This is second modification of Tiny Context compiler
with Fortran-style function arguments and local variables. It placed in
global data area, but arguments are passed by value. This modification
make source code more readable and saves small size of source and binary.
Slightly improved first modification are here.
Next elements are taken from:
Simple conditions in if and while operators (single comparison) - from PL/0
Functions without arguments - also from PL/0 (now not used)
Arrays - from Fortran, there are no arrays in PL/0
Function agruments and local variables implementation - from Fortran
Compilation algorithm - from Context
Functions without arguments are allow to implement very small compiler,
but it is unnatural. In mathematics function without arguments are constant.
In Fortran function arguments are passed by reference. To pass constant
memory area are statically allocated and constant value are stored in this area.
Area address are passed to called function ant it make side effect - function
can change constant value:
DO 10 I=1,2
CALL S(0)
10 CONTINUE
STOP
END
SUBROUTINE S(N)
901 FORMAT (1X,'N = ',I1/)
INTEGER N
WRITE(2, 901) N
N=1
END
Output of this program listed below and it is not two zeroes:
N = 0
N = 1
Passing arguments by value sole this problem, but when recursive call occurs
statically allocated arguments and local variables may be changed. To prevent
this explicit stack are used.
Compiler source code listed below may be compiled with
Tiny Context 1.18 (c.118), or with
Context but it requires three modifications
of source code:
char Temp [16640]; // Before char Text [16384]; // Because memory models are different
word Digraph(char C1, char C2) is -> word Digraph(char C1; char C2) is
word Emi3(word P, word W) is -> word Emi3(word P; word W) is
Compiled program must be placed in file with name C.PRG, compiled result are saved
in file C.COM. MS DOS are oblolete now but it has simplest executable file format
without header and sections. When DOS unavailable DOSBox may be used:).
Later compiler was ported to number different platforms, modern and obsolete:
char Text [16384];
word pText;
word nText;
word nLine;
byte Code [16384];
word nCode;
word hFile;
char Heap [ 2048];
word nHeap;
word Name [ 256];
word Cls [ 256];
word Sub [ 256];
word Type [ 256];
word Size [ 256];
word Ofs [ 256];
word nName;
word nData;
word Stk [ 128];
word pStk;
char Buff [ 128];
word open() is
inline 0xB4, 0x3D; // mov AH, 3DH
inline 0xB0, 0x00; // mov AL, 00H
inline 0xBA, 0x4A, 0xC1; // mov DX, @@Data+Ofs(Heap[64])
inline 0xCD, 0x21; // int 21H
end
word create() is
inline 0xB4, 0x3C; // mov AH, 03CH
inline 0xB9, 0x00, 0x00; // mov CX, 00H
inline 0xBA, 0x50, 0xC1; // mov DX, @@Data+Ofs(Heap[70])
inline 0xCD, 0x21; // int 21H
end
word read() is
inline 0xB4, 0x3F; // mov AH, 3FH
inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)]
inline 0xB9, 0x00, 0x40; // mov CX, 16384
inline 0xBA, 0x00, 0x41; // mov DX, @@DATA+Ofs(Text)
inline 0xCD, 0x21; // int 21H
end
word write() is
inline 0xB4, 0x40; // mov AH, 40H
inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)]
inline 0x8B, 0x0E, 0x06, 0xC1; // mov CX, word [@@DATA+Ofs(nCode)]
inline 0xBA, 0x06, 0x81; // mov DX, @@DATA+Ofs(Code)
