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Starting to implement addressing modes

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This commit is contained in:
AnonymusRaccoon
2020-02-07 18:56:24 +01:00
parent 36d615ba64
commit fc94563b41
2 changed files with 75 additions and 6 deletions
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sources/CPU/CPU.cpp
+60 -2
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@@ -195,18 +195,66 @@ namespace ComSquare::CPU
int CPU::executeInstruction()
{
uint8_t opcode = this->_bus->read(this->_registers.pc++);
uint8_t opcode = this->_bus->read(this->_registers.pc);
switch (opcode) {
case 0x0: return this->BRK();
case 0x0:
return this->BRK();
case 0x61:
case 0x63:
case 0x65:
case 0x67:
case 0x69:
case 0x6D:
case 0x6F:
case 0x71:
case 0x72:
case 0x73:
case 0x75:
case 0x77:
case 0x79:
case 0x7D:
case 0x7F:
return this->ADC();
default:
throw InvalidOpcode("CPU", opcode);
}
}
////////////////////////////////////////////////////////////////////
/// Addressing modes
////////////////////////////////////////////////////////////////////
uint24_t CPU::_GetImmediateAddr()
{
return this->_registers.pc++;
}
uint24_t CPU::_GetDirectAddr()
{
uint8_t addr = this->_bus->read(this->_registers.pc++);
return this->_registers.d + addr;
}
uint24_t CPU::_GetAbsoluteAddr()
{
uint24_t addr = this->_registers.dbr << 16u;
addr += this->_bus->read(this->_registers.pc++) << 8u;
addr += this->_bus->read(this->_registers.pc++);
return addr;
}
uint24_t CPU::_GetAbsoluteLongAddr()
{
return 0;
}
int CPU::BRK()
{
this->_registers.pc += 2;
this->_registers.p.i = true;
if (this->_isEmulationMode)
this->_registers.pc = this->_cartridgeHeader.emulationInterrupts.brk;
@@ -215,4 +263,14 @@ namespace ComSquare::CPU
this->_registers.p.d = false;
return 7 + !this->_isEmulationMode;
}
////////////////////////////////////////////////////////////////////
/// Mathematical operations
////////////////////////////////////////////////////////////////////
int CPU::ADC()
{
// this->_registers.a +=
}
}