YayIguess/GBpp
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minor bug squishing

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This commit is contained in:
Braiden Gent
2024-02-05 21:40:41 -08:00
parent e8d8c0fb3d
commit d677ca9934
3 changed files with 22 additions and 20 deletions
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4
src/defines.hpp
View File

@@ -37,8 +37,8 @@
#define SCANLINE_DURATION 456
#define FRAME_DURATION 70224
#define MODE2_DURATION 80
#define MODE3_BASE_DURATION 168
#define MODE0_3_DURATION 376 //mode3 is 168 to 291, mode0 85 to 208
#define MODE3_MIN_DURATION 172
#define MODE0_3_DURATION 376 //mode3 is 172 to 289, mode0 87 to 204
#define MODE1_DURATION 4560
#define H_SYNC 9198

1
src/gameboy.hpp
View File

@@ -188,6 +188,7 @@ class GameBoy {
SDL_Event event;
void opcodeHandler();
void incLY();
void ppuUpdate();
void drawLine();
void SDL2present();

37
src/ppu.cpp
View File

@@ -20,13 +20,11 @@ void GameBoy::ppuUpdate() {
Byte mode = (*STAT) & 0x03;
switch (mode) {
case 0:
if (cyclesSinceLastScanline() > MODE2_DURATION + MODE3_BASE_DURATION) {
if (cyclesSinceLastScanline() > MODE2_DURATION + MODE3_MIN_DURATION) {
drawLine();
cyclesToStayInHblank = SCANLINE_DURATION - cyclesSinceLastScanline();
lastScanline = cycles;
(*LY)++;
if ((*LY) > 153)
(*LY) = 0;
incLY();
}
currentMode = PPUMode::mode0;
break;
@@ -35,14 +33,11 @@ void GameBoy::ppuUpdate() {
case 1:
if (currentMode != PPUMode::mode1) {
setPPUMode(PPUMode::mode1);
//drawLine();
*IF |= 0x1;
}
if (cyclesSinceLastScanline() > SCANLINE_DURATION) {
lastScanline = cycles;
(*LY)++;
if ((*LY) > 153)
(*LY) = 0;
incLY();
}
currentMode = PPUMode::mode1;
break;
@@ -55,8 +50,8 @@ void GameBoy::ppuUpdate() {
}
if ((*LY) == (*LYC) || (*STAT) & (1 << 6)) {
// Request STAT interrupt if LY matches LYC
//bug on DMG models triggers a STAT interrupt anytime the STAT register is written
//Road Rage and Zerd no Denetsu rely on this
// bug on DMG models triggers a STAT interrupt anytime the STAT register is written
// Road Rage and Zerd no Denetsu rely on this
(*STAT) |= (1 << 2);
} else {
(*STAT) &= ~(1 << 2);
@@ -74,31 +69,37 @@ void GameBoy::ppuUpdate() {
}
}
void GameBoy::incLY() {
(*LY)++;
if ((*LY) > 153)
(*LY) = 0;
}
uint32_t GameBoy::cyclesSinceLastScanline() {
uint32_t difference = cycles - lastScanline;
const uint32_t difference = cycles - lastScanline;
return difference;
}
uint32_t GameBoy::cyclesSinceLastRefresh() {
uint32_t difference = cycles - lastRefresh;
const uint32_t difference = cycles - lastRefresh;
return difference;
}
void GameBoy::checkPPUMode() {
int oamFetchTime = 0;
uint32_t oamFetchTime = 0;
if ((*LY) < 144) {
uint32_t currentDuration = cyclesSinceLastScanline();
const uint32_t currentDuration = cyclesSinceLastScanline();
// Active Display Period (HBlank, OAM Search, and Pixel Transfer)
if (currentDuration < MODE2_DURATION)
setPPUMode(PPUMode::mode2);
else if (currentDuration < MODE2_DURATION + MODE3_BASE_DURATION + oamFetchTime)
else if (currentDuration < MODE2_DURATION + MODE3_MIN_DURATION + oamFetchTime)
setPPUMode(PPUMode::mode3);
else
setPPUMode(PPUMode::mode0);
}
// VBlank Period
else
} else {
// VBlank Period
setPPUMode(PPUMode::mode1);
}
}
void GameBoy::setPPUMode(PPUMode mode) {