mos6502-delphi/VIC-20/Source/VIC20.pas
2017-03-18 22:05:49 +01:00

213 lines
4.3 KiB
ObjectPascal

unit VIC20;
interface
uses
System.Classes, WinApi.Messages, MOS6502;
const
WM_SCREEN_WRITE = WM_USER + 0;
CIA1 = $9120; // $DC00;
// VIC-20 keyboard matrix
KEY_TRANSLATION = '2q'#0' '#27#0#0'1'+
'4esz'#0'aw3'+
'6tfcxdr5'+
'8uhbvgy7'+
'0okmnji9'+
'-@:.,lp+'+
#0#0'='#0'/;*£'+
#0#0#0#0#0#0#13#8+
'"'#0#0#0#0#0#0'!'+
'$'#0#0#0#0#0#0'#'+
'&'#0#0#0#0#0#0'%'+
'('#0#0#0#0#0#0''''+
'0'#0#0#0#0#0#0')'+
'_'#0'[><l'#0#0+
#0#0'='#0'?]'#0#0+
#0#0#0#0#0#0#13#8;
type
TVC20 = class;
TVC20Thread = class(TThread)
private
VC20: TVC20;
protected
public
procedure Execute; override;
constructor Create(VC20Instance: TVC20);
end;
TVC20 = class(TMOS6502)
private
Thread: TVC20Thread;
TimerHandle: Integer;
LastKey: Char;
procedure BusWrite(Adr: Word; Value: Byte);
function BusRead(Adr: Word): Byte;
function KeyRead: Byte;
protected
KeyMatrix: Array[0 .. 7, 0 .. 7] of Byte;
Memory: PByte;
InterruptRequest: Boolean;
public
WndHandle: THandle;
constructor Create;
destructor Destroy; override;
procedure LoadROM(Filename: String; Addr: Word);
procedure Exec;
procedure SetKey(Key: Char; Value: Byte);
end;
implementation
uses
System.SysUtils, Winapi.Windows, WinApi.MMSystem;
{ TVC20 }
procedure TimerProcedure(TimerID, Msg: Uint; dwUser, dw1, dw2: DWORD); pascal;
var
VC20: TVC20;
begin
VC20 := TVC20(dwUser);
if VC20.Status and VC20.INTERRUPT = 0 then // if IRQ allowed then set irq
VC20.InterruptRequest := True;
end;
function TVC20.BusRead(Adr: Word): Byte;
begin
Result := Memory[Adr];
end;
procedure TVC20.BusWrite(Adr: Word; Value: Byte);
begin
// test for I/O requests
case Adr of
CIA1:
begin
// Handle keyboard reading
Memory[Adr] := Value;
Memory[CIA1 + 1] := KeyRead;
end;
CIA1 + 5: // Timer
if TimerHandle = 0 then
TimerHandle := TimeSetEvent(34, 2, @TimerProcedure, DWORD(Self), TIME_PERIODIC);
end;
if (Adr >= $2000) then // $A000 // treat anything above as ROM
Exit;
Memory[Adr] := Value;
// video RAM
if (Adr >= $1E00) and (Adr <= $1FF9) then // $400 - $07E7
PostMessage(WndHandle, WM_SCREEN_WRITE, Adr - $1E00, Value); // $400
end;
constructor TVC20.Create;
begin
inherited Create(BusRead, BusWrite);
// create 64kB memory table
GetMem(Memory, 65536);
Thread := TVC20Thread.Create(Self);
end;
destructor TVC20.Destroy;
begin
if TimerHandle <> 0 then
Timekillevent(TimerHandle);
Thread.Terminate;
Thread.WaitFor;
FreeMem(Memory);
inherited;
end;
procedure TVC20.Exec;
begin
Reset;
Thread.Start;
end;
function TVC20.KeyRead: Byte;
var
Row, Col, Cols: Byte;
begin
Result := 0;
Cols := Memory[CIA1];
for Col := 0 to 7 do
if Cols and (1 shl Col) = 0 then // a 0 indicates a column read
for Row := 0 to 7 do
if KeyMatrix[7 - Col, Row] = 1 then
Result := Result + (1 shl Row);
Result := not Result;
end;
procedure TVC20.LoadROM(Filename: String; Addr: Word);
var
Stream: TFileStream;
begin
Stream := TFileStream.Create(Filename, fmOpenRead);
try
Stream.Read(Memory[Addr], Stream.Size);
finally
Stream.Free;
end;
end;
procedure TVC20.SetKey(Key: Char; Value: Byte);
var
KeyPos: Integer;
begin
KeyPos := Pos(Key, KEY_TRANSLATION) - 1;
if KeyPos >= 0 then
begin
// always release last key on keypress
if Value = 1 then
begin
SetKey(LastKey, 0);
LastKey := Key;
end;
if KeyPos > 63 then // set right shift on/off
begin
KeyMatrix[3, 6] := Value; // 1, 4
Dec(KeyPos, 64);
end;
KeyMatrix[KeyPos mod 8, KeyPos div 8] := Value;
end;
end;
{ TVC20Thread }
constructor TVC20Thread.Create(VC20Instance: TVC20);
begin
inherited Create(True);
VC20 := VC20Instance;
end;
procedure TVC20Thread.Execute;
begin
while (not Terminated) do
begin
if VC20.InterruptRequest then
begin
VC20.InterruptRequest := False;
VC20.IRQ;
end;
VC20.Step;
Sleep(0);
end;
end;
end.