inline 0xCD, 0x21; // int 21H
end
word close() is
inline 0xB4, 0x3E; // mov AH, 3EH
inline 0x8B, 0x1E, 0x08, 0xC1; // mov BX, word [@@DATA+Ofs(hFile)]
inline 0xCD, 0x21; // int 21H
end
char putc(char C) is
char C1:=C;
inline 0x92; // xchg DX, AX
inline 0xB4, 0x02; // mov AH, 2
inline 0xCD, 0x21; // int 21H
end
word halt() is
inline 0xB8, 0x00, 0x4C; // mov AX, 4C00H
inline 0xCD, 0x21; // int 21H
end
word Init() is
Heap[ 0]:='0';
Heap[ 1]:='1';
Heap[ 2]:='2';
Heap[ 3]:='3';
Heap[ 4]:='4';
Heap[ 5]:='5';
Heap[ 6]:='6';
Heap[ 7]:='7';
Heap[ 8]:='8';
Heap[ 9]:='9';
Heap[10]:='A';
Heap[11]:='B';
Heap[12]:='C';
Heap[13]:='D';
Heap[14]:='E';
Heap[15]:='F';
Heap[16]:='c';
Heap[17]:='h';
Heap[18]:='a';
Heap[19]:='r';
Heap[20]:= char(0);
Heap[21]:='b';
Heap[22]:='y';
Heap[23]:='t';
Heap[24]:='e';
Heap[25]:= char(0);
Heap[26]:='w';
Heap[27]:='o';
Heap[28]:='r';
Heap[29]:='d';
Heap[30]:= char(0);
Heap[31]:='b';
Heap[32]:='e';
Heap[33]:='g';
Heap[34]:='i';
Heap[35]:='n';
Heap[36]:= char(0);
Heap[37]:='i';
Heap[38]:='f';
Heap[39]:= char(0);
Heap[40]:='w';
Heap[41]:='h';
Heap[42]:='i';
Heap[43]:='l';
Heap[44]:='e';
Heap[45]:= char(0);
Heap[46]:='i';
Heap[47]:='n';
Heap[48]:='l';
Heap[49]:='i';
Heap[50]:='n';
Heap[51]:='e';
Heap[52]:= char(0);
Heap[53]:='r';
Heap[54]:='e';
Heap[55]:='t';
Heap[56]:='u';
Heap[57]:='r';
Heap[58]:='n';
Heap[59]:= char(0);
Heap[60]:='e';
Heap[61]:='n';
Heap[62]:='d';
Heap[63]:= char(0);
Heap[64]:='c';
Heap[65]:='.';
Heap[66]:='p';
Heap[67]:='r';
Heap[68]:='g';
Heap[69]:= char(0);
Heap[70]:='c';
Heap[71]:='.';
Heap[72]:='c';
Heap[73]:='o';
Heap[74]:='m';
Heap[75]:= char(0);
nHeap :=76;
Name[ 0]:=16;
Cls [ 0]:= 1;
Size[ 0]:= 1;
Name[ 1]:=21;
Cls [ 1]:= 1;
Size[ 1]:= 1;
Name[ 2]:=26;
Cls [ 2]:= 1;
Size[ 2]:= 2;
nName := 3;
pStk := 0;
nCode := 0;
nData := 16640;
end
word Push(word V) is
Stk[pStk]:=V;
pStk:=pStk+1;
end
word Pop () is
pStk:=pStk-1;
return Stk[pStk];
end
word Stop() is
pStk:=0;
while nLine!=0 do
Push (nLine%10);
nLine:=nLine/10;
end
while pStk!=0 do
putc(char(Pop()+48));
end
close();
halt ();
end
word val () is
word E:=10;
word I:= 0;
if Buff[0]='0' then
if Buff[1]='x' then
E:=16;
I:= 2;
end
end
word N:=0;
while Buff[I]!=char(0) do
word K:=0;
while Heap[K]!=Buff[I] do
if K=E then
Stop();
end
K:=K+1;
end
N:=E*N;
N:=N+K;
I:=I+1;
end
return N;
end
char Look() is
if pText>=nText then
pText :=0;
nText :=read();
if pText>=nText then
return char(0);
end
end
return Text[pText];
end
char Read() is
char Ch:=Look();
if Ch =char(10) then
nLine :=nLine+1;
end
pText :=pText+1;
return Ch;
end
word isalnum() is
if 'A'<=Look() then
if Look()<='Z' then
return 0;
end
end
if 'a'<=Look() then
if Look()<='z' then
return 0;
end
end
if '0'<=Look() then
if Look()<='9' then
return 0;
end
end
return 1;
end
word Digraph(char C1, char C2) is
if Buff[0]=C1 then
if Look()=C2 then
Buff[1]:=Read();
Buff[2]:=char(0);
end
end
end
char Scan() is
word pBuff:=0;
while pBuff =0 do
word sFlag:=0;
while sFlag =0 do
if Look()!=char( 9) then
if Look()!=char(10) then
if Look()!=char(13) then
if Look()!=char(32) then
sFlag:=1;
end
end
end
end
if sFlag=0 then
Read();
end
end
while isalnum()=0 do
Buff[pBuff]:= Read();
pBuff :=pBuff+1;
end
if pBuff=0 then
Buff[pBuff]:= Read();
pBuff :=pBuff+1;
