begin (*main*)
for ch∶=′ ′ to ′!′ do ssym[ch]∶=nul;
(*changed because of different character set
note the typos below in the original where
the alfas were not given the correct space*)
word[1]∶=′begin′; word[2]∶=′call ′;
word[3]∶=′const′; word[4]∶=′do ′;
word[5]∶=′end′; word[6]∶=′if ′;
word[7]∶=′odd ′; word[8]∶=′procedur e ′;
word[9]∶=′read′; word[10]∶=′then ′;
word[11]∶=′var ′;word[12]∶=′while ′;
word[13]∶=′write ′;
wsym[1]∶=beginsym; wsym[2]∶=callsym;
wsym[3]∶=constsym; wsym[4]∶=dosym;
wsym[5]∶=endsym; wsym[6]∶=ifsym;
wsym[7]∶=oddsym; wsym[8]∶=procsym;
wsym[9]∶=readsym;wsym[10]∶=thensym;
wsym[11]∶=varsym;wsym[12]∶=whilesym;
wsym[13]∶=writesym;
ssym[′+′]∶=plus; ssym[′-′]∶=minus;
ssym[′*′]∶=times;ssym[′/′]∶=slash;
ssym[′(′]∶=lparen; ssym[′)′]∶=rparen;
ssym[′=′]∶=eql;ssym[′,′]∶=comma;
ssym[′.′]∶=period; ssym[′#′]∶=neq;
ssym[′;′]∶=semicolon;
mnemonic[lit]∶=′lit′; mnemonic[opr]∶ =′opr′;
mnemonic[lod]∶=′lod′; mnemonic[sto]∶= ′sto′;
mnemonic[cal]∶=′cal′; mnemonic[int]∶= ′int′;
mnemonic[jmp]∶=′jmp′; mnemonic[jpc]∶= ′jpc′;
declbegsys∶=[constsym,varsym,procsym];
statbegsys∶=[beginsym,callsym,ifsym,whilesym];
facbegsys∶=[ident,number,lparen];
(*page(output)*)
rewrite(fa1);
write(′input file?′);
write(fa1,′input file? ′);
readln(fname);
openf(fin,fname,′r′);
write(′list object code?′);
readln(fname);
write(fa1,′list object code?′);
listswitch∶=(fname[1]=′y′);
err∶=0;
cc∶=0; cx∶=0; ll∶=0;
ch∶=′ ′; kk∶=al;
getsym;
rewrite(fa);
rewrite(fa2);
block(0,0,[period]+declbegsys+statbegsys);
closef(fa);
closef(fa1);
if sym<>period
then error(9);
if err=0
then interpret
else write(′errors in pl/0 program′);
99:
closef(fin);
writeln
end.
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