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melonDS/src/GPU2D.cpp
Arisotura 529a690089 fix potential issues with 32bit GPU writes
2022-04-10 15:11:30 +02:00

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/*
Copyright 2016-2022 melonDS team
This file is part of melonDS.
melonDS is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your option)
any later version.
melonDS is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with melonDS. If not, see http://www.gnu.org/licenses/.
*/
#include <stdio.h>
#include <string.h>
#include "NDS.h"
#include "GPU.h"
// notes on color conversion
//
// * BLDCNT special effects are applied on 18bit colors
// -> layers are converted to 18bit before being composited
// -> 'brightness up' effect does: x = x + (63-x)*factor
// * colors are converted as follows: 18bit = 15bit * 2
// -> white comes out as 62,62,62 and not 63,63,63
// * VRAM/FIFO display modes convert colors the same way
// * 3D engine converts colors differently (18bit = 15bit * 2 + 1, except 0 = 0)
// * 'screen disabled' white is 63,63,63
// * [Gericom] bit15 is used as bottom green bit for palettes. TODO: check where this applies.
// tested on the normal BG palette and applies there
//
// for VRAM display mode, VRAM must be mapped to LCDC
//
// FIFO display mode:
// * the 'FIFO' is a circular buffer of 32 bytes (16 pixels)
// * the buffer doesn't get empty, the display controller keeps reading from it
// -> if it isn't updated, the contents will be repeated every 16 pixels
// * the write pointer is incremented when writing to the higher 16 bits of the FIFO register (0x04000068)
// * the write pointer is reset upon VBlank
// * FIFO DMA (mode 4) is triggered every 8 pixels. start bit is cleared upon VBlank.
//
// sprite blending rules
// * destination must be selected as 2nd target
// * sprite must be semitransparent or bitmap sprite
// * blending is applied instead of the selected color effect, even if it is 'none'.
// * for bitmap sprites: EVA = alpha+1, EVB = 16-EVA
// * for bitmap sprites: alpha=0 is always transparent, even if blending doesn't apply
//
// 3D blending rules
//
// 3D/3D blending seems to follow these equations:
// dstColor = srcColor*srcAlpha + dstColor*(1-srcAlpha)
// dstAlpha = max(srcAlpha, dstAlpha)
// blending isn't applied if dstAlpha is zero.
//
// 3D/2D blending rules
// * if destination selected as 2nd target:
// blending is applied instead of the selected color effect, using full 5bit alpha from 3D layer
// this even if the selected color effect is 'none'.
// apparently this works even if BG0 isn't selected as 1st target
// * if BG0 is selected as 1st target, destination not selected as 2nd target:
// brightness up/down effect is applied if selected. if blending is selected, it doesn't apply.
// * 3D layer pixels with alpha=0 are always transparent.
//
// mosaic:
// * mosaic grid starts at 0,0 regardless of the BG/sprite position
// * when changing it midframe: new X setting is applied immediately, new Y setting is applied only
// after the end of the current mosaic row (when Y counter needs reloaded)
// * for rotscaled sprites: coordinates that are inside the sprite are clamped to the sprite region
// after being transformed for mosaic
// TODO: master brightness, display capture and mainmem FIFO are separate circuitry, distinct from
// the tile renderers.
// for example these aren't affected by POWCNT GPU-disable bits.
// to model the hardware more accurately, the relevant logic should be moved to GPU.cpp.
