gzip support for miniz

ext/tmxlite/include/tmxlite/detail/gzip.hpp

@@ -0,0 +1,39 @@
+// gzip.hpp - portable memory miniz based gzip reader
+// SPDX-License-Identifier: Zlib
+// SPDX-FileCopyrightText: (c) 2024 a dinosaur
+
+#ifndef GZIP_HPP
+#define GZIP_HPP
+
+#include "miniz.h"
+#include <cstdint>
+#include <span>
+
+
+class GZipReader
+{
+	static constexpr uint8_t
+		FTEXT = 1, FHCRC = 1<<1, FEXTRA = 1<<2, FNAME = 1<<3, FCOMMENT = 1<<4;
+
+	static constexpr uint8_t XFL_BEST = 2, XFL_FASTEST = 4;
+
+	tinfl_decompressor mState;
+	std::span<const uint8_t>::iterator mIt;
+
+	size_t mSourceLen, mBytesRead;
+	uint32_t mModificationTime, mCrc, mInputSize, mComputedCrc;
+	uint16_t crc16;
+	uint8_t mFlags, mXflags, mOsId;
+
+public:
+	GZipReader() noexcept;
+
+	constexpr size_t SourceLength() const noexcept { return mSourceLen; }
+	constexpr uint32_t OutputLength() const noexcept { return mInputSize; }
+
+	bool OpenMemory(const std::span<const uint8_t> source) noexcept;
+	bool Read(std::span<uint8_t> out) noexcept;
+	bool Check() const noexcept;
+};
+
+#endif//GZIP_HPP