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/*
* qrencode - QR Code encoder
*
* Masking for Micro QR Code.
* Copyright (C) 2006-2011 Kentaro Fukuchi <kentaro@fukuchi.org>
*
* This library 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 any later version.
*
* This library 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 library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#if HAVE_CONFIG_H
# include "config.h"
#endif
#include <stdlib.h>
#include <string.h>
#include <limits.h>
#include <errno.h>
#include "qrencode.h"
#include "mqrspec.h"
#include "mmask.h"
__STATIC void MMask_writeFormatInformation(int version, int width, unsigned char *frame, int mask, QRecLevel level)
{
unsigned int format;
unsigned char v;
int i;
format = MQRspec_getFormatInfo(mask, version, level);
for(i=0; i<8; i++) {
v = 0x84 | (format & 1);
frame[width * (i + 1) + 8] = v;
format = format >> 1;
}
for(i=0; i<7; i++) {
v = 0x84 | (format & 1);
frame[width * 8 + 7 - i] = v;
format = format >> 1;
}
}
#define MASKMAKER(__exp__) \
int x, y;\
\
for(y=0; y<width; y++) {\
for(x=0; x<width; x++) {\
if(*s & 0x80) {\
*d = *s;\
} else {\
*d = *s ^ ((__exp__) == 0);\
}\
s++; d++;\
}\
}
static void Mask_mask0(int width, const unsigned char *s, unsigned char *d)
{
MASKMAKER(y&1)
}
static void Mask_mask1(int width, const unsigned char *s, unsigned char *d)
{
MASKMAKER(((y/2)+(x/3))&1)
}
static void Mask_mask2(int width, const unsigned char *s, unsigned char *d)
{
MASKMAKER((((x*y)&1)+(x*y)%3)&1)
}
static void Mask_mask3(int width, const unsigned char *s, unsigned char *d)
{
MASKMAKER((((x+y)&1)+((x*y)%3))&1)
}
#define maskNum (4)
typedef void MaskMaker(int, const unsigned char *, unsigned char *);
static MaskMaker *maskMakers[maskNum] = {
Mask_mask0, Mask_mask1, Mask_mask2, Mask_mask3
};
#ifdef WITH_TESTS
unsigned char *MMask_makeMaskedFrame(int width, unsigned char *frame, int mask)
{
unsigned char *masked;
masked = (unsigned char *)malloc(width * width);
if(masked == NULL) return NULL;
maskMakers[mask](width, frame, masked);
return masked;
}
#endif
unsigned char *MMask_makeMask(int version, unsigned char *frame, int mask, QRecLevel level)
{
unsigned char *masked;
int width;
if(mask < 0 || mask >= maskNum) {
errno = EINVAL;
return NULL;
}
width = MQRspec_getWidth(version);
masked = (unsigned char *)malloc(width * width);
if(masked == NULL) return NULL;
maskMakers[mask](width, frame, masked);
MMask_writeFormatInformation(version, width, masked, mask, level);
return masked;
}
__STATIC int MMask_evaluateSymbol(int width, unsigned char *frame)
{
int x, y;
unsigned char *p;
int sum1 = 0, sum2 = 0;
p = frame + width * (width - 1);
for(x=1; x<width; x++) {
sum1 += (p[x] & 1);
}
p = frame + width * 2 - 1;
for(y=1; y<width; y++) {
sum2 += (*p & 1);
p += width;
}
return (sum1 <= sum2)?(sum1 * 16 + sum2):(sum2 * 16 + sum1);
}
unsigned char *MMask_mask(int version, unsigned char *frame, QRecLevel level)
{
int i;
unsigned char *mask, *bestMask;
int maxScore = 0;
int score;
int width;
width = MQRspec_getWidth(version);
mask = (unsigned char *)malloc(width * width);
if(mask == NULL) return NULL;
bestMask = NULL;
for(i=0; i<maskNum; i++) {
score = 0;
maskMakers[i](width, frame, mask);
MMask_writeFormatInformation(version, width, mask, i, level);
score = MMask_evaluateSymbol(width, mask);
if(score > maxScore) {
maxScore = score;
free(bestMask);
bestMask = mask;
mask = (unsigned char *)malloc(width * width);
if(mask == NULL) break;
}
}
free(mask);
return bestMask;
}