namespace GPU2D
{
Unit::Unit(u32 num)
{
Num = num;
}
void Unit::Reset()
{
Enabled = false;
DispCnt = 0;
memset(BGCnt, 0, 4*2);
memset(BGXPos, 0, 4*2);
memset(BGYPos, 0, 4*2);
memset(BGXRef, 0, 2*4);
memset(BGYRef, 0, 2*4);
memset(BGXRefInternal, 0, 2*4);
memset(BGYRefInternal, 0, 2*4);
memset(BGRotA, 0, 2*2);
memset(BGRotB, 0, 2*2);
memset(BGRotC, 0, 2*2);
memset(BGRotD, 0, 2*2);
memset(Win0Coords, 0, 4);
memset(Win1Coords, 0, 4);
memset(WinCnt, 0, 4);
Win0Active = 0;
Win1Active = 0;
BGMosaicSize[0] = 0;
BGMosaicSize[1] = 0;
OBJMosaicSize[0] = 0;
OBJMosaicSize[1] = 0;
BGMosaicY = 0;
BGMosaicYMax = 0;
OBJMosaicY = 0;
OBJMosaicYMax = 0;
OBJMosaicYCount = 0;
BlendCnt = 0;
EVA = 16;
EVB = 0;
EVY = 0;
memset(DispFIFO, 0, 16*2);
DispFIFOReadPtr = 0;
DispFIFOWritePtr = 0;
memset(DispFIFOBuffer, 0, 256*2);
CaptureCnt = 0;
CaptureLatch = false;
MasterBrightness = 0;
}
void Unit::DoSavestate(Savestate* file)
{
file->Section((char*)(Num ? "GP2B" : "GP2A"));
file->Var32(&DispCnt);
file->VarArray(BGCnt, 4*2);
file->VarArray(BGXPos, 4*2);
file->VarArray(BGYPos, 4*2);
file->VarArray(BGXRef, 2*4);
file->VarArray(BGYRef, 2*4);
file->VarArray(BGXRefInternal, 2*4);
file->VarArray(BGYRefInternal, 2*4);
file->VarArray(BGRotA, 2*2);
file->VarArray(BGRotB, 2*2);
file->VarArray(BGRotC, 2*2);
file->VarArray(BGRotD, 2*2);
file->VarArray(Win0Coords, 4);
file->VarArray(Win1Coords, 4);
file->VarArray(WinCnt, 4);
file->VarArray(BGMosaicSize, 2);
file->VarArray(OBJMosaicSize, 2);
file->Var8(&BGMosaicY);
file->Var8(&BGMosaicYMax);
file->Var8(&OBJMosaicY);
file->Var8(&OBJMosaicYMax);
file->Var16(&BlendCnt);
file->Var16(&BlendAlpha);
file->Var8(&EVA);
file->Var8(&EVB);
file->Var8(&EVY);
file->Var16(&MasterBrightness);
if (!Num)
{
file->VarArray(DispFIFO, 16*2);
file->Var32(&DispFIFOReadPtr);
file->Var32(&DispFIFOWritePtr);
file->VarArray(DispFIFOBuffer, 256*2);
file->Var32(&CaptureCnt);
}
file->Var32(&Win0Active);
file->Var32(&Win1Active);
}
u8 Unit::Read8(u32 addr)
{
switch (addr & 0x00000FFF)
{
case 0x000: return DispCnt & 0xFF;
case 0x001: return (DispCnt >> 8) & 0xFF;
case 0x002: return (DispCnt >> 16) & 0xFF;
case 0x003: return DispCnt >> 24;
case 0x008: return BGCnt[0] & 0xFF;
case 0x009: return BGCnt[0] >> 8;
case 0x00A: return BGCnt[1] & 0xFF;
case 0x00B: return BGCnt[1] >> 8;
case 0x00C: return BGCnt[2] & 0xFF;
case 0x00D: return BGCnt[2] >> 8;
case 0x00E: return BGCnt[3] & 0xFF;
case 0x00F: return BGCnt[3] >> 8;
case 0x048: return WinCnt[0];
case 0x049: return WinCnt[1];
case 0x04A: return WinCnt[2];
case 0x04B: return WinCnt[3];
// there are games accidentally trying to read those
// those are write-only
case 0x04C:
case 0x04D: return 0;
}
printf("unknown GPU read8 %08X\n", addr);
return 0;
}
u16 Unit::Read16(u32 addr)
{
