lex.c

这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

#define	EXTERN
#include "a.h"
#include "y.tab.h"
#include <ctype.h>

void
main(int argc, char *argv[])
{
	char *p;
	int nout, nproc, status, i, c;

	thechar = '5';
	thestring = "arm";
	memset(debug, 0, sizeof(debug));
	cinit();
	outfile = 0;
	include[ninclude++] = ".";
	ARGBEGIN {
	default:
		c = ARGC();
		if(c >= 0 || c < sizeof(debug))
			debug[c] = 1;
		break;

	case 'o':
		outfile = ARGF();
		break;

	case 'D':
		p = ARGF();
		if(p)
			Dlist[nDlist++] = p;
		break;

	case 'I':
		p = ARGF();
		setinclude(p);
		break;
	case 't':
		thechar = 't';
		thestring = "thumb";
		break;
	} ARGEND
	if(*argv == 0) {
		print("usage: %ca [-options] file.s\n", thechar);
		errorexit();
	}
	if(argc > 1 && systemtype(Windows)){
		print("can't assemble multiple files on windows\n");
		errorexit();
	}
	if(argc > 1 && !systemtype(Windows)) {
		nproc = 1;
		if(p = getenv("NPROC"))
			nproc = atol(p);	/* */
		c = 0;
		nout = 0;
		for(;;) {
			while(nout < nproc && argc > 0) {
				i = myfork();
				if(i < 0) {
					i = mywait(&status);
					if(i < 0)
						errorexit();
					if(status)
						c++;
					nout--;
					continue;
				}
				if(i == 0) {
					print("%s:\n", *argv);
					if(assemble(*argv))
						errorexit();
					exits(0);
				}
				nout++;
				argc--;
				argv++;
			}
			i = mywait(&status);
			if(i < 0) {
				if(c)
					errorexit();
				exits(0);
			}
			if(status)
				c++;
			nout--;
		}
	}
	if(assemble(argv[0]))
		errorexit();
	exits(0);
}

int
assemble(char *file)
{
	char ofile[100], incfile[20], *p;
	int i, of;

	strcpy(ofile, file);
	p = utfrrune(ofile, pathchar());
	if(p) {
		include[0] = ofile;
		*p++ = 0;
	} else
		p = ofile;
	if(outfile == 0) {
		outfile = p;
		if(outfile){
			p = utfrrune(outfile, '.');
			if(p)
				if(p[1] == 's' && p[2] == 0)
					p[0] = 0;
			p = utfrune(outfile, 0);
			p[0] = '.';
			p[1] = thechar;
			p[2] = 0;
		} else
			outfile = "/dev/null";
	}
	p = getenv("INCLUDE");
	if(p) {
		setinclude(p);
	} else {
		if(systemtype(Plan9)) {
			sprint(incfile,"/%s/include", thestring);
			setinclude(strdup(incfile));
		}
	}

	of = mycreat(outfile, 0664);
	if(of < 0) {
		yyerror("%ca: cannot create %s", thechar, outfile);
		errorexit();
	}
	Binit(&obuf, of, OWRITE);

	pass = 1;
	pinit(file);
	for(i=0; i<nDlist; i++)
		dodefine(Dlist[i]);
	yyparse();
	if(nerrors) {
		cclean();
		return nerrors;
	}

	pass = 2;
	outhist();
	pinit(file);
	for(i=0; i<nDlist; i++)
		dodefine(Dlist[i]);
	yyparse();
	cclean();
	return nerrors;
}

struct
{
	char	*name;
	ushort	type;
	ushort	value;
} itab[] =
{
	"SP",		LSP,	D_AUTO,
	"SB",		LSB,	D_EXTERN,
	"FP",		LFP,	D_PARAM,
	"PC",		LPC,	D_BRANCH,

