/* ---------------------------------------------------------------------- * FILE: lexer.c * PACKAGE: as31 - 8031/8051 Assembler. * * DESCRIPTION: *	This file contains the lexical tokenizer for the assembler. *	Since yacc is being used the lexer is called yylex(). * *	In order to produce a listing, some record of the users *	source line must be kept. This is done by adding *	get_ch(), and unget_ch() routine which returns/ungets a character *	but also places information into a secret array. * *	When a newline is encountered the text line is returned as *	an attribute on the '\n' character. * * REVISION HISTORY: *	Jan. 19, 1990 - Created. (Ken Stauffer) * * AUTHOR: *	All code in this file written by Ken Stauffer (University of Calgary). *	January, 1990. * */#include <stdio.h>#include <ctype.h>#include "as31.h"extern union ystack yylval;extern int pass;struct symbol *looksym();struct opcode *lookop();char *malloc();int lineno;static char line[100],*lineptr=line;/* ---------------------------------------------------------------------- * get_ch: *	Get a character from stdin, place char in line[] */get_ch(){	register int c;	c = getchar();	if( c != EOF && lineptr - line < sizeof(line) )		*lineptr++ = c;	return(c);}/* ---------------------------------------------------------------------- * unget_ch: *	Unget a character and move lineptr back by one. */unget_ch(c)int c;{	ungetc(c,stdin);	if( lineptr > line )		lineptr--;}/* ---------------------------------------------------------------------- * yylex: *	The tokens themselves are returned via return(token) * *	Some tokens have attributes. These attributes are returned *	by setting a global variable yylval: * *		yylval.value *			numbers (any base) *			strings (in pass 1). *			bit positions .0, .1, .2, ... * *		yylval.str *			strings (in pass 2). *			'\n' (both passes). * *		yylval.sym *			User defined symbols. * *		yylval.op *			Reserved keyword (opcode/directive/misc.) * *		No other fields in yylval are used by yylex(). *  *		Characters that do not have an attribute do *		not set anything in the yylval variable. * */yylex(){	static nl_flag=0;	/* sync. error messages and the cur. line */	register int c;	char buf[120];		/* temporary buffer */	char *p;		/* general pointer */	struct symbol *sym;	struct opcode *op;	int octal=0,hex=0,decimal=0,binary=0;	register long value = 0;	if( nl_flag ) {		nl_flag = 0;		lineno++;	}for(;;) {	c = get_ch();	switch(c) {	case EOF: return(EOF);	case ' ':	case '\t':		break;	case '\n':		nl_flag = 1;		yylval.str = line;		*lineptr = '\0';		lineptr = line;		return('\n');	case ';':		while((c=get_ch()) != EOF && c!='\n');		nl_flag= 1;		yylval.str = line;		*lineptr = '\0';		lineptr = line;		return(c);	case '"':		p = buf;		while((c=get_ch()) != EOF && c!='"' && c!