[unix-history] / usr / src / old / as.vax / as.h

/* Copyright (c) 1980 Regents of the University of California */
/* "@(#)as.h 4.1 %G%" */
#ifdef VMS
# define	vax	1
# define	VAX	1
#endif VMS

#define readonly

#define	NINST		300

#define	NEXP		20	/* max number of expr. terms per instruction */
#define	NARG		6	/* max number of args per instruction */
#define	NHASH		1103	/* hash table is dynamically extended */
#define TNAMESIZE	32	/* maximum length of temporary file names */
#define	NLOC		4	/* number of location ctrs */

#ifdef UNIX
# ifndef	FLEXNAMES
#	ifndef	NCPS
#		define	NCPS	8	/* number of characters per symbol*/
#	endif
# else
#	ifdef NCPS
#		undef	NCPS
#	endif
#	define	NCPS	BUFSIZ	/* needed to allocate yytext */
# endif
# endif UNIX

# ifdef VMS
# ifdef NCPS
#	undef	NCPS
# endif NCPS
#	define	NCPS	15
# endif VMS

/*
 * Symbol types
 */
#define	XUNDEF	0x0
#define	XABS	0x2
#define	XTEXT	0x4
#define	XDATA	0x6
#define	XBSS	0x8

#define	XXTRN	0x1
#define	XTYPE	0x1E

#define	XFORW	0x20	/* Was forward-referenced when undefined */

#define	ERR	(-1)
#define	NBPW	32	/* Bits per word */

#define	AMASK	017

/*
 * Actual argument syntax types
 */
#define AREG	1	/* %r */
#define ABASE	2	/* (%r) */
#define ADECR	3	/* -(%r) */
#define AINCR	4	/* (%r)+ */
#define ADISP	5	/* expr(%r) */
#define AEXP	6	/* expr */
#define AIMM	7	/* $ expr */
#define ASTAR	8	/* * */
#define AINDX	16	/* [%r] */

/*
 * Argument access types used to test validity of operands to operators
 */
#define ACCA	(8<<3)	/* address only */
#define ACCR	(1<<3)	/* read */
#define ACCW	(2<<3)	/* write */
#define ACCM	(3<<3)	/* modify */
#define ACCB	(4<<3)	/* branch displacement */
#define ACCI	(5<<3)	/* XFC code */

/*
 * Argument data types
 */
#define TYPB	0	/* byte */
#define TYPW	1	/* word */
#define TYPL	2	/* long */
#define TYPQ	3	/* quad */
#define TYPF	4	/* floating */
#define TYPD	5	/* double floating */

#define TYPMASK 7

/* reference types for loader */
#define PCREL 1
#define LEN1 2
#define LEN2 4
#define LEN4 6
#define LEN8 8
	/*
	 *	reflen table converts between LEN* and PCREL to numbers
	 *		of bytes.
	 *	lgreflen table is the lg base 2 of the values in reflen.
	 */
	extern	int	reflen[];	/* reference lengths */
	extern	int	lgrefltn[];	/* lg reference lengths */

#define	TMPC	7	
#define	HW	01
#define	FW	03
#define	DW	07

#ifdef UNIX
#  include <pagsiz.h>
#endif UNIX

#ifdef VMS
#  define PAGRND	0x1FFL
#endif VMS

#define	round(x,y)	(((x)+(y)) & ~(y))

#define	STABTYPS	0340
#define STABFLAG	0200

/*
 *	Follows are the definitions for the symbol table tags, which are
 *	all unsigned characters..
 *	High value tags are generated by the asembler for internal
 *	use.
 *	Low valued tags are the parser coded tokens the scanner returns.
 *	There are several pertinant bounds in this ordering:
 *		a)	Symbols greater than JXQUESTIONABLE
 *			are used by the jxxx bumper, indicating that
 *			the symbol table entry is a jxxx entry
 *			that has yet to be bumped.
 *		b)	Symbols greater than IGNOREBOUND are not
 *			bequeathed to the loader; they are truly
 *			for assembler internal use only.
 *		c)	Symbols greater than OKTOBUMP represent
 *			indices into the program text that should
 *			be changed in preceeding jumps or aligns
 *			must get turned into their long form.
 */