	"R",		LR,	0,
	"R0",		LREG,	0,
	"R1",		LREG,	1,
	"R2",		LREG,	2,
	"R3",		LREG,	3,
	"R4",		LREG,	4,
	"R5",		LREG,	5,
	"R6",		LREG,	6,
	"R7",		LREG,	7,
	"R8",		LREG,	8,
	"R9",		LREG,	9,
	"R10",		LREG,	10,
	"R11",		LREG,	11,
	"R12",		LREG,	12,
	"R13",		LREG,	13,
	"R14",		LREG,	14,
	"R15",		LREG,	15,

	"F",		LF,	0,

	"F0",		LFREG,	0,
	"F1",		LFREG,	1,
	"F2",		LFREG,	2,
	"F3",		LFREG,	3,
	"F4",		LFREG,	4,
	"F5",		LFREG,	5,
	"F6",		LFREG,	6,
	"F7",		LFREG,	7,
	"F8",		LFREG,	8,
	"F9",		LFREG,	9,
	"F10",		LFREG,	10,
	"F11",		LFREG,	11,
	"F12",		LFREG,	12,
	"F13",		LFREG,	13,
	"F14",		LFREG,	14,
	"F15",		LFREG,	15,

	"C",		LC,	0,

	"C0",		LCREG,	0,
	"C1",		LCREG,	1,
	"C2",		LCREG,	2,
	"C3",		LCREG,	3,
	"C4",		LCREG,	4,
	"C5",		LCREG,	5,
	"C6",		LCREG,	6,
	"C7",		LCREG,	7,
	"C8",		LCREG,	8,
	"C9",		LCREG,	9,
	"C10",		LCREG,	10,
	"C11",		LCREG,	11,
	"C12",		LCREG,	12,
	"C13",		LCREG,	13,
	"C14",		LCREG,	14,
	"C15",		LCREG,	15,

	"CPSR",		LPSR,	0,
	"SPSR",		LPSR,	1,

	"FPSR",		LFCR,	0,
	"FPCR",		LFCR,	1,

	".EQ",		LCOND,	0,
	".NE",		LCOND,	1,
	".CS",		LCOND,	2,
	".HS",		LCOND,	2,
	".CC",		LCOND,	3,
	".LO",		LCOND,	3,
	".MI",		LCOND,	4,
	".PL",		LCOND,	5,
	".VS",		LCOND,	6,
	".VC",		LCOND,	7,
	".HI",		LCOND,	8,
	".LS",		LCOND,	9,
	".GE",		LCOND,	10,
	".LT",		LCOND,	11,
	".GT",		LCOND,	12,
	".LE",		LCOND,	13,
	".AL",		LCOND,	Always,

	".U",		LS,	C_UBIT,
	".S",		LS,	C_SBIT,
	".W",		LS,	C_WBIT,
	".P",		LS,	C_PBIT,
	".PW",		LS,	C_WBIT|C_PBIT,
	".WP",		LS,	C_WBIT|C_PBIT,

	".F",		LS,	C_FBIT,

	".IBW",		LS,	C_WBIT|C_PBIT|C_UBIT,
	".IAW",		LS,	C_WBIT|C_UBIT,
	".DBW",		LS,	C_WBIT|C_PBIT,
	".DAW",		LS,	C_WBIT,
	".IB",		LS,	C_PBIT|C_UBIT,
	".IA",		LS,	C_UBIT,
	".DB",		LS,	C_PBIT,
	".DA",		LS,	0,

	"@",		LAT,	0,

	"AND",		LTYPE1,	AAND,
	"EOR",		LTYPE1,	AEOR,
	"SUB",		LTYPE1,	ASUB,
	"RSB",		LTYPE1,	ARSB,
	"ADD",		LTYPE1,	AADD,
	"ADC",		LTYPE1,	AADC,
	"SBC",		LTYPE1,	ASBC,
	"RSC",		LTYPE1,	ARSC,
	"ORR",		LTYPE1,	AORR,
	"BIC",		LTYPE1,	ABIC,

