//?pl/0?compiler?with?code?generation
#include?
#include?
#include?“pl0.h“

void?error（long?n）{
????long?i;

????printf（“?****“）;
????for?（i=1;?i<=cc-1;?i++）{
	printf（“?“）;
????}
????printf（“^%2d\n“n）;
????err++;
}

void?getch（）?{
????if（cc==ll）{
	if（feof（infile））{
	????printf（“************************************\n“）;
	????printf（“??????program?incomplete\n“）;
	????printf（“************************************\n“）;
	????exit（1）;
	}
	ll=0;?cc=0;
	printf（“%5d?“?cx）;
	while（（!feof（infile））&&（（ch=getc（infile））!=‘\n‘））{
	????printf（“%c“ch）;
	????ll=ll+1;?line[ll]=ch;
	}
	printf（“\n“）;
	ll=ll+1;?line[ll]=‘?‘;
????}
????cc=cc+1;?ch=line[cc];
}

void?getsym（）{
????long?ijk;

????while（ch==‘?‘||ch==‘\t‘）{
	getch（）;
????}
????if（isalpha（ch））{?	//?identified?or?reserved
	k=0;
	do{
	????if（k		a[k]=ch;?k=k+1;
	????}
	????getch（）;
	}while（isalpha（ch）||isdigit（ch））;
	if（k>=kk）{
	????kk=k;
	}else{
	????do{
		kk=kk-1;?a[kk]=‘?‘;
	????}while（k	}
	strcpy（ida）;?i=0;?j=norw-1;
	do{
	????k=（i+j）/2;
	????if（strcmp（idword[k]）<=0）{
		j=k-1;
	????}
	????if（strcmp（idword[k]）>=0）{
		i=k+1;
	????}
	}while（i<=j）;
	if（i-1>j）{
	????sym=wsym[k];
	}else{
	????sym=ident;
	}
????}else?if（isdigit（ch））{?//?number
	k=0;?num=0;?sym=number;
	do{
	????num=num*10+（ch-‘0‘）;
	????k=k+1;?getch（）;
	}while（isdigit（ch））;
	if（k>nmax）{
	????error（31）;
	}
????}else?if（ch==‘:‘）{
	getch（）;
	if（ch==‘=‘）{
	????sym=becomes;?getch（）;
	}else{
	????sym=nul;
	}
????}else?if（ch==‘<‘）{
	getch（）;
	if（ch==‘=‘）{
	????sym=leq;?getch（）;
	}else?if（ch==‘>‘）{
	????sym=neq;?getch（）;
	}else{
	????sym=lss;
	}
????}else?if（ch==‘>‘）{
	getch（）;
	if（ch==‘=‘）{
	????sym=geq;?getch（）;
	}else{
	????sym=gtr;
	}
????}else{
	sym=ssym[（unsigned?char）ch];?getch（）;
????}
}

void?gen（enum?fct?x?long?y?long?z）{
????if（cx>cxmax）{
	printf（“program?too?long\n“）;
	exit（1）;
????}
????code[cx].f=x;?code[cx].l=y;?code[cx].a=z;
????cx=cx+1;
}

void?test（unsigned?long?s1?unsigned?long?s2?long?n）{
????if?（!（sym?&?s1））{
	error（n）;
	s1=s1|s2;
	while（!（sym?&?s1））{
	????getsym（）;
	}
????}
}

void?enter（enum?object?k）{		//?enter?object?into?table
????tx=tx+1;
????strcpy（table[tx].nameid）;
????table[tx].kind=k;
????switch（k）{
	case?constant:
	????if（num>amax）{
		error（31）;
		num?=?0;
	????}
	????table[tx].val=num;
	????break;
	case?variable:
	????table[tx].level=lev;?table[tx].addr=dx;?dx=dx+1;
	????break;
	case?proc:
	????table[tx].level=lev;
	????break;
????}
}

long?position（char*?id）{	//?find?identifier?id?in?table
????long?i;

????strcpy（table[0].nameid）;
????i=tx;
????while（strcmp（table[i].nameid）!=0）{
	i=i-1;
????}
????return?i;
}

void?constdeclaration（）{
????if（sym==ident）{
	getsym（）;
	if（sym==eql||sym==becomes）{
	????if（sym==becomes）{
		error（1）;
	????}
	????getsym（）;
	????if（sym==number）{
		enter（constant）;?getsym（）;
	????}els