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Implementing CPX and CPY

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This commit is contained in:
AnonymusRaccoon
2020-02-28 17:23:27 +01:00
parent 7b34473e63
commit 68b82c9cda
5 changed files with 133 additions and 1 deletions
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sources/CPU/Instructions/InternalInstruction.cpp
+38
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@@ -188,4 +188,42 @@ namespace ComSquare::CPU
this->_registers.p.z = this->_registers.y == 0;
this->_registers.p.n = this->_registers.y & negativeFlag;
}
void CPU::CPX(uint24_t valueAddr)
{
unsigned value = this->_bus->read(valueAddr++);
if (this->_registers.p.x_b) {
uint8_t x = this->_registers.x;
x -= value;
this->_registers.p.z = x == 0;
this->_registers.p.n = x & 0x80u;
} else {
value += this->_bus->read(valueAddr) << 8u;
uint16_t x = this->_registers.x;
x -= value;
this->_registers.p.z = x == 0;
this->_registers.p.n = x & 0x8000u;
}
this->_registers.p.c = this->_registers.x >= value;
}
void CPU::CPY(uint24_t valueAddr)
{
unsigned value = this->_bus->read(valueAddr++);
this->_registers.p.c = this->_registers.y >= value;
if (this->_registers.p.x_b) {
uint8_t y = this->_registers.y;
y -= value;
this->_registers.p.z = y == 0;
this->_registers.p.n = y & 0x80u;
} else {
value += this->_bus->read(valueAddr) << 8u;
uint16_t y = this->_registers.y;
y -= value;
this->_registers.p.z = y == 0;
this->_registers.p.n = y & 0x8000u;
}
}
}