2.9BSD/usr/contrib/jove/jove_temp.h

/*
 * The editor uses a temporary file for files being edited, in a structure
 * similar to that of ed.
 * Lines are represented in core by a pointer into the temporary file which
 * is packed into 16 bits.  15 of these bits index the temporary file,
 * the 16'th is used by by redisplay.  The parameters below control
 * how much the 15 bits are shifted left before they index the temp file.
 * Larger shifts give more slop in the temp file but allow larger files
 * to be edited.
 */

#ifndef VMUNIX
#ifndef BIGTMP		/* 256k in tmp file */

#define	BLKMSK	0777
#define	BNDRY	8
#define	INCRMT	0200
#define	LBTMSK	0770
#define	NMBLKS	506
#define	OFFBTS	7
#define	OFFMSK	0177
#define	SHFT	2

#else		/* 512 K in temp file with more slop, but it's worth it */

#define	BLKMSK	01777
#define	BNDRY	16
#define	INCRMT	0100
#define	LBTMSK	0760
#define	NMBLKS	1018
#define	OFFBTS	6
#define	OFFMSK	077
#define	SHFT	3

#endif BIGTMP

#else VMUNIX
#define	BLKMSK	077777
#define	BNDRY	2
#define	INCRMT	02000
#define	LBTMSK	01776
#define	NMBLKS	077770
#define	OFFBTS	10
#define	OFFMSK	01777
#define	SHFT	0
#endif VMUNIX


char	ibuff1[BUFSIZ],	/* Holds block `iblock1' of the tmp file */
	ibuff2[BUFSIZ],	/*   "     "   `iblock2' of the tmp file */
	obuff[BUFSIZ];	/* Holds the last block of the tmp file */
int	ichng1,		/* ibuff1 should be written to its
			 * blocks when it is used to read
			 * another block.
			 */
	ichng2,		/* "" */
	iblock1,	/* Block number of ibuff1 */
	iblock2,	/*		   ibuff2 */
	oblock,		/* 		   obuff  */
	nleft,		/* Number of good characters left in current block */
	hitin2,		/* Last read was in ibuff2 */
	tmpfd;
disk_line	tline;		/* Pointer to end of tmp file */

char	*tfname;