diff --git a/include/bio.h b/include/bio.h
new file mode 100644
index 0000000..c481239
--- /dev/null
+++ b/include/bio.h
@@ -0,0 +1,79 @@
+#ifndef _BIOH_
+#define _BIOH_ 1
+
+#include <sys/types.h>	/* for off_t */
+#include <fcntl.h>	/* for O_RDONLY, O_WRONLY */
+
+typedef	struct	Biobuf	Biobuf;
+
+enum
+{
+	Bsize		= 8*1024,
+	Bungetsize	= 4,		/* space for ungetc */
+	Bmagic		= 0x314159,
+	Beof		= -1,
+	Bbad		= -2,
+
+	Binactive	= 0,		/* states */
+	Bractive,
+	Bwactive,
+	Bracteof,
+
+	Bend
+};
+
+struct	Biobuf
+{
+	int	icount;		/* neg num of bytes at eob */
+	int	ocount;		/* num of bytes at bob */
+	int	rdline;		/* num of bytes after rdline */
+	int	runesize;		/* num of bytes of last getrune */
+	int	state;		/* r/w/inactive */
+	int	fid;		/* open file */
+	int	flag;		/* magic if malloc'ed */
+	off_t	offset;		/* offset of buffer in file */
+	int	bsize;		/* size of buffer */
+	unsigned char*	bbuf;		/* pointer to beginning of buffer */
+	unsigned char*	ebuf;		/* pointer to end of buffer */
+	unsigned char*	gbuf;		/* pointer to good data in buf */
+	unsigned char	b[Bungetsize+Bsize];
+};
+
+#define	BGETC(bp)\
+	((bp)->icount?(bp)->bbuf[(bp)->bsize+(bp)->icount++]:Bgetc((bp)))
+#define	BPUTC(bp,c)\
+	((bp)->ocount?(bp)->bbuf[(bp)->bsize+(bp)->ocount++]=(c),0:Bputc((bp),(c)))
+#define	BOFFSET(bp)\
+	(((bp)->state==Bractive)?\
+		(bp)->offset + (bp)->icount:\
+	(((bp)->state==Bwactive)?\
+		(bp)->offset + ((bp)->bsize + (bp)->ocount):\
+		-1))
+#define	BLINELEN(bp)\
+	(bp)->rdline
+#define	BFILDES(bp)\
+	(bp)->fid
+
+int	Bbuffered(Biobuf*);
+int	Bfildes(Biobuf*);
+int	Bflush(Biobuf*);
+int	Bgetc(Biobuf*);
+int	Bgetd(Biobuf*, double*);
+int	Binit(Biobuf*, int, int);
+int	Binits(Biobuf*, int, int, unsigned char*, int);
+int	Blinelen(Biobuf*);
+off_t	Boffset(Biobuf*);
+Biobuf*	Bopen(char*, int);
+int	Bprint(Biobuf*, char*, ...);
+int	Bputc(Biobuf*, int);
+void*	Brdline(Biobuf*, int);
+long	Bread(Biobuf*, void*, long);
+off_t	Bseek(Biobuf*, off_t, int);
+int	Bterm(Biobuf*);
+int	Bungetc(Biobuf*);
+long	Bwrite(Biobuf*, void*, long);
+char*	Brdstr(Biobuf*, int, int);
+long	Bgetrune(Biobuf*);
+int	Bputrune(Biobuf*, long);
+
+#endif