end
Buff[pBuff] :=char(0);
Digraph('<', '=');
Digraph('!', '=');
Digraph('>', '=');
Digraph(':', '=');
if Buff[0]='/' then
if Look()='/' then
while Look()!=char(10) do
if Read()=char(0) then
Stop();
end
end
pBuff:=0;
end
end
end
end
word Comp(word pHeap) is
word pBuff:=0;
while Buff[pBuff]=Heap[pHeap] do
if Buff[pBuff]=char(0) then
return 0;
end
pHeap:=pHeap+1;
pBuff:=pBuff+1;
end
return 1;
end
word Find(word fFlag) is
word pName:=0;
while pName< nName do
if Comp(Name[pName])=0 then
return pName;
end
pName:=pName+1;
end
if fFlag=0 then
Stop();
end
return pName;
end
byte Emi1(byte B) is
Code[nCode]:=B;
nCode:=nCode+1;
end
word Emi2(word W) is
Emi1(W%256);
Emi1(W/256);
end
word Emi3(word P, word W) is
W:=W-3;
Code[P] :=W%256;
Code[P+1]:=W/256;
end
word Assign(word I) is
if Size[I]>1 then
Emi1(0x5B); // pop BX
end
byte B:=0x89; // mov [(BX+)Ofs], AX
if Size[Type[I]]=1 then
B:=0x88; // mov [(BX+)Ofs], AL
end
Emi1(B);
B:=0x06; // [Ofs]
if Size[I]>1 then
B:=0x87; // [BX+Ofs]
end
Emi1(B);
Emi2(Ofs[I]);
end
word Expr() is
word eFlag:=0;
//if eFlag =0 then
if '0'<=Buff[0] then
if Buff[0]<='9' then
Emi1(0xB8); // mov AX, Val
Emi2(val());
eFlag:=1;
end
end
if Buff[0]=''' then
Emi1(0xB8); // mov AX, Val
Emi2(word(Read()));
Read();
eFlag:=1;
end
if Buff[0]='(' then
Scan();
Expr();
eFlag:=1;
end
//end
if eFlag =0 then
word I:=Find(0);
if Cls[I]=1 then
Push(I);
Scan(); // (
Scan();
Expr();
I:=Pop();
end
if Cls[I]=2 then
if Size[I]>1 then
Push(I);
Scan(); // [
Scan();
Expr();
I:=Pop();
if Size[Type[I]]=2 then
Emi1(0xD1); // shl AX, 1
Emi1(0xE0);
end
Emi1(0x93); // xchg BX, AX
end
byte B:=0x8B; // mov AX, [(BX+)Ofs]
if Size[Type[I]]=1 then
Emi1(0x32); // xor AH, AH
Emi1(0xE4);
B:=0x8A; // mov AL, [(BX+)Ofs]
end
Emi1(B);
B:=0x06; // [Ofs]
if Size[I]>1 then
B:=0x87; // [BX+Ofs]
end
Emi1(B);
Emi2(Ofs[I]);
end
if Cls[I]=3 then
Scan(); // (
Push(I);
Sub[nName]:= 0;
word J:=I+1;
while Sub[J]=1 do
Push(J);
Scan();
Expr();
J:=Pop();
Assign(J);
J:=J+1;
end
I:=Pop();
if J=I+1 then
Scan(); // )
end
word W:=(0xFFFF-((nCode+3)-Ofs[I]))+1;
Emi1(0xE8); // call Ofs
Emi2(W);
end
end
Scan();
word I:=0;
if Buff[0]='+' then
I:=1;
end
if Buff[0]='-' then
I:=2;
end
if Buff[0]='*' then
I:=3;
end
if Buff[0]='/' then
I:=4;
end
if Buff[0]='%' then
I:=5;
end
if I!=0 then
Emi1(0x50); // push AX
Push(I);
Scan();
Expr();
I:=Pop();
Emi1(0x5B); // pop BX
if I =1 then
Emi1(0x03); // add AX, BX
Emi1(0xC3);
end
if I =2 then
Emi1(0x93); // xchg BX, AX
Emi1(0x2B); // sub AX, BX
Emi1(0xC3);
end
if I =3 then
Emi1(0xF7); // mul BX
Emi1(0xE3);
end
if I>=4 then
Emi1(0x93); // xchg BX, AX
Emi1(0x33); // xor DX, DX
Emi1(0xD2);
Emi1(0xF7); // div BX
Emi1(0xF3);
end
if I =5 then
Emi1(0x92); // xchg DX, AX
end
end
end
word Cond() is
Scan();
Expr();
word jCode:=0;
if Buff[0]='<' then
jCode:=0x72; // jb Ofs
if Buff[1]='=' then
jCode:=0x76; // jbe Ofs
end
end
if Buff[0]='=' then
jCode:=0x74; // je Ofs
end
if Buff[0]='!' then
jCode:=0x75; // jne Ofs
end
if Buff[0]='>' then
jCode:=0x77; // ja Ofs
if Buff[1]='=' then
jCode:=0x73; // jae Ofs
end
end
if jCode=0 then
Stop();
end
Emi1(0x50); // push AX
Scan();
Expr();
Emi1(0x5B); // pop BX
Emi1(0x3B); // cmp BX, AX
Emi1(0xD8);
Emi1(jCode); // jxx Ofs
Emi1(0x03);
Push(nCode);
Emi1(0xE9); // jmp ?
