program Pascals(input{+ [sam]}, output, srcfil{ [sam]}); (* 1.6.75 *)
(* N. Wirth, E.T.H
CH-8092 Zurich *)
const nkw = 27; (* no. of key words *)
alng = 10; (* no. of significant chars in identifiers *)
llng = 250 {120 [sam]}; (* input line length *)
emax = 308 {322 [sam]}; (* max exponent of real numbers *)
emin = -308 {-292 [sam]}; (* min exponent *)
kmax = 15; (* max no. of significant digits *)
tmax = 10000 {100 [sam]}; (* size of table *)
bmax = 1000 {20 [sam]}; (* size of block-table *)
amax = 1000 {30 [sam]}; (* size of array-table *)
c2max = 1000 {20 [sam]}; (* size of real constant table *)
csmax = 1000 {30 [sam]}; (* max no. of cases *)
cmax = 100000 {850 [sam]}; (* size of code *)
lmax = 100 {7 [sam]}; (* maximum level *)
smax = 100000 {600 [sam]}; (* size of string table *)
ermax = 58; (* max error no. *)
omax = 63; (* highest order code *)
xmax = 131071; (* 2**17 - 1 *)
nmax = maxint {281474976710655 [sam]}; (* 2**48 - 1 *)
lineleng = 250 {136 [sam] }; (* output line length *)
linelimit = 100000 {200 [sam]};
stacksize = 100000 {1500 [sam]};
inxmax = 127; { maximum index for character (ASCII) [sam] }
intfld = 10; { default output field for integer [sam] }
relfld = 22; { default output field for real [sam] }
bolfld = 10; { default output field for boolean [sam] }
chrfld = 1; { default output field for character [sam] }
type symbol = (intcon, realcon, charcon, stringt, {3}
notsy, plus, minus, times, idiv, rdiv, imod, andsy, orsy, {12}
egl, neg, gtr, geg, lss, leg, {18}
lparent, rparent, lbrack, rbrack, comma, semicolon, period, {25}
colon, becomes, constsy, typesy, varsy, functionsy, {32}
proceduresy, arraysy, recordsy, programsy, ident, {37}
beginsy, ifsy, casesy, repeatsy, whilesy, forsy, {43}
endsy, elsesy, untilsy, ofsy, dosy, tosy, downtosy, thensy); {51}
{ BPW - make all integers long, avoids problems like unreachable code for errors }
integer=longint;
index = -xmax .. +xmax;
alfa = packed array [1..alng] of char;
objects = (konstant, variable, typel, prozedure, funktion);
types = (notyp, ints, reals, bools, chars, arrays, records);
symset = set of symbol;
typset = set of types;
item = record
typ: types; ref: index;
end;
order = packed record
f: -omax..+omax;
x: -lmax..+lmax;
y: -nmax..+nmax;
end;
var sy: symbol; (* last symbol read by insymbol *)
id: alfa; (* identifier from insymbol *)
inum: integer; (* integer from insymbol *)
rnum: real; (* real number from insymbol *)
sleng: integer; (* string length *)
ch: char; (* last character read from source program *)
line: array [1..llng] of char;
cc: integer; (* character counter *)
lc: integer; (* program location counter *)
ll: integer; (* length of current line *)
errs: set of 0..ermax;
errpos: integer;
progname: alfa;
iflag, oflag: boolean;
constbegsys, typebegsys, blockbegsys, facbegsys, statbegsys: symset;
key: array [1..nkw] of alfa;
ksy: array [1..nkw] of symbol;
sps: array [char] of symbol; (* special symbols *)
t, a, b, sx, c1, c2: integer; (* indicies to tables *)
stantyps: typset;
display: array [0..lmax] of integer;
tab: array [0..tmax] of (* identifier table *)
packed record
name: alfa; link: index;
obj: objects; typ: types;
ref: index; normal: boolean;
lev: 0..lmax; adr: integer;
end;
atab: array [1..amax] of (* array-table *)
packed record
inxtyp, eltyp: types;
elref, low, high, elsize, size: index;
end;
btab: array [1..bmax] of (* block table *)
packed record
last, lastpar, psize, vsize: index
end;
stab: packed array [0..smax] of char; (* string table *)
rconst: array [1..c2max] of real;
code: array [0..cmax] of order;
srcfil: text; { source input file [sam] }
procedure errormsg;
var k: integer;
msg: array [0..ermax] of alfa;
begin
msg[ 0] := 'undef id '; msg[ 1] := 'multi def ';
msg[ 2] := 'identifier'; msg[ 3] := 'program ';
msg[ 4] := ') '; msg[ 5] := ': ';
msg[ 6] := 'syntax '; msg[ 7] := 'ident, var';
msg[ 8] := 'of '; msg[ 9] := '( ';
msg[10] := 'id, array '; msg[11] := '[ ';
msg[12] := '] '; msg[13] := '.. ';
msg[14] := '; '; msg[15] := 'func. type';
msg[16] := '= '; msg[17] := 'boolean ';
msg[18] := 'convar typ'; msg[19] := 'type ';
msg[20] := 'prog.param'; msg[21] := 'too big ';
msg[22] := '. '; msg[23] := 'typ (case)';
msg[24] := 'character '; msg[25] := 'const id ';
msg[26] := 'index type'; msg[27] := 'indexbound';
msg[28] := 'no array '; msg[29] := 'type id ';
msg[30] := 'undef type'; msg[31] := 'no record ';
msg[32] := 'boole type'; msg[33] := 'arith type';
msg[34] := 'integer '; msg[35] := 'types ';
msg[36] := 'param type'; msg[37] := 'variab id ';
msg[38] := 'string '; msg[39] := 'no.of pars';
msg[40] := 'type '; msg[41] := 'type ';
msg[42] := 'real type '; msg[43] := 'integer ';
msg[44] := 'var, const'; msg[45] := 'var, proc ';
msg[46] := 'types (:=)'; msg[47] := 'typ (case)';
msg[48] := 'type '; msg[49] := 'store ovfl';
msg[50] := 'constant '; msg[51] := ':= ';
msg[52] := 'then '; msg[53] := 'until ';
msg[54] := 'do '; msg[55] := 'to downto ';
msg[56] := 'begin '; msg[57] := 'end ';
msg[58] := 'factor ';
k := 0; writeln; writeln(' key words');
while errs <> [] do
begin while not (k in errs) do k := k+1;
writeln(k,' ',msg[k]); errs := errs - [k]
end
end (* errormsg *);
procedure nextch; (* read next character; process line end *)
begin if cc = ll then
begin if eof(srcfil) {[sam]} then
begin writeln;
writeln(' program incomplete');
errormsg; halt(1);
end;
if errpos <> 0 then
begin writeln; errpos := 0
end;
write(lc:5, ' ');
ll := 0; cc := 0;
while not eoln(srcfil) {[sam]} do
begin ll := ll+1; read(srcfil{[sam]}, ch); write(ch); line[ll] := ch
end;
writeln; ll := ll+1; read(srcfil{[sam]}, line[ll]);
end;
cc := cc+1; ch := line[cc];
end (* nextch *);
procedure error(n: integer);
begin
if errpos = 0 then write(' ****');
if cc > errpos then begin
write(' ': cc-errpos, '^', n:2);
errpos := cc+3;
errs := errs + [n]
end;
end (* error *);
procedure fatal(n: integer);
var msg: array [1..7] of alfa;
begin writeln; errormsg;
msg[ 1] := 'identifier'; msg[ 2] := 'procedures';
msg[ 3] := 'reals '; msg[ 4] := 'arrays ';
msg[ 5] := 'levels '; msg[ 6] := 'code ';
