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package cpu
func ldaExec(c *CPU, op operand) { c.A = c.operandValue(op); c.setZN(c.A) }
func ldxExec(c *CPU, op operand) { c.X = c.operandValue(op); c.setZN(c.X) }
func ldyExec(c *CPU, op operand) { c.Y = c.operandValue(op); c.setZN(c.Y) }
func staExec(c *CPU, op operand) { c.write(op.addr, c.A) }
func stxExec(c *CPU, op operand) { c.write(op.addr, c.X) }
func styExec(c *CPU, op operand) { c.write(op.addr, c.Y) }
func taxExec(c *CPU, op operand) { c.X = c.A; c.setZN(c.X) }
func txaExec(c *CPU, op operand) { c.A = c.X; c.setZN(c.A) }
func tayExec(c *CPU, op operand) { c.Y = c.A; c.setZN(c.Y) }
func tyaExec(c *CPU, op operand) { c.A = c.Y; c.setZN(c.A) }
func tsxExec(c *CPU, op operand) { c.X = c.SP; c.setZN(c.X) }
func txsExec(c *CPU, op operand) { c.SP = c.X } // no flags affected
func phaExec(c *CPU, op operand) { c.push(c.A) }
func plaExec(c *CPU, op operand) { c.A = c.pop(); c.setZN(c.A) }
func phpExec(c *CPU, op operand) { c.push(c.Status | FlagB | FlagU) }
func plpExec(c *CPU, op operand) {
pulled := c.pop()
c.Status = (pulled &^ FlagB) | FlagU
}
func (c *CPU) addWithCarry(v uint8) {
var carryIn uint16
if c.flag(FlagC) {
carryIn = 1
}
sum := uint16(c.A) + uint16(v) + carryIn
result := uint8(sum)
c.setFlag(FlagC, sum > 0xFF)
c.setFlag(FlagV, (c.A^v)&0x80 == 0 && (c.A^result)&0x80 != 0)
c.A = result
c.setZN(c.A)
}
func adcExec(c *CPU, op operand) { c.addWithCarry(c.operandValue(op)) }
func sbcExec(c *CPU, op operand) { c.addWithCarry(^c.operandValue(op)) }
func andExec(c *CPU, op operand) { c.A &= c.operandValue(op); c.setZN(c.A) }
func oraExec(c *CPU, op operand) { c.A |= c.operandValue(op); c.setZN(c.A) }
func eorExec(c *CPU, op operand) { c.A ^= c.operandValue(op); c.setZN(c.A) }
func bitExec(c *CPU, op operand) {
v := c.operandValue(op)
c.setFlag(FlagZ, c.A&v == 0)
c.setFlag(FlagV, v&0x40 != 0)
c.setFlag(FlagN, v&0x80 != 0)
}
func aslExec(c *CPU, op operand) {
v := c.operandValue(op)
c.setFlag(FlagC, v&0x80 != 0)
result := v << 1
c.writeOperand(op, result)
c.setZN(result)
}
func lsrExec(c *CPU, op operand) {
v := c.operandValue(op)
c.setFlag(FlagC, v&0x01 != 0)
result := v >> 1
c.writeOperand(op, result)
c.setZN(result)
}
func rolExec(c *CPU, op operand) {
v := c.operandValue(op)
var carryIn uint8
if c.flag(FlagC) {
carryIn = 1
}
c.setFlag(FlagC, v&0x80 != 0)
result := v<<1 | carryIn
c.writeOperand(op, result)
c.setZN(result)
}
func rorExec(c *CPU, op operand) {
v := c.operandValue(op)
var carryIn uint8
if c.flag(FlagC) {
carryIn = 0x80
}
c.setFlag(FlagC, v&0x01 != 0)
result := v>>1 | carryIn
c.writeOperand(op, result)
c.setZN(result)
}
func incExec(c *CPU, op operand) { v := c.operandValue(op) + 1; c.writeOperand(op, v); c.setZN(v) }
func decExec(c *CPU, op operand) { v := c.operandValue(op) - 1; c.writeOperand(op, v); c.setZN(v) }
func inxExec(c *CPU, op operand) { c.X++; c.setZN(c.X) }
func dexExec(c *CPU, op operand) { c.X--; c.setZN(c.X) }
func inyExec(c *CPU, op operand) { c.Y++; c.setZN(c.Y) }
func deyExec(c *CPU, op operand) { c.Y--; c.setZN(c.Y) }
func (c *CPU) compare(reg, v uint8) {
result := reg - v
