56 lines
1.3 KiB
Kotlin
56 lines
1.3 KiB
Kotlin
package android.emu6502.instructions.impl
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import android.emu6502.CPU
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import android.emu6502.instructions.BaseInstruction
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import android.emu6502.instructions.Instruction
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/** ADd with Carry */
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class ADC(private val cpu: CPU) : BaseInstruction(Instruction.ADC, cpu.instructionList) {
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override fun immediate() {
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testADC(cpu.popByte())
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}
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private fun testADC(value: Int) {
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var tmp: Int
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if (cpu.A.xor(value).and(0x80) != 0) {
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cpu.CLV()
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} else {
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cpu.setOverflow()
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}
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if (cpu.decimalMode()) {
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tmp = cpu.A.and(0xf) + value.and(0xf) + cpu.P.and(1)
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if (tmp >= 10) {
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tmp = 0x10.or((tmp + 6).and(0xf))
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}
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tmp += cpu.A.and(0xf0) + value.and(0xf0)
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if (tmp >= 160) {
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cpu.SEC()
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if (cpu.overflow() && tmp >= 0x180) {
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cpu.CLV()
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}
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tmp += 0x60
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} else {
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cpu.CLC()
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if (cpu.overflow() && tmp < 0x80) {
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cpu.CLV()
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}
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}
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} else {
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tmp = cpu.A + value + cpu.P.and(1)
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if (tmp >= 0x100) {
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cpu.SEC()
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if (cpu.overflow() && tmp >= 0x180) {
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cpu.CLV()
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}
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} else {
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cpu.CLC()
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if (cpu.overflow() && tmp < 0x80) {
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cpu.CLV()
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}
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}
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}
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cpu.A = tmp.and(0xff)
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cpu.setSZFlagsForRegA()
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}
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} |