switch (addr & 0x00000FFF)
{
case 0x000: return DispCnt & 0xFFFF;
case 0x002: return DispCnt >> 16;
case 0x008: return BGCnt[0];
case 0x00A: return BGCnt[1];
case 0x00C: return BGCnt[2];
case 0x00E: return BGCnt[3];
case 0x048: return WinCnt[0] | (WinCnt[1] << 8);
case 0x04A: return WinCnt[2] | (WinCnt[3] << 8);
case 0x050: return BlendCnt;
case 0x052: return BlendAlpha;
// BLDY is write-only
case 0x064: return CaptureCnt & 0xFFFF;
case 0x066: return CaptureCnt >> 16;
case 0x06C: return MasterBrightness;
}
printf("unknown GPU read16 %08X\n", addr);
return 0;
}
u32 Unit::Read32(u32 addr)
{
switch (addr & 0x00000FFF)
{
case 0x000: return DispCnt;
case 0x064: return CaptureCnt;
}
return Read16(addr) | (Read16(addr+2) << 16);
}
void Unit::Write8(u32 addr, u8 val)
{
switch (addr & 0x00000FFF)
{
case 0x000:
DispCnt = (DispCnt & 0xFFFFFF00) | val;
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x001:
DispCnt = (DispCnt & 0xFFFF00FF) | (val << 8);
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x002:
DispCnt = (DispCnt & 0xFF00FFFF) | (val << 16);
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x003:
DispCnt = (DispCnt & 0x00FFFFFF) | (val << 24);
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x10:
if (!Num) GPU3D::SetRenderXPos((GPU3D::RenderXPos & 0xFF00) | val);
break;
case 0x11:
if (!Num) GPU3D::SetRenderXPos((GPU3D::RenderXPos & 0x00FF) | (val << 8));
break;
}
if (!Enabled) return;
switch (addr & 0x00000FFF)
{
case 0x008: BGCnt[0] = (BGCnt[0] & 0xFF00) | val; return;
case 0x009: BGCnt[0] = (BGCnt[0] & 0x00FF) | (val << 8); return;
case 0x00A: BGCnt[1] = (BGCnt[1] & 0xFF00) | val; return;
case 0x00B: BGCnt[1] = (BGCnt[1] & 0x00FF) | (val << 8); return;
case 0x00C: BGCnt[2] = (BGCnt[2] & 0xFF00) | val; return;
case 0x00D: BGCnt[2] = (BGCnt[2] & 0x00FF) | (val << 8); return;
case 0x00E: BGCnt[3] = (BGCnt[3] & 0xFF00) | val; return;
case 0x00F: BGCnt[3] = (BGCnt[3] & 0x00FF) | (val << 8); return;
case 0x010: BGXPos[0] = (BGXPos[0] & 0xFF00) | val; return;
case 0x011: BGXPos[0] = (BGXPos[0] & 0x00FF) | (val << 8); return;
case 0x012: BGYPos[0] = (BGYPos[0] & 0xFF00) | val; return;
case 0x013: BGYPos[0] = (BGYPos[0] & 0x00FF) | (val << 8); return;
case 0x014: BGXPos[1] = (BGXPos[1] & 0xFF00) | val; return;
case 0x015: BGXPos[1] = (BGXPos[1] & 0x00FF) | (val << 8); return;
case 0x016: BGYPos[1] = (BGYPos[1] & 0xFF00) | val; return;
case 0x017: BGYPos[1] = (BGYPos[1] & 0x00FF) | (val << 8); return;
case 0x018: BGXPos[2] = (BGXPos[2] & 0xFF00) | val; return;
case 0x019: BGXPos[2] = (BGXPos[2] & 0x00FF) | (val << 8); return;
case 0x01A: BGYPos[2] = (BGYPos[2] & 0xFF00) | val; return;
case 0x01B: BGYPos[2] = (BGYPos[2] & 0x00FF) | (val << 8); return;
case 0x01C: BGXPos[3] = (BGXPos[3] & 0xFF00) | val; return;
