1 #ifndef lint
2 static char sccsid[] = "@(#)yylex.c 1.4 10/15/86";
3 #endif lint
4
5 #define isid(a) ((fastab+COFF)[a]&IB)
6 #define IB 1
7 /* #if '\377' < 0 it would be nice if this worked properly!!!!! */
8 #if pdp11 | vax | mc68000 | tahoe
9 #define COFF 128
10 #else
11 #define COFF 0
12 #endif
13
yylex()14 yylex() {
15 static int ifdef=0;
16 static char *op2[]={"||", "&&" , ">>", "<<", ">=", "<=", "!=", "=="};
17 static int val2[]={OROR, ANDAND, RS, LS, GE, LE, NE, EQ};
18 static char *opc="b\bt\tn\nf\fr\r\\\\";
19 extern char fastab[];
20 extern char *outp,*inp,*newp; extern int flslvl;
21 register char savc, *s; char *skipbl(); int val;
22 register char **p2;
23 struct symtab {
24 char *name;
25 char *value;
26 } *sp, *lookup();
27
28 for (;;) {
29 extern int passcom; /* this crap makes #if's work */
30 int opt_passcom = passcom; /* even with -C option */
31 passcom = 0; /* (else comments make syntax errs) */
32 newp=skipbl(newp);
33 passcom = opt_passcom; /* nb: lint uses -C so its useful! */
34 if (*inp=='\n') return(stop); /* end of #if */
35 savc= *newp; *newp='\0';
36 for (p2=op2+8; --p2>=op2; ) /* check 2-char ops */
37 if (0==strcmp(*p2,inp)) {val=val2[p2-op2]; goto ret;}
38 s="+-*/%<>&^|?:!~(),"; /* check 1-char ops */
39 while (*s) if (*s++== *inp) {val= *--s; goto ret;}
40 if (*inp<='9' && *inp>='0') {/* a number */
41 if (*inp=='0') yylval= (inp[1]=='x' || inp[1]=='X') ?
42 tobinary(inp+2,16) : tobinary(inp+1,8);
43 else yylval=tobinary(inp,10);
44 val=number;
45 } else if (isid(*inp)) {
46 if (0==strcmp(inp,"defined")) {ifdef=1; ++flslvl; val=DEFINED;}
47 else {
48 sp=lookup(inp,-1); if (ifdef!=0) {ifdef=0; --flslvl;}
49 yylval= (sp->value==0) ? 0 : 1;
50 val=number;
51 }
52 } else if (*inp=='\'') {/* character constant */
53 val=number;
54 if (inp[1]=='\\') {/* escaped */
55 char c; if (newp[-1]=='\'') newp[-1]='\0';
56 s=opc;
57 while (*s) if (*s++!=inp[2]) ++s; else {yylval= *s; goto ret;}
58 if (inp[2]<='9' && inp[2]>='0') yylval=c=tobinary(inp+2,8);
59 else yylval=inp[2];
60 } else yylval=inp[1];
61 } else if (0==strcmp("\\\n",inp)) {*newp=savc; continue;}
62 else {
63 *newp=savc; pperror("Illegal character %c in preprocessor if", *inp);
64 continue;
65 }
66 ret:
67 *newp=savc; outp=inp=newp; return(val);
68 }
69 }
70
tobinary(st,b)71 tobinary(st, b) char *st; {
72 int n, c, t;
73 char *s;
74 n=0;
75 s=st;
76 while (c = *s++) {
77 switch(c) {
78 case '0': case '1': case '2': case '3': case '4':
79 case '5': case '6': case '7': case '8': case '9':
80 t = c-'0'; break;
81 case 'a': case 'b': case 'c': case 'd': case 'e': case 'f':
82 t = c-'a'+10; if (b>10) break;
83 case 'A': case 'B': case 'C': case 'D': case 'E': case 'F':
84 t = c - 'A'+10; if (b>10) break;
85 default:
86 t = -1;
87 if ( c=='l' || c=='L') if (*s=='\0') break;
88 pperror("Illegal number %s", st);
89 }
90 if (t<0) break;
91 n = n*b+t;
92 }
93 return(n);
94 }
95