zoriya/ComSquare
1
0
Fork 0
mirror of https://github.com/zoriya/ComSquare.git synced 2026-05-25 15:39:28 +00:00
Code Issues Packages Projects Releases Wiki Activity

Implementing the ORA

Browse Source
This commit is contained in:
Anonymus Raccoon
2020-04-03 15:51:35 +02:00
parent 8e7d28dc4d
commit d73d570139
2 changed files with 50 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
sources/CPU/Instructions/MathematicalOperations.cpp
+33
View File
@@ -91,6 +91,39 @@ namespace ComSquare::CPU
return cycles;
}
int CPU::ORA(uint24_t valueAddr, AddressingMode mode)
{
unsigned negativeMask = this->_registers.p.m ? 0x80u : 0x8000u;
unsigned value = this->_bus->read(valueAddr);
if (!this->_registers.p.m)
value += this->_bus->read(valueAddr + 1) << 8u;
this->_registers.a |= value;
this->_registers.p.z = this->_registers.a == 0;
this->_registers.p.n = this->_registers.a & negativeMask;
int cycles = !this->_registers.p.m;
switch (mode) {
case DirectPage:
case DirectPageIndirect:
case DirectPageIndirectLong:
case DirectPageIndexedByX:
case DirectPageIndirectIndexedByX:
case DirectPageIndirectIndexedByYLong:
cycles += this->_registers.dl != 0;
break;
case AbsoluteIndexedByX:
case AbsoluteIndexedByY:
cycles += this->_hasIndexCrossedPageBoundary;
break;
case DirectPageIndirectIndexedByY:
cycles += this->_registers.dl != 0 + this->_hasIndexCrossedPageBoundary;
break;
default:
break;
}
return cycles;
}
int CPU::DEX(uint24_t, AddressingMode)
{
unsigned negativeMask = this->_registers.p.x_b ? 0x80 : 0x8000;