Skip to content

Commit

Permalink
#2 Cycle-based StandardCharacterMode rendering
Browse files Browse the repository at this point in the history
  • Loading branch information
@hagronnestad
hagronnestad committed Mar 29, 2020
1 parent 32facd3 commit fa0ced6
Showing 1 changed file with 65 additions and 13 deletions.
78 changes: 65 additions & 13 deletions ComputerSystems/Commodore64/VicIi.cs
View file
Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
using System;
using System.Drawing;
using Commodore64.Enums;
using Extensions.Byte;
using Extensions.Enums;

Expand All @@ -19,7 +20,8 @@ public class VicIi {
//TODO: Temporary dependency
public C64 C64;

private const byte REGISTER_SCREEN_CONTROL_0x11 = 0x11;
private const byte REGISTER_SCREEN_CONTROL_1_0x11 = 0x11;
private const byte REGISTER_SCREEN_CONTROL_2_0x16 = 0x16;
private const byte REGISTER_CURRENT_RASTER_LINE_0x12 = 0x12;
private const byte REGISTER_RASTER_LINE_IRQ_0x12 = 0x12;

Expand All @@ -36,8 +38,7 @@ public byte this[int index] {
get {
switch (index) {


case REGISTER_SCREEN_CONTROL_0x11:
case REGISTER_SCREEN_CONTROL_1_0x11:
// Bit #7 og 0x11 is set if current raster line > 255
_registers[index].SetBit(BitFlag.BIT_7, CurrentLine > 255);

Expand All @@ -55,7 +56,7 @@ public byte this[int index] {
set {
switch (index) {

case REGISTER_SCREEN_CONTROL_0x11:
case REGISTER_SCREEN_CONTROL_1_0x11:
_registers[index] = value;
UpdateRasterLineToGenerateInterruptAt();
break;
Expand All @@ -76,7 +77,7 @@ public byte this[int index] {

private void UpdateRasterLineToGenerateInterruptAt() {
_rasterLineToGenerateInterruptAt = _registers[REGISTER_RASTER_LINE_IRQ_0x12];
if (_registers[REGISTER_SCREEN_CONTROL_0x11].IsBitSet(BitFlag.BIT_7)) _rasterLineToGenerateInterruptAt += 255;
if (_registers[REGISTER_SCREEN_CONTROL_1_0x11].IsBitSet(BitFlag.BIT_7)) _rasterLineToGenerateInterruptAt += 255;
}

public enum TvSystem {
Expand Down Expand Up @@ -110,10 +111,10 @@ public enum TvSystem {
public ulong TotalCycles = 0;

// Screen control register
public bool ScreenControlRegisterScreenHeight => this[REGISTER_SCREEN_CONTROL_0x11].IsBitSet(BitFlag.BIT_3); // False = 24 rows, True = 25 rows
public bool ScreenControlRegisterScreenOffOn => this[REGISTER_SCREEN_CONTROL_0x11].IsBitSet(BitFlag.BIT_4);
public bool ScreenControlRegisterTextModeBitmapMode => this[REGISTER_SCREEN_CONTROL_0x11].IsBitSet(BitFlag.BIT_5); // False = Text mode, True = Bitmap mode
public bool ScreenControlRegisterExtendedBackgroundModeOn => this[REGISTER_SCREEN_CONTROL_0x11].IsBitSet(BitFlag.BIT_6); // True = Extended background mode on
public bool ScreenControlRegisterScreenHeight => this[REGISTER_SCREEN_CONTROL_1_0x11].IsBitSet(BitFlag.BIT_3); // False = 24 rows, True = 25 rows
public bool ScreenControlRegisterScreenOffOn => this[REGISTER_SCREEN_CONTROL_1_0x11].IsBitSet(BitFlag.BIT_4);
public bool ScreenControlRegisterTextModeBitmapMode => this[REGISTER_SCREEN_CONTROL_1_0x11].IsBitSet(BitFlag.BIT_5); // False = Text mode, True = Bitmap mode
public bool ScreenControlRegisterExtendedBackgroundModeOn => this[REGISTER_SCREEN_CONTROL_1_0x11].IsBitSet(BitFlag.BIT_6); // True = Extended background mode on