#define TAGMASK		0xFF

#	define	JXACTIVE	0xFF	/*jxxx size unknown*/
#	define	JXNOTYET	0xFE	/*jxxx size known, but not yet expanded*/
#	define	JXALIGN		0xFD	/*align jxxx entry*/
#	define	JXINACTIVE	0xFC	/*jxxx size known and expanded*/

#define JXQUESTIONABLE		0xFB

#	define	JXTUNNEL	0xFA	/*jxxx that jumps to another*/
#	define	OBSOLETE	0xF9	/*erroneously entered symbol*/

#define	IGNOREBOUND	0xF8		/*symbols greater than this are ignored*/
#	define	STABFLOATING	0xF7
#	define	LABELID		0xF6

#define	OKTOBUMP	0xF5
#	define	STABFIXED	0xF4

/*
 *	astoks.h contains reserved word codings the parser should
 *	know about
 */
#include "astoks.h"

/*
 *	The structure for one symbol table entry.
 *	Symbol table entries are used for both user defined symbols,
 *	and symbol slots generated to create the jxxx jump from
 *	slots.
 */

#define symfirstfields	char	*name;	unsigned char tag, type

struct symtab{
		symfirstfields;
		short	___hole;
		char	ptype;		/*tag == NAME*/

#define		jxbump	ptype		/*tag == JX..., how far to expand*/

		char	other;		/*for stab info*/

 		short	desc;		/*tag == NAME*/

#define		jxfear	desc		/*how far needs to be bumped*/

		long	value;		/*address in the segment*/
		char	jxoveralign;	/*if a JXXX, jumped over an align*/
		short	index;		/*which segment*/
		struct	symtab *dest;	/*if JXXX, where going to*/
#ifdef DJXXX
		short	jxline;		/*source line of the jump from*/
#endif
};

struct instab{
	symfirstfields;

#define		opcode type		/*use the same field as symtab.type*/

	char	nargs;			/*how many arguments*/
	char	argtype[6];		/*argument type info*/
};

struct	arg {				/*one argument to an instruction*/
	char	atype;
	char	areg1;
	char	areg2;
	char	dispsize;		/*usually d124, unless have B^, etc*/
	struct	exp *xp;
};

struct	exp {
	long	xvalue;		/* MUST be the first field (look at union Double) */
	long	yvalue;		/* MUST be second field; least sig word of a double */
	char	xtype;
	char	xloc;
	struct	symtab *xname;
};

#define doub_MSW xvalue
#define doub_LSW yvalue

union Double {
	struct{
		long	doub_MSW;
		long	doub_LSW;
	} dis_dvalue;
	double	dvalue;
};

struct Quad {
	long	quad_low_long;
	long	quad_high_long;
};

/*
 *	Magic layout macros
 */
#define 	MINBYTE	-128
#define		MAXBYTE	127
#define		MINWORD	-32768
#define		MAXWORD	32767

#define		LITFLTMASK 0x000043F0	/*really magic*/
/*
 *		Is the floating point double word in xp a
 *		short literal floating point number?
 */
#define 	slitflt(xp) \
			(    (xp->doub_LSW == 0) \
			 &&  ( (xp->doub_MSW & LITFLTMASK) \
			      == xp->doub_MSW) )
/*
 *	If it is a slitflt, then extract the 6 interesting bits
 */
#define		extlitflt(xp) \
			xp->doub_MSW >> 4

	extern	struct	arg	arglist[NARG];	/*building operands in instructions*/
	extern	struct	exp	explist[NEXP];	/*building up a list of expressions*/
	extern	struct	exp	*xp;		/*current free expression*/
	/*
	 *	Communication between the scanner and the jxxx handlers.
	 *	lastnam:	the last name seen on the input
	 *	lastjxxx:	pointer to the last symbol table entry for
	 *			a jump from
	 */
	extern	struct	symtab	*lastnam;
	extern	struct	symtab	*lastjxxx;	

