scc

  1#include <assert.h>
  2#include <ctype.h>
  3#include <errno.h>
  4#include <limits.h>
  5#include <setjmp.h>
  6#include <stdarg.h>
  7#include <stdio.h>
  8#include <stdlib.h>
  9#include <string.h>
 10
 11#include <scc/cstd.h>
 12#include <scc/mach.h>
 13#include <scc/scc.h>
 14
 15#include "as.h"
 16
 17#define NARGS 20
 18#define NR_INPUTS 10
 19#define MAXLINE 100
 20
 21struct input {
 22	char *fname;
 23	unsigned lineno;
 24	FILE *fp;
 25};
 26
 27int nerrors;
 28jmp_buf recover;
 29char yytext[INTIDENTSIZ+1];
 30int yytoken;
 31size_t yylen;
 32union yylval yylval;
 33
 34static char *textp, *endp;
 35static int regmode;
 36static struct input inputs[NR_INPUTS], *isp = inputs;
 37
 38static int
 39follow(int expect1, int expect2, int ifyes1, int ifyes2, int ifno)
 40{
 41	int c;
 42
 43	if ((c = *++textp) == expect1)
 44		return ifyes1;
 45	if (c == expect2)
 46		return ifyes2;
 47	--textp;
 48	return ifno;
 49}
 50
 51static void
 52tok2str(void)
 53{
 54	if ((yylen = endp - textp) > INTIDENTSIZ) {
 55		error("token too big");
 56		yylen = INTIDENTSIZ;
 57	}
 58	memcpy(yytext, textp, yylen);
 59	yytext[yylen] = '\0';
 60	textp = endp;
 61}
 62
 63static int
 64iden(void)
 65{
 66	int c;
 67	char *p;
 68
 69	for ( ; c = *endp; ++endp) {
 70		if (isalnum(c))
 71			continue;
 72		switch (c) {
 73		case '\'':
 74		case '_':
 75		case '.':
 76		case '$':
 77			continue;
 78		default:
 79			goto out_loop;
 80		}
 81	}
 82
 83out_loop:
 84	tok2str();
 85	yylval.sym = lookup(yytext);
 86
 87	return (yylval.sym->flags & FREG) ? REG : IDEN;
 88}
 89
 90static int
 91number(void)
 92{
 93	int c, base = 10;
 94	char *p;
 95	unsigned long long n;
 96	static char digits[] = "0123456789ABCDEF";
 97
 98	if (*endp == '0') {
 99		base = 8;
100		++endp;
101		if (*endp == 'x') {
102			base = 16;
103			++endp;
104		}
105	}
106	for (n = 0; (c = *endp) && isxdigit(c); n += c) {
107		p = strchr(digits, toupper(c));
108		c = p - digits;
109		if (c > base)
110			error("invalid digit in number");
111		if (n >= ULLONG_MAX/base - c)
112			error("overflow in number");
113		n *= base;
114		endp++;
115	}
116	tok2str();
117	yylval.sym = tmpsym(n);
118
119	return NUMBER;
120}
121
122static int
123character(void)
124{
125	int c;
126	char *p;
127
128	while (*endp != '\'')
129		++endp;
130	return NUMBER;
131}
132
133static int
134string(void)
135{
136	int c;
137	size_t l;
138	char *s;
139	Symbol *sym = tmpsym(0);
140
141	for (++endp; *endp != '"'; ++endp)
142		;
143	++endp;
144	tok2str();
145	yylval.sym = sym;
146	/* FIXME: this memory is not freed ever */
147	l = yylen-2;
148	s = memcpy(xmalloc(l+1), yytext+1, l);
149	s[l] = '\0';
150	sym->name = s;
151
152	return STRING;
153}
154
155static int
156operator(void)
157{
158	int c;
159
160	++endp;
161	if ((c = *textp) == '>')
162		c = follow('=', '>', LE, SHL, '>');
163	else if (c == '<')
164		c = follow('=', '<', GE, SHR, '>');
165	tok2str();
166
167	return c;
168}
169
170int
171ahead(void)
172{
173	while (isspace(*textp))
174		++textp;
175
176	if (*textp != '\0')
177		return *textp;
178	return EOS;
179}
180
181int
182next(void)
183{
184	int c;
185
186	while (isspace(*textp))
187		++textp;
188
189	endp = textp;
190
191	switch (c = *textp) {
192	case '\0':
193		strcpy(yytext, "EOS");
194		yylen = 3;
195		c = EOS;
196		break;
197	case '"':
198		c = string();
199		break;
200	case '\'':
201		c = character();
202		break;
203	case '%':
204		c = (regmode ? iden : operator)();
205		break;
206	case '.':
207	case '_':
208		c = iden();
209		break;
210	default:
211		if (isdigit(c))
212			c = number();
213		else if (isalpha(c))
214			c = iden();
215		else
216			c = operator();
217		break;
218	}
219	return yytoken = c;
220}
221
222void
223expect(int token)
224{
225	if (yytoken != token)
226		unexpected();
227	next();
228}
229
230void
231unexpected(void)
232{
233	error("unexpected '%s'", yytext);
234}
235
236void
237error(char *msg, ...)
