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andersonsp/pascals.pas

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pascal-s pretify project
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pascals.pas
{******************************************************************************
* *
* Pascal-s entered from wirth's Pascal-s document and converted for *
* ISO 7185 use. *
* *
* The original environment of pascal (CDC computer) used a special access *
* method where the input file was split into "segments" and special methods *
* were used to access these segments. I have changed things to open the file *
* "input.pas", and compile the program from there. Input and output then *
* occur from the simulated program normally. Very few changes were made to *
* accomplish this. *
* *
* See the original document for more information. *
* *
* Changes were also made to bring the program into compliance with *
* ISO 7185 Pascal. *
* *
* S. A. Moore *
* [email protected] *
* *
* A brief overview of what is subsetted in Pascal-S: *
* *
* 1. Curly bracket mode comments are not supported. They are recognized and *
* dealt with as an error, however (see "insymbol"). *
* *
* 2. Subrange types are not implemented (type a = 1..10). *
* *
* 3. Scalar types are not implemented (type a = (one, two, three). *
* *
* 4. Sets are not implemented. *
* *
* 5. Files other than the "input" or "output" files are not implemented. *
* *
* 6. Dynamic variables (pointers) are not implemented. *
* *
* 7. Variant records are not implemented. *
* *
* 8. Gotos are not implemented. *
* *
* 9. The predefined functions succ and pred only function on type char. *
* *
* 10. Packing, the "packed" keyword, and the "pack" and "unpack" procedures, *
* are not implemented. *
* *
* 11. "get", "put", and file buffer variable handling are not implemented. *
* *
* 12. Strings are unimplemented, except for literals as parameters to *
* write/writeln, and those cannot have field lengths applied to them. *
* *
* 13. The "forward" specifier, and forwarded procedures and functions, are *
* not implemented. *
* *
* For more details on what is or is not implemented in Pascal-s, see the *
* original documentation by N. Wirth. *
* *
* Changes made: *
* *
* 1. The "+" sign was removed from "input" in the header. This signaled to *
* The CDC 6400 compiler that the input file was segmented, and contained both *
* The program and its input. *
* *
* To complete the separation of the program file from the input file, the *
* program file was formalized as "srcfil", placed in the header, and all *
* source reads directed to that. The "getseg" call used to advance segmented *
* input to the next section was removed. This actually makes the program *
* closer to both the standard and [J&W] (non CDC methods). *
* *
* 2. "downto" and "do" were swapped in the key table. This is nessary because *
* the CDC 6400 character set places space above, not below the other *
* characters as in ASCII. *
* *
* 3. On the CDC 6400 computer, integers greater than 48 bits are not *
* garanteed to be valid, so the maximum for any number is set to that in *
* nmax. I set it to maxint, which should work anywhere. *
* *
* 4. I increased the sizes quite a bit to enable large program processing. *
* Included are the string table, the code table, and various others. Pascal-s *
* came from a time when memory was more precious. *
* *
* 5. I changed the exponent of real minimum and maximum to match IEEE 754 *
* standard 64 bit floating point numbers. The size of significant digits did *
* not need changing, since both IEEE 754 and CDC 6400 use a 48 bit mantissa. *
* *
* 6. Added a constant "inxmax" that indicates the maximum ordinal value of *
* the character set, and replaced the old, in source limit of 63, which was *
* the CDC 6400 character limit (0-63). Updated the constant value for ASCII. *
* *
* 7. The original Wirth convention of having the first character of each *
* output line be a print control character (' ', '0', '1', '+') is long gone. *
* These were removed, and replaced by their equivalent in modern Pascal. *
* *
* 8. "The instruction 36 mystery" in simpleexpression, a single negate *
* instruction is emitted for both integer and real, and indeed, the 36 *
* instruction in interpret performs an integer negate, regardless of the real *
* or integer status of the stack operand. It SEEMS like a bug, but its not. *
* To understand why not, you have to do some serious dumpster diving into the *
* CDC 6000 machine documentation. Seymore Cray was a very clever fellow, and *
* the CDC 6600 series floating point notation is "compatible" with its *
* integer notation, that is, has its sign in the same place, and essentially *
* appears as an integer with an embedded exponent. Among other interesting *
* effects, it means that a negate operation works on both integer and real, *
* regardless of which type is being done. Try to find THAT in the Pascal-s *
* documentation ! The fix for this is to stick a real/integer indicator in *
* the "y" field of an "order" record, this tells a non-CDC 6000 computer to *
* treat the negate differently for real and integer. *
* *
* 9. I added a sign-on for the program. *
* *
* I have marked all my changes to the original source with [sam] in a comment *
* (my initals). *
* *
* Notes on compiling and running: *
* *
* 1. Pascal-s does not tolerate upper case input. On most systems, this will *