	"SLL",		LTYPE1,	ASLL,
	"SRL",		LTYPE1,	ASRL,
	"SRA",		LTYPE1,	ASRA,

	"MUL",		LTYPE1, AMUL,
	"MULA",		LTYPEN, AMULA,
	"DIV",		LTYPE1,	ADIV,
	"MOD",		LTYPE1,	AMOD,

	"MULL",		LTYPEM, AMULL,
	"MULAL",	LTYPEM, AMULAL,
	"MULLU",	LTYPEM, AMULLU,
	"MULALU",	LTYPEM, AMULALU,

	"MVN",		LTYPE2, AMVN,	/* op2 ignored */

	"MOVB",		LTYPE3, AMOVB,
	"MOVBU",	LTYPE3, AMOVBU,
	"MOVH",		LTYPE3, AMOVH,
	"MOVHU",	LTYPE3, AMOVHU,
	"MOVW",		LTYPE3, AMOVW,

	"MOVD",		LTYPE3, AMOVD,
	"MOVDF",		LTYPE3, AMOVDF,
	"MOVDW",	LTYPE3, AMOVDW,
	"MOVF",		LTYPE3, AMOVF,
	"MOVFD",		LTYPE3, AMOVFD,
	"MOVFW",		LTYPE3, AMOVFW,
	"MOVWD",	LTYPE3, AMOVWD,
	"MOVWF",		LTYPE3, AMOVWF,

/*
	"ABSF",		LTYPEI, AABSF,
	"ABSD",		LTYPEI, AABSD,
	"NEGF",		LTYPEI, ANEGF,
	"NEGD",		LTYPEI, ANEGD,
	"SQTF",		LTYPEI,	ASQTF,
	"SQTD",		LTYPEI,	ASQTD,
	"RNDF",		LTYPEI,	ARNDF,
	"RNDD",		LTYPEI,	ARNDD,
	"URDF",		LTYPEI,	AURDF,
	"URDD",		LTYPEI,	AURDD,
	"NRMF",		LTYPEI,	ANRMF,
	"NRMD",		LTYPEI,	ANRMD,
*/

	"CMPF",		LTYPEL, ACMPF,
	"CMPD",		LTYPEL, ACMPD,
	"ADDF",		LTYPEK,	AADDF,
	"ADDD",		LTYPEK,	AADDD,
	"SUBF",		LTYPEK,	ASUBF,
	"SUBD",		LTYPEK,	ASUBD,
	"MULF",		LTYPEK,	AMULF,
	"MULD",		LTYPEK,	AMULD,
	"DIVF",		LTYPEK,	ADIVF,
	"DIVD",		LTYPEK,	ADIVD,

	"B",		LTYPE4, AB,
	"BL",		LTYPE4, ABL,
	"BX",		LTYPEBX,	ABX,

	"BEQ",		LTYPE5,	ABEQ,
	"BNE",		LTYPE5,	ABNE,
	"BCS",		LTYPE5,	ABCS,
	"BHS",		LTYPE5,	ABHS,
	"BCC",		LTYPE5,	ABCC,
	"BLO",		LTYPE5,	ABLO,
	"BMI",		LTYPE5,	ABMI,
	"BPL",		LTYPE5,	ABPL,
	"BVS",		LTYPE5,	ABVS,
	"BVC",		LTYPE5,	ABVC,
	"BHI",		LTYPE5,	ABHI,
	"BLS",		LTYPE5,	ABLS,
	"BGE",		LTYPE5,	ABGE,
	"BLT",		LTYPE5,	ABLT,
	"BGT",		LTYPE5,	ABGT,
	"BLE",		LTYPE5,	ABLE,
	"BCASE",	LTYPE5,	ABCASE,

