shithub: scc

ref: 33983a06ec430df20df57df38c3b142dc495c5a2
dir: /as/main.c/

#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "../inc/scc.h"
#include "as.h"

#define MAXLINE 100
#define NARGS 20

int nerrors;

void
error(char *msg, ...)
{
	va_list va;

	va_start(va, msg);
	fputs("as: ", stderr);
	vfprintf(stderr, msg, va);
	putc('\n', stderr);
	nerrors++;
	va_end(va);
}

int
cmp(const void *f1, const void *f2)
{
	const Ins *ins = f2;

	return strcmp(f1, ins->str);
}

int
match(Op *op, Arg *args)
{
	return 1;
}

Arg
number(char *s, int base)
{
	Arg arg;
	TUINT n;

	/* TODO: Check overflow here */
	arg.type = AIMM;
	for (n = 0; *s; n += *s++ - '0')
		n *= base;
	arg.val = n;

	return arg;
}

Arg *
getargs(char *s)
{
	char *t;
	int ch, len;
	Arg *ap;
	static Arg args[NARGS];

	for (ap = args; s; ++ap) {
		while (isspace(*s))
			++s;
		if (*s == '\0')
			break;
		if (ap == &args[NARGS-1])
			die("too many arguments in one instruction");

		for (t = s; *s && *s != ','; s++)
			/* nothing */;
		len = t - s;
		if (len == 0)
			goto wrong_operand;

		if (*s)
			*s++ = '\0';

		ch = *t;
		if (isdigit(ch)) {
			*ap = number(t, (s[len-1] == 'H') ? 16 : 10);
			continue;
		}
wrong_operand:
		error("wrong operand '%s'", t);
	}
	ap->type = 0;

	return args;
}

void
incpc(int siz)
{
	TUINT pc, curpc;
	pc = cursec->pc;
	curpc = cursec->curpc;

	cursec->curpc += siz;
	cursec->pc += siz;

	if (pass == 2)
		return;

	if (cursec->pc > cursec->max)
		cursec->max = cursec->pc;

	if (pc > cursec->pc ||
	    curpc > cursec->curpc ||
	    cursec->curpc > maxaddr ||
	    cursec->pc > maxaddr) {
		die("address overflow");
	}
}

void
as(char *text, char *xargs)
{
	Ins *ins;
	Op *op, *lim;
	Arg *args;
	
	ins = bsearch(text, instab, nr_ins, sizeof(Ins), cmp);

	if (!ins) {
		error("invalid instruction");
		return;
	}

	args = getargs(xargs);
	lim = &optab[ins->end];
	for (op = &optab[ins->begin]; op < lim; ++op) {
		if (match(op, args))
			break;
	}
	if (op == lim) {
		error("invalid operands");
		return;
	}
	(*op->format)(op, args);
}

int
extract(char *p, char **lbl, char **ins, char **args)
{
	*lbl = p;
	*ins = NULL;
	*args = NULL;

	if ((p = strchr(p, '\t')) == NULL)
		return 0;
	*p++ = '\0';

	*ins = p;
	if ((p = strchr(p, '\t')) == NULL)
		return 1;
	*p++ = '\0';

	*args = p;
	if ((p = strchr(p, '\t')) == NULL)
		return 2;
	*p = '\0';
	return 3;
}

int
dopass(char *file)
{
	FILE *in;
	char line[MAXLINE], *ins, *lbl, *args;

	if ((in = fopen(file, "r")) == NULL)
		die("error opening '%s'", file);

	isections();

	while (fgets(line, sizeof(line), in)) {
		size_t n = strlen(line);
		if (n == 0 || line[0] == ';')
			continue;
		if (line[n-1] != '\n') {
			error("line too long");
			continue;
		}
		line[n-1] = '\0';
		if (extract(line, &lbl, &ins, &args) > 0)
			as(ins, args);
	}

	if (fclose(in))
		die("error reading from input file");
	return nerrors == 0;
}

static void
usage(void)
{
	fputs("usage: as filename\n", stderr);
	exit(1);
}

int
main(int argc, char *argv[])
{
	if (argc != 2)
		usage();

	for (pass = 1; pass <= 2 && dopass(argv[1]); pass++)
		/* nothing */;
	writeout("a.out");

	return 0;
}