128 lines
4.9 KiB
C#
128 lines
4.9 KiB
C#
using Core.Memory;
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using System;
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namespace Core.Io
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{
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public class ULA
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{
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private readonly MemoryBus _memoryBus;
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private readonly IO_Bus _simpleIoBus;
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// The ULA owns the frame buffer now!
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public const int ScreenWidth = 320;
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public const int ScreenHeight = 256; // Perfectly cropped size
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public int[] FrameBuffer { get; private set; }
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private int _ulaFrameCount = 0;
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// The hardware color palette belongs to the ULA, not the Windows Form!
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private readonly int[] SpectrumColors = new int[]
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{
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unchecked((int)0xFF000000), unchecked((int)0xFF0000D7),
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unchecked((int)0xFFD70000), unchecked((int)0xFFD700D7),
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unchecked((int)0xFF00D700), unchecked((int)0xFF00D7D7),
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unchecked((int)0xFFD7D700), unchecked((int)0xFFD7D7D7),
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unchecked((int)0xFF000000), unchecked((int)0xFF0000FF),
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unchecked((int)0xFFFF0000), unchecked((int)0xFFFF00FF),
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unchecked((int)0xFF00FF00), unchecked((int)0xFF00FFFF),
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unchecked((int)0xFFFFFF00), unchecked((int)0xFFFFFFFF)
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};
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public ULA(MemoryBus memoryBus, IO_Bus ioBus)
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{
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_memoryBus = memoryBus;
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_simpleIoBus = ioBus;
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FrameBuffer = new int[ScreenWidth * ScreenHeight];
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}
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// We will wire this up to the Z80 in Phase 3 so the CPU stays system-agnostic!
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public int GetContentionDelay(ushort address, long currentTStates)
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{
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if (address < 0x4000 || address > 0x7FFF) return 0;
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long frameT = currentTStates % 69888;
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if (frameT < 14336 || frameT >= 57344) return 0;
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int lineT = (int)(frameT % 224);
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if (lineT < 14 || lineT > 141) return 0;
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int delayOffset = (lineT - 14) % 8;
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int[] delayPattern = { 6, 5, 4, 3, 2, 1, 0, 0 };
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return delayPattern[delayOffset];
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}
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// The perfectly cropped, 320x256 Scanline Renderer
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public void RenderScanline(int scanline)
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{
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// 1. Drop the invisible lines instantly (VBlank/Overscan)
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if (scanline < 32 || scanline > 287) return;
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// 2. Calculate our visual Y coordinate (0 to 255) for the bitmap array
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int renderY = scanline - 32;
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int currentBorderColor = SpectrumColors[_simpleIoBus.BorderColorIndex];
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// --- Are we in the Top or Bottom Border? ---
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if (scanline < 64 || scanline > 255)
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{
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int yOffset = renderY * ScreenWidth;
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for (int x = 0; x < ScreenWidth; x++)
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{
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FrameBuffer[yOffset + x] = currentBorderColor;
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}
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return;
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}
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// --- We are in the Visible Display Area (Lines 64 to 255) ---
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int y = scanline - 64;
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// Handle Flash Phase (only increment once per frame when y == 0)
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if (y == 0) _ulaFrameCount++;
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bool invertFlashPhase = (_ulaFrameCount % 32) >= 16;
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int rowStartIndex = renderY * ScreenWidth;
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// Draw the 32 pixels of left border
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for (int b = 0; b < 32; b++) FrameBuffer[rowStartIndex + b] = currentBorderColor;
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int third = y / 64;
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int characterRow = (y % 64) / 8;
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int pixelRow = y % 8;
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// Draw the 32 horizontal character blocks of the visible screen
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for (int col = 0; col < 32; col++)
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{
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ushort pixelAddress = (ushort)(0x4000 | (third << 11) | (pixelRow << 8) | (characterRow << 5) | col);
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ushort attrAddress = (ushort)(0x5800 + (y / 8) * 32 + col);
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byte pixels = _memoryBus.Read(pixelAddress);
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byte attr = _memoryBus.Read(attrAddress);
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int ink = attr & 0x07;
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int paper = (attr >> 3) & 0x07;
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int brightOffset = (attr & 0x40) != 0 ? 8 : 0;
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bool isFlashSet = (attr & 0x80) != 0;
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int inkColor = SpectrumColors[ink + brightOffset];
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int paperColor = SpectrumColors[paper + brightOffset];
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if (isFlashSet && invertFlashPhase)
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{
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int temp = inkColor; inkColor = paperColor; paperColor = temp;
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}
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// Draw the 8 pixels in this block
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for (int bit = 0; bit < 8; bit++)
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{
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bool isPixelSet = (pixels & (1 << (7 - bit))) != 0;
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int renderX = 32 + (col * 8) + bit;
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FrameBuffer[rowStartIndex + renderX] = isPixelSet ? inkColor : paperColor;
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}
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}
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// Draw the 32 pixels of right border
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for (int b = ScreenWidth - 32; b < ScreenWidth; b++)
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{
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FrameBuffer[rowStartIndex + b] = currentBorderColor;
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}
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}
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}
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} |