1 files changed, 77 insertions, 0 deletions
diff --git a/gzip.h b/gzip.h
new file mode 100644
index 0000000..e5d5947
--- /dev/null
+++ b/gzip.h
@@ -0,0 +1,77 @@
+#ifndef GZIP_H
+#define GZIP_H
+
+#include <stdint.h>
+
+/* RFC 1952 */
+
+#define ID1 31
+#define ID2 139
+
+enum compression_method {
+	DEFLATE = 8,
+};
+
+enum flag {
+	FTEXT    = 1 << 0,
+	FHCRC    = 1 << 1,
+	FEXTRA   = 1 << 2,
+	FNAME    = 1 << 3,
+	FCOMMENT = 1 << 4,
+};
+
+const char *flag_str (enum flag f) {
+	switch (f) {
+		case FTEXT:    return "Content is probably text";
+		case FHCRC:    return "CRC16 is present";
+		case FEXTRA:   return "Extra field is populated";
+		case FNAME:    return "A file name is present";
+		case FCOMMENT: return "A comment is present";
+		default:       return "unknown flag";
+	}
+}
+
+enum operating_system {
+	FAT = 0,
+	AMIGA,
+	VMS,
+	UNIX,
+	CMS,
+	ATARI_TOS,
+	HPFS,
+	MACINTOSH,
+	Z_SYSTEM,
+	CP_M,
+	TOPS20,
+	NTFS,
+	QDOS,
+	ACORN_RISCOS,
+};
+
+const char *os_str(enum operating_system os) {
+	switch (os) {
+		case FAT:          return "FAT filesystem (MS-DOS, OS/2, NT/Win32)";
+		case AMIGA:        return "Amiga";
+		case VMS:          return "VMS (or OpenVMS)";
+		case UNIX:         return "Unix";
+		case CMS:          return "VM/CMS";
+		case ATARI_TOS:    return "Atari TOS";
+		case HPFS:         return "HPFS filesystem (OS/2, NT)";
+		case MACINTOSH:    return "Macintosh";
+		case Z_SYSTEM:     return "Z-System";
+		case CP_M:         return "CP/M";
+		case TOPS20:       return "TOPS-20";
+		case NTFS:         return "NTFS filesystem (NT)";
+		case QDOS:         return "QDOS";
+		case ACORN_RISCOS: return "Acorn RISCOS";
+		default:           return "unknown";
+	}
+}
+
+struct member {
+	uint8_t id1, id2, cm, flg;
+	uint32_t mtime;
+	uint8_t xfl, os;
+} __attribute__((packed));
+
+#endif /* GZIP_H */