144 lines
4.9 KiB
C#
144 lines
4.9 KiB
C#
using Codice.CM.Client.Differences;
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using System;
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namespace VirtualNes.Core
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{
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public class PPU
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{
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// PPU Control Register #1 PPU #0
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public const byte PPU_VBLANK_BIT = 0x80;
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public const byte PPU_SPHIT_BIT = 0x40; // 堘偆丠
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public const byte PPU_SP16_BIT = 0x20;
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public const byte PPU_BGTBL_BIT = 0x10;
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public const byte PPU_SPTBL_BIT = 0x08;
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public const byte PPU_INC32_BIT = 0x04;
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public const byte PPU_NAMETBL_BIT = 0x03;
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// PPU Control Register #2 PPU #1
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public const byte PPU_BGCOLOR_BIT = 0xE0;
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public const byte PPU_SPDISP_BIT = 0x10;
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public const byte PPU_BGDISP_BIT = 0x08;
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public const byte PPU_SPCLIP_BIT = 0x04;
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public const byte PPU_BGCLIP_BIT = 0x02;
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public const byte PPU_COLORMODE_BIT = 0x01;
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// PPU Status Register PPU #2
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public const byte PPU_VBLANK_FLAG = 0x80;
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public const byte PPU_SPHIT_FLAG = 0x40;
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public const byte PPU_SPMAX_FLAG = 0x20;
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public const byte PPU_WENABLE_FLAG = 0x10;
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// SPRITE Attribute
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public const byte SP_VMIRROR_BIT = 0x80;
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public const byte SP_HMIRROR_BIT = 0x40;
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public const byte SP_PRIORITY_BIT = 0x20;
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public const byte SP_COLOR_BIT = 0x03;
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private NES m_nes;
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private byte[] lpScreen;
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private byte[] lpColormode;
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private bool bVSMode;
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private int nVSColorMap;
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private byte VSSecurityData;
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private byte[] Bit2Rev = new byte[256];
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private int ScanlineNo;
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/// <summary> 作为lpScreen数组的索引 </summary>
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private int lpScanline;
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public PPU(NES nes)
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{
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m_nes = nes;
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lpScreen = null;
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lpColormode = null;
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bVSMode = false;
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nVSColorMap = -1;
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VSSecurityData = 0;
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for (int i = 0; i < 256; i++)
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{
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byte m = 0x80;
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byte c = 0;
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for (int j = 0; j < 8; j++)
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{
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if ((i & (1 << j)) > 0) c |= m;
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m >>= 1;
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}
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Bit2Rev[i] = c;
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}
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}
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public void Dispose()
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{
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}
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internal byte Read(ushort addr)
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{
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byte data = 0x00;
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switch (addr)
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{
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// Write only Register
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case 0x2000: // PPU Control Register #1(W)
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case 0x2001: // PPU Control Register #2(W)
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case 0x2003: // SPR-RAM Address Register(W)
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case 0x2005: // PPU Scroll Register(W2)
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case 0x2006: // VRAM Address Register(W2)
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data = MMU.PPU7_Temp; // 懡暘
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break;
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// Read/Write Register
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case 0x2002: // PPU Status Register(R)
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//DEBUGOUT( "2002 RD L:%3d C:%8d\n", ScanlineNo, nes->cpu->GetTotalCycles() );
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data = (byte)(MMU.PPUREG[2] | VSSecurityData);
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MMU.PPU56Toggle = 0;
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byte temp = unchecked((byte)~PPU_VBLANK_FLAG);
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MMU.PPUREG[2] &= temp;
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break;
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case 0x2004: // SPR_RAM I/O Register(RW)
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data = MMU.SPRAM[MMU.PPUREG[3]++];
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break;
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case 0x2007: // VRAM I/O Register(RW)
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addr = (ushort)(MMU.loopy_v & 0x3FFF);
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data = MMU.PPU7_Temp;
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if ((MMU.PPUREG[0] & PPU_INC32_BIT) != 0) MMU.loopy_v += 32;
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else MMU.loopy_v++;
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if (addr >= 0x3000)
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{
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if (addr >= 0x3F00)
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{
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// data &= 0x3F;
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if ((addr & 0x0010) == 0)
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{
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return MMU.BGPAL[addr & 0x000F];
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}
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else
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{
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return MMU.SPPAL[addr & 0x000F];
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}
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}
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addr &= 0xEFFF;
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}
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MMU.PPU7_Temp = MMU.PPU_MEM_BANK[addr >> 10][addr & 0x03FF];
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break;
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}
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return data;
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}
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internal void SetRenderScanline(int scanline)
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{
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ScanlineNo = scanline;
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if (scanline < 240)
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{
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lpScanline = (int)(Screen.SCREEN_WIDTH) * scanline;
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}
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}
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private enum Screen
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{
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SCREEN_WIDTH = 256 + 16,
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SCREEN_HEIGHT = 240
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}
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}
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}
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