From ac675cfd528d84ca7b8625aa7e90c38e5cb7ad0d Mon Sep 17 00:00:00 2001
From: Bill Joy <bill@ucbvax.Berkeley.EDU>
Date: Thu, 14 Aug 1980 01:55:52 -0800
Subject: [PATCH] date and time created 80/08/13 18:55:52 by bill

SCCS-vsn: old/as.vax/asexpr.h 4.1
---
 usr/src/old/as.vax/asexpr.h | 90 +++++++++++++++++++++++++++++++++++++
 1 file changed, 90 insertions(+)
 create mode 100644 usr/src/old/as.vax/asexpr.h

diff --git a/usr/src/old/as.vax/asexpr.h b/usr/src/old/as.vax/asexpr.h
new file mode 100644
index 0000000000..c3ebd6b943
--- /dev/null
+++ b/usr/src/old/as.vax/asexpr.h
@@ -0,0 +1,90 @@
+/* Copyright (c) 1980 Regents of the University of California */
+/* "@(#)asexpr.h 4.1 %G%" */
+/*
+ *	Definitions to parse tokens
+ */
+
+#define ERROR(string)		yyerror(string); goto errorfix
+
+#define peekahead (*tokptr)
+
+#define shift 			val = yylex()
+#define advance 	shift
+
+#define shiftover(token)	if (val != token) { \
+					yyerror("token expected"); \
+					goto errorfix; \
+				} \
+				shift
+
+#define advanceover 	shiftover
+
+/*
+ *	To speed up the expression processing, we class the input tokens
+ *	into various sets.
+ *
+ *	We don't call the recursive descent expression analyzer if we can
+ *	determine by looking at the next token after the first token in
+ *	an expression that the expression is simple (name, integer or floating
+ *	point value).  Expressions with operators are parsed using the recursive
+ *	descent method.
+ */
+
+/*
+ *	Functional forwards for expression utility routines
+ */
+struct	exp	*combine();
+struct	exp	*boolterm();
+struct	exp	*term();
+struct	exp	*factor();
+struct	exp	*yukkyexpr();
+
+/*
+ *	The set definitions
+ */
+
+extern	char	tokensets[(LASTTOKEN) - (FIRSTTOKEN) + 1];
+
+#define LINSTBEGIN	01	/*SEMI, NL, NAME*/
+#define	EBEGOPS		02	/*LP, MINUS, TILDE*/
+#define	YUKKYEXPRBEG	04	/*NAME, INSTn, INST0, REG, DOT*/
+#define	SAFEEXPRBEG	010	/*INT, FLTNUM*/
+#define ADDOPS		020	/*PLUS, MINUS*/
+#define	BOOLOPS		040	/*IOR, XOR, AND*/
+#define MULOPS		0100	/*LSH, RSH, MUL, DIV, TILDE*/
+
+#define	INTOKSET(val, set)	(tokensets[(val)] & (set) )
+
+#define expr(xp, val) { \
+	if ( (!INTOKSET(val, EBEGOPS)) && (!INTOKSET(peekahead, ADDOPS+BOOLOPS+MULOPS))) { \
+		if (INTOKSET(val, YUKKYEXPRBEG)) xp = yukkyexpr(val, yylval); \
+		else xp = (struct exp *) yylval; \
+		shift; \
+	} else { \
+		val = exprparse(val, ptrloc1xp); \
+		xp = loc1xp; \
+	} \
+    }
+
+/*
+ *	Registers can be either of the form r0...pc, or
+ *	of the form % <expression>
+ *	NOTE:	Reizers documentation on the assembler says that it
+ *	can be of the form r0 + <expression>.. That's not true.
+ *
+ *	NOTE:	Reizer's yacc grammar would seem to allow an expression
+ *	to be: (This is undocumented)
+ *		a)	a register
+ *		b)	an Instruction (INSTn or INST0)
+ */
+
+#define findreg(regno) \
+	if (val == REG) { \
+		regno = yylval; \
+		shift; \
+	} else \
+	if (val == REGOP) { \
+		shift;	/*over the REGOP*/ \
+		val = funnyreg(val, ptrregno); \
+	} \
+	else { ERROR ("register expected"); }
-- 
2.20.1