	"SWI",		LTYPE6, ASWI,

	"CMP",		LTYPE7,	ACMP,
	"TST",		LTYPE7,	ATST,
	"TEQ",		LTYPE7,	ATEQ,
	"CMN",		LTYPE7,	ACMN,

	"MOVM",		LTYPE8, AMOVM,

	"SWPBU",	LTYPE9, ASWPBU,
	"SWPW",		LTYPE9, ASWPW,

	"RET",		LTYPEA, ARET,
	"RFE",		LTYPEA, ARFE,

	"TEXT",		LTYPEB, ATEXT,
	"GLOBL",	LTYPEB, AGLOBL,
	"DATA",		LTYPEC, ADATA,
	"CASE",		LTYPED, ACASE,
	"END",		LTYPEE, AEND,
	"WORD",		LTYPEH, AWORD,
	"NOP",		LTYPEI, ANOP,

	"MCR",		LTYPEJ, 0,
	"MRC",		LTYPEJ, 1,
	0
};

void
cinit(void)
{
	Sym *s;
	int i;

	nullgen.sym = S;
	nullgen.offset = 0;
	nullgen.type = D_NONE;
	nullgen.name = D_NONE;
	nullgen.reg = NREG;
	if(FPCHIP)
		nullgen.dval = 0;
	for(i=0; i<sizeof(nullgen.sval); i++)
		nullgen.sval[i] = 0;

	nerrors = 0;
	iostack = I;
	iofree = I;
	peekc = IGN;
	nhunk = 0;
	for(i=0; i<NHASH; i++)
		hash[i] = S;
	for(i=0; itab[i].name; i++) {
		s = slookup(itab[i].name);
		s->type = itab[i].type;
		s->value = itab[i].value;
	}

	pathname = allocn(pathname, 0, 100);
	if(mygetwd(pathname, 99) == 0) {
		pathname = allocn(pathname, 100, 900);
		if(mygetwd(pathname, 999) == 0)
			strcpy(pathname, "/???");
	}
}

void
syminit(Sym *s)
{

	s->type = LNAME;
	s->value = 0;
}

int
isreg(Gen *g)
{

	USED(g);
	return 1;
}

void
cclean(void)
{

	outcode(AEND, Always, &nullgen, NREG, &nullgen);
	Bflush(&obuf);
}

void
zname(char *n, int t, int s)
{

	Bputc(&obuf, ANAME);
	Bputc(&obuf, t);	/* type */
	Bputc(&obuf, s);	/* sym */
	while(*n) {
		Bputc(&obuf, *n);
		n++;
	}
	Bputc(&obuf, 0);
}

void
zaddr(Gen *a, int s)
{
	long l;
	int i;
	char *n;
	Ieee e;

	Bputc(&obuf, a->type);
	Bputc(&obuf, a->reg);
	Bputc(&obuf, s);
	Bputc(&obuf, a->name);
	switch(a->type) {
	default:
		print("unknown type %d\n", a->type);
		exits("arg");

	case D_NONE:
	case D_REG:
	case D_FREG:
	case D_PSR:
	case D_FPCR:
		break;

	case D_REGREG:
		Bputc(&obuf, a->offset);
		break;

	case D_OREG:
	case D_CONST:
	case D_BRANCH:
	case D_SHIFT:
		l = a->offset;
		Bputc(&obuf, l);
		Bputc(&obuf, l>>8);
		Bputc(&obuf, l>>16);
		Bputc(&obuf, l>>24);
		break;

	case D_SCONST:
		n = a->sval;
		for(i=0; i<NSNAME; i++) {
			Bputc(&obuf, *n);
			n++;
		}
		break;

	case D_FCONST:
		ieeedtod(&e, a->dval);
		Bputc(&obuf, e.l);
		Bputc(&obuf, e.l>>8);
		Bputc(&obuf, e.l>>16);
		Bputc(&obuf, e.l>>24);
		Bputc(&obuf, e.h);
		Bputc(&obuf, e.h>>8);
		Bputc(&obuf, e.h>>16);
		Bputc(&obuf, e.h>>24);
		break;
	}
}

static int bcode[] =
{
	ABEQ,
	ABNE,
	ABCS,
	ABCC,
	ABMI,
	ABPL,
	ABVS,
	ABVC,
	ABHI,
	ABLS,
	ABGE,
	ABLT,
	ABGT,
	ABLE,
	AB,
	ANOP,
};

void
outcode(int a, int scond, Gen *g1, int reg, Gen *g2)
{
	int sf, st, t;
	Sym *s;

