asparse.c

<B>Digital的Unix操作系统VAX 4.2源码</B>

   case ILONG:	curlen = NBPW;   goto elist;

   elist:
	seg_type = val;
	shift;

	/*
	 *	Expression List processing
	 */
	if (INTOKSET(val, EBEGOPS+YUKKYEXPRBEG+SAFEEXPRBEG)){
	    do{
		/*
		 *	expression list consists of a list of :
		 *	<expr>
		 *	<expr> : <expr> 
		 *		(pack expr2 into expr1 bits
		 */
		expr(locxp, val);
		/*
		 *	now, pointing at the next token
		 */
		if (val == COLON){
			shiftover(COLON);
			expr(pval, val);
			if ((locxp->e_xtype & XTYPE) != XABS) /* tekmdp */
				yyerror("Width not absolute");
			field_width = locxp->e_xvalue;
			locxp = pval;
			if (bitoff + field_width > curlen)
				flushfield(curlen);
			if (field_width > curlen)
				yyerror("Expression crosses field boundary");
		} else {
			field_width = curlen;
			flushfield(curlen);
		}

		if ((locxp->e_xtype & XTYPE) != XABS) {
			if (bitoff)
				yyerror("Illegal relocation in field");
			switch(curlen){
				case NBPW/4:	reloc_how = TYPB; break;
				case NBPW/2:	reloc_how = TYPW; break;
				case NBPW:	reloc_how = TYPL; break;
			}
			if (passno == 1){
				dotp->e_xvalue += ty_nbyte[reloc_how];
			} else {
				outrel(locxp, reloc_how);
			}
		} else {
			/*
			 *	
			 *	See if we are doing a case instruction.
			 *	If so, then see if the branch distance,
			 *	stored as a word,
			 *	is going to loose sig bits.
			 */
			if (passno == 2 && incasetable){
				if (  (locxp->e_xvalue < -32768)
				    ||(locxp->e_xvalue > 32767)){
					yyerror("Case will branch too far: try -bswitch flag");
				}
			}
			field_value = locxp->e_xvalue & ( (1L << field_width)-1);
			bitfield |= field_value << bitoff;
			bitoff += field_width;
		}
		xp = explist;
		if (auxval = (val == CM))
			shift;
	    } while (auxval);
	}	/* there existed an expression at all */

	flushfield(curlen);
	if ( ( curlen == NBPW/4) && bitoff)
		dotp->e_xvalue ++;
	break;
	/*end of case IBYTE, IWORD, ILONG, IINT*/

   case ISPACE: 	/* .space <expr> */
	shift;
	expr(locxp, val);
	if ((locxp->e_xtype & XTYPE) != XABS)	/* tekmdp */
		yyerror("Space size not absolute");
	space_value = locxp->e_xvalue;
	if (space_value < 0)			/* jlr005 */
		yyerror("Space size negative");
  ospace:
	flushfield(NBPW/4);
	{
		static char spacebuf[128];
		while (space_value > sizeof(spacebuf)){
			outs(spacebuf, sizeof(spacebuf));
			space_value -= sizeof(spacebuf);
		}
		outs(spacebuf, space_value);
	}
	break;

	/*
	 *	.fill rep, size, value
	 *	repeat rep times: fill size bytes with (truncated) value
	 *	size must be between 1 and 8
	 */
   case	IFILL:
	shift;
	expr(locxp, val);
	if ( (locxp->e_xtype & XTYPE) != XABS)	/* tekmdp */
		yyerror("Fill repetition count not absolute");
	fill_rep = locxp->e_xvalue;
	shiftover(CM);
	expr(locxp, val);
	if ( (locxp->e_xtype & XTYPE) != XABS)	/* tekmdp */
		yyerror("Fill size not absolute");
	fill_size = locxp->e_xvalue;
	if (fill_size <= 0 || fill_size > 8)
		yyerror("Fill count not in in 1..8");
	shiftover(CM);
	expr(locxp, val);
	if (passno == 2 && (locxp->e_xtype & XTYPE) != XABS)	/* tekmdp */
		yyerror("Fill value not absolute");
	flushfield(NBPW/4);