* result in a "case select" error in the procedure "insymbol". *
* *
* 2. The file program header file "srcfil" is going to need to be connected *
* to an external file. If your Pascal does not have the ability to connect *
* header files to external files, then you need to do this manually. See the *
* comment shortly after the main program "begin". *
* *
* 3. You may need to change the emin, emax, and kmax parameters to match your *
* particular floating point implementation. *
* *
* 4. You may want to increase alng, the number of significant characters in *
* identifiers, to match your needs. This will allow programs with long *
* idenfitiers to run, but will increase the space requirements to run *
* Pascal-s, perhaps dramatically. *
* *
* 5. Pascal-s can, by option, dump all of its tables after program *
* compilation, including identifers, blocks, arrays, and internal execution *
* code. This option is invoked by naming the program "test0" (the name in the *
* "program" statement). *
* *
******************************************************************************}
program Pascals(input{+ [sam]}, output, srcfil{ [sam]}); (* 1.6.75 *)
(* N. Wirth, E.T.H
CH-8092 Zurich *)
label 99;
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] }
type
symbol = (intcon, realcon, charcon, stringt,
notsy, plus, minus, times, idiv, rdiv, imod, andsy, orsy,
egl, neg, gtr, geg, lss, leg,
lparent, rparent, lbrack, rbrack, comma, semicolon, period,
colon, becomes, constsy, typesy, varsy, functionsy,
proceduresy, arraysy, recordsy, programsy, ident,
beginsy, ifsy, casesy, repeatsy, whilesy, forsy,
endsy, elsesy, untilsy, ofsy, dosy, tosy, downtosy, thensy);
index = -xmax .. +xmax;
alfa = packed array [1..alng] of char;
object = (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 packed record (* identifier table *)
name: alfa; link: index;
obj: object; typ: types;
ref: index; normal: boolean;
lev: 0..lmax; adr: integer;
end;
atab: array [1..amax] of packed record (* array-tabvle *)
inxtyp, eltyp: types;
elref, low, high, elsize, size: index;
end;
btab: array [1..bmax] of packed record (* block table *)
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;
goto 99
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');
goto 99 (* 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 = ' ' do nextch;
if ch in ['a'..'z'] then begin (* word *)
k := 0;
id := ' ';
repeat
if k < alng then begin
k := k+1;
id[k] := ch
end;
nextch
until not (ch in ['a'..'z', '0'..'9']);
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 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 else case ch of
':':
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;
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;
'(':
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;
'$', '%', '@', '\', '~', '{', '}', '^':
begin
error(24);
nextch;
goto 1
end
end
end (* insymbol *);
procedure enter(x0: alfa; x1: object; 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, 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
if i mod 5 = 0 then begin
writeln;
write(i: 5)
end;
o := code[i]; write(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(o.x:2, o.y:5)
else write(o.y:7)
else write(' ');
write(',')
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: object);
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) or (j<>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
0, 2: (* abs, sqr *)
begin
ts:= [ints, reals];
tab[i].typ := x.typ;
if x.typ = reals then n := n+1
end;
4, 5: (* odd, chr *)
ts := [ints];
6: (* ord *)
ts := [ints, bools, chars];
7, 8: (* succ, pred *)
ts := [chars];
9, 10, 11, 12, 13, 14, 15, 16: (* round, trunc, 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 begin (* eof, eoln *)
(* 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)
{ Changed the negate instruction 36 to also emit a parameter that
says if the operand is real or integer. See comments at top. [sam] }
else if op = minus then emit1(36, ord(x.typ = reals))
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);
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 = 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] := 10;
fld[2] := 22;
fld[3] := 10;
fld[4] := 1;
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); *)
if (s[t].i < 0) or (s[t].i > inxmax {[sam]}) then ps := inxchk
end;
6: (* s[t].i := ord(s[t].c) *);
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 *)
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;
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
if ir.y = 0 then s[t].i := - s[t].i
else s[t].r := -s[t].r
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;
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');
{ [sam] If you need to associate 'srcfil' with an external file in the source, do that here }
reset(srcfil);
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;
if sy <> programsy then error(3)
else begin
insymbol;
if sy <> ident then error(2)
else begin
progname := id;
insymbol;
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);
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
if iflag then begin
if eof then writeln(' input data missing')
else begin
writeln(' (eor) '); (* copy input data *)
while not eof do begin
write(' ');
while not eoln do begin
read(ch);
write(ch)
end;
writeln; read(ch)
end;
end
end;
writeln(' (eof) ');
interpret
end else errormsg;
99:
end.
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