msg[ 7] := 'strings ';
writeln(' compiler table for ', msg[n], ' is too small');
halt(1); (* terminate compilation *)
end (* fatal *);
procedure insymbol; (* reads next symbol *)
label 1, 2, 3;
var i, j, k, e: integer;
procedure readscale;
var s, sign: integer;
begin nextch; sign := 1; s := 0;
if ch = '+' then nextch else
if ch = '-' then begin nextch; sign := -1 end;
while ch in ['0'..'9'] do
begin s := 10*s + ord(ch) - ord('0'); nextch
end;
e := s*sign + e
end (* readscale *);
procedure adjustscale;
var s: integer; d, t: real;
begin if k+e > emax then error(21) else
if k+e < emin then rnum := 0 else
begin s := abs(e); t := 1.0; d := 10.0;
repeat
while not odd(s) do
begin s := s div 2; d := sqr(d)
end;
s := s-1; t := d*t
until s = 0;
if e >= 0 then rnum := rnum*t else rnum := rnum/t
end
end (* adjustscale *);
begin (* insymbol *)
1:
while ch in [#9,#10,#13,#32] do nextch; // OZZ
{ Allow upper case BPW }
if ch in ['a'..'z','A'..'Z']
then begin { word }
k := 0;
id := ' ';
repeat
if k < alng then begin
k := k+1;
id[k] := ch
end;
nextch;
{ Allow upper case BPW }
until not (ch in ['a'..'z', '0'..'9', 'A'..'Z']);
i := 1;
j := nkw; (* binary search *)
repeat
k := (i+j) div 2;
if id <= key[k] then j := k-1;
if id >= key[k] then i := k+1
until i > j;
if i-1 > j then sy := ksy[k]
else sy := ident
end { word }
else if ch in ['0'..'9'] then begin { number }
k := 0;
inum := 0;
sy := intcon;
repeat
inum := inum*10 + ord(ch) - ord('0');
k := k+1;
nextch;
until not (ch in ['0'..'9']);
if (k > kmax) or (inum > nmax) then begin
error(21);
inum := 0;
k := 0
end;
if ch = '.' then
begin
nextch;
if ch = '.' then ch := ':'
else begin
sy := realcon;
rnum := inum;
e := 0;
while ch in ['0'..'9'] do begin
e := e-1;
rnum := 10.0*rnum + (ord(ch)-ord('0'));
nextch;
end;
if ch = 'e' then readscale;
if e <> 0 then adjustscale
end
end
else if ch = 'e' then begin
sy := realcon;
rnum := inum;
e := 0;
readscale;
if e <> 0 then adjustscale
end;
end { number }
else case ch of { special }
':': begin
nextch;
if ch = '=' then begin
sy := becomes;
nextch;
end
else sy := colon
end;
'<': begin nextch;
if ch = '=' then begin sy := leg; nextch end else
if ch = '>' then begin sy := neg; nextch end else sy := lss
end;
'>': begin nextch;
if ch = '=' then begin sy := geg; nextch end else sy := gtr
end;
'.': begin nextch;
if ch = '.' then
begin sy := colon; nextch
end else sy := period
end;
'''': begin k := 0; { char or string }
2: nextch;
if ch = '''' then
begin nextch; if ch <> '''' then goto 3
end;
if sx+k = smax then fatal(7);
stab[sx+k] := ch; k := k+1;
if cc = 1 then
begin (* end of line *) k := 0;
end
else goto 2;
3: if k = 1 then
begin sy := charcon; inum := ord(stab[sx])
end else
if k = 0 then
begin error(38); sy := charcon; inum := 0
end else
begin sy := stringt; inum := sx; sleng := k; sx := sx+k
end
end; { char or string }
'(': begin nextch;
if ch <> '*' then sy := lparent else
begin (* comment *) nextch;
repeat
while ch <> '*' do nextch;
nextch
until ch = ')';
nextch; goto 1
end
end;
'+', '-', '*', '/', ')', '=', ',', '[', ']', '#', '&', ';':
begin sy := sps[ch]; nextch
end;
{ BPW - simplify checking bad symbols }
//'$', '%', '@', '\', '~', '{', '}', '^':
else
begin
error(24);
halt(1); {BPW - included due to scanner nontermination
depending on what follows!}
nextch; goto 1
end
end { special }
end (* insymbol *);
procedure enter(x0: alfa; x1: objects;
x2: types; x3: integer);
begin t := t+1; (* enter standard identifier *)
with tab[t] do
begin name := x0; link := t-1; obj := x1;
typ := x2; ref := 0; normal := true;
lev := 0; adr := x3
end
end (* enter *);
procedure enterarray(tp: types; l, h: integer);
begin if l > h then error(27);
if (abs(l)>xmax) or (abs(h)>xmax) then
begin error(27); l := 0; h := 0;
end;
if a = amax then fatal(4) else
begin a:= a+1;
with atab[a] do
begin inxtyp := tp; low := l; high := h
end
end
end (* enterarray *);
procedure enterblock;
begin
if b = bmax then fatal(2)
else begin
b := b+1;
btab[b].last := 0;
btab[b].lastpar := 0
end
end (* enterblock *);
procedure enterreal(x: real);
begin if c2 = c2max-1 then fatal(3) else
begin rconst[c2+1] := x; c1 := 1;
while rconst[c1] <> x do c1 := c1+1;
if c1 > c2 then c2 := c1
end
end (* enterreal *);
procedure emit(fct: integer);
begin if lc = cmax then fatal(6);
code[lc].f := fct; lc := lc+1
end (* emit *);
procedure emit1(fct, b: integer);
begin if lc = cmax then fatal(6);
with code[lc] do
begin f := fct; y := b end;
lc := lc+1
end (* emit1 *);
procedure emit2(fct, a, b: integer);
begin if lc = cmax then fatal(6);
with code[lc] do
begin f := fct; x := a; y := b end;
lc := lc+1
end (* emit2 *);
procedure printtables;
var i: integer; o: order;
begin
{ Changed to double spacing [sam] }
writeln('identifiers link obj typ ref nrm lev adr');
writeln;
for i := btab[1].last +1 to t do
with tab[i] do
writeln(i, ' ', name, link:5, ord(obj):5, ord(typ):5, ref:5,
ord(normal):5, lev:5, adr:5);
{ Changed to double spacing [sam] }
writeln('blocks last lpar psze vsze');
writeln;
for i := 1 to b do
with btab[i] do
writeln(i:10, last:5, lastpar:5, psize:5, vsize:5);
{ Changed to double spacing [sam] }
writeln('arrays xtyp etyp eref low high elsz size');
writeln;
for i := 1 to a do
with atab[i] do
writeln(i, ord(inxtyp):5, ord(eltyp):5,
elref:5, low:5, high:5, elsize:5, size:5);
{ Changed to double spacing [sam] }
writeln('code:');
writeln;
for i := 0 to lc-1 do begin
write('Line: ',i: 5,') ');
o := code[i];
write(' func: ',o.f:5);
{ Changed 36 to have a parameter, see notes in header [sam] }
if (o.f < 31) or (o.f = 36) then
if o.f < 4 then write(' parm: ',o.x:2, ' y: ',o.y:5)
else write(' option: ',o.y:7)
else write(' ');
writeln('')
end;
writeln
end (* printtables *);
procedure block(fsys: symset; isfun: boolean; level: integer);
type conrec =
record case tp: types of
ints, chars, bools: (i: integer);
reals: (r: real);
notyp, arrays, records: ();
end;
var dx: integer; (* data allocation index *)
prt: integer; (* t-index of this procedure *)
prb: integer; (* b-index of this procedure *)
x: integer;
procedure skip(fsys: symset; n: integer);