	/*RAP001
		Update the location counter on both passes. Used to do it
		only for pass 1, causing a relocation problem. Whoever
		may have thought bwrite did update it (like Outb, outs, ..)
		but it doesn't, so it has to be done here.
	*/
	dotp->e_xvalue += fill_rep * fill_size;
	if (passno == 2) {
		while(fill_rep-- > 0)
			bwrite((char *)&locxp->e_xvalue, fill_size, txtfil);
	}
	break;

   case IASCII:		/* .ascii [ <stringlist> ] */
   case IASCIZ: 	/* .asciz [ <stringlist> ] */
	auxval = val;
	shift;
	/*
	 *	Code to consume a string list
	 *
	 *	stringlist: empty | STRING | stringlist STRING
	 */
	while (val == STRING){
		int	mystrlen;
		flushfield(NBPW/4);
		if (bitoff)
			dotp->e_xvalue++;
		stringp = (struct strdesc *)yylval;
		/*
		 *	utilize the string scanner cheat;
		 *	the scanner appended a null byte on the string,
		 *	but didn't charge it to sd_strlen
		 */
		mystrlen = stringp->sd_strlen;
		mystrlen += (auxval == IASCIZ) ? 1 : 0;
		if (passno == 2){
			if (stringp->sd_place & STR_CORE){
				outs(stringp->sd_string, mystrlen);
			} else {
				int	i, nread;
				fseek(strfile, stringp->sd_stroff, 0);
				for (i = 0; i < mystrlen;/*VOID*/){
					nread = fread(yytext, 1,
						min(mystrlen - i,
						  sizeof(yytext)), strfile);
					outs(yytext, nread);
					i += nread;
				}
			}
		} else {
			dotp->e_xvalue += mystrlen;
		}
		shift;		/*over the STRING*/
		if (val == CM)	/*could be a split string*/
			shift;
	}
	break;
	
   case IORG: 	/* .org <expr> */
	shift;
	expr(locxp, val);

	if ((locxp->e_xtype & XTYPE) == XABS)	/* tekmdp */
		orgwarn++;
	else if ((locxp->e_xtype & ~XXTRN) != dotp->e_xtype)
		yyerror("Illegal expression to set origin");
	space_value = locxp->e_xvalue - dotp->e_xvalue;
	if (space_value < 0)
		yyerror("Backwards 'org'");
	goto ospace;
	break;

/*
 *
 *	Process stabs.  Stabs are created only by the f77
 *	and the C compiler with the -g flag set.
 *	We only look at the stab ONCE, during pass 1, and
 *	virtually remove the stab from the intermediate file
 *	so it isn't seen during pass2.  This makes for some
 *	hairy processing to handle labels occuring in
 *	stab entries, but since most expressions in the
 *	stab are integral we save lots of time in the second
 *	pass by not looking at the stabs.
 *	A stab that is tagged floating will be bumped during
 *	the jxxx resolution phase.  A stab tagged fixed will
 *	not be be bumped.
 *
 *	.stab:	Old fashioned stabs
 *	.stabn: For stabs without names
 *	.stabs:	For stabs with string names
 *	.stabd: For stabs for line numbers or bracketing,
 *		without a string name, without
 *		a final expression.  The value of the
 *		final expression is taken to be  the current
 *		location counter, and is patched by the 2nd pass
 *
 *	.stab{<expr>,}*NCPName,<expr>, <expr>, <expr>, <expr>
 *	.stabn		 <expr>, <expr>, <expr>, <expr>
 *	.stabs   STRING, <expr>, <expr>, <expr>, <expr>
 *	.stabd		 <expr>, <expr>, <expr> # . 
 */
   case ISTAB: 
	yyerror(".stab directive no longer supported");
	goto errorfix;

  tailstab:
	expr(locxp, val);
	if (! (locxp->e_xvalue & STABTYPS)){
		yyerror("Invalid type in %s", stabname);
		goto errorfix;
	}
	stpt->s_ptype = locxp->e_xvalue;
	shiftover(CM);
	expr(locxp, val);
	stpt->s_other = locxp->e_xvalue;
	shiftover(CM);
	expr(locxp, val);
	stpt->s_desc = locxp->e_xvalue;
	shiftover(CM);
	exprisname = 0;
	expr(locxp, val);
	p = locxp->e_xname;
	if ((locxp->e_xtype&XTYPE)!=XUNDEF) {	/* 004 not forward reference */
		stpt->s_value = locxp->e_xvalue;
		stpt->s_index = dotp - usedot;
		if (exprisname){
			switch(stpt->s_ptype) {
				case N_GSYM:
				case N_FNAME:
				case N_RSYM:
				case N_SSYM:
				case N_LSYM:
				case N_PSYM:
				case N_BCOMM:
				case N_ECOMM:
				case N_LENG:
					stpt->s_tag = FIXEDSTAB;
					break;

