gzip: istream

kernel/gzip.h

@@ -0,0 +1,79 @@
+#include <string>
+#include <unistd.h>
+#include "kernel/yosys_common.h"
+
+#ifndef YOSYS_GZIP_H
+#define YOSYS_GZIP_H
+
+YOSYS_NAMESPACE_BEGIN
+
+#ifdef YOSYS_ENABLE_ZLIB
+
+namespace Zlib {
+#include <zlib.h>
+}
+
+/*
+An output stream that uses a stringbuf to buffer data internally,
+using zlib to write gzip-compressed data every time the stream is flushed.
+*/
+class gzip_ostream : public std::ostream {
+public:
+	gzip_ostream(): std::ostream(nullptr) {
+		rdbuf(&outbuf);
+	}
+	bool open(const std::string &filename) {
+		return outbuf.open(filename);
+	}
+private:
+	class obuf : public std::stringbuf {
+	public:
+		obuf();
+		bool open(const std::string &filename);
+		virtual int sync() override;
+		virtual ~obuf();
+	private:
+		static const int buffer_size = 4096;
+		char buffer[buffer_size];             // Internal buffer for compressed data
+		Zlib::gzFile gzf = nullptr;                 // Handle to the gzip file
+	};
+
+	obuf outbuf;  // The stream buffer instance
+};
+
+/*
+An input stream that uses zlib to read gzip-compressed data from a file,
+buffering the decompressed data internally using its own buffer.
+*/
+class gzip_istream final : public std::istream {
+public:
+	gzip_istream() : std::istream(&inbuf) {}
+	bool open(const std::string& filename) {
+		return inbuf.open(filename);
+	}
+private:
+	class ibuf final : public std::streambuf {
+	public:
+		ibuf() : gzf(nullptr) {}
+		bool open(const std::string& filename);
+		virtual ~ibuf();
+
+	protected:
+		// Called when the buffer is empty and more input is needed
+		virtual int_type underflow() override;
+	private:
+		static const int buffer_size = 8192;
+		char buffer[buffer_size];
+		Zlib::gzFile gzf;
+	};
+
+	ibuf inbuf;  // The stream buffer instance
+};
+
+#endif // YOSYS_ENABLE_ZLIB
+
+std::istream* uncompressed(std::ifstream* f, const std::string filename);
+
+YOSYS_NAMESPACE_END
+
+#endif // YOSYS_GZIP_H