#ifdef VMS
	extern char	*vms_obj_ptr;		/* object buffer pointer */
	extern char	sobuf[];		/* object buffer         */
	extern	int	objfil;			/* VMS object file descriptor */
#endif VMS

	/*
	 *	Lgensym is used to make up funny names for local labels.
	 *	lgensym[i] is the current funny number to put after
	 *	references to if, lgensym[i]-1 is for ib.
	 *	genref[i] is set when the label is referenced before
	 *	it is defined (i.e. 2f) so that we can be sure these
	 *	labels are always defined to avoid weird diagnostics
	 *	from the loader later.
	 */
	extern	int	lgensym[10];
	extern	char	genref[10];

	extern	char	tmpn1[TNAMESIZE];	/* Interpass temporary */
	extern	struct	exp	*dotp;		/* the current dot location */
	extern	int	loctr;

	extern	struct	exec	hdr;		/* a.out header */
	extern	u_long	tsize;			/* total text size */
	extern	u_long	dsize;			/* total data size */
	extern	u_long	trsize;			/* total text relocation size */
	extern	u_long	drsize;			/* total data relocation size */
	extern	u_long	datbase;		/* base of the data segment */
	/*
	 *	Bitoff and bitfield keep track of the packing into 
	 *	bytes mandated by the expression syntax <expr> ':' <expr>
	 */
	extern	int	bitoff;	
	extern	long	bitfield;
	
	/*
	 *	The lexical analyzer builds up symbols in yytext.  Lookup
	 *	expects its argument in this buffer
	 */
	extern	char	yytext[NCPS+2];		/* text buffer for lexical */
	/*
	 *	Variables to manage the input assembler source file
	 */
	extern	int	lineno;			/*the line number*/
	extern	char	*dotsname;		/*the name of the as source*/

	extern	FILE	*tmpfil;		/* interpass communication*/

	extern	int	passno;			/* 1 or 2 */

	extern	int	anyerrs;		/*errors assembling arguments*/
	extern	int	silent;			/*don't mention the errors*/
	extern	int	savelabels;		/*save labels in a.out*/
	extern	int	orgwarn;		/* questionable origin ? */
	extern	int	useVM;			/*use virtual memory temp file*/
#ifdef DEBUG
	extern	int	debug;
	extern	int	toktrace;
#endif
	/*
	 *	Information about the instructions
	 */
	extern	struct	instab	*itab[NINST];	/*maps opcodes to instructions*/
	extern  readonly struct instab instab[];

	extern	int	curlen;			/*current literal storage size*/
	extern	int	d124;			/*current pointer storage size*/
	
	struct	symtab	**lookup();		/*argument in yytext*/
	struct 	symtab	*symalloc();

#define outb(val) {dotp->xvalue++; if (passno==2) bputc((val), (txtfil));}

#define outs(cp, lg) dotp->xvalue += (lg); if (passno == 2) bwrite((cp), (lg), (txtfil))

/*
 *	Most of the time, the argument to flushfield is a power of two constant,
 *	the calculations involving it can be optimized to shifts.
 */
#define flushfield(n) if (bitoff != 0)  Flushfield( ( (bitoff+n-1) /n ) * n)

