ref: faab83b89701457c3dff6b9780af8968b8132d95
dir: /as/parser.c/
static char sccsid[] = "@(#) ./as/parser.c"; #include <ctype.h> #include <stdarg.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include "../inc/scc.h" #include "as.h" #define NARGS 20 #define MAXLINE 100 char *filename; int nerrors; static unsigned lineno; void error(char *msg, ...) { va_list va; va_start(va, msg); fprintf(stderr, "as:%s:%u: ", filename, lineno); vfprintf(stderr, msg, va); putc('\n', stderr); nerrors++; va_end(va); if (nerrors == 10) die("as: too many errors"); } 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; } static char * field(char **oldp) { char *s, *begin; int c; if ((begin = *oldp) == NULL) return NULL; for (s = begin; ; s++) { switch (c = *s) { case '\t': *s++ = '\0'; *oldp = s; goto out_loop; case ';': *s = '\0'; case '\0': *oldp = NULL; goto out_loop; case '\'': if (*++s == '\0' || *++s != '\'') error("invalid character constant"); break; case '"': while ((c = *++s) && c != '"') /* nothing */; if (c == '\0') error("unterminated string"); break; default: *s = toupper(c); break; } } out_loop: return (*begin != '\0') ? begin : NULL; } static int extract(char *s, struct line *lp) { int r = 0; if (lp->label = field(&s)) r++; if (lp->op = field(&s)) r++; if (lp->args = field(&s)) r++; if (s) { while (isspace(*s)) ++s; if (*s != '\0' && *s != ';') error("trailing characters at the end of the line"); } return r; } int next(FILE *fp, struct line *lp) { size_t n; static char buff[MAXLINE]; repeat: if (!fgets(buff, sizeof(buff), fp)) return 0; if (++lineno == 0) die("as: file too long"); n = strlen(buff); if (n == 0) goto repeat; if (buff[n-1] != '\n') { error("line too long"); goto repeat; } buff[n-1] = '\0'; if (extract(buff, lp) == 0) goto repeat; return 1; }