c.setFlag(FlagC, reg >= v)
c.setZN(result)
}
func cmpExec(c *CPU, op operand) { c.compare(c.A, c.operandValue(op)) }
func cpxExec(c *CPU, op operand) { c.compare(c.X, c.operandValue(op)) }
func cpyExec(c *CPU, op operand) { c.compare(c.Y, c.operandValue(op)) }
func (c *CPU) branch(op operand, cond bool) {
if !cond {
return
}
c.extraCycles++
if !samePage(c.PC, op.addr) {
c.extraCycles++
}
c.PC = op.addr
}
func bccExec(c *CPU, op operand) { c.branch(op, !c.flag(FlagC)) }
func bcsExec(c *CPU, op operand) { c.branch(op, c.flag(FlagC)) }
func bneExec(c *CPU, op operand) { c.branch(op, !c.flag(FlagZ)) }
func beqExec(c *CPU, op operand) { c.branch(op, c.flag(FlagZ)) }
func bplExec(c *CPU, op operand) { c.branch(op, !c.flag(FlagN)) }
func bmiExec(c *CPU, op operand) { c.branch(op, c.flag(FlagN)) }
func bvcExec(c *CPU, op operand) { c.branch(op, !c.flag(FlagV)) }
func bvsExec(c *CPU, op operand) { c.branch(op, c.flag(FlagV)) }
func jmpExec(c *CPU, op operand) { c.PC = op.addr }
func jsrExec(c *CPU, op operand) {
c.push16(c.PC - 1) // address of the last byte of the jsr instruction
c.PC = op.addr
}
func rtsExec(c *CPU, op operand) { c.PC = c.pop16() + 1 }
func rtiExec(c *CPU, op operand) {
pulled := c.pop()
c.Status = (pulled &^ FlagB) | FlagU
c.PC = c.pop16()
}
func clcExec(c *CPU, op operand) { c.setFlag(FlagC, false) }
func secExec(c *CPU, op operand) { c.setFlag(FlagC, true) }
func cliExec(c *CPU, op operand) { c.setFlag(FlagI, false) }
func seiExec(c *CPU, op operand) { c.setFlag(FlagI, true) }
func cldExec(c *CPU, op operand) { c.setFlag(FlagD, false) }
func sedExec(c *CPU, op operand) { c.setFlag(FlagD, true) }
func clvExec(c *CPU, op operand) { c.setFlag(FlagV, false) }
func nopExec(c *CPU, op operand) {}
func brkExec(c *CPU, op operand) {
c.PC++ // brk is logically 2 bytes: the byte after the opcode is skipped
c.interrupt(vectorIRQ, true)
}
func laxExec(c *CPU, op operand) {
v := c.operandValue(op)
c.A, c.X = v, v
c.setZN(v)
}
func saxExec(c *CPU, op operand) { c.write(op.addr, c.A&c.X) }
func dcpExec(c *CPU, op operand) {
v := c.operandValue(op) - 1
c.writeOperand(op, v)
c.compare(c.A, v)
}
func sloExec(c *CPU, op operand) {
v := c.operandValue(op)
c.setFlag(FlagC, v&0x80 != 0)
result := v << 1
c.writeOperand(op, result)
c.A |= result
c.setZN(c.A)
}
func rlaExec(c *CPU, op operand) {
v := c.operandValue(op)
var carryIn uint8
if c.flag(FlagC) {
carryIn = 1
}
c.setFlag(FlagC, v&0x80 != 0)
result := v<<1 | carryIn
c.writeOperand(op, result)
c.A &= result
c.setZN(c.A)
}
func sreExec(c *CPU, op operand) {
v := c.operandValue(op)
c.setFlag(FlagC, v&0x01 != 0)
result := v >> 1
c.writeOperand(op, result)
c.A ^= result
c.setZN(c.A)
}
func rraExec(c *CPU, op operand) {
v := c.operandValue(op)
var carryIn uint8
if c.flag(FlagC) {
carryIn = 0x80
}
c.setFlag(FlagC, v&0x01 != 0)
result := v>>1 | carryIn
c.writeOperand(op, result)
c.addWithCarry(result)
}
func iscExec(c *CPU, op operand) {
v := c.operandValue(op) + 1
c.writeOperand(op, v)
c.addWithCarry(^v)
}
func jamExec(c *CPU, op operand) {
c.Jammed = true
c.PC--
}
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