nCode:=nCode+2;
end
word Obj (word T) is
if Cls[T]!=1 then
Stop();
end
Name[nName]:=nHeap;
Type[nName]:= T;
Scan();
if Find(1)<nName then
Stop();
end
word pBuff:=0;
char Ch :=char(1);
while Ch !=char(0) do
Ch := Buff[pBuff];
Heap[nHeap]:= Ch;
nHeap :=nHeap+1;
pBuff :=pBuff+1;
end
Scan();
return nName;
end
char Var (word Subclass) is
Cls [nName]:= 2;
Sub [nName]:= Subclass;
Size[nName]:= 1;
Ofs [nName]:=nData;
if Buff[0]='[' then
if Subclass!=0 then
Stop();
end
Scan();
Size[nName]:=val();
Scan(); // ]
Scan(); // ;
end
nData :=nData+(Size[Type[nName]]*Size[nName]);
if nData%2!=0 then
nData :=nData+1;
end
nName :=nName+1;
return Buff[0];
end
word Hide() is
word I:=Pop();
while I< nName do
Heap[Name[I]]:=char(0);
I :=I+1;
end
end
word rFlag;
word Ctrl() is
word cFlag:=0;
//if cFlag =0 then
if Comp(37)=0 then // if
Cond();
Push(nName);
Scan();
Ctrl();
while Comp(60)!=0 do // !end
Ctrl();
end
Hide();
word pSkip:=Pop();
Emi3(pSkip+1, nCode-pSkip);
rFlag:=1; // 14.05.2006
cFlag:=1;
end
//end
if cFlag =0 then
if Comp(40)=0 then // while
Push(nCode);
Cond();
Push(nName);
Scan();
Ctrl();
while Comp(60)!=0 do // !end
Ctrl();
end
Hide();
word pExit:=Pop();
word pLoop:=Pop();
Emi1(0xE9); // jmp Ofs
Emi2((0xFFFF-((nCode+2)-pLoop))+1);
Emi3(pExit+1, nCode-pExit);
rFlag:=1; // 14.05.2006
cFlag:=1;
end
end
if cFlag =0 then
if Comp(46)=0 then // inline
Buff[0]:=',';
while Buff[0]=',' do
Scan();
Emi1(val()); // db Val
Scan();
end
rFlag:=1; // 14.05.2006
cFlag:=1;
end
end
if cFlag =0 then
if Comp(53)=0 then // return
Scan();
Expr();
Emi1(0xC3); // retn
rFlag:=0; // 14.05.2006
cFlag:=1;
end
end
if cFlag =0 then
word I:=Find(0);
if Cls[I]=1 then
word N:=Obj(I);
if Var(2)=':' then
Scan();
Expr();
Assign(N);
end
end
if Cls[I]=2 then
if Size[I]>1 then
Scan(); // [
Scan();
Expr();
if Size[Type[I]]=2 then
Emi1(0xD1); // shl AX, 1
Emi1(0xE0);
end
Emi1(0x50); // push AX
end
Scan(); // :=
Scan();
Expr();
Assign(I);
end
if Cls[I]=3 then
Expr();
end
rFlag:=1; // 14.05.2006
end
Scan();
end
word Func() is
Scan();
Ctrl();
while Comp(60)!=0 do // !end
Ctrl();
end
if rFlag!=0 then // 14.05.2006 // if rFlag=0 then
Emi1(0xC3); // retn
end
end
begin
Init();
hFile:=open();
pText:=0;
nText:=0;
nLine:=1;
Emi1(0xE9); // jmp ?
nCode:=nCode+2;
Scan();
while Comp(31)!=0 do // !begin
Obj (Find(0));
char Ch:=Buff[0];
if Ch ='(' then
Cls [nName]:= 3;
Sub [nName]:= 0;
Ofs [nName]:=nCode;
nName :=nName+1;
Push(nName);
Scan();
if Buff[0]!=')' then
Obj (Find(0));
while Var(1)=',' do
Scan();
Obj (Find(0));
end
end
Scan(); // is
Func();
Hide();
end
if Ch!='(' then
Var(0);
end
Scan();
end
Emi3 (1, nCode);
Func ();
close();
hFile:=create();
write();
close();
end