160 lines
6.5 KiB
C++
160 lines
6.5 KiB
C++
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/*
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* Copyright 2016 Nu-book Inc.
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* Copyright 2016 ZXing authors
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* Copyright 2023 Axel Waggershauser
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* Copyright 2023 gitlost
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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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namespace ZXing::QRCode {
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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(const std::vector<uint32_t>& masks, const std::vector<uint32_t>& bits)
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{
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// See ISO 18004:2015, Annex C, Table C.1
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constexpr uint32_t MODEL2_MASKED_PATTERNS[] = {
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0x5412, 0x5125, 0x5E7C, 0x5B4B, 0x45F9, 0x40CE, 0x4F97, 0x4AA0, 0x77C4, 0x72F3, 0x7DAA, 0x789D, 0x662F, 0x6318, 0x6C41, 0x6976,
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0x1689, 0x13BE, 0x1CE7, 0x19D0, 0x0762, 0x0255, 0x0D0C, 0x083B, 0x355F, 0x3068, 0x3F31, 0x3A06, 0x24B4, 0x2183, 0x2EDA, 0x2BED,
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};
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FormatInformation fi;
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for (auto mask : masks)
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for (int bitsIndex = 0; bitsIndex < Size(bits); ++bitsIndex)
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for (uint32_t pattern : MODEL2_MASKED_PATTERNS) {
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// 'unmask' the pattern first to get the original 5-data bits + 10-ec bits back
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pattern ^= FORMAT_INFO_MASK_MODEL2;
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// Find the pattern with fewest bits differing
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if (int hammingDist = BitHacks::CountBitsSet((bits[bitsIndex] ^ mask) ^ pattern);
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hammingDist < fi.hammingDistance) {
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fi.mask = mask; // store the used mask to discriminate between types/models
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fi.data = pattern >> 10; // drop the 10 BCH error correction bits
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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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static FormatInformation FindBestFormatInfoRMQR(const std::vector<uint32_t>& bits, const std::vector<uint32_t>& subbits)
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{
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// See ISO/IEC 23941:2022, Annex C, Table C.1 - Valid format information sequences
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constexpr uint32_t MASKED_PATTERNS[64] = { // Finder pattern side
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0x1FAB2, 0x1E597, 0x1DBDD, 0x1C4F8, 0x1B86C, 0x1A749, 0x19903, 0x18626,
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0x17F0E, 0x1602B, 0x15E61, 0x14144, 0x13DD0, 0x122F5, 0x11CBF, 0x1039A,
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0x0F1CA, 0x0EEEF, 0x0D0A5, 0x0CF80, 0x0B314, 0x0AC31, 0x0927B, 0x08D5E,
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0x07476, 0x06B53, 0x05519, 0x04A3C, 0x036A8, 0x0298D, 0x017C7, 0x008E2,
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0x3F367, 0x3EC42, 0x3D208, 0x3CD2D, 0x3B1B9, 0x3AE9C, 0x390D6, 0x38FF3,
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0x376DB, 0x369FE, 0x357B4, 0x34891, 0x33405, 0x32B20, 0x3156A, 0x30A4F,
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0x2F81F, 0x2E73A, 0x2D970, 0x2C655, 0x2BAC1, 0x2A5E4, 0x29BAE, 0x2848B,
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0x27DA3, 0x26286, 0x25CCC, 0x243E9, 0x23F7D, 0x22058, 0x21E12, 0x20137,
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};
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constexpr uint32_t MASKED_PATTERNS_SUB[64] = { // Finder sub pattern side
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0x20A7B, 0x2155E, 0x22B14, 0x23431, 0x248A5, 0x25780, 0x269CA, 0x276EF,
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0x28FC7, 0x290E2, 0x2AEA8, 0x2B18D, 0x2CD19, 0x2D23C, 0x2EC76, 0x2F353,
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0x30103, 0x31E26, 0x3206C, 0x33F49, 0x343DD, 0x35CF8, 0x362B2, 0x37D97,
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0x384BF, 0x39B9A, 0x3A5D0, 0x3BAF5, 0x3C661, 0x3D944, 0x3E70E, 0x3F82B,
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0x003AE, 0x01C8B, 0x022C1, 0x03DE4, 0x04170, 0x05E55, 0x0601F, 0x07F3A,
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0x08612, 0x09937, 0x0A77D, 0x0B858, 0x0C4CC, 0x0DBE9, 0x0E5A3, 0x0FA86,
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0x108D6, 0x117F3, 0x129B9, 0x1369C, 0x14A08, 0x1552D, 0x16B67, 0x17442,
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0x18D6A, 0x1924F, 0x1AC05, 0x1B320, 0x1CFB4, 0x1D091, 0x1EEDB, 0x1F1FE,
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};
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FormatInformation fi;
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auto best = [&fi](const std::vector<uint32_t>& bits, const uint32_t (&patterns)[64], uint32_t mask)
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{
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for (int bitsIndex = 0; bitsIndex < Size(bits); ++bitsIndex)
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for (uint32_t pattern : patterns) {
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// 'unmask' the pattern first to get the original 6-data bits + 12-ec bits back
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pattern ^= mask;
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// Find the pattern with fewest bits differing
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if (int hammingDist = BitHacks::CountBitsSet((bits[bitsIndex] ^ mask) ^ pattern);
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hammingDist < fi.hammingDistance) {
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fi.mask = mask; // store the used mask to discriminate between types/models
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fi.data = pattern >> 12; // drop the 12 BCH error correction bits
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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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};
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best(bits, MASKED_PATTERNS, FORMAT_INFO_MASK_RMQR);
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if (Size(subbits)) // TODO probably remove if `sampleRMQR()` done properly
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best(subbits, MASKED_PATTERNS_SUB, FORMAT_INFO_MASK_RMQR_SUB);
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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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// Some (Model2) QR codes apparently do not apply the XOR mask. Try with (standard) and without (quirk) masking.
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auto fi = FindBestFormatInfo({FORMAT_INFO_MASK_MODEL2, 0, FORMAT_INFO_MASK_MODEL1},
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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.data >> 3) & 0x03);
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fi.dataMask = static_cast<uint8_t>(fi.data & 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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auto fi = FindBestFormatInfo({FORMAT_INFO_MASK_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.data >> 2) & 0x07, true);
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fi.dataMask = static_cast<uint8_t>(fi.data & 0x03);
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fi.microVersion = BITS_TO_VERSION[(fi.data >> 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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/**
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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::DecodeRMQR(uint32_t formatInfoBits1, uint32_t formatInfoBits2)
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{
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FormatInformation fi;
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if (formatInfoBits2)
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fi = FindBestFormatInfoRMQR({formatInfoBits1}, {formatInfoBits2});
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else // TODO probably remove if `sampleRMQR()` done properly
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fi = FindBestFormatInfoRMQR({formatInfoBits1}, {});
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// Bit 6 is error correction (M/H), and bits 0-5 version.
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fi.ecLevel = ECLevelFromBits(((fi.data >> 5) & 1) << 1); // Shift to match QRCode M/H
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fi.dataMask = 4; // ((y / 2) + (x / 3)) % 2 == 0
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fi.microVersion = (fi.data & 0x1F) + 1;
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fi.isMirrored = false; // TODO: implement mirrored format bit reading
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return fi;
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}
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} // namespace ZXing::QRCode
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