/*
 * The biobuf structure and associated routines are used to write
 * into one file at several places concurrently.  Calling bopen
 * with a biobuf structure sets it up to write ``biofd'' starting
 * at the specified offset.  You can then use ``bwrite'' and/or ``bputc''
 * to stuff characters in the stream, much like ``fwrite'' and ``fputc''.
 * Calling bflush drains all the buffers and MUST be done before exit.
 */
struct	biobuf {
	short	b_nleft;		/* Number free spaces left in b_buf */
/* Initialize to be less than BUFSIZ initially, to boundary align in file */
	char	*b_ptr;			/* Next place to stuff characters */
	char	b_buf[BUFSIZ];		/* The buffer itself */
	off_t	b_off;			/* Current file offset */
	struct	biobuf *b_link;		/* Link in chain for bflush() */
};
#define	bputc(c,b) ((b)->b_nleft ? (--(b)->b_nleft, *(b)->b_ptr++ = (c)) \
		       : bflushc(b, c))
#define BFILE	struct biobuf

	extern	BFILE	*biobufs;	/* head of the block I/O buffer chain */
	extern	int	biofd;		/* file descriptor for block I/O file */
	extern	off_t	boffset;	/* physical position in logical file */

	/*
	 *	For each of the named .text .data segments
	 *	(introduced by .text <expr>), we maintain
	 *	the current value of the dot, and the BFILE where
	 *	the information for each of the segments is placed
	 *	during the second pass.
	 */
	extern	struct	exp	usedot[NLOC + NLOC];
	extern		BFILE	*usefile[NLOC + NLOC];
	extern		BFILE	*txtfil;/* file for text and data: into usefile */
	/*
	 *	Relocation information for each segment is accumulated
	 *	seperately from the others.  Writing the relocation
	 *	information is logically viewed as writing to one
	 *	relocation saving file for  each segment; physically
	 *	we have a bunch of buffers allocated internally that
	 *	contain the relocation information.
	 */
	struct	relbufdesc	*rusefile[NLOC + NLOC];
	struct	relbufdesc	*relfil;
Commit	Line	Data
8c1020c4 BJ	1	/* Copyright (c) 1980 Regents of the University of California */
	2	/* "@(#)as.h 4.1 %G%" */
	3	#ifdef VMS
	4	# define vax 1
	5	# define VAX 1
	6	#endif VMS
	7
	8	#define readonly
	9
	10	#define NINST 300
	11
	12	#define NEXP 20 /* max number of expr. terms per instruction */
	13	#define NARG 6 /* max number of args per instruction */
	14	#define NHASH 1103 /* hash table is dynamically extended */
	15	#define TNAMESIZE 32 /* maximum length of temporary file names */
	16	#define NLOC 4 /* number of location ctrs */
	17
	18	#ifdef UNIX
	19	# ifndef FLEXNAMES
	20	# ifndef NCPS
	21	# define NCPS 8 /* number of characters per symbol*/
	22	# endif
	23	# else
	24	# ifdef NCPS
	25	# undef NCPS
	26	# endif
	27	# define NCPS BUFSIZ /* needed to allocate yytext */
	28	# endif
	29	# endif UNIX
	30
	31	# ifdef VMS
	32	# ifdef NCPS
	33	# undef NCPS
	34	# endif NCPS
	35	# define NCPS 15
	36	# endif VMS
	37
	38	/*
	39	* Symbol types
	40	*/
	41	#define XUNDEF 0x0
	42	#define XABS 0x2
	43	#define XTEXT 0x4
	44	#define XDATA 0x6
	45	#define XBSS 0x8
	46
	47	#define XXTRN 0x1
	48	#define XTYPE 0x1E
	49
	50	#define XFORW 0x20 /* Was forward-referenced when undefined */
	51
	52	#define ERR (-1)
	53	#define NBPW 32 /* Bits per word */
	54
	55	#define AMASK 017
	56
	57	/*
	58	* Actual argument syntax types
	59	*/
	60	#define AREG 1 /* %r */
	61	#define ABASE 2 /* (%r) */
	62	#define ADECR 3 /* -(%r) */
	63	#define AINCR 4 /* (%r)+ */
	64	#define ADISP 5 /* expr(%r) */
65	#define AEXP 6 /* expr */
66	#define AIMM 7 /* $ expr */
67	#define ASTAR 8 /* * */
