kc3-lang/libqrencode/mmask.c

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• Hash : 27b292d1
  Author :
  Date : 2011-11-24T02:20:26
  

  A bug in mask evaluation function has been eliminatd.
  

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• mmask.c

• /*
   * 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;
  }
  

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