begin error(n);
while not (sy in fsys) do insymbol
end (* skip *);
procedure test(s1, s2: symset; n: integer);
begin if not (sy in s1) then
skip(s1+s2, n)
end (* test *);
procedure testsemicolon;
begin
if sy = semicolon then insymbol else
begin error(14);
if sy in [comma, colon] then insymbol
end;
test([ident]+blockbegsys, fsys, 6)
end (* testsemicolon *);
procedure enter(id: alfa; k: objects);
var j, l: integer;
begin if t = tmax then fatal(1) else
begin tab[0].name := id;
j := btab[display[level]].last; l := j;
while tab[j].name <> id do j := tab[j].link;
if j <> 0 then error(1) else
begin t := t+1;
with tab[t] do
begin name := id; link := l;
obj := k; typ := notyp; ref := 0; lev := level;
adr := 0
end;
btab[display[level]].last := t
end
end
end (* enter *);
function loc(id: alfa): integer;
var i, j: integer; (* locate id in table *)
begin i := level; tab[0].name := id; (* sentinel *)
repeat j := btab[display[i]].last;
while tab[j].name <> id do j := tab[j].link;
i := i-1;
until (i<0 j="" or="">0);
if j = 0 then error(0); loc := j
end (* loc *);
procedure entervariable;
begin if sy = ident then
begin enter(id, variable); insymbol
end
else error(2)
end (* entervariable *);
procedure constant(fsys: symset; var c: conrec);
var x, sign: integer;
begin c.tp := notyp; c.i := 0;
test(constbegsys, fsys, 50);
if sy in constbegsys then
begin
if sy = charcon then
begin c.tp := chars; c.i := inum; insymbol
end
else
begin sign := 1;
if sy in [plus, minus] then
begin if sy = minus then sign := -1;
insymbol
end;
if sy = ident then
begin x := loc(id);
if x <> 0 then
if tab[x].obj <> konstant then error(25) else
begin c.tp := tab[x].typ;
if c.tp = reals
then c.r := sign*rconst[tab[x].adr]
else c.i := sign*tab[x].adr
end;
insymbol
end
else
if sy = intcon then
begin c.tp := ints; c.i := sign*inum; insymbol
end else
if sy = realcon then
begin c.tp := reals; c.r := sign*rnum; insymbol
end else skip(fsys, 50)
end;
test(fsys, [], 6)
end
end (* constant *);
procedure typ(fsys: symset; var tp: types; var rf, sz: integer);
var x: integer;
eltp: types; elrf: integer;
elsz, offset, t0, t1: integer;
procedure arraytyp(var aref, arsz: integer);
var eltp: types;
low, high: conrec;
elrf, elsz: integer;
begin constant([colon, rbrack, rparent, ofsy]+fsys, low);
if low.tp = reals then
begin error(27); low.tp := ints; low.i := 0
end;
if sy = colon then insymbol else error(13);
constant([rbrack, comma, rparent, ofsy]+fsys, high);
if high.tp <> low.tp then
begin error(27); high.i := low.i
end;
enterarray(low.tp, low.i, high.i); aref := a;
if sy = comma then
begin insymbol; eltp := arrays; arraytyp(elrf, elsz)
end else
begin
if sy = rbrack then insymbol else
begin error(12);
if sy = rparent then insymbol
end;
if sy = ofsy then insymbol else error(8);
typ(fsys, eltp, elrf, elsz)
end;
with atab[aref] do
begin arsz := (high-low+1)*elsz; size := arsz;
eltyp := eltp; elref := elrf; elsize := elsz
end;
end (* arraytyp *);
begin (* typ *) tp := notyp; rf := 0; sz := 0;
test(typebegsys, fsys, 10);
if sy in typebegsys then
begin
if sy = ident then
begin x := loc(id);
if x <> 0 then
with tab[x] do
if obj <> typel then error(29) else
begin tp := typ; rf := ref; sz := adr;
if tp = notyp then error(30)
end;
insymbol
end else
if sy = arraysy then
begin insymbol;
if sy = lbrack then insymbol else
begin error(11);
if sy = lparent then insymbol
end;
tp := arrays; arraytyp(rf, sz)
end else
begin (* records *) insymbol;
enterblock; tp := records; rf := b;
if level = lmax then fatal(5);
level := level+1; display[level] := b; offset := 0;
while sy <> endsy do
begin (* field section *)
if sy = ident then
begin t0 := t; entervariable;
while sy = comma do
begin insymbol; entervariable
end;
if sy = colon then insymbol else error(5);
t1 := t;
typ(fsys+[semicolon, endsy, comma, ident],
eltp, elrf, elsz);
while t0 < t1 do
begin t0 := t0+1;
with tab[t0] do
begin typ := eltp; ref := elrf; normal := true;
adr := offset; offset := offset + elsz
end
end
end;
if sy <> endsy then
begin if sy = semicolon then insymbol else
begin error(14);
if sy = comma then insymbol
end;
test([ident, endsy, semicolon], fsys, 6)
end
end;
btab[rf].vsize := offset; sz := offset;
btab[rf].psize := 0; insymbol; level := level-1
end;
test(fsys, [], 6)
end
end (* typ *);
procedure parameterlist; (* formal parameter list *)
var tp: types;
rf, sz, x, t0: integer;
valpar: boolean;
begin insymbol; tp := notyp; rf := 0; sz := 0;
test([ident, varsy], fsys+[rparent], 7);
while sy in [ident, varsy] do
begin if sy <> varsy then valpar := true else
begin insymbol; valpar := false
end;
t0 := t; entervariable;
while sy = comma do
begin insymbol; entervariable;
end;
if sy = colon then
begin insymbol;
if sy <> ident then error(2) else
begin x := loc(id); insymbol;
if x <> 0 then
with tab[x] do
if obj <> typel then error(29) else
begin tp := typ; rf := ref;
if valpar then sz := adr else sz := 1
end;
end;
test([semicolon, rparent], [comma, ident]+fsys, 14)
end
else error(5);
while t0 < t do
begin t0 := t0+1;
with tab[t0] do
begin typ := tp; ref := rf;
normal := valpar; adr := dx; lev := level;
dx := dx + sz
end
end;
if sy <> rparent then
begin if sy = semicolon then insymbol else
begin error(14);
if sy = comma then insymbol
end;
test([ident, varsy], [rparent]+fsys, 6)
end
end (* while *);
if sy = rparent then
begin insymbol;
test([semicolon, colon], fsys, 6)
end
else error(4)
end (* parameter list *);
procedure constantdeclaration;
var c: conrec;
begin insymbol;
test([ident], blockbegsys, 2);
while sy = ident do
begin enter(id, konstant); insymbol;
if sy = egl then insymbol else
begin error(16);
if sy = becomes then insymbol
end;
constant([semicolon, comma, ident]+fsys, c);
tab[t].typ := c.tp; tab[t].ref := 0;
if c.tp = reals then
begin enterreal(c.r); tab[t].adr := c1 end
else tab[t].adr := c.i;
testsemicolon
end
end (* constantdeclaration *);
procedure typedeclaration;
var tp: types; rf, sz, t1: integer;
begin insymbol;
test([ident], blockbegsys, 2);
while sy = ident do
begin enter(id, typel); t1 := t; insymbol;
if sy = egl then insymbol else
