PETSCIIdad/main.ras at master · gabochi/PETSCIIdad · GitHub

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program C64Project;

// PETSCIIdad by gabochi, still a lot to improve...

var
	t : integer = 0;
	expression : integer;

	i : byte;
	j : byte;
	k : byte;

	opcode : array[4] of byte;
	opcodeindex : byte;
	stack : byte;
	temparray : array[256] of byte;
	output : byte;

	key : byte;
	lastkey : byte;

    saddr : array[25] of integer;
    caddr : array[25] of integer;

begin

//											Screen preparation

	asm("	lda #0
			sta $d020
			sta $d021");

    definescreen();
    CreateAddressTable( saddr, $0400, 40, 25 );
	CreateAddressTable( caddr, $D800, 40, 25 );

    ClearScreen($20, ^$0400);

// 											"Game" loop begins
    while(True) do
    begin

//											Cursor effect

		screenmemory := AddressTable(saddr, 0, 0);
		screenmemory[opcodeindex]:=(128 xor peek(screenmemory,opcodeindex));

//											Read code, evaluate, write temparray
 		for i:=0 to 256 do
		begin

			expression:=t;
//											Four-operation code
		    for j:=0 to 4 do
			begin
				stack:=opcode[j-1];
				if stack=36 then stack:=t;

				if opcode[j]=34 then expression:=expression>>stack;
				if opcode[j]=28 then expression:=expression<<stack;
				if opcode[j]=17 then expression:=expression&stack;
				if opcode[j]=31 then expression:=expression|stack;
				if opcode[j]=40 then expression:=(expression xor stack);
				if opcode[j]=35 then expression:=expression-stack;
				if opcode[j]=29 then expression:=expression*stack;

//											In the meanwhile, check for key interaction

					key:=getkey();

					if key=48 then
					begin
						opcodeindex:=0;
						lastkey:=key;
					end;

					if key<>lastkey then
					begin
						if (key>48 and key<91) then
						begin
							screenmemory[opcodeindex]:=key;
							lastkey:=key;
							opcode[opcodeindex]:=key-48;
							opcodeindex:=opcodeindex+1;
							if opcodeindex=4 then opcodeindex:=0;
						end;
					end;
				end;

			temparray[i]:=expression;
			t:=t+1;
		end;


//											Screen write

		for k:=0 to 2 do
		begin
			for j:=0 to 2 do
			begin
				screenmemory:= AddressTable(saddr, 4, 4+j*4+k*8);
				for i:=0 to 128 do
				begin
						screenmemory[i+(i/32)*8]:=temparray[i+j*128];
				end;
			end;
		end;

		for k:=0 to 2 do
		begin
			for j:=0 to 2 do
			begin
				screenmemory:= AddressTable(caddr, 4, 4+j*4+k*8);
				for i:=0 to 128 do
				begin
					screenmemory[i+(i/32)*8]:=temparray[i+j*128];
				end;
			end;
		end;


    end;

	loop();
end.