2019-01-26 15:59:36 +00:00
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package main
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const (
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2019-01-27 18:57:17 +00:00
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regA = 0
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regX = 1
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regY = 2
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regP = 4
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regSP = 5
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regPC = 6 // 2 bytes
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2019-01-26 15:59:36 +00:00
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)
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2019-01-27 22:03:08 +00:00
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const (
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flagN uint8 = 1 << 7
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flagV uint8 = 1 << 6
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flagB uint8 = 1 << 4
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flagD uint8 = 1 << 3
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flagI uint8 = 1 << 2
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flagZ uint8 = 1 << 1
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flagC uint8 = 1 << 0
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)
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2019-01-26 15:59:36 +00:00
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type registers struct {
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data [8]uint8
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}
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2019-01-26 17:57:03 +00:00
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func (r *registers) getRegister(i int) uint8 { return r.data[i] }
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2019-01-26 15:59:36 +00:00
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2019-01-27 18:57:17 +00:00
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func (r *registers) getA() uint8 { return r.data[regA] }
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func (r *registers) getX() uint8 { return r.data[regX] }
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func (r *registers) getY() uint8 { return r.data[regY] }
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func (r *registers) getP() uint8 { return r.data[regP] }
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func (r *registers) getSP() uint8 { return r.data[regSP] }
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2019-01-26 17:57:03 +00:00
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func (r *registers) setRegister(i int, v uint8) {
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2019-01-26 15:59:36 +00:00
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r.data[i] = v
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}
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2019-01-27 18:57:17 +00:00
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func (r *registers) setA(v uint8) { r.setRegister(regA, v) }
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func (r *registers) setX(v uint8) { r.setRegister(regX, v) }
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func (r *registers) setY(v uint8) { r.setRegister(regY, v) }
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func (r *registers) setP(v uint8) { r.setRegister(regP, v) }
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func (r *registers) setSP(v uint8) { r.setRegister(regSP, v) }
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2019-01-26 15:59:36 +00:00
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2019-01-26 17:57:03 +00:00
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func (r *registers) getPC() uint16 {
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2019-01-26 15:59:36 +00:00
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return uint16(r.data[regPC])*256 + uint16(r.data[regPC+1])
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}
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2019-01-26 17:57:03 +00:00
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func (r *registers) setPC(v uint16) {
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2019-01-26 15:59:36 +00:00
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r.data[regPC] = uint8(v >> 8)
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r.data[regPC+1] = uint8(v)
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}
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2019-01-27 22:03:08 +00:00
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2019-01-27 22:49:16 +00:00
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func (r *registers) getFlagBit(i uint8) uint8 {
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if r.getFlag(i) {
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return 1
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} else {
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return 0
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}
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}
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2019-01-27 22:03:08 +00:00
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func (r *registers) getFlag(i uint8) bool {
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return (r.data[regP] & i ) != 0
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}
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func (r *registers) setFlag(i uint8) {
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r.data[regP] |= i
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}
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func (r *registers) clearFlag(i uint8) {
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r.data[regP] &^= i
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}
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func (r *registers) updateFlag(i uint8, v bool) {
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if v {
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r.setFlag(i)
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} else {
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r.clearFlag(i)
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}
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}
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func (r *registers) updateFlagZN(t uint8) {
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r.updateFlag(flagZ, t == 0)
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r.updateFlag(flagN, t >= (1<<7))
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}
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