begin error(16);
if sy = becomes then insymbol
end;
typ([semicolon, comma, ident]+fsys, tp, rf, sz);
with tab[t1] do
begin typ := tp; ref := rf; adr := sz
end;
testsemicolon
end
end (* typedeclaration *);
procedure variabledeclaration;
var t0, t1, rf, sz: integer;
tp: types;
begin insymbol;
while sy = ident do
begin t0 := t; entervariable;
while sy = comma do
begin insymbol; entervariable;
end;
if sy = colon then insymbol else error(5);
t1 := t;
typ([semicolon, comma, ident]+fsys, tp, rf, sz);
while t0 < t1 do
begin t0 := t0+1;
with tab[t0] do
begin typ := tp; ref := rf;
lev := level; adr := dx; normal := true;
dx := dx + sz
end
end;
testsemicolon
end
end (* variabledeclaration *);
procedure procdeclaration;
var isfun: boolean;
begin isfun := sy = functionsy; insymbol;
if sy <> ident then
begin error(2); id := ' ';
end;
if isfun then enter(id, funktion) else enter(id, prozedure);
tab[t].normal := true;
insymbol; block([semicolon]+fsys, isfun, level+1);
if sy = semicolon then insymbol else error(14);
emit(32+ord(isfun)) (* exit *)
end (* proceduredeclaration *);
procedure statement(fsys: symset);
var i: integer;
procedure expression(fsys: symset; var x: item); forward;
procedure selector(fsys: symset; var v: item);
var x: item; a, j: integer;
begin (* sy in [lparent, lbrack, period] *)
repeat if sy = period then
begin insymbol; (* field selector *)
if sy <> ident then error(2) else
begin
if v.typ <> records then error(31) else
begin (* search field identifier *)
j := btab[v.ref].last; tab[0].name := id;
while tab[j].name <> id do j := tab[j].link;
if j = 0 then error(0);
v.typ := tab[j].typ; v.ref := tab[j].ref;
a := tab[j].adr; if a <> 0 then emit1(9, a)
end;
insymbol
end
end else
begin (* array selector *)
if sy <> lbrack then error(11);
repeat insymbol;
expression(fsys+[comma, rbrack], x);
if v.typ <> arrays then error(28) else
begin a := v.ref;
if atab[a].inxtyp <> x.typ then error(26) else
if atab[a].elsize = 1 then emit1(20, a)
else emit1(21, a);
v.typ := atab[a].eltyp; v.ref := atab[a].elref
end
until sy <> comma;
if sy = rbrack then insymbol else
begin error(12); if sy = rparent then insymbol
end
end
until not (sy in [lbrack, lparent, period]);
test(fsys, [], 6)
end (* selector *);
procedure call(fsys: symset; i: integer);
var x: item;
lastp, cp, k: integer;
begin emit1(18, i); (* mark stack *)
lastp := btab[tab[i].ref].lastpar; cp := i;
if sy = lparent then
begin (* actual parameter list *)
repeat insymbol;
if cp >= lastp then error(39) else
begin cp := cp+1;
if tab[cp].normal then
begin (* value parameter *)
expression(fsys+[comma, colon, rparent], x);
if x.typ = tab[cp].typ then
begin
if x.ref <> tab[cp].ref then error(36) else
if x.typ = arrays then emit1(22, atab[x.ref].size) else
if x.typ = records then emit1(22, btab[x.ref].vsize)
end else
if (x.typ = ints) and (tab[cp].typ = reals) then
emit1(26, 0) else
if x.typ <> notyp then error(36);
end else
begin (* variable parameter *)
if sy <> ident then error(2) else
begin k := loc(id); insymbol;
if k <> 0 then
begin if tab[k].obj <> variable then error(37);
x.typ := tab[k].typ; x.ref := tab[k].ref;
if tab[k].normal
then emit2(0, tab[k].lev, tab[k].adr)
else emit2(1, tab[k].lev, tab[k].adr);
if sy in [lbrack, lparent, period] then
selector(fsys+[comma, colon, rparent], x);
if (x.typ <> tab[cp].typ) or (x.ref<>tab[cp].ref)
then error(36)
end
end
end
end;
test([comma, rparent], fsys, 6)
until sy <> comma;
if sy = rparent then insymbol else error(4)
end;
if cp < lastp then error(39); (* too few actual parameters *)
emit1(19, btab[tab[i].ref].psize-1);
if tab[i].lev < level then emit2(3, tab[i].lev, level)
end (* call *);
function resulttype(a, b: types): types;
begin
if (a>reals) or (b>reals) then
begin error(33); resulttype := notyp
end else
if (a=notyp) or (b=notyp) then resulttype := notyp else
if a=ints then
if b=ints then resulttype := ints else
begin resulttype := reals; emit1(26, 1)
end
else
begin resulttype := reals;
if b=ints then emit1(26, 0)
end
end (* resulttype *);
procedure expression;
var y: item; op: symbol;
procedure simpleexpression(fsys: symset; var x: item);
var y: item; op: symbol;
procedure term(fsys: symset; var x: item);
var y: item; op: symbol;
procedure factor(fsys: symset; var x: item);
var i, f: integer;
procedure standfct(n: integer);
var ts: typset;
begin (* standard function no. n *)
if sy = lparent then insymbol else error(9);
if n < 17 then
begin expression(fsys+[rparent], x);
case n of
(* abs, sqr *) 0, 2: begin ts:= [ints, reals];
tab[i].typ := x.typ;
if x.typ = reals then n := n+1
end;
(* odd, chr *) 4, 5: ts := [ints];
(* ord *) 6: ts := [ints, bools, chars];
(* succ, pred *) 7, 8: ts := [chars];
(* round, trunc *) 9, 10, 11, 12, 13, 14, 15, 16:
(* sin, cos, ...*) begin ts := [ints, reals];
if x.typ = ints then emit1(26, 0)
end;
end;
if x.typ in ts then emit1(8, n) else
if x.typ <> notyp then error(48)
end else
(* eof, eoln *) begin (* n in [17, 18] *)
if sy <> ident then error(2) else
if id <> 'input ' then error(0) else insymbol;
emit1(8, n);
end;
x.typ := tab[i].typ;
if sy = rparent then insymbol else error(4)
end (* standfct *);
begin (* factor *) x.typ := notyp; x.ref := 0;
test(facbegsys, fsys, 58);
while sy in facbegsys do
begin
if sy = ident then
begin i := loc(id); insymbol;
with tab[i] do
case obj of
konstant: begin x.typ := typ; x.ref := 0;
if x.typ = reals then
emit1(25, adr) else
emit1(24, adr)
end;
variable: begin x.typ := typ; x.ref := ref;
if sy in [lbrack, lparent, period] then
begin if normal then f := 0 else f := 1;
emit2(f, lev, adr);
selector(fsys, x);
if x.typ in stantyps then emit(34)
end else
begin
if x.typ in stantyps then
if normal then f := 1 else f := 2
else
if normal then f := 0 else f := 1;
emit2(f, lev, adr)
end
end;
typel, prozedure: error(44);
funktion: begin x.typ := typ;
if lev <> 0 then call(fsys, i)
else standfct(adr)
end
end (* case, with *)
end else
if sy in [charcon, intcon, realcon] then
begin
if sy = realcon then
begin x.typ := reals; enterreal(rnum);
emit1(25, c1)
end else
