1BSD/pi/gen.c

#
/*
 * pi - Pascal interpreter code translator
 *
 * Charles Haley, Bill Joy UCB
 * Version 1.0 August 1977
 */

#include "whoami"
#include "0.h"
#include "tree.h"
#include "opcode.h"

/*
 * This array tells the type
 * returned by an arithmetic
 * operation.  It is indexed
 * by the logarithm of the
 * lengths base 2.
 */
char	arret[]	{
	T4INT,		T4INT,		T4INT,		TDOUBLE,
	T4INT,		T4INT,		T4INT,		TDOUBLE,
	T4INT,		T4INT,		T4INT,		TDOUBLE,
	TDOUBLE,	TDOUBLE,	TDOUBLE,	TDOUBLE
};

/*
 * These array of arithmetic and set
 * operators are indexed by the
 * tree nodes and is highly dependent
 * on their order.  They thus take
 * on the flavor of magic.
 */
int	arop[] {
	0, O_NEG2, O_MOD2, O_DIV2, O_DVD2, O_MUL2, O_ADD2, O_SUB2,
	O_REL2, O_REL2, O_REL2, O_REL2, O_REL2, O_REL2
};
int	setop[] {
	O_MULT, O_ADDT, O_SUBT,
	O_RELT, O_RELT, O_RELT, O_RELT, O_RELT, O_RELT,
};

/*
 * The following array is
 * used when operating on
 * two reals since they are
 * shoved off in a corner in
 * the interpreter table.
 */
int	ar8op[] {
	O_DVD8, O_MUL8, O_ADD8, O_SUB8,
	O_REL8, O_REL8, O_REL8, O_REL8, O_REL8, O_REL8,
};

/*
 * The following arrays, which are linearizations
 * of two dimensional arrays, are the offsets for
 * arithmetic, relational and assignment operations
 * indexed by the logarithms of the argument widths.
 */
char artab[]{
	O_ADD2-O_ADD2,	O_ADD2-O_ADD2,	O_ADD42-O_ADD2,	O_ADD82-O_ADD2,
	O_ADD2-O_ADD2,	O_ADD2-O_ADD2,	O_ADD42-O_ADD2,	O_ADD82-O_ADD2,
	O_ADD24-O_ADD2,	O_ADD24-O_ADD2,	O_ADD4-O_ADD2,	O_ADD84-O_ADD2,
	O_ADD28-O_ADD2,	O_ADD28-O_ADD2,	O_ADD48-O_ADD2,	-1
};
char reltab[] {
	O_REL2-O_REL2,	O_REL2-O_REL2,	O_REL42-O_REL2,	O_REL82-O_REL2,
	O_REL2-O_REL2,	O_REL2-O_REL2,	O_REL42-O_REL2,	O_REL82-O_REL2,
	O_REL24-O_REL2,	O_REL24-O_REL2,	O_REL4-O_REL2,	O_REL84-O_REL2,
	O_REL28-O_REL2,	O_REL28-O_REL2,	O_REL48-O_REL2,	O_REL8-O_REL2
};

char asgntab[] {
	O_AS21-O_AS2,	O_AS21-O_AS2,	O_AS41-O_AS2,	-1,
	O_AS2-O_AS2,	O_AS2-O_AS2,	O_AS42-O_AS2,	-1,
	O_AS24-O_AS2,	O_AS24-O_AS2,	O_AS4-O_AS2,	-1,
	O_AS28-O_AS2,	O_AS28-O_AS2,	O_AS48-O_AS2,	O_AS8-O_AS2,
};

/*
 * Gen generates code for assignments,
 * and arithmetic and string operations
 * and comparisons.
 */
gen(p, o, w1, w2)
	int p, o, w1, w2;
{
	register i, j;
	int op, off;

	switch (p) {
		case O_AS2:
		case NIL:
			i = j = -1;
			/*
			 * Take the log2 of the widths
			 * and linearize them for indexing.
			 * width for indexing.
			 */
			do i++; while (w1=>> 1);
			do j++; while (w2=>> 1);
			i =<< 2;
			i =| j;
			if (p == O_AS2) {
				put1(O_AS2 + asgntab[i]);
				return (NIL);
			}
			op = arop[o];
			if (op == O_REL2) {
				put1((op + reltab[i]) | (o - T_EQ) << 9);
				return (nl+TBOOL);
			}
			put1(i == 15 ? ar8op[o-T_DIVD] : op | artab[i]);
			return (op == O_DVD2 && !divchk ? nl+TDOUBLE : nl+arret[i]);
		case TSTR:
			put2(O_RELG | (o - T_EQ) << 9, w1);
			return (nl+TBOOL);
		case TSET:
			op = setop[o-T_MULT];
			if (op == O_RELT)
				op =| (o - T_EQ)<<9;
			put2(op, w1);
			return (o >= T_EQ ? nl+TBOOL : nl+TSET);
		default:
			panic("gen");
	}
}