238{
239	va_list va;
240	struct input *ip;
241
242	assert(isp > inputs);
243	ip = &isp[-1];
244
245	va_start(va, msg);
246	fprintf(stderr, "as:%s:%u: ", ip->fname, ip->lineno);
247	vfprintf(stderr, msg, va);
248	putc('\n', stderr);
249	nerrors++;
250	va_end(va);
251
252	if (nerrors == 10)
253		die("as: too many errors");
254	longjmp(recover, 1);
255}
256
257Node *
258getreg(void)
259{
260	Node *np;
261
262	np = node(REG, NULL, NULL);
263	np->sym = yylval.sym;
264	np->addr = AREG;
265	expect(REG);
266	return np;
267}
268
269void
270regctx(int mode)
271{
272	regmode = mode;
273}
274
275Node *
276operand(char **strp)
277{
278	int c, imm = 0;
279	Node *np;
280
281	textp = *strp;
282	regctx(1);
283	switch (next()) {
284	case EOS:
285		np = NULL;
286		break;
287	case REG:
288		np = getreg();
289		break;
290	case STRING:
291		np = node(yytoken, NULL, NULL);
292		np->sym = yylval.sym;
293		np->addr = ASTR;
294		next();
295		break;
296	case IDEN:
297		c = ahead();
298		if (c != EOS && c != ',')
299			goto expression;
300		np = node(IDEN, NULL, NULL);
301		np->sym = yylval.sym;
302		np->addr = ANUMBER;
303		next();
304		break;
305	case '$':
306		next();
307		imm = 1;
308	default:
309	expression:
310		if (!imm) {
311			np = moperand();
312		} else {
313			np = expr();
314			np->addr = AIMM;
315		}
316	}
317	if (yytoken != ',' && yytoken != EOS)
318		error("trailing characters in expression '%s'", textp);
319	*strp = endp;
320
321	return np;
322}
323
324Node **
325getargs(char *s)
326{
327	Node **ap;
328	static Node *args[NARGS];
329
330	if (!s)
331		return NULL;
332
333	for (ap = args; ap < &args[NARGS-1]; ++ap) {
334		if ((*ap = operand(&s)) == NULL)
335			return args;
336	}
337	error("too many arguments in one instruction");
338}
339
340static char *
341field(char **oldp, size_t *siz)
342{
343	char *s, *t, *begin;
344	size_t n;
345
346	if ((begin = *oldp) == NULL)
347		return NULL;
348
349	for (s = begin; isspace(*s) && *s != '\t'; ++s)
350		;
351	if (*s == '\0' || *s == '#') {
352		*s = '\0';
353		return *oldp = NULL;
354	}
355
356	for (t = s; *t && *t != '\t'; ++t)
357		;
358	if (*t == '\t')
359		*t++ = '\0';
360	*siz -= begin - t;
361	*oldp = t;
362
363	while (t >= s && isspace(*t))
364		*t-- = '\0';
365	return (*s != '\0') ? s : NULL;
366}
367
368static int
369validlabel(char *name)
370{
371	int c;
372
373	while ((c = *name++) != '\0') {
374		if (isalnum(c))
375			continue;
376		switch (c) {
377		case '_':
378		case '.':
379		case '$':
380			continue;
381		case ':':
382			if (*name != '\0')
383				return 0;
384			*--name = '\0';
385			continue;
386		default:
387			return 0;
388		}
389	}
390	return 1;
391}
392
393static int
394extract(char *s, size_t len, struct line *lp)
395{
396	int r = 0;
397
398	if (lp->label = field(&s, &len))
399		r++;
400	if (lp->op = field(&s, &len))
401		r++;
402	if (lp->args = field(&s, &len))
403		r++;
404
405	if (s && *s && *s != '#')
406		error("trailing characters at the end of the line");
407	if (lp->label && !validlabel(lp->label))
408		error("incorrect label name '%s'", lp->label);
409
410	return r;
411}
412
413static size_t
414getln(FILE *fp, char buff[MAXLINE])
415{
416	int c;
417	char *bp;
418
419	for (bp = buff; (c = getc(fp)) != EOF; *bp++ = c) {
420		if (c == '\n')
421			break;
422
423		if (c > UCHAR_MAX)
424			error("invalid character '%x'", c);
425
426		if (bp == &buff[MAXLINE-1])
427			error("line too long");
428	}
429	*bp = '\0';
430
431	return bp - buff;
432}
433
434int
435nextline(struct line *lp)
436{
437	struct input *ip;
438	size_t n;
439	static char buff[MAXLINE];
440
441	assert(isp > inputs);
442repeat:
443	if (isp == inputs)
444		return 0;
445	ip = &isp[-1];
446	if (feof(ip->fp)) {
447		delinput();
448		goto repeat;
449	}
450	n = getln(ip->fp, buff);
451	if (++ip->lineno == 0)
452		die("as: %s: file too long", infile);
453	if (n == 0)
454		goto repeat;
455	if (extract(buff, n, lp) == 0)
456		goto repeat;
457	return 1;
458}
459
460void
461addinput(char *fname)
462{
463	FILE *fp;
464
465	if (isp == &inputs[NR_INPUTS])
466		die("as: too many included files");
467	if ((fp = fopen(fname, "r")) == NULL)
468		die("as: %s: %s", fname, strerror(errno));
469	isp->fname = xstrdup(fname);
470	isp->fp = fp;
471	isp->lineno = 0;
472	++isp;
473}
474
475int
476delinput(void)
477{
478	if (isp == inputs)
479		return EOF;
480	--isp;
481	if (fclose(isp->fp) == EOF)
482		die("as: %s: %s", isp->fname, strerror(errno));
483	free(isp->fname);
484	return 0;
485}