begin if sy = charcon then x.typ := chars
else x.typ := ints;
emit1(24, inum)
end;
x.ref := 0; insymbol
end else
if sy = lparent then
begin insymbol; expression(fsys+[rparent], x);
if sy = rparent then insymbol else error(4)
end else
if sy = notsy then
begin insymbol; factor(fsys, x);
if x.typ=bools then emit(35) else
if x.typ<>notyp then error(32)
end;
test(fsys, facbegsys, 6)
end (* while *)
end (* factor *);
begin (* term *)
factor(fsys+[times, rdiv, idiv, imod, andsy], x);
while sy in [times, rdiv, idiv, imod, andsy] do
begin op := sy; insymbol;
factor(fsys+[times, rdiv, idiv, imod, andsy], y);
if op = times then
begin x.typ := resulttype(x.typ, y.typ);
case x.typ of
notyp: ;
ints : emit(57);
reals: emit(60);
end
end else
if op = rdiv then
begin
if x.typ = ints then
begin emit1(26, 1); x.typ := reals
end;
if y.typ = ints then
begin emit1(26, 0); y.typ := reals
end;
if (x.typ=reals) and (y.typ=reals) then
emit(61) else
begin if (x.typ<>notyp) and (y.typ<>notyp) then
error(32);
x.typ := notyp
end
end else
if op = andsy then
begin if (x.typ=bools) and (y.typ=bools) then
emit(56) else
begin if (x.typ<>notyp) and (y.typ<>notyp)
then error(32);
x.typ := notyp
end
end else
begin (* op in [idiv, imod] *)
if (x.typ=ints) and (y.typ=ints) then
if op=idiv then emit(58)
else emit(59) else
begin if (x.typ<>notyp) and (y.typ<>notyp) then
error(34);
x.typ := notyp
end
end
end
end (* term *);
begin (* simpleexpression *)
if sy in [plus, minus] then
begin op := sy; insymbol;
term(fsys+[plus, minus], x);
if x.typ > reals then error(33) else
{ Changed the negate instruction 36 to also emit a parameter that
says if the operand is real or integer. See comments at top. [sam] }
if op = minus then emit1(36, ord(x.typ))
end else
term(fsys+[plus, minus, orsy], x);
while sy in [plus, minus, orsy] do
begin op := sy; insymbol;
term(fsys+[plus, minus, orsy], y);
if op = orsy then
begin
if (x.typ=bools) and (y.typ=bools) then emit(51) else
begin if (x.typ<>notyp) and (y.typ<>notyp) then
error(32);
x.typ := notyp
end
end else
begin x.typ := resulttype(x.typ, y.typ);
case x.typ of
notyp: ;
ints: if op = plus then emit (52)
else emit(53);
reals: if op = plus then emit(54)
else emit(55)
end
end
end
end (* simpleexpression *);
begin (* expression *)
simpleexpression(fsys+[egl, neg, lss, leg, gtr, geg], x);
if sy in [egl, neg, lss, leg, gtr, geg] then
begin op := sy; insymbol;
simpleexpression(fsys, y);
if (x.typ in [notyp, ints, bools, chars]) and
(x.typ = y.typ) then
case op of
egl: emit(45);
neg: emit(46);
lss: emit(47);
leg: emit(48);
gtr: emit(49);
geg: emit(50);
end else
begin if x.typ = ints then
begin x.typ := reals; emit1(26, 1)
end else
if y.typ = ints then
begin y.typ := reals; emit1(26, 0)
end;
if (x.typ=reals) and (y.typ=reals) then
case op of
egl: emit(39);
neg: emit(40);
lss: emit(41);
leg: emit(42);
gtr: emit(43);
geg: emit(44);
end
else error(35)
end;
x.typ := bools
end
end (* expression *);
procedure assignment(lv, ad: integer);
var x,y: item; f: integer;
(* tab[i].obj in [variable, prozedure] *)
begin x.typ := tab[i].typ; x.ref := tab[i].ref;
if tab[i].normal then f := 0 else f := 1;
emit2(f, lv, ad);
if sy in [lbrack, lparent, period] then
selector([becomes, egl]+fsys, x);
if sy = becomes then insymbol else
begin error(51); if sy = egl then insymbol
end;
expression(fsys, y);
if x.typ = y.typ then
if x.typ in stantyps then emit(38) else
if x.ref <> y.ref then error(46) else
if x.typ = arrays then emit1(23, atab[x.ref].size)
else emit1(23, btab[x.ref].vsize)
else
if (x.typ=reals) and (y.typ=ints) then
begin emit1(26, 0); emit(38)
end else
if (x.typ<>notyp) and (y.typ<>notyp) then error(46)
end (* assignment *);
procedure compoundstatement;
begin insymbol;
statement([semicolon, endsy]+fsys);
while sy in [semicolon]+statbegsys do
begin if sy = semicolon then insymbol else error(14);
statement([semicolon, endsy]+fsys)
end;
if sy = endsy then insymbol else error(57)
end (* compoundstatement *);
procedure ifstatement;
var x: item; lc1, lc2: integer;
begin insymbol;
expression(fsys+[thensy, dosy], x);
if not (x.typ in [bools, notyp]) then error(17);
lc1 := lc; emit(11); (* jmpc *)
if sy = thensy then insymbol else
begin error(52); if sy = dosy then insymbol
end;
statement(fsys+[elsesy]);
if sy = elsesy then
begin insymbol; lc2 := lc; emit(10);
code[lc1].y := lc; statement(fsys); code[lc2].y := lc
end
else code[lc1].y := lc
end (* if statment *);
procedure casestatement;
var x: item;
i, j, k, lc1: integer;
casetab: array [1..csmax] of
packed record val, lc: index end;
exittab: array [1..csmax] of integer;
procedure caselabel;
var lab: conrec; k: integer;
begin constant(fsys+[comma, colon], lab);
if lab.tp <> x.typ then error(47) else
if i = csmax then fatal(6) else
begin i := i+1; k := 0;
casetab[i].val := lab.i; casetab[i].lc := lc;
repeat k := k+1 until casetab[k].val = lab.i;
if k < i then error(1); (* multiple definition *)
end
end (* caselabel *);
procedure onecase;
begin if sy in constbegsys then
begin caselabel;
while sy = comma do
begin insymbol; caselabel
end;
if sy = colon then insymbol else error(5);
statement([semicolon, endsy]+fsys);
j := j+1; exittab[j] := lc; emit(10)
end
end (* onecase *);
begin insymbol; i := 0; j := 0;
expression(fsys+[ofsy, comma, colon], x);
if not (x.typ in [ints, bools, chars, notyp]) then error(23);
lc1 := lc; emit(12); (* jmpx *)
if sy = ofsy then insymbol else error(8);
onecase;
while sy = semicolon do
begin insymbol; onecase
end;
code[lc1].y := lc;
for k := 1 to i do
begin emit1(13, casetab[k].val); emit1(13, casetab[k].lc)
end;
emit1(10, 0);
for k := 1 to j do code[exittab[k]].y := lc;
if sy = endsy then insymbol else error(57)
end (* casestement *);
procedure repeatstatement;
var x: item; lc1: integer;
begin lc1 := lc;
insymbol; statement([semicolon, untilsy]+fsys);
while sy in [semicolon]+statbegsys do
begin if sy = semicolon then insymbol else error(14);
statement([semicolon, untilsy]+fsys)
end;
if sy = untilsy then
begin insymbol; expression(fsys, x);
if not (x.typ in [bools, notyp]) then error(17);
emit1(11, lc1)
end
else error(53)