				/* Special handling of LCSYM.  Although
				 * the named symbol representing the lcomm has
				 * been seen, the address (s_value field)
				 * will be changed in freezesymtab() once
				 * the start address of BSS is known.
				 * So treat this as a forward reference.
				 */
				case N_LCSYM:
					stpt->s_tag = FIXEDSTAB;
					stpt->s_dest = p;
					stpt->s_index = p->s_index;
					stpt->s_type = p->s_type | STABFLAG;
					stpt->s_value = 0;
					break;

				default:
					stpt->s_tag = FLOATINGSTAB;
					break;
			}
		} else
			stpt->s_tag = FIXEDSTAB;

	/* Forward reference. */
	/* Final address will be calculated in stabfix(), when */
	/* stpt->s_dest->s_value has been assigned its final */
	/* address. */
	} else {
		stpt->s_tag = FORWARDSTAB;
		stpt->s_dest = p;
		stpt->s_index = p->s_index;
		stpt->s_type = p->s_type | STABFLAG;

		/* e_xvalue may contain an offset, as in the case v.4+2; */
		/* although the address of v.4 is unknown here, the 2 */
		/* will be added in stabfix(). */
		stpt->s_value = locxp->e_xvalue;
	}
	/*
	 *	tokptr now points at one token beyond
	 *	the current token stored in val and yylval,
	 *	which are the next tokens after the end of
	 *	this .stab directive.  This next token must
	 *	be either a SEMI or NL, so is of width just
	 *	one.  Therefore, to point to the next token
	 *	after the end of this stab, just back up one..
	 */
	buildskip(stabstart, (bytetoktype *)tokptr - sizeof(bytetoktype));
	break;	/*end of the .stab*/

   case ISTABDOT:	
	stabname = ".stabd";
	stpt = (struct symtab *)yylval;
	/*
	 *	We clobber everything after the
	 *	.stabd and its pointer... we MUST
	 *	be able to get back to this .stabd
	 *	so that we can resolve its final value
	 */
	stabstart = tokptr;
	shift;		/*over the ISTABDOT*/
	if (passno == 1){
		expr(locxp, val);
		if (! (locxp->e_xvalue & STABTYPS)){
			yyerror("Invalid type in .stabd");
			goto errorfix;
		}
		stpt->s_ptype = locxp->e_xvalue;
		shiftover(CM);
		expr(locxp, val);
		stpt->s_other = locxp->e_xvalue;
		shiftover(CM);
		expr(locxp, val);
		stpt->s_desc = locxp->e_xvalue;
		/*
		 *
		 *	Now, clobber everything but the
		 *	.stabd pseudo and the pointer
		 *	to its symbol table entry
		 *	tokptr points to the next token,
		 *	build the skip up to this
		 */
		buildskip(stabstart, (bytetoktype *)tokptr - sizeof(bytetoktype));
	}
	/*
	 *	pass 1:	Assign a good guess for its position
	 *		(ensures they are sorted into right place)/
	 *	pass 2:	Fix the actual value
	 */
	stpt->s_value = dotp->e_xvalue;
	stpt->s_index = dotp - usedot;
	stpt->s_tag = FLOATINGSTAB;	/*although it has no effect in pass 2*/
	break;

   case ISTABNONE:
   case ISTABSTR:
        stabname = ((val == ISTABSTR) ? ".stabs" : ".stabn");
	auxval = val;
	if (passno == 2) goto errorfix;
	stpt = (struct symtab *)yylval;
	stabstart = tokptr;
	(bytetoktype *)stabstart -= sizeof(struct symtab *);
	(bytetoktype *)stabstart -= sizeof(bytetoktype);
	shift;
	if (auxval == ISTABSTR){
		stringp = (struct strdesc *)yylval;
		shiftover(STRING);
		stpt->s_name = (char *)stringp;
		/*
		 *	We want the trailing null included in this string.
		 *	We utilize the cheat the string scanner used,
		 *	and merely increment the string length
		 */
		stringp->sd_strlen += 1;
		shiftover(CM);
	} else {
		stpt->s_name = (char *)savestr("\0", 0, STR_BOTH);
	}
	goto tailstab;
	break;

