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[GBA] Do not draw BG tiles from outside of BG VRAM 

This was fixed by endrift in mGBA in commit
4ce9b83362
This commit is contained in:
Fabrice de Gans 2023-05-05 14:06:32 -07:00 committed by Fabrice de Gans
parent b139572424
commit fda429fc64
1 changed files with 28 additions and 7 deletions
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29
src/gba/GBAGfx.h
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@ -81,7 +81,7 @@ static inline void gfxClearArray(uint32_t* array)
static inline void gfxDrawTextScreen(uint16_t control, uint16_t hofs, uint16_t vofs, uint32_t* line)
{
uint16_t* palette = (uint16_t*)paletteRAM;
uint8_t* charBase = &vram[((control >> 2) & 0x03) * 0x4000];
const size_t charBankBaseOffset = ((control >> 2) & 0x03) * 0x4000;
uint16_t* screenBase = (uint16_t*)&vram[((control >> 8) & 0x1f) * 0x800];
uint32_t prio = ((control & 3) << 25) + 0x1000000;
int sizeX = 256;
@ -143,7 +143,18 @@ static inline void gfxDrawTextScreen(uint16_t control, uint16_t hofs, uint16_t v
if (data & 0x0800)
tileY = 7 - tileY;
uint8_t color = charBase[tile * 64 + tileY * 8 + tileX];
const size_t charBankOffset = tile * 64 + tileY * 8 + tileX;
const size_t charBankTotalOffset = charBankOffset + charBankBaseOffset;
uint8_t color;
if (charBankTotalOffset >= 0x10000) {
// Adapted from https://github.com/mgba-emu/mgba/commit/4ce9b83362ad66b1421afea7372adfc753bce97c
// Real hardware PPU uses the most recently read from background
// VRAM. This can't be easily emulated in vba-m, so we simply
// use 0 here.
color = 0;
} else {
color = vram[charBankTotalOffset];
}
line[x] = color ? (READ16LE(&palette[color]) | prio) : 0x80000000;
@ -177,13 +188,23 @@ static inline void gfxDrawTextScreen(uint16_t control, uint16_t hofs, uint16_t v
if (data & 0x0800)
tileY = 7 - tileY;
uint8_t color = charBase[(tile << 5) + (tileY << 2) + (tileX >> 1)];
const size_t charBankOffset = (tile << 5) + (tileY << 2) + (tileX >> 1);
const size_t charBankTotalOffset = charBankOffset + charBankBaseOffset;
uint8_t color;
if (charBankTotalOffset >= 0x10000) {
// Adapted from https://github.com/mgba-emu/mgba/commit/4ce9b83362ad66b1421afea7372adfc753bce97c
// Real hardware PPU uses the most recently read from background
// VRAM. This can't be easily emulated in vba-m, so we simply
// use 0 here.
color = 0;
} else {
color = vram[charBankTotalOffset];
if (tileX & 1) {
color = (color >> 4);
} else {
color &= 0x0F;
}
}
int pal = (data >> 8) & 0xF0;
line[x] = color ? (READ16LE(&palette[pal + color]) | prio) : 0x80000000;