68	#define AINDX 16 /* [%r] */
69
70	/*
71	* Argument access types used to test validity of operands to operators
72	*/
73	#define ACCA (8<<3) /* address only */
74	#define ACCR (1<<3) /* read */
75	#define ACCW (2<<3) /* write */
76	#define ACCM (3<<3) /* modify */
77	#define ACCB (4<<3) /* branch displacement */
78	#define ACCI (5<<3) /* XFC code */
79
80	/*
81	* Argument data types
82	*/
83	#define TYPB 0 /* byte */
84	#define TYPW 1 /* word */
85	#define TYPL 2 /* long */
86	#define TYPQ 3 /* quad */
87	#define TYPF 4 /* floating */
88	#define TYPD 5 /* double floating */
89
90	#define TYPMASK 7
91
92	/* reference types for loader */
93	#define PCREL 1
94	#define LEN1 2
95	#define LEN2 4
96	#define LEN4 6
97	#define LEN8 8
98	/*
99	* reflen table converts between LEN* and PCREL to numbers
100	* of bytes.
101	* lgreflen table is the lg base 2 of the values in reflen.
102	*/
103	extern int reflen[]; /* reference lengths */
104	extern int lgrefltn[]; /* lg reference lengths */
105
106	#define TMPC 7
107	#define HW 01
108	#define FW 03
109	#define DW 07
110
111	#ifdef UNIX
112	# include <pagsiz.h>
113	#endif UNIX
114
115	#ifdef VMS
116	# define PAGRND 0x1FFL
117	#endif VMS
118
119	#define round(x,y) (((x)+(y)) & ~(y))
120
121	#define STABTYPS 0340
122	#define STABFLAG 0200
123
124	/*
125	* Follows are the definitions for the symbol table tags, which are
126	* all unsigned characters..
127	* High value tags are generated by the asembler for internal
128	* use.
129	* Low valued tags are the parser coded tokens the scanner returns.
130	* There are several pertinant bounds in this ordering:
131	* a) Symbols greater than JXQUESTIONABLE
132	* are used by the jxxx bumper, indicating that
133	* the symbol table entry is a jxxx entry
134	* that has yet to be bumped.
135	* b) Symbols greater than IGNOREBOUND are not
136	* bequeathed to the loader; they are truly
137	* for assembler internal use only.
138	* c) Symbols greater than OKTOBUMP represent
139	* indices into the program text that should
140	* be changed in preceeding jumps or aligns
141	* must get turned into their long form.
142	*/
143
144	#define TAGMASK 0xFF
145
146	# define JXACTIVE 0xFF /jxxx size unknown/
147	# define JXNOTYET 0xFE /jxxx size known, but not yet expanded/
148	# define JXALIGN 0xFD /align jxxx entry/
149	# define JXINACTIVE 0xFC /jxxx size known and expanded/
150
151	#define JXQUESTIONABLE 0xFB
152
153	# define JXTUNNEL 0xFA /jxxx that jumps to another/
154	# define OBSOLETE 0xF9 /erroneously entered symbol/
155
156	#define IGNOREBOUND 0xF8 /symbols greater than this are ignored/
157	# define STABFLOATING 0xF7
158	# define LABELID 0xF6
159
160	#define OKTOBUMP 0xF5
161	# define STABFIXED 0xF4
162
163	/*
164	* astoks.h contains reserved word codings the parser should
165	* know about
166	*/
167	#include "astoks.h"
168
169	/*
170	* The structure for one symbol table entry.
171	* Symbol table entries are used for both user defined symbols,
172	* and symbol slots generated to create the jxxx jump from
173	* slots.
174	*/
175
176	#define symfirstfields char *name; unsigned char tag, type
177
178	struct symtab{
179	symfirstfields;
180	short ___hole;
181	char ptype; /tag == NAME/
182
183	#define jxbump ptype /tag == JX..., how far to expand/
184
185	char other; /for stab info/
186
187	short desc; /tag == NAME/
188
189	#define jxfear desc /how far needs to be bumped/
190
191	long value; /address in the segment/