case 0x01D: BGXPos[3] = (BGXPos[3] & 0x00FF) | (val << 8); return;
case 0x01E: BGYPos[3] = (BGYPos[3] & 0xFF00) | val; return;
case 0x01F: BGYPos[3] = (BGYPos[3] & 0x00FF) | (val << 8); return;
case 0x040: Win0Coords[1] = val; return;
case 0x041: Win0Coords[0] = val; return;
case 0x042: Win1Coords[1] = val; return;
case 0x043: Win1Coords[0] = val; return;
case 0x044: Win0Coords[3] = val; return;
case 0x045: Win0Coords[2] = val; return;
case 0x046: Win1Coords[3] = val; return;
case 0x047: Win1Coords[2] = val; return;
case 0x048: WinCnt[0] = val; return;
case 0x049: WinCnt[1] = val; return;
case 0x04A: WinCnt[2] = val; return;
case 0x04B: WinCnt[3] = val; return;
case 0x04C:
BGMosaicSize[0] = val & 0xF;
BGMosaicSize[1] = val >> 4;
return;
case 0x04D:
OBJMosaicSize[0] = val & 0xF;
OBJMosaicSize[1] = val >> 4;
return;
case 0x050: BlendCnt = (BlendCnt & 0x3F00) | val; return;
case 0x051: BlendCnt = (BlendCnt & 0x00FF) | (val << 8); return;
case 0x052:
BlendAlpha = (BlendAlpha & 0x1F00) | (val & 0x1F);
EVA = val & 0x1F;
if (EVA > 16) EVA = 16;
return;
case 0x053:
BlendAlpha = (BlendAlpha & 0x001F) | ((val & 0x1F) << 8);
EVB = val & 0x1F;
if (EVB > 16) EVB = 16;
return;
case 0x054:
EVY = val & 0x1F;
if (EVY > 16) EVY = 16;
return;
}
printf("unknown GPU write8 %08X %02X\n", addr, val);
}
void Unit::Write16(u32 addr, u16 val)
{
switch (addr & 0x00000FFF)
{
case 0x000:
DispCnt = (DispCnt & 0xFFFF0000) | val;
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x002:
DispCnt = (DispCnt & 0x0000FFFF) | (val << 16);
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x010:
if (!Num) GPU3D::SetRenderXPos(val);
break;
case 0x068:
DispFIFO[DispFIFOWritePtr] = val;
return;
case 0x06A:
DispFIFO[DispFIFOWritePtr+1] = val;
DispFIFOWritePtr += 2;
DispFIFOWritePtr &= 0xF;
return;
case 0x06C: MasterBrightness = val; return;
}
if (!Enabled) return;
switch (addr & 0x00000FFF)
{
case 0x008: BGCnt[0] = val; return;
case 0x00A: BGCnt[1] = val; return;
case 0x00C: BGCnt[2] = val; return;
case 0x00E: BGCnt[3] = val; return;
case 0x010: BGXPos[0] = val; return;
case 0x012: BGYPos[0] = val; return;
case 0x014: BGXPos[1] = val; return;
case 0x016: BGYPos[1] = val; return;
case 0x018: BGXPos[2] = val; return;
case 0x01A: BGYPos[2] = val; return;
case 0x01C: BGXPos[3] = val; return;
case 0x01E: BGYPos[3] = val; return;
case 0x020: BGRotA[0] = val; return;
case 0x022: BGRotB[0] = val; return;
case 0x024: BGRotC[0] = val; return;
case 0x026: BGRotD[0] = val; return;
case 0x028:
BGXRef[0] = (BGXRef[0] & 0xFFFF0000) | val;
if (GPU::VCount < 192) BGXRefInternal[0] = BGXRef[0];
return;
case 0x02A:
if (val & 0x0800) val |= 0xF000;
BGXRef[0] = (BGXRef[0] & 0xFFFF) | (val << 16);
if (GPU::VCount < 192) BGXRefInternal[0] = BGXRef[0];
return;
case 0x02C:
BGYRef[0] = (BGYRef[0] & 0xFFFF0000) | val;
if (GPU::VCount < 192) BGYRefInternal[0] = BGYRef[0];
return;
case 0x02E:
if (val & 0x0800) val |= 0xF000;
BGYRef[0] = (BGYRef[0] & 0xFFFF) | (val << 16);
if (GPU::VCount < 192) BGYRefInternal[0] = BGYRef[0];
return;
case 0x030: BGRotA[1] = val; return;
case 0x032: BGRotB[1] = val; return;
case 0x034: BGRotC[1] = val; return;
case 0x036: BGRotD[1] = val; return;
case 0x038:
BGXRef[1] = (BGXRef[1] & 0xFFFF0000) | val;
if (GPU::VCount < 192) BGXRefInternal[1] = BGXRef[1];
return;
case 0x03A:
if (val & 0x0800) val |= 0xF000;
BGXRef[1] = (BGXRef[1] & 0xFFFF) | (val << 16);
if (GPU::VCount < 192) BGXRefInternal[1] = BGXRef[1];
return;
case 0x03C:
BGYRef[1] = (BGYRef[1] & 0xFFFF0000) | val;
if (GPU::VCount < 192) BGYRefInternal[1] = BGYRef[1];
return;
case 0x03E:
if (val & 0x0800) val |= 0xF000;
BGYRef[1] = (BGYRef[1] & 0xFFFF) | (val << 16);
if (GPU::VCount < 192) BGYRefInternal[1] = BGYRef[1];
return;
case 0x040:
Win0Coords[1] = val & 0xFF;
Win0Coords[0] = val >> 8;
return;
case 0x042:
Win1Coords[1] = val & 0xFF;
Win1Coords[0] = val >> 8;
return;
case 0x044:
Win0Coords[3] = val & 0xFF;
Win0Coords[2] = val >> 8;
return;
case 0x046:
Win1Coords[3] = val & 0xFF;
Win1Coords[2] = val >> 8;
return;
case 0x048:
WinCnt[0] = val & 0xFF;
WinCnt[1] = val >> 8;
return;
case 0x04A:
WinCnt[2] = val & 0xFF;
WinCnt[3] = val >> 8;
return;
case 0x04C:
BGMosaicSize[0] = val & 0xF;
BGMosaicSize[1] = (val >> 4) & 0xF;
OBJMosaicSize[0] = (val >> 8) & 0xF;
OBJMosaicSize[1] = val >> 12;
return;
case 0x050: BlendCnt = val & 0x3FFF; return;
case 0x052:
BlendAlpha = val & 0x1F1F;
EVA = val & 0x1F;
if (EVA > 16) EVA = 16;
EVB = (val >> 8) & 0x1F;
if (EVB > 16) EVB = 16;
return;
case 0x054:
EVY = val & 0x1F;
if (EVY > 16) EVY = 16;
return;
}
//printf("unknown GPU write16 %08X %04X\n", addr, val);
}
void Unit::Write32(u32 addr, u32 val)
{
switch (addr & 0x00000FFF)
{
case 0x000:
DispCnt = val;
if (Num) DispCnt &= 0xC0B1FFF7;
return;
case 0x064:
CaptureCnt = val & 0xEF3F1F1F;
return;
case 0x068:
DispFIFO[DispFIFOWritePtr] = val & 0xFFFF;
DispFIFO[DispFIFOWritePtr+1] = val >> 16;
DispFIFOWritePtr += 2;
DispFIFOWritePtr &= 0xF;
return;
}
if (Enabled)
{
switch (addr & 0x00000FFF)
{
case 0x028:
if (val & 0x08000000) val |= 0xF0000000;
BGXRef[0] = val;
if (GPU::VCount < 192) BGXRefInternal[0] = BGXRef[0];
return;
case 0x02C:
if (val & 0x08000000) val |= 0xF0000000;
BGYRef[0] = val;
if (GPU::VCount < 192) BGYRefInternal[0] = BGYRef[0];
return;
case 0x038:
if (val & 0x08000000) val |= 0xF0000000;
BGXRef[1] = val;
if (GPU::VCount < 192) BGXRefInternal[1] = BGXRef[1];
return;
case 0x03C:
if (val & 0x08000000) val |= 0xF0000000;
BGYRef[1] = val;
if (GPU::VCount < 192) BGYRefInternal[1] = BGYRef[1];
return;
}
}