end (* repeatstement *);
procedure whilestatement;
var x: item; lc1, lc2: integer;
begin insymbol; lc1 := lc;
expression(fsys+[dosy], x);
if not (x.typ in [bools, notyp]) then error(17);
lc2 := lc; emit(11);
if sy = dosy then insymbol else error(54);
statement(fsys); emit1(10, lc1); code[lc2].y := lc
end (* whilestatement *);
procedure forstatement;
var cvt: types; x: item;
i, f, lc1, lc2: integer;
begin insymbol;
if sy = ident then
begin i := loc(id); insymbol;
if i = 0 then cvt := ints else
if tab[i].obj = variable then
begin cvt := tab[i].typ;
emit2(0, tab[i].lev, tab[i].adr);
if not (cvt in [notyp, ints, bools, chars])
then error(18)
end else
begin error(37); cvt := ints
end
end else skip([becomes, tosy, downtosy, dosy]+fsys, 2);
if sy = becomes then
begin insymbol; expression([tosy, downtosy, dosy]+fsys, x);
if x.typ <> cvt then error(19);
end else skip([tosy, downtosy, dosy]+fsys, 51);
f := 14;
if sy in [tosy, downtosy] then
begin if sy = downtosy then f := 16;
insymbol; expression([dosy]+fsys, x);
if x.typ <> cvt then error(19)
end else skip([dosy]+fsys, 55);
lc1 := lc; emit(f);
if sy = dosy then insymbol else error(54);
lc2 := lc; statement(fsys);
emit1(f+1, lc2); code[lc1].y := lc
end (* forstatement *);
procedure standproc(n: integer);
var i, f: integer;
x, y: item;
begin
case n of
1, 2: begin (* read *)
if not iflag then
begin error(20); iflag := true
end;
if sy = lparent then
begin
repeat insymbol;
if sy <> ident then error(2) else
begin i := loc(id); insymbol;
if i <> 0 then
if tab[i].obj <> variable then error(37) else
begin x.typ := tab[i].typ; x.ref := tab[i].ref;
if tab[i].normal then f := 0 else f := 1;
emit2(f, tab[i].lev, tab[i].adr);
if sy in [lbrack, lparent, period] then
selector(fsys+[comma, rparent], x);
if x.typ in [ints, reals, chars, notyp] then
emit1(27, ord(x.typ)) else error(40)
end
end;
test([comma, rparent], fsys, 6);
until sy <> comma;
if sy = rparent then insymbol else error(4)
end;
if n = 2 then emit(62)
end;
3, 4: begin (* write *)
if sy = lparent then
begin
repeat insymbol;
if sy = stringt then
begin emit1(24, sleng); emit1(28, inum); insymbol
end else
begin expression(fsys+[comma, colon, rparent], x);
if not (x.typ in stantyps) then error(41);
if sy = colon then
begin insymbol;
expression(fsys+[comma, colon, rparent], y);
if y.typ <> ints then error(43);
if sy = colon then
begin if x.typ <> reals then error(42);
insymbol; expression(fsys+[comma, rparent], y);
if y.typ <> ints then error(43);
emit(37)
end
else emit1(30, ord(x.typ))
end
else emit1(29, ord(x.typ))
end
until sy <> comma;
if sy = rparent then insymbol else error(4)
end;
if n = 4 then emit(63)
end;
end(* case *)
end (* standproc *);
begin (* statement *)
if sy in statbegsys+[ident] then
case sy of
ident: begin i:= loc(id); insymbol;
if i <> 0 then
case tab[i].obj of
konstant, typel: error(45);
variable:
assignment(tab[i].lev, tab[i].adr);
prozedure:
if tab[i].lev <> 0 then call(fsys, i)
else standproc(tab[i].adr);
funktion:
if tab[i].ref = display[level]
then assignment(tab[i].lev+1, 0)
else error(45)
end
end;
beginsy: compoundstatement;
ifsy: ifstatement;
casesy: casestatement;
whilesy: whilestatement;
repeatsy: repeatstatement;
forsy: forstatement;
end;
test(fsys, [], 14)
end (* statement *);
begin (* block *)
dx := 5;
prt := t;
if level > lmax then fatal(5);
if (sy<>beginsy) then // OZZ
test([lparent, colon, semicolon], fsys, 7);
enterblock;
display[level] := b;
prb := b;
tab[prt].typ := notyp;
tab[prt].ref := prb;
if sy = lparent then parameterlist;
btab[prb].lastpar := t;
btab[prb].psize := dx;
if isfun then
if sy = colon then begin
insymbol; (* function type *)
if sy = ident then begin
x := loc(id);
insymbol;
if x <> 0 then if tab[x].obj <> typel then error(29)
else if tab[x].typ in stantyps then tab[prt].typ := tab[x].typ
else error(15)
end
else skip([semicolon]+fsys, 2)
end
else error(5);
if (sy<>beginsy) then // OZZ
if sy = semicolon then insymbol
else error(14);
repeat
if sy = constsy then constantdeclaration;
if sy = typesy then typedeclaration;
if sy = varsy then variabledeclaration;
btab[prb].vsize := dx;
while sy in [proceduresy, functionsy] do procdeclaration;
test([beginsy], blockbegsys+statbegsys, 56)
until sy in statbegsys;
tab[prt].adr := lc;
insymbol;
statement([semicolon, endsy]+fsys);
while sy in [semicolon]+statbegsys do begin
if sy = semicolon then insymbol
else error(14);
statement([semicolon, endsy]+fsys)
end;
if sy = endsy then insymbol
else error(57);
test(fsys+[period], [], 6)
end (* block *);
procedure interpret;
(* global code, tab, btab *)
var ir: order; (* instruction buffer *)
pc: integer; (* program counter *)
ps: (run, fin, caschk, divchk, inxchk, stkchk, linchk,
lngchk, redchk);
t: integer; (* top stack index *)
b: integer; (* base index *)
lncnt, ocnt, blkcnt, chrcnt: integer; (* counters *)
h1, h2, h3, h4: integer;
fld: array [1..4] of integer; (* default field widths *)
display: array [1..lmax] of integer;
s: array [1..stacksize] of (* blockmark: *)
record case types of (* s[b+0] = fct result *)
ints: (i: integer); (* s[b+1] = return adr *)
reals: (r: real); (* s[b+2] = static link *)
bools: (b: boolean); (* s[b+3] = dynamic link *)
chars: (c: char); (* s[b+4] = table index *)
notyp, arrays, records: ()
end;
begin (* interpret *)
s[1].i := 0;
s[2].i := 0;
s[3].i := -1;
s[4].i := btab[1].last;
b := 0;
display[1] := 0;
t := btab[2].vsize - 1;
pc := tab[s[4].i].adr;
ps := run;
lncnt := 0;
ocnt := 0;
chrcnt := 0;
fld[1] := intfld;
fld[2] := relfld;
fld[3] := bolfld;
fld[4] := chrfld;
repeat
ir := code[pc];
pc := pc+1;
ocnt := ocnt + 1;
case ir.f of
0: begin (* load address *)
t := t+1;
if t > stacksize then ps := stkchk
else s[t].i := display[ir.x] + ir.y;
end;
1: begin (* load value *)
t := t+1;
if t > stacksize then ps := stkchk
else s[t] := s[display[ir.x] + ir.y];
end;
2: begin (* load indirect *)
t := t+1;
if t > stacksize then ps := stkchk
else s[t] := s[s[display[ir.x] + ir.y].i];
end;
3: begin (* update display *)
h1 := ir.y;
h2 := ir.x;
h3 := b;
repeat
display[h1] := h3;
h1 := h1-1;
h3 := s[h3+2].i;
