date and time created 80/08/13 18:55:52 by bill

SCCS-vsn: old/as.vax/asexpr.h 4.1

diff --git a/usr/src/old/as.vax/asexpr.h b/usr/src/old/as.vax/asexpr.h
new file mode 100644 (file)
index 0000000..c3ebd6b
--- /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"); }