192	char jxoveralign; /if a JXXX, jumped over an align/
193	short index; /which segment/
194	struct symtab dest; /if JXXX, where going to*/
195	#ifdef DJXXX
196	short jxline; /source line of the jump from/
197	#endif
198	};
199
200	struct instab{
201	symfirstfields;
202
203	#define opcode type /use the same field as symtab.type/
204
205	char nargs; /how many arguments/
206	char argtype[6]; /argument type info/
207	};
208
209	struct arg { /one argument to an instruction/
210	char atype;
211	char areg1;
212	char areg2;
213	char dispsize; /usually d124, unless have B^, etc/
214	struct exp *xp;
215	};
216
217	struct exp {
218	long xvalue; /* MUST be the first field (look at union Double) */
219	long yvalue; /* MUST be second field; least sig word of a double */
220	char xtype;
221	char xloc;
222	struct symtab *xname;
223	};
224
225	#define doub_MSW xvalue
226	#define doub_LSW yvalue
227
228	union Double {
229	struct{
230	long doub_MSW;
231	long doub_LSW;
232	} dis_dvalue;
233	double dvalue;
234	};
235
236	struct Quad {
237	long quad_low_long;
238	long quad_high_long;
239	};
240
241	/*
242	* Magic layout macros
243	*/
244	#define MINBYTE -128
245	#define MAXBYTE 127
246	#define MINWORD -32768
247	#define MAXWORD 32767
248
249	#define LITFLTMASK 0x000043F0 /really magic/
250	/*
251	* Is the floating point double word in xp a
252	* short literal floating point number?
253	*/
254	#define slitflt(xp) \
255	( (xp->doub_LSW == 0) \
256	&& ( (xp->doub_MSW & LITFLTMASK) \
257	== xp->doub_MSW) )
258	/*
259	* If it is a slitflt, then extract the 6 interesting bits
260	*/
261	#define extlitflt(xp) \
262	xp->doub_MSW >> 4
263
264	extern struct arg arglist[NARG]; /building operands in instructions/
265	extern struct exp explist[NEXP]; /building up a list of expressions/
266	extern struct exp xp; /current free expression*/
267	/*
268	* Communication between the scanner and the jxxx handlers.
269	* lastnam: the last name seen on the input
270	* lastjxxx: pointer to the last symbol table entry for
271	* a jump from
272	*/
273	extern struct symtab *lastnam;
274	extern struct symtab *lastjxxx;
275
276	#ifdef VMS
277	extern char vms_obj_ptr; / object buffer pointer */
278	extern char sobuf[]; /* object buffer */
279	extern int objfil; /* VMS object file descriptor */
280	#endif VMS
281
282	/*
283	* Lgensym is used to make up funny names for local labels.
284	* lgensym[i] is the current funny number to put after
285	* references to if, lgensym[i]-1 is for ib.
286	* genref[i] is set when the label is referenced before
287	* it is defined (i.e. 2f) so that we can be sure these
288	* labels are always defined to avoid weird diagnostics
289	* from the loader later.
290	*/
291	extern int lgensym[10];
292	extern char genref[10];
293
294	extern char tmpn1[TNAMESIZE]; /* Interpass temporary */
295	extern struct exp dotp; / the current dot location */
296	extern int loctr;
297
298	extern struct exec hdr; /* a.out header */
299	extern u_long tsize; /* total text size */
300	extern u_long dsize; /* total data size */
301	extern u_long trsize; /* total text relocation size */
302	extern u_long drsize; /* total data relocation size */
303	extern u_long datbase; /* base of the data segment */
304	/*
305	* Bitoff and bitfield keep track of the packing into
306	* bytes mandated by the expression syntax <expr> ':' <expr>
307	*/
308	extern int bitoff;
309	extern long bitfield;
310
311	/*
312	* The lexical analyzer builds up symbols in yytext. Lookup
