zxing-cpp: strip to core library only (remove tests/wrappers/examples/docs); .gitignore: fix /core to allow zxing-cpp/core/ dir

tools/chatgui/zxing-cpp/core/src/ReedSolomon.cpp

@@ -0,0 +1,101 @@
+// Copyright 2026 Axel Waggershauser
+// SPDX-License-Identifier: Apache-2.0
+
+#include "ReedSolomon.h"
+#include "Version.h"
+#include "ZXAlgorithms.h"
+
+#include "librscpp/encode.h"
+#include "librscpp/decode.h"
+
+#include <algorithm>
+#include <type_traits>
+#include <stdexcept>
+#include <utility>
+
+namespace ZXing {
+
+namespace rs = librscpp;
+
+using GF2nI = rs::GF2n<>;
+
+const GF2nI& GetGF2n(RSField field)
+{
+	static GF2nI gf2n_4_1(0x0013, 1);      // x^4 + x + 1
+	static GF2nI gf2n_6_1(0x0043, 1);      // x^6 + x + 1
+	static GF2nI gf2n_8_5_3_2(0x012D, 1);  // x^8 + x^5 + x^3 + x^2 + 1 : DataMatrix
+	static GF2nI gf2n_8_4_3_2(0x011D, 0);  // x^8 + x^4 + x^3 + x^2 + 1 : QRCode
+	static GF2nI gf2n_10_3(0x0409, 1);     // x^10 + x^3 + 1
+	static GF2nI gf2n_12_6_5_3(0x1069, 1); // x^12 + x^6 + x^5 + x^3 + 1
+
+	switch (field) {
+	case RSField::Aztec4: return gf2n_4_1;
+	case RSField::Aztec6: return gf2n_6_1;
+	case RSField::Aztec8: return gf2n_8_5_3_2;
+	case RSField::Aztec10: return gf2n_10_3;
+	case RSField::Aztec12: return gf2n_12_6_5_3;
+	case RSField::DataMatrix: return gf2n_8_5_3_2;
+	case RSField::MaxiCode: return gf2n_6_1;
+	case RSField::QRCode: return gf2n_8_4_3_2;
+	default: throw std::invalid_argument("Unsupported RSField");
+	}
+}
+
+const rs::GFp<>& GetGFPDF417()
+{
+	static rs::GFp<> gf929_3(929, 3, 1);
+	return gf929_3;
+}
+
+// See ISO/IEC 15415:2024 7.5.9
+static std::optional<double> UEC(std::optional<int> usedECC, int numECC)
+{
+	return usedECC ? std::optional(std::clamp(1.0 - static_cast<double>(*usedECC) / numECC, 0.0, 1.0)) : std::nullopt;
+}
+
+#ifdef ZXING_READERS
+std::optional<double> ReedSolomonDecode(RSField field, std::span<uint8_t> codeword, int numECC, std::span<const int> erasures)
+{
+	return UEC(rs::decode(GetGF2n(field), codeword, numECC, erasures), numECC);
+}
+
+std::optional<double> ReedSolomonDecode(RSField field, std::span<int> codeword, int numECC, std::span<const int> erasures)
+{
+	// The number of erasures may at most be numECC.
+	// Note that leaves 0 parity symbols to error correction (or even detection) but the final syndrome verification in rs::decode will
+	// still catch any errors in that case.
+	if (Size(erasures) > numECC)
+		return {};
+
+#if ZXING_ENABLE_PDF417
+	if (field == RSField::PDF417)
+		return UEC(rs::decode(GetGFPDF417(), codeword, numECC, erasures), numECC);
+	else
+#endif
+		return UEC(rs::decode(GetGF2n(field), codeword, numECC, erasures), numECC);
+}
+#endif
+
+#ifdef ZXING_WRITERS
+void ReedSolomonEncode(RSField field, std::span<const uint8_t> data, std::span<uint8_t> parity)
+{
+	rs::encode(GetGF2n(field), data, parity);
+}
+
+void ReedSolomonEncode(RSField field, std::span<uint8_t> codeword, int numECC)
+{
+	rs::encode_inplace(GetGF2n(field), codeword, numECC);
+}
+
+void ReedSolomonEncode(RSField field, std::span<int> codeword, int numECC)
+{
+#if ZXING_ENABLE_PDF417
+	if (field == RSField::PDF417)
+		return rs::encode_inplace(GetGFPDF417(), codeword, numECC);
+	else
+#endif
+		rs::encode_inplace(GetGF2n(field), codeword, numECC);
+}
+#endif
+
+} // namespace ZXing