Write16(addr, val&0xFFFF);
Write16(addr+2, val>>16);
}
void Unit::UpdateMosaicCounters(u32 line)
{
// Y mosaic uses incrementing 4-bit counters
// the transformed Y position is updated every time the counter matches the MOSAIC register
if (OBJMosaicYCount == OBJMosaicSize[1])
{
OBJMosaicYCount = 0;
OBJMosaicY = line + 1;
}
else
{
OBJMosaicYCount++;
OBJMosaicYCount &= 0xF;
}
}
void Unit::VBlank()
{
if (CaptureLatch)
{
CaptureCnt &= ~(1<<31);
CaptureLatch = false;
}
DispFIFOReadPtr = 0;
DispFIFOWritePtr = 0;
}
void Unit::VBlankEnd()
{
// TODO: find out the exact time this happens
BGXRefInternal[0] = BGXRef[0];
BGXRefInternal[1] = BGXRef[1];
BGYRefInternal[0] = BGYRef[0];
BGYRefInternal[1] = BGYRef[1];
BGMosaicY = 0;
BGMosaicYMax = BGMosaicSize[1];
//OBJMosaicY = 0;
//OBJMosaicYMax = OBJMosaicSize[1];
//OBJMosaicY = 0;
//OBJMosaicYCount = 0;
}
void Unit::SampleFIFO(u32 offset, u32 num)
{
for (u32 i = 0; i < num; i++)
{
u16 val = DispFIFO[DispFIFOReadPtr];
DispFIFOReadPtr++;
DispFIFOReadPtr &= 0xF;
DispFIFOBuffer[offset+i] = val;
}
}
u16* Unit::GetBGExtPal(u32 slot, u32 pal)
{
const u32 PaletteSize = 256 * 2;
const u32 SlotSize = PaletteSize * 16;
return (u16*)&(Num == 0
? GPU::VRAMFlat_ABGExtPal
: GPU::VRAMFlat_BBGExtPal)[slot * SlotSize + pal * PaletteSize];
}
u16* Unit::GetOBJExtPal()
{
return Num == 0
? (u16*)GPU::VRAMFlat_AOBJExtPal
: (u16*)GPU::VRAMFlat_BOBJExtPal;
}
void Unit::CheckWindows(u32 line)
{
line &= 0xFF;
if (line == Win0Coords[3]) Win0Active &= ~0x1;
else if (line == Win0Coords[2]) Win0Active |= 0x1;
if (line == Win1Coords[3]) Win1Active &= ~0x1;
else if (line == Win1Coords[2]) Win1Active |= 0x1;
}
void Unit::CalculateWindowMask(u32 line, u8* windowMask, u8* objWindow)
{
for (u32 i = 0; i < 256; i++)
windowMask[i] = WinCnt[2]; // window outside
if (DispCnt & (1<<15))
{
// OBJ window
for (int i = 0; i < 256; i++)
{
if (objWindow[i])
windowMask[i] = WinCnt[3];
}
}
if (DispCnt & (1<<14))
{
// window 1
u8 x1 = Win1Coords[0];
u8 x2 = Win1Coords[1];
for (int i = 0; i < 256; i++)
{
if (i == x2) Win1Active &= ~0x2;
else if (i == x1) Win1Active |= 0x2;
if (Win1Active == 0x3) windowMask[i] = WinCnt[1];
}
}
if (DispCnt & (1<<13))
{
// window 0
u8 x1 = Win0Coords[0];
u8 x2 = Win0Coords[1];
for (int i = 0; i < 256; i++)
{
if (i == x2) Win0Active &= ~0x2;
else if (i == x1) Win0Active |= 0x2;
if (Win0Active == 0x3) windowMask[i] = WinCnt[0];
}
}
}
void Unit::GetBGVRAM(u8*& data, u32& mask)
{
if (Num == 0)
{
data = GPU::VRAMFlat_ABG;
mask = 0x7FFFF;
}
else
{
data = GPU::VRAMFlat_BBG;
mask = 0x1FFFF;
}
}
void Unit::GetOBJVRAM(u8*& data, u32& mask)
{
if (Num == 0)
{
data = GPU::VRAMFlat_AOBJ;
mask = 0x3FFFF;
}
else
{
data = GPU::VRAMFlat_BOBJ;
mask = 0x1FFFF;
}
}
}
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