='\n') {			if( c == '\\' ) {				switch(c=get_ch()) {				case 'n': c = '\n'; break;				case 'r': c = '\r'; break;				case 't': c = '\t'; break;				case 'b': c = '\b'; break;				case '"': c = '"'; break;				case '\\': c = '\\'; break;				default:				  error("Invalid escape character: \\%c",c);				  break;				}			}			if( p-buf<sizeof(buf)-1 ) 				*p++ = c;			else {			   error("String constant longer than %d bytes",					sizeof(buf));			}		}		*p = '\0';		if( c == '\n' || c == EOF ) {			error("String terminated improperly.");			unget_ch(c);		}		if(pass1)			yylval.value = strlen(buf);		else {			if( (p = malloc(strlen(buf)+1)) == NULL )			   error("Cannot allocate %d bytes",strlen(buf)+1);			strcpy(p,buf);			yylval.str = p;		}		return(STRING);	case '.':		if( (c=get_ch())>='0' && c<='7' ) {			yylval.value = c-'0';			return(BITPOS);		}		unget_ch(c);		return('.');	case '\'':		c = get_ch();		if( c=='\\' ) {			switch(c=get_ch()) {			case 'n': c = '\n'; break;			case 'r': c = '\r'; break;			case 't': c = '\t'; break;			case 'b': c = '\b'; break;			case '\\': c = '\\'; break;			case '\'': c = '\''; break;			default:				error("Invalid escape character: \\%c",c);			}		}		if( get_ch() != '\'' )			error("Missing quote in character constant");		yylval.value = c;		return(VALUE);	case '0':	/* parse a number			*/	case '1':	/* could be followed by a:		*/	case '2':	/*	'b','B' - Binary		*/	case '3':	/*	'h','H' - Hex			*/	case '4':	/*	'd','D' - Decimal		*/	case '5':	/*	'o','O' - Octal			*/	case '6':	/* *** Numbers must start with a digit	*/	case '7':	/* Numbers could be also preceeded by:  */	case '8':	/*	0x	- Hex,	0b     - binary */	case '9':	/*	0	- Octal			*/		p = buf;		do {			if( p-buf<sizeof(buf)-1 )				*p++ = c;			c = get_ch();		} while( c=='H' || c=='h' || c=='O' || c=='o' ||				c=='x' || c=='X' || isxdigit(c) );		unget_ch(c);		*p = '\0';		/* Check any preceeding chars */		if( buf[0]=='0' && (buf[1]=='x' || buf[1]=='X') ) {				hex++;				buf[1] = '0';		} else if( buf[0]=='0' &&			(buf[1]=='b' || buf[1]=='B') ) {				binary++;				buf[1] = '0';			}		else if( buf[0]=='0' ) octal++;		/* check any trailing chars */		c = *(p-1);		if( !hex && (c=='b' || c=='B') )			{ binary++; *(p-1) = '\0'; }		else if( c=='H' || c=='h' )			{ hex++; *(p-1) = '\0'; }		else if( !hex && (c=='D' || c=='d') )			{ decimal++; *(p-1) = '\0'; }		else if( c=='O' || c=='o' )			{ octal++; *(p-1) = '\0'; }		else if( !hex && !octal && !binary) decimal++;		if( binary ) {			for(p=buf; *p; p++ ) {				if( *p=='1' ) value = value<<1 + 1;				else if( *p=='0' ) value = value<<1;				else				  error("Invalid binary digit: %c",*p);			}			yylval.value = value;			return(VALUE);		}		if( hex ) {			for(p=buf; *p; p++ ) {				value <<= 4;				if( isdigit(*p) )					value += *p-'0';				else if( *p>='a' && *p<='f' )					value += *p-'a'+ 10;				else if( *p>='A' && *p<='F' )					value += *p-'A'+ 10;				else				  error("Invalid hex digit: %c",*p);			}			yylval.value = value;			return(VALUE);		}		if( decimal ) {			for(p=buf; *p; p++ ) {				if( isdigit(*p) )					value = value*10 + *p-'0';				else				   error("Invalid decimal digit: %c",*p);			}			yylval.value = value;			return(VALUE);		}		if( octal ) {			for(p=buf; *p; p++ ) {				if( *p>='0' && *p<='7' )					value = value<<3 + *p-'0';				else				   error("Invalid octal digit: %c",*p);			}			yylval.value = value;			return(VALUE);		}	default:		if( isalpha(c) || c=='_' ) {			p = buf;			do {				if( p-buf<sizeof(buf)-1 )					*p++ = c;				c = get_ch();			} while( isalnum(c) || c=='_' );			*p = '\0';			unget_ch(c);			if( op = lookop(buf) ) {				yylval.op = op;				return(op->type);			}			sym = looksym(buf);			yylval.sym = sym;			return(SYMBOL);		} else			return(c);	} /* switch */} /* for */} /* yylex */