313	* expects its argument in this buffer
314	*/
315	extern char yytext[NCPS+2]; /* text buffer for lexical */
316	/*
317	* Variables to manage the input assembler source file
318	*/
319	extern int lineno; /the line number/
320	extern char dotsname; /the name of the as source*/
321
322	extern FILE tmpfil; / interpass communication*/
323
324	extern int passno; /* 1 or 2 */
325
326	extern int anyerrs; /errors assembling arguments/
327	extern int silent; /don't mention the errors/
328	extern int savelabels; /save labels in a.out/
329	extern int orgwarn; /* questionable origin ? */
330	extern int useVM; /use virtual memory temp file/
331	#ifdef DEBUG
332	extern int debug;
333	extern int toktrace;
334	#endif
335	/*
336	* Information about the instructions
337	*/
338	extern struct instab itab[NINST]; /maps opcodes to instructions*/
339	extern readonly struct instab instab[];
340
341	extern int curlen; /current literal storage size/
342	extern int d124; /current pointer storage size/
343
344	struct symtab *lookup(); /argument in yytext*/
345	struct symtab *symalloc();
346
347	#define outb(val) {dotp->xvalue++; if (passno==2) bputc((val), (txtfil));}
348
349	#define outs(cp, lg) dotp->xvalue += (lg); if (passno == 2) bwrite((cp), (lg), (txtfil))
350
351	/*
352	* Most of the time, the argument to flushfield is a power of two constant,
353	* the calculations involving it can be optimized to shifts.
354	*/
355	#define flushfield(n) if (bitoff != 0) Flushfield( ( (bitoff+n-1) /n ) * n)
356
357	/*
358	* The biobuf structure and associated routines are used to write
359	* into one file at several places concurrently. Calling bopen
360	* with a biobuf structure sets it up to write ``biofd'' starting
361	* at the specified offset. You can then use ``bwrite'' and/or ``bputc''
362	* to stuff characters in the stream, much like ``fwrite'' and ``fputc''.
363	* Calling bflush drains all the buffers and MUST be done before exit.
364	*/
365	struct biobuf {
366	short b_nleft; /* Number free spaces left in b_buf */
367	/* Initialize to be less than BUFSIZ initially, to boundary align in file */
368	char b_ptr; / Next place to stuff characters */
369	char b_buf[BUFSIZ]; /* The buffer itself */
370	off_t b_off; /* Current file offset */
371	struct biobuf b_link; / Link in chain for bflush() */
372	};
373	#define bputc(c,b) ((b)->b_nleft ? (--(b)->b_nleft, *(b)->b_ptr++ = (c)) \
374	: bflushc(b, c))
375	#define BFILE struct biobuf
376
377	extern BFILE biobufs; / head of the block I/O buffer chain */
378	extern int biofd; /* file descriptor for block I/O file */
379	extern off_t boffset; /* physical position in logical file */
380
381	/*
382	* For each of the named .text .data segments
383	* (introduced by .text <expr>), we maintain
384	* the current value of the dot, and the BFILE where
385	* the information for each of the segments is placed
386	* during the second pass.
387	*/
388	extern struct exp usedot[NLOC + NLOC];
389	extern BFILE *usefile[NLOC + NLOC];
390	extern BFILE txtfil;/ file for text and data: into usefile */
391	/*
392	* Relocation information for each segment is accumulated
393	* seperately from the others. Writing the relocation
394	* information is logically viewed as writing to one
395	* relocation saving file for each segment; physically
396	* we have a bunch of buffers allocated internally that
397	* contain the relocation information.
398	*/
399	struct relbufdesc *rusefile[NLOC + NLOC];
400	struct relbufdesc *relfil;