Made actual GHDMA source and dest registers increment during transfer…

…, instead of copies - fixes #2 , #23 , #24 , #25 , #26
MeGaL0DoN · Feb 4, 2025 · 01858ad · 01858ad
1 parent e77ed76
commit 01858ad
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Showing 2 changed files with 3 additions and 9 deletions.
diff --git a/src/MMU.cpp b/src/MMU.cpp
@@ -136,7 +136,7 @@ void MMU::executeGHDMA()
 		gbc.ghdma.transferLength -= 0x10;
 
 		for (int i = 0; i < 0x10; i++)
-			gb.ppu->VRAM[gbc.ghdma.currentDestAddr++] = (this->*read_func)(gbc.ghdma.currentSourceAddr++);
+			gb.ppu->VRAM[(gbc.ghdma.destAddr++) & 0x1FFF] = (this->*read_func)(gbc.ghdma.sourceAddr++);
 
 		if (gbc.ghdma.transferLength == 0)
 		{
@@ -333,15 +333,15 @@ void MMU::write8(uint16_t addr, uint8_t val)
 			break;
 		case 0xFF52:
 			if constexpr (sys == GBSystem::CGB)
-				gbc.ghdma.sourceAddr = (gbc.ghdma.sourceAddr & 0xFF00) | val;
+				gbc.ghdma.sourceAddr = (gbc.ghdma.sourceAddr & 0xFF00) | (val & 0xF0);
 			break;
 		case 0xFF53:
 			if constexpr (sys == GBSystem::CGB)
 				gbc.ghdma.destAddr = (gbc.ghdma.destAddr & 0x00FF) | (val << 8);
 			break;
 		case 0xFF54:
 			if constexpr (sys == GBSystem::CGB)
-				gbc.ghdma.destAddr = (gbc.ghdma.destAddr & 0xFF00) | val;
+				gbc.ghdma.destAddr = (gbc.ghdma.destAddr & 0xFF00) | (val & 0xF0);
 			break;
 		case 0xFF55:
 			if constexpr (sys == GBSystem::CGB)
@@ -353,9 +353,6 @@ void MMU::write8(uint16_t addr, uint8_t val)
 				}
 				else
 				{
-					gbc.ghdma.currentSourceAddr = gbc.ghdma.sourceAddr & 0xFFF0;
-					gbc.ghdma.currentDestAddr = gbc.ghdma.destAddr & 0x1FF0; // ignore 3 upper bits too, because destination is always in VRAM
-
 					gbc.ghdma.transferLength = ((val & 0x7F) + 1) * 0x10;
 					gbc.ghdma.cycles = 0;
 

diff --git a/src/MMU.h b/src/MMU.h
@@ -52,9 +52,6 @@ class MMU
 		uint16_t sourceAddr{ 0xFF };
 		uint16_t destAddr{ 0xFF };
 
-		uint16_t currentSourceAddr{ 0x00 };
-		uint16_t currentDestAddr { 0x00 };
-
 		uint16_t transferLength{ 0xFF };
 		uint8_t cycles{ 0x00 };
 		GHDMAStatus status { GHDMAStatus::None };