mqrspec.c

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/*
 * qrencode - QR Code encoder
 *
 * Micro QR Code specification in convenient format.
 * Copyright (C) 2006-2017 Kentaro Fukuchi <kentaro@fukuchi.org>
 *
 * The following data / specifications are taken from
 * "Two dimensional symbol -- QR-code -- Basic Specification" (JIS X0510:2004)
 *  or
 * "Automatic identification and data capture techniques --
 *  QR Code 2005 bar code symbology specification" (ISO/IEC 18004:2006)
 *
 * 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
 */

#include "config.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "mqrspec.h"

/******************************************************************************
 * Version and capacity
 *****************************************************************************/

typedef struct {
    int width; 
    int ec[4]; 
} MQRspec_Capacity;

static const MQRspec_Capacity mqrspecCapacity[MQRSPEC_VERSION_MAX + 1] = {
    {  0, {0,  0,  0, 0}},
    { 11, {2,  0,  0, 0}},
    { 13, {5,  6,  0, 0}},
    { 15, {6,  8,  0, 0}},
    { 17, {8, 10, 14, 0}}
};

int MQRspec_getDataLengthBit(int version, QRecLevel level)
{
    int w;
    int ecc;

    w = mqrspecCapacity[version].width - 1;
    ecc = mqrspecCapacity[version].ec[level];
    if(ecc == 0) return 0;
    return w * w - 64 - ecc * 8;
}

int MQRspec_getDataLength(int version, QRecLevel level)
{
    return (MQRspec_getDataLengthBit(version, level) + 4) / 8;
}

int MQRspec_getECCLength(int version, QRecLevel level)
{
    return mqrspecCapacity[version].ec[level];
}

int MQRspec_getWidth(int version)
{
    return mqrspecCapacity[version].width;
}

/******************************************************************************
 * Length indicator
 *****************************************************************************/

static const int lengthTableBits[4][4] = {
    { 3, 4, 5, 6},
    { 0, 3, 4, 5},
    { 0, 0, 4, 5},
    { 0, 0, 3, 4}
};

int MQRspec_lengthIndicator(QRencodeMode mode, int version)
{
    return lengthTableBits[mode][version - 1];
}

int MQRspec_maximumWords(QRencodeMode mode, int version)
{
    int bits;
    int words;

    bits = lengthTableBits[mode][version - 1];
    words = (1 << bits) - 1;
    if(mode == QR_MODE_KANJI) {
        words *= 2; // the number of bytes is required
    }

    return words;
}

/******************************************************************************
 * Format information
 *****************************************************************************/

/* See calcFormatInfo in tests/test_mqrspec.c */
static const unsigned int formatInfo[4][8] = {
    {0x4445, 0x55ae, 0x6793, 0x7678, 0x06de, 0x1735, 0x2508, 0x34e3},
    {0x4172, 0x5099, 0x62a4, 0x734f, 0x03e9, 0x1202, 0x203f, 0x31d4},
    {0x4e2b, 0x5fc0, 0x6dfd, 0x7c16, 0x0cb0, 0x1d5b, 0x2f66, 0x3e8d},
    {0x4b1c, 0x5af7, 0x68ca, 0x7921, 0x0987, 0x186c, 0x2a51, 0x3bba}
};

/* See Table 10 of Appendix 1. (pp.115) */
static const int typeTable[MQRSPEC_VERSION_MAX + 1][3] = {
    {-1, -1, -1},
    { 0, -1, -1},
    { 1,  2, -1},
    { 3,  4, -1},
    { 5,  6,  7}
};

unsigned int MQRspec_getFormatInfo(int mask, int version, QRecLevel level)
{
    int type;

    if(mask < 0 || mask > 3) return 0;
    if(version <= 0 || version > MQRSPEC_VERSION_MAX) return 0;
    if(level == QR_ECLEVEL_H) return 0;
    type = typeTable[version][level];
    if(type < 0) return 0;

    return formatInfo[mask][type];
}

/******************************************************************************
 * Frame
 *****************************************************************************/

static void putFinderPattern(unsigned char *frame, int width, int ox, int oy)
{
    static const unsigned char finder[] = {
        0xc1, 0xc1, 0xc1, 0xc1, 0xc1, 0xc1, 0xc1,
        0xc1, 0xc0, 0xc0, 0xc0, 0xc0, 0xc0, 0xc1,
        0xc1, 0xc0, 0xc1, 0xc1, 0xc1, 0xc0, 0xc1,
        0xc1, 0xc0, 0xc1, 0xc1, 0xc1, 0xc0, 0xc1,
        0xc1, 0xc0, 0xc1, 0xc1, 0xc1, 0xc0, 0xc1,
        0xc1, 0xc0, 0xc0, 0xc0, 0xc0, 0xc0, 0xc1,
        0xc1, 0xc1, 0xc1, 0xc1, 0xc1, 0xc1, 0xc1,
    };
    int x, y;
    const unsigned char *s;

    frame += oy * width + ox;
    s = finder;
    for(y = 0; y < 7; y++) {
        for(x = 0; x < 7; x++) {
            frame[x] = s[x];
        }
        frame += width;
        s += 7;
    }
}

static unsigned char *MQRspec_createFrame(int version)
{
    unsigned char *frame, *p, *q;
    int width;
    int x, y;

    width = mqrspecCapacity[version].width;
    frame = (unsigned char *)malloc((size_t)(width * width));
    if(frame == NULL) return NULL;

    memset(frame, 0, (size_t)(width * width));
    /* Finder pattern */
    putFinderPattern(frame, width, 0, 0);
    /* Separator */
    p = frame;
    for(y = 0; y < 7; y++) {
        p[7] = 0xc0;
        p += width;
    }
    memset(frame + width * 7, 0xc0, 8);
    /* Mask format information area */
    memset(frame + width * 8 + 1, 0x84, 8);
    p = frame + width + 8;
    for(y = 0; y < 7; y++) {
        *p = 0x84;
        p += width;
    }
    /* Timing pattern */
    p = frame + 8;
    q = frame + width * 8;
    for(x = 1; x < width-7; x++) {
        *p =  0x90 | (x & 1);
        *q =  0x90 | (x & 1);
        p++;
        q += width;
    }

    return frame;
}

unsigned char *MQRspec_newFrame(int version)
{
    if(version < 1 || version > MQRSPEC_VERSION_MAX) return NULL;

    return MQRspec_createFrame(version);
}