	/* hack to make B.NE etc. work: turn it into the corresponding conditional */
	if(a == AB){
		a = bcode[scond&0xf];
		scond = (scond & ~0xf) | Always;
	}

	if(pass == 1)
		goto out;
jackpot:
	sf = 0;
	s = g1->sym;
	while(s != S) {
		sf = s->sym;
		if(sf < 0 || sf >= NSYM)
			sf = 0;
		t = g1->name;
		if(h[sf].type == t)
		if(h[sf].sym == s)
			break;
		zname(s->name, t, sym);
		s->sym = sym;
		h[sym].sym = s;
		h[sym].type = t;
		sf = sym;
		sym++;
		if(sym >= NSYM)
			sym = 1;
		break;
	}
	st = 0;
	s = g2->sym;
	while(s != S) {
		st = s->sym;
		if(st < 0 || st >= NSYM)
			st = 0;
		t = g2->name;
		if(h[st].type == t)
		if(h[st].sym == s)
			break;
		zname(s->name, t, sym);
		s->sym = sym;
		h[sym].sym = s;
		h[sym].type = t;
		st = sym;
		sym++;
		if(sym >= NSYM)
			sym = 1;
		if(st == sf)
			goto jackpot;
		break;
	}
	Bputc(&obuf, a);
	Bputc(&obuf, scond);
	Bputc(&obuf, reg);
	Bputc(&obuf, lineno);
	Bputc(&obuf, lineno>>8);
	Bputc(&obuf, lineno>>16);
	Bputc(&obuf, lineno>>24);
	zaddr(g1, sf);
	zaddr(g2, st);

out:
	if(a != AGLOBL && a != ADATA)
		pc++;
}

void
outhist(void)
{
	Gen g;
	Hist *h;
	char *p, *q, *op, c;
	int n;

	g = nullgen;
	c = pathchar();
	for(h = hist; h != H; h = h->link) {
		p = h->name;
		op = 0;
		/* on windows skip drive specifier in pathname */
		if(systemtype(Windows) && p && p[1] == ':'){
			p += 2;
			c = *p;
		}
		if(p && p[0] != c && h->offset == 0 && pathname){
			/* on windows skip drive specifier in pathname */
			if(systemtype(Windows) && pathname[1] == ':') {
				op = p;
				p = pathname+2;
				c = *p;
			} else if(pathname[0] == c){
				op = p;
				p = pathname;
			}
		}
		while(p) {
			q = strchr(p, c);
			if(q) {
				n = q-p;
				if(n == 0){
					n = 1;	/* leading "/" */
					*p = '/';	/* don't emit "\" on windows */
				}
				q++;
			} else {
				n = strlen(p);
				q = 0;
			}
			if(n) {
				Bputc(&obuf, ANAME);
				Bputc(&obuf, D_FILE);	/* type */
				Bputc(&obuf, 1);	/* sym */
				Bputc(&obuf, '<');
				Bwrite(&obuf, p, n);
				Bputc(&obuf, 0);
			}
			p = q;
			if(p == 0 && op) {
				p = op;
				op = 0;
			}
		}
		g.offset = h->offset;

		Bputc(&obuf, AHISTORY);
		Bputc(&obuf, Always);
		Bputc(&obuf, 0);
		Bputc(&obuf, h->line);
		Bputc(&obuf, h->line>>8);
		Bputc(&obuf, h->line>>16);
		Bputc(&obuf, h->line>>24);
		zaddr(&nullgen, 0);
		zaddr(&g, 0);
	}
}

#include "../cc/lexbody"
#include "../cc/macbody"
#include "../cc/compat"