until h1 = h2
end;
8: case ir.y of
0: s[t].i := abs(s[t].i);
1: s[t].r := abs(s[t].r);
2: s[t].i := sqr(s[t].i);
3: s[t].r := sqr(s[t].r);
4: s[t].b := odd(s[t].i);
5: begin
s[t].c := chr(s[t].i); { [sam] commented section restored }
if (s[t].i < 0) or (s[t].i > inxmax {[sam]}) then ps := inxchk;
end;
6: s[t].i := ord(s[t].c); { [sam] commented section restored }
7: s[t].c := succ(s[t].c);
8: s[t].c := pred(s[t].c);
9: s[t].i := round(s[t].r);
10: s[t].i := trunc(s[t].r);
11: s[t].r := sin(s[t].r);
12: s[t].r := cos(s[t].r);
13: s[t].r := exp(s[t].r);
14: s[t].r := ln(s[t].r);
15: s[t].r := sqrt(s[t].r);
16: s[t].r := arctan(s[t].r);
17: begin
t := t+1;
if t > stacksize then ps := stkchk
else s[t].b := eof(input);
end;
18: begin
t := t+1;
if t > stacksize then ps := stkchk
else s[t].b := eoln(input);
end;
end;
9: s[t].i := s[t].i + ir.y; (* offset *)
10: pc := ir.y; (* jump *)
11: begin (* conditional jump *)
if not s[t].b then pc := ir.y;
t := t-1
end;
12: begin (* switch *)
h1 := s[t].i;
t := t-1;
h2 := ir.y;
h3 := 0;
repeat
if code[h2].f <> 13 then begin
h3 := 1;
ps := caschk;
end
else
if code[h2].y = h1 then begin
h3 := 1;
pc := code[h2+1].y;
end
else h2 := h2 + 2;
until h3 <> 0;
end;
14: begin (* forlup *)
h1 := s[t-1].i;
if h1 <= s[t].i then s[s[t-2].i].i := h1
else begin
t := t-3;
pc := ir.y;
end;
end;
15: begin (* for2up *) h2 := s[t-2].i; h1 := s[h2].i + 1;
if h1 <= s[t].i then
begin s[h2].i := h1; pc := ir.y end
else t := t-3;
end;
16: begin (* for1down *) h1 := s[t-1].i;
if h1 >= s[t].i then s[s[t-2].i].i := h1 else
begin pc := ir.y; t := t-3
end
end;
17: begin (* for2down *) h2 := s[t-2].i; h1 := s[h2].i - 1;
if h1 >= s[t].i then
begin s[h2].i := h1; pc := ir.y end
else t := t-3;
end;
18: begin (* mark stack *) h1 := btab[tab[ir.y].ref].vsize;
if t+h1 > stacksize then ps := stkchk else
begin t := t+5; s[t-1].i := h1-1; s[t].i := ir.y
end
end;
19: begin (* call *) h1 := t - ir.y; (* h1 points top base *)
h2 := s[h1+4].i;
h3 := tab[h2].lev; display[h3+1] := h1;
h4 := s[h1+3].i + h1;
s[h1+1].i := pc; s[h1+2].i := display[h3]; s[h1+3].i := b;
for h3 := t+1 to h4 do s[h3].i := 0;
b := h1; t := h4; pc := tab[h2].adr
end;
20: begin (* index *) h1 := ir.y; (* h1 points to atab *)
h2 := atab[h1].low; h3 := s[t].i;
if h3 < h2 then ps := inxchk else
if h3 > atab[h1].high then ps := inxchk else
begin t := t-1; s[t].i := s[t].i + (h3-h2)
end
end;
21: begin (* index *) h1 := ir.y; (* h1 points to atab *)
h2 := atab[h1].low; h3 := s[t].i;
if h3 < h2 then ps := inxchk else
if h3 > atab[h1].high then ps := inxchk else
begin t := t-1; s[t].i := s[t].i + (h3-h2)*atab[h1].elsize
end
end;
22: begin (* load block *) h1 := s[t].i; t := t-1;
h2 := ir.y + t; if h2 > stacksize then ps := stkchk else
while t < h2 do
begin t := t+1; s[t] := s[h1]; h1 := h1+1
end
end;
23: begin (* copy block *) h1 := s[t-1].i;
h2 := s[t].i; h3 := h1 + ir.y;
while h1 < h3 do
begin s[h1] := s[h2]; h1 := h1+1; h2 := h2+1
end;
t := t-2
end;
24: begin (* literal *)
t := t+1;
if t > stacksize then ps := stkchk
else s[t].i := ir.y
end;
25: begin (* load real *) t := t+1;
if t > stacksize then ps := stkchk else s[t].r := rconst[ir.y]
end;
26: begin (* float *) h1 := t - ir.y; s[h1].r := s[h1].i
end;
27: begin (* read *)
(* BPW - input follows source
if eof(input) then ps := redchk else
case ir.y of
1: read(s[s[t].i].i);
2: read(s[s[t].i].r);
4: read(s[s[t].i].c)
end;
*)
if eof(srcfil) then ps := redchk else
case ir.y of
1: read(srcfil, s[s[t].i].i);
2: read(srcfil, s[s[t].i].r);
4: read(srcfil, s[s[t].i].c)
end;
t := t-1
end;
28: begin (* write string *)
h1 := s[t].i;
h2 := ir.y;
t := t-1;
chrcnt := chrcnt+h1;
if chrcnt > lineleng then ps := lngchk;
repeat
write(stab[h2]);
h1 := h1-1;
h2 := h2+1
until h1 = 0
end;
29: begin (* write1 *)
chrcnt := chrcnt + fld[ir.y];
if chrcnt > lineleng then ps := lngchk else
case ir.y of
1: write(s[t].i: fld[1]);
2: write(s[t].r: fld[2]);
3: write(s[t].b: fld[3]);
4: write(s[t].c);
end;
t := t-1
end;
30: begin (* write2 *)
chrcnt := chrcnt + s[t].i;
if chrcnt > lineleng then ps := lngchk else
case ir.y of
1: write(s[t-1].i: s[t].i);
2: write(s[t-1].r: s[t].i);
3: write(s[t-1].b: s[t].i);
4: write(s[t-1].c: s[t].i);
end;
t := t-2
end;
31: ps := fin;
32: begin (* exit procedure *)
t := b-1; pc := s[b+1].i; b := s[b+3].i
end;
33: begin (* exit function *)
t := b; pc := s[b+1].i; b := s[b+3].i
end;
34: s[t] := s[s[t].i];
35: s[t].b := not s[t].b;
{ Changed the negate instruction to work according to the type of the
operand. See the header comments. [sam] }
36: begin (* negate *)
case ir.y of
1: s[t].i := - s[t].i;
2: s[t].r := -s[t].r;
end
end;
37: begin chrcnt := chrcnt + s[t-1].i;
if chrcnt > lineleng then ps := lngchk else
write(s[t-2].r: s[t-1].i: s[t].i);
t := t-3
end;
38: begin (* store *) s[s[t-1].i] := s[t]; t := t-2;
end;
39: begin t := t-1; s[t].b := s[t].r = s[t+1].r
end;
40: begin t := t-1; s[t].b := s[t].r <> s[t+1].r
end;
41: begin t := t-1; s[t].b := s[t].r < s[t+1].r
end;
42: begin t := t-1; s[t].b := s[t].r <= s[t+1].r
end;
43: begin t := t-1; s[t].b := s[t].r > s[t+1].r
end;
44: begin t := t-1; s[t].b := s[t].r >= s[t+1].r
end;
45: begin t := t-1; s[t].b := s[t].i = s[t+1].i
end;
46: begin t := t-1; s[t].b := s[t].i <> s[t+1].i
end;
47: begin t := t-1; s[t].b := s[t].i < s[t+1].i
end;
48: begin t := t-1; s[t].b := s[t].i <= s[t+1].i
end;
49: begin t := t-1; s[t].b := s[t].i > s[t+1].i
end;
50: begin t := t-1; s[t].b := s[t].i >= s[t+1].i
end;
51: begin t := t-1; s[t].b := s[t].b or s[t+1].b
end;
52: begin t := t-1; s[t].i := s[t].i + s[t+1].i
end;
53: begin t := t-1; s[t].i := s[t].i - s[t+1].i
end;
54: begin t := t-1; s[t].r := s[t].r + s[t+1].r;
end;
55: begin t := t-1; s[t].r := s[t].r - s[t+1].r;
end;
56: begin t := t-1; s[t].b := s[t].b and s[t+1].b;
end;
57: begin t := t-1; s[t].i := s[t].i * s[t+1].i
end;
58: begin t := t-1;
if s[t+1].i = 0 then ps := divchk else
s[t].i := s[t].i div s[t+1].i
end;
59: begin t := t-1;
if s[t+1].i = 0 then ps := divchk else
s[t].i := s[t].i mod s[t+1].i
end;
60: begin t := t-1; s[t].r := s[t].r * s[t+1].r;
