156 lines
4.1 KiB
C++
156 lines
4.1 KiB
C++
/*
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* Copyright 2016 Nu-book Inc.
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* Copyright 2016 ZXing authors
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*/
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// SPDX-License-Identifier: Apache-2.0
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#include "QRFormatInformation.h"
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#include "BitHacks.h"
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#include "ZXAlgorithms.h"
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#include <array>
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namespace ZXing::QRCode {
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static const int FORMAT_INFO_MASK_QR = 0x5412;
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/**
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* See ISO 18004:2006, Annex C, Table C.1
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*/
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static const std::array<std::pair<int, int>, 32> FORMAT_INFO_DECODE_LOOKUP = {{
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{0x5412, 0x00},
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{0x5125, 0x01},
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{0x5E7C, 0x02},
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{0x5B4B, 0x03},
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{0x45F9, 0x04},
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{0x40CE, 0x05},
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{0x4F97, 0x06},
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{0x4AA0, 0x07},
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{0x77C4, 0x08},
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{0x72F3, 0x09},
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{0x7DAA, 0x0A},
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{0x789D, 0x0B},
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{0x662F, 0x0C},
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{0x6318, 0x0D},
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{0x6C41, 0x0E},
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{0x6976, 0x0F},
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{0x1689, 0x10},
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{0x13BE, 0x11},
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{0x1CE7, 0x12},
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{0x19D0, 0x13},
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{0x0762, 0x14},
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{0x0255, 0x15},
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{0x0D0C, 0x16},
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{0x083B, 0x17},
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{0x355F, 0x18},
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{0x3068, 0x19},
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{0x3F31, 0x1A},
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{0x3A06, 0x1B},
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{0x24B4, 0x1C},
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{0x2183, 0x1D},
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{0x2EDA, 0x1E},
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{0x2BED, 0x1F},
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}};
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static const std::array<std::pair<int, int>, 32> FORMAT_INFO_DECODE_LOOKUP_MICRO = {{
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{0x4445, 0x00},
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{0x4172, 0x01},
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{0x4E2B, 0x02},
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{0x4B1C, 0x03},
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{0x55AE, 0x04},
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{0x5099, 0x05},
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{0x5FC0, 0x06},
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{0x5AF7, 0x07},
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{0x6793, 0x08},
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{0x62A4, 0x09},
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{0x6DFD, 0x0A},
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{0x68CA, 0x0B},
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{0x7678, 0x0C},
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{0x734F, 0x0D},
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{0x7C16, 0x0E},
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{0x7921, 0x0F},
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{0x06DE, 0x10},
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{0x03E9, 0x11},
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{0x0CB0, 0x12},
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{0x0987, 0x13},
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{0x1735, 0x14},
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{0x1202, 0x15},
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{0x1D5B, 0x16},
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{0x186C, 0x17},
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{0x2508, 0x18},
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{0x203F, 0x19},
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{0x2F66, 0x1A},
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{0x2A51, 0x1B},
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{0x34E3, 0x1C},
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{0x31D4, 0x1D},
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{0x3E8D, 0x1E},
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{0x3BBA, 0x1F},
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}};
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static uint32_t MirrorBits(uint32_t bits)
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{
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return BitHacks::Reverse(bits) >> 17;
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}
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static FormatInformation FindBestFormatInfo(int mask, const std::array<std::pair<int, int>, 32> lookup,
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const std::vector<uint32_t>& bits)
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{
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FormatInformation fi;
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// Some QR codes apparently do not apply the XOR mask. Try without and with additional masking.
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for (auto mask : {0, mask})
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for (int bitsIndex = 0; bitsIndex < Size(bits); ++bitsIndex)
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for (const auto& [pattern, index] : lookup) {
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// Find the int in lookup with fewest bits differing
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if (int hammingDist = BitHacks::CountBitsSet((bits[bitsIndex] ^ mask) ^ pattern); hammingDist < fi.hammingDistance) {
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fi.index = index;
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fi.hammingDistance = hammingDist;
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fi.bitsIndex = bitsIndex;
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}
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}
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return fi;
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}
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/**
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* @param formatInfoBits1 format info indicator, with mask still applied
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* @param formatInfoBits2 second copy of same info; both are checked at the same time to establish best match
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*/
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FormatInformation FormatInformation::DecodeQR(uint32_t formatInfoBits1, uint32_t formatInfoBits2)
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{
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// maks out the 'Dark Module' for mirrored and non-mirrored case (see Figure 25 in ISO/IEC 18004:2015)
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uint32_t mirroredFormatInfoBits2 = MirrorBits(((formatInfoBits2 >> 1) & 0b111111110000000) | (formatInfoBits2 & 0b1111111));
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formatInfoBits2 = ((formatInfoBits2 >> 1) & 0b111111100000000) | (formatInfoBits2 & 0b11111111);
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auto fi = FindBestFormatInfo(FORMAT_INFO_MASK_QR, FORMAT_INFO_DECODE_LOOKUP,
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{formatInfoBits1, formatInfoBits2, MirrorBits(formatInfoBits1), mirroredFormatInfoBits2});
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// Use bits 3/4 for error correction, and 0-2 for mask.
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fi.ecLevel = ECLevelFromBits((fi.index >> 3) & 0x03);
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fi.dataMask = static_cast<uint8_t>(fi.index & 0x07);
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fi.isMirrored = fi.bitsIndex > 1;
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return fi;
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}
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/**
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* @param formatInfoBits format info indicator, with mask still applied
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*/
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FormatInformation FormatInformation::DecodeMQR(uint32_t formatInfoBits)
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{
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// We don't use the additional masking (with 0x4445) to work around potentially non complying MicroQRCode encoders
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auto fi = FindBestFormatInfo(0, FORMAT_INFO_DECODE_LOOKUP_MICRO, {formatInfoBits, MirrorBits(formatInfoBits)});
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constexpr uint8_t BITS_TO_VERSION[] = {1, 2, 2, 3, 3, 4, 4, 4};
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// Bits 2/3/4 contain both error correction level and version, 0/1 contain mask.
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fi.ecLevel = ECLevelFromBits((fi.index >> 2) & 0x07, true);
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fi.dataMask = static_cast<uint8_t>(fi.index & 0x03);
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fi.microVersion = BITS_TO_VERSION[(fi.index >> 2) & 0x07];
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fi.isMirrored = fi.bitsIndex == 1;
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return fi;
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}
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} // namespace ZXing::QRCode
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