < pkg_A; i++) {
*channel_AB++ = *channel_A++;
}
/* Put bytes from the 2-nd channel */
for (i = 0; i < pkg_B; i++) {
*channel_AB++ = *channel_B++;
}
}
}
void split_channels(unsigned char *channel_AB,
unsigned char *channel_A, unsigned char *channel_B,
int len_AB, int len_A, int len_B,
int *real_len_A, int *real_len_B)
{
int pkg_A, pkg_B; /* Real number of bytes in the package */
int div_A, div_B; /* Base number of bytes in the package */
int rem_A, rem_B; /* Instant reminder */
int cur_A, cur_B; /* Current savings */
int tr0_A, tr0_B; /* Lower threshold */
int tr1_A, tr1_B; /* Upper threshold */
int i, pkg, min;
unsigned char *end_AB;
unsigned char *end_A;
unsigned char *end_B;
/* Sanity checks */
assert((len_A > 0) && (len_B > 0) && (len_AB > 0));
assert(real_len_A && real_len_B);
assert(len_A + len_B >= len_AB);
/* Set end-of-buffer pointers */
end_AB = channel_AB + len_AB;
end_A = channel_A + len_A;
end_B = channel_B + len_B;
/* Real amount of saved bytes */
*real_len_A = *real_len_B = 0;
/* Original number of packages (real stream may be truncated) */
min = MIN(len_A, len_B);
/* 1-st channel setup */
div_A = len_A / min;
cur_A = len_A;
rem_A = 0;
tr0_A = div_A * min;
tr1_A = tr0_A + min;
/* 2-nd channel setup */
div_B = len_B / min;
cur_B = len_B;
rem_B = 0;
tr0_B = div_B * min;
tr1_B = tr0_B + min;
/* Loop for all packages */
for (pkg = 0; pkg < min; pkg++) {
/* Update current savings */
cur_A = len_A + rem_A;
if (cur_A >= tr1_A) {
/* Choose maximal package & update reminder */
pkg_A = div_A + 1;
rem_A = cur_A - tr1_A;
} else {
/* Choose minimal package & update reminder */
pkg_A = div_A;
rem_A = cur_A - tr0_A;
}
/* Update current savings */
cur_B = len_B + rem_B;
if (cur_B >= tr1_B) {
/* Choose maximal package & update reminder */
pkg_B = div_B + 1;
rem_B = cur_B - tr1_B;
} else {
/* Choose minimal package & update reminder */
pkg_B = div_B;
rem_B = cur_B - tr0_B;
}
/* Extract pkg_A bytes from the stream into the channel_A */
for (i = 0; (i < pkg_A) && (channel_A < end_A) && (channel_AB < end_AB); i++) {
*channel_A++ = *channel_AB++;
(*real_len_A)++;
}
/* Extract pkg_B bytes from the stream into the channel_B */
for (i = 0; (i < pkg_B) && (channel_B < end_B) && (channel_AB < end_AB); i++) {
*channel_B++ = *channel_AB++;
(*real_len_B)++;
}
/* All avaiable bytes are processed */
if (channel_AB >= end_AB) {
assert(*real_len_A + *real_len_B == len_AB);
if ((pkg == min - 1) && (channel_A == end_A) && (channel_B == end_B)) {
assert((*real_len_A == len_A) && (*real_len_B == len_B));
}
return;
}
}
}
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