end;
61: begin t := t-1; s[t].r := s[t].r / s[t+1].r;
end;
62: (*if eof(input) then ps := redchk else readln;*)
if eof(srcfil) then ps := redchk else readln(srcfil);
63: begin writeln; lncnt := lncnt + 1; chrcnt := 0;
if lncnt > linelimit then ps := linchk
end
end (* case *);
until ps <> run;
if ps <> fin then begin
writeln;
{ Changed to double spacing [sam] }
write('halt at', pc:5, ' because of ');
writeln;
case ps of
caschk: writeln('undefined case');
divchk: writeln('division by 0');
inxchk: writeln('invalid index');
stkchk: writeln('storage overflow');
linchk: writeln('too much output');
lngchk: writeln('line too long');
redchk: writeln('reading past end of file');
end;
h1 := b;
blkcnt := 10; (* post mortem dump *)
repeat writeln; blkcnt := blkcnt - 1;
if blkcnt = 0 then h1 := 0; h2 := s[h1+4].i;
if h1 <> 0 then
writeln(' ',tab[h2].name, ' called at', s[h1+1].i: 5);
h2 := btab[tab[h2].ref].last;
while h2 <> 0 do
with tab[h2] do
begin if obj = variable then
if typ in stantyps then
begin write(' ', name, ' = ');
if normal then h3 := h1+adr else h3 := s[h1+adr].i;
case typ of
ints: writeln(s[h3].i);
reals: writeln(s[h3].r);
bools: writeln(s[h3].b);
chars: writeln(s[h3].c);
end
end;
h2 := link
end;
h1 := s[h1+3].i
until h1 < 0;
end;
writeln; writeln(ocnt, ' steps')
end (* interpret *);
begin { main program }
{ [sam] Added sign-on }
writeln;
writeln('Pascal-S Compiler/Interpreter v0.03');
writeln(' v0.01: Nikolas Wirth');
writeln(' v0.02: Scott Moore');
writeln(' v0.03: Ozz Nixon');
writeln;
if (paramcount<>1) then begin
writeln('USAGE: pascals sourcefile');
halt(2);
end;
{ [sam] If you need to associate 'srcfil' with an external file in the
source, do that here }
assign(srcfil,paramstr(1));
reset(srcfil);
writeln('Phase I {parsing}');
key[ 1] := 'and '; key[ 2] := 'array ';
key[ 3] := 'begin '; key[ 4] := 'case ';
key[ 5] := 'const '; key[ 6] := 'div ';
key[ 7] := 'do '; key[ 8] := 'downto ';
key[ 9] := 'else '; key[10] := 'end ';
key[11] := 'for '; key[12] := 'function ';
key[13] := 'if '; key[14] := 'mod ';
key[15] := 'not '; key[16] := 'of ';
key[17] := 'or '; key[18] := 'procedure ';
key[19] := 'program '; key[20] := 'record ';
key[21] := 'repeat '; key[22] := 'then ';
key[23] := 'to '; key[24] := 'type ';
key[25] := 'until '; key[26] := 'var ';
key[27] := 'while ';
ksy[ 1] := andsy; ksy[ 2] := arraysy;
ksy[ 3] := beginsy; ksy[ 4] := casesy;
ksy[ 5] := constsy; ksy[ 6] := idiv;
ksy[ 7] := dosy; ksy[ 8] := downtosy;
ksy[ 9] := elsesy; ksy[10] := endsy;
ksy[11] := forsy; ksy[12] := functionsy;
ksy[13] := ifsy; ksy[14] := imod;
ksy[15] := notsy; ksy[16] := ofsy;
ksy[17] := orsy; ksy[18] := proceduresy;
ksy[19] := programsy; ksy[20] := recordsy;
ksy[21] := repeatsy; ksy[22] := thensy;
ksy[23] := tosy; ksy[24] := typesy;
ksy[25] := untilsy; ksy[26] := varsy;
ksy[27] := whilesy;
sps['+'] := plus; sps['-'] := minus;
sps['*'] := times; sps['/'] := rdiv;
sps['('] := lparent; sps[')'] := rparent;
sps['='] := egl; sps[','] := comma;
sps['['] := lbrack; sps[']'] := rbrack;
sps['#'] := neg; sps['&'] := andsy;
sps[';'] := semicolon;
constbegsys := [plus, minus, intcon, realcon, charcon, ident];
typebegsys := [ident, arraysy, recordsy];
blockbegsys := [constsy, typesy, varsy, proceduresy,
functionsy, beginsy];
facbegsys := [intcon, realcon, charcon, ident, lparent, notsy];
statbegsys := [beginsy, ifsy, whilesy, repeatsy, forsy, casesy];
stantyps := [notyp, ints, reals, bools, chars];
lc := 0; ll := 0; cc := 0; ch := ' ';
errpos := 0; errs := []; insymbol;
t := -1; a := 0; b := 1; sx := 0; c2 := 0;
display[0] := 1;
iflag := false; oflag := false;
// does it start with "program"?
if sy <> programsy then error(3)
else begin
insymbol;
if sy <> ident then error(2)
else begin
progname := id;
insymbol;
if (sy=semicolon) then begin
iflag:=false;
oflag:=true;
insymbol;
end
else begin
if sy <> lparent then error(9)
else repeat
insymbol;
if sy <> ident then error(2)
else begin
if id = 'input ' then iflag := true
else if id = 'output ' then oflag := true
else error(0);
insymbol;
end
until sy <> comma;
if sy = rparent then insymbol
else error(4);
end;
if not oflag then error(20)
end
end;
enter(' ', variable, notyp, 0); (* sentinel *)
enter('false ', konstant, bools, 0);
enter('true ', konstant, bools, 1);
enter('real ', typel, reals, 1);
enter('char ', typel, chars, 1);
enter('boolean ', typel, bools, 1);
enter('integer ', typel, ints , 1);
enter('abs ', funktion, reals, 0);
enter('sqr ', funktion, reals, 2);
enter('odd ', funktion, bools, 4);
enter('chr ', funktion, chars, 5);
enter('ord ', funktion, ints, 6);
enter('succ ', funktion, chars, 7);
enter('pred ', funktion, chars, 8);
enter('round ', funktion, ints, 9);
enter('trunc ', funktion, ints, 10);
enter('sin ', funktion, reals, 11);
enter('cos ', funktion, reals, 12);
enter('exp ', funktion, reals, 13);
enter('ln ', funktion, reals, 14);
enter('sqrt ', funktion, reals, 15);
enter('arctan ', funktion, reals, 16);
enter('eof ', funktion, bools, 17);
enter('eoln ', funktion, bools, 18);
enter('read ', prozedure, notyp, 1);
enter('readln ', prozedure, notyp, 2);
enter('write ', prozedure, notyp, 3);
enter('writeln ', prozedure, notyp, 4);
enter(' ', prozedure, notyp, 0);
with btab[1] do begin
last := t;
lastpar := 1;
psize := 0;
vsize := 0
end;
block(blockbegsys+statbegsys, false, 1);
if sy <> period then error(22);
emit(31); (* halt *)
if btab[2].vsize > stacksize then error(49);
if progname = 'test0 ' then printtables;
if errs = [] then begin
(* BPW - source file is immediately followed by input
writeln('Phase II {reading stdin}');
if iflag then begin
if eof(input) then writeln(' no input data...')
else begin
writeln(' (eor) ');
while not eof do begin
write(' ');
while not eoln do
begin read(input,ch); write(ch)
end;
writeln; read(input,ch)
end;
end
end;
*)
writeln(' (eof) ');
writeln('Phase III {running}');
interpret;
{printtables;}
end
else errormsg;
close(srcfil);
end.
Teknik Kompilasi
Scanner Pascal
Tarkiman
09:39:00
Contoh Program Scanner Pascal :
Design by Blogger Templates
0 Comments