// Interrupt control register
public bool InterruptControlRegisterRasterInterruptEnabled => this[REGISTER_INTERRUPT_CONTROL_0x1A].IsBitSet(BitFlag.BIT_0);
Expand Down Expand Up @@ -161,6 +162,32 @@ public void Cycle() {

if (IsInDisplay(p) && ScreenControlRegisterScreenOffOn) {

switch (GetCurrentGraphicsMode()) {
case GraphicsMode.StandardCharacterMode:
RenderCharacterMode();
break;

case GraphicsMode.MultiColorCharacterMode:
break;

case GraphicsMode.StandardBitmapMode:
break;

case GraphicsMode.MulticolorBitmapMode:
break;

case GraphicsMode.ExtendedBackgroundColorMode:
break;

case GraphicsMode.UNOFFICIAL_ExtendedBackgroundColorMulticolorCharacterMode:
break;
case GraphicsMode.UNOFFICIAL_ExtendedBackgroundColorStandardBitmapMode:
break;
case GraphicsMode.UNOFFICIAL_ExtendedBackgroundColorMulticolorBitmapMode:
break;
default:
break;
}

} else {

Expand All @@ -185,14 +212,35 @@ public void Cycle() {
OnLastScanLine?.Invoke(this, null);

// Frame based character mode rendering
if (ScreenControlRegisterScreenOffOn) UpdateScreenBufferPixels();
//if (ScreenControlRegisterScreenOffOn) UpdateScreenBufferPixels();
}
}


TotalCycles++;
}

private void RenderCharacterMode() {
// 40 x 25 characters
var p = GetScanlinePoint();

var bgColor = Colors.FromByte((byte)(C64.Vic._registers[0x21] & 0b00001111));

var charLine = (CurrentLine - DisplayFrame.Y) / 8;
var charNumberInLine = (p.X - DisplayFrame.X) / 8;
var charNumber = charLine * 40 + charNumberInLine;

var petsciiCode = vicRead((ushort)(getScreenMemoryPointer() + charNumber));
var fgColor = Colors.FromByte((byte)(C64.Memory[C64MemoryOffsets.SCREEN_COLOR_RAM + charNumber] & 0b00001111));

var charRow = (CurrentLine - DisplayFrame.Y) % 8;
var charRowData = vicRead((ushort)(getCharacterMemoryPointer() + (petsciiCode * 8) + charRow));

for (int col = 0; col <= 7; col++) {
ScreenBufferPixels[DisplayFrame.Y + (charLine * 8) + charRow, DisplayFrame.X + (charNumberInLine * 8) + col] = charRowData.IsBitSet(7 - (BitIndex)col) ? fgColor : bgColor;
}
}

private void RenderBorder() {

var bgColor = Colors.FromByte((byte)(_registers[0x20] & 0b00001111));
Expand All @@ -203,14 +251,18 @@ private void RenderBorder() {

}

private void RenderCharacterMode() {
public GraphicsMode GetCurrentGraphicsMode() {
var ecm_bmm_r0x11_b65 = (this[REGISTER_SCREEN_CONTROL_1_0x11] >> 5) & 0b00000011;
var mcm_r0x16_b4 = (this[REGISTER_SCREEN_CONTROL_2_0x16] >> 4) & 0b00000001;

var graphicsMode = mcm_r0x16_b4 | (ecm_bmm_r0x11_b65 << 1);
return (GraphicsMode)graphicsMode;
}

private Point GetScanlinePoint() {
var p = new Point {
Y = CurrentLine,
X = (CurrentLineCycle) * 8
X = CurrentLineCycle * 8,
Y = CurrentLine
};

return p;
Expand Down

0 comments on commit fa0ced6

Please sign in to comment.