Fix zero-page address mask

drhelius · drhelius · commit c33f9c5cee43 · 2026-03-05T15:04:55.000+01:00
diff --git a/src/m6502_inline.h b/src/m6502_inline.h
@@ -313,17 +313,17 @@ INLINE u16 M6502::ZeroPageIndirectAddressing()
 
 INLINE u16 M6502::ZeroPageIndexedIndirectAddressing()
 {
-    u16 address = (ZeroPageAddressing() + m_s.X.GetValue()) & 0x20FF;
+    u16 address = (ZeroPageAddressing() + m_s.X.GetValue()) & 0x00FF;
     u8 l = MemRead8(address);
-    u8 h = MemRead8((address + 1) & 0x20FF);
+    u8 h = MemRead8((address + 1) & 0x00FF);
     return Address16(h, l);
 }
 
 INLINE u16 M6502::ZeroPageIndirectIndexedAddressing()
 {
     u16 address = ZeroPageAddressing();
     u8 l = MemRead8(address);
-    u8 h = MemRead8((address + 1) & 0x20FF);
+    u8 h = MemRead8((address + 1) & 0x00FF);
     return Address16(h, l) + m_s.Y.GetValue();
 }
 

Original file line number	Diff line number	Diff line change
`@@ -313,17 +313,17 @@ INLINE u16 M6502::ZeroPageIndirectAddressing()`
`313`	`313`
`314`	`314`	`INLINE u16 M6502::ZeroPageIndexedIndirectAddressing()`
`315`	`315`	`{`
`316`		`- u16 address = (ZeroPageAddressing() + m_s.X.GetValue()) & 0x20FF;`
	`316`	`+ u16 address = (ZeroPageAddressing() + m_s.X.GetValue()) & 0x00FF;`
`317`	`317`	`u8 l = MemRead8(address);`
`318`		`- u8 h = MemRead8((address + 1) & 0x20FF);`
	`318`	`+ u8 h = MemRead8((address + 1) & 0x00FF);`
`319`	`319`	`return Address16(h, l);`
`320`	`320`	`}`
`321`	`321`
`322`	`322`	`INLINE u16 M6502::ZeroPageIndirectIndexedAddressing()`
`323`	`323`	`{`
`324`	`324`	`u16 address = ZeroPageAddressing();`
`325`	`325`	`u8 l = MemRead8(address);`
`326`		`- u8 h = MemRead8((address + 1) & 0x20FF);`
	`326`	`+ u8 h = MemRead8((address + 1) & 0x00FF);`
`327`	`327`	`return Address16(h, l) + m_s.Y.GetValue();`
`328`	`328`	`}`
`329`	`329`