   case ICOMM:		/* .comm  <name> , <expr> */
   case ILCOMM: 	/* .lcomm <name> , <expr> */
	auxval = val;
	shift;
	np = (struct symtab *)yylval;
	shiftover(NAME);
	shiftover(CM);
	expr(locxp, val);

	if ( (locxp->e_xtype & XTYPE) != XABS)	/* tekmdp */
		yyerror("comm size not absolute");
	if (passno == 1 && (np->s_type&XTYPE) != XUNDEF)
		yyerror("Redefinition of %s", FETCHNAME(np));
	if (passno==1) {
		np->s_value = locxp->e_xvalue;
		if (auxval == ICOMM)
			np->s_type |= XXTRN;
		else {
			np->s_type &= ~XTYPE;
			np->s_type |= XBSS;
		}
	}
	break;

   case IALIGN: 		/* .align <align_expr> [, <fill_expr> ]*/
   	{
		int	align_expr;
		int	fill_expr;

		/* Get the .align statement, and shift over .align.
		 */
		stpt = (struct symtab *)yylval;
		shift;

		/* Evaluate the alignment expression.
		 */
		expr(locxp, val);
		if ( (locxp->e_xtype & XTYPE) != XABS) {
			yyerror("Alignment expression not absolute");
			break ;
		} else if ( ! LEGAL_ALIGN_VAL(locxp->e_xvalue)) {
			yyerror("Illegal value for alignment expression");
			break ;
		} else if (locxp->e_xvalue > ALIGN_GUARANTEE) {
			/*
			 * If more alignment was specified, than is guaranteed
			 * by the loader, then issue a warning and convert
			 * the value to the maximum guaranteed by the loader.
			 */
			if (passno == 1){
				yywarning(
					".align %d is NOT preserved by the loader",
					locxp->e_xvalue);
				yywarning(".align %d converted to .align %d",
					locxp->e_xvalue,
					ALIGN_GUARANTEE);
			}
			align_expr = ALIGN_GUARANTEE;
		} else {
			/* Use the user specified alignment expression.
			 */
			align_expr = locxp->e_xvalue;
		}
		/* Evalutate the fill expression if there is one, else use 0.
		 */
		if (val == CM) {
			shiftover(CM);
			expr(locxp, val);
			if (passno == 2 && (locxp->e_xtype & XTYPE) != XABS) {
				yyerror("Fill expression not absolute");
				break;
			} else {
				fill_expr = locxp->e_xvalue;
			}
		} else {
			fill_expr = 0;	/* default to 0 */
		}
		/* Create the appropriate entry for the .align, so it
		 * can be used in calculating positions for symbols.
		 */
		jalign(align_expr, fill_expr, stpt);
	}
	break;

   case VINST0:		/* vector instructions w/o arguments*/
	np = (struct symtab *)yylval;
	incasetable = 0;
	shift;	
	vmod.imod = 0;
	if (val == VMODIFIER){
	  vmod.imod = yylval; /* save vector instr modifiers */
	  shift;              /* now bring in the first token for the arg list*/
	} /* end if VMODIFIER */
	format_vinst (np, &vmod, (struct arg *)0);
	break;

   case INST0: 		/* instructions w/o arguments*/
	incasetable = 0;
	insout(yyopcode, (struct arg *)0, 0);
	shift;	
	break;

   case INSTn:		/* instructions with arguments*/
   case IJXXX: 		/* UNIX style jump instructions */
   case VINSTn:		/* vector instructions with arguments*/

	if (val == VINSTn){
		np = (struct symtab *)yylval;
		auxval = val;
		shift;		/* bring in the first token for the arg list*/
	  	vmod.imod = 0;
	  	if (val == VMODIFIER){
	    	vmod.imod = yylval; /* save vector instr modifiers */
	    	shift;            /* now bring in the first token for the arg list*/
	  	} /* end if VMODIFIER */
		/*
	 	 *	Code to process an argument list
	 	 */
		ap = arglist;
		xp = explist;	

	} /* end if VINSTn */
	else {
		auxval = val;
		/*
	 	 *	Code to process an argument list
	 	 */
		ap = arglist;
		xp = explist;