//
//  TimingTests.swift
//  Clock Signal
//
//  Created by Thomas Harte on 13/08/2015.
//  Copyright © 2015 Thomas Harte. All rights reserved.
//

import Foundation
import XCTest

class MOS6502TimingTests: XCTestCase, CSTestMachineJamHandler {

	fileprivate var endTime: UInt32 = 0

	func testImplied() {
		let code: [UInt8] = [
			0xea,		// [2] NOP
			0x88,		// [2] DEY
			0xca,		// [2] DEX
			0x18,		// [2] CLC
			0x2a,		// [2] ROL A
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 10)
	}

	func testLDA() {
		let code: [UInt8] = [
			0xa9, 0x00,			// [2] LDA #$00
			0xa5, 0x00,			// [3] LDA $00
			0xb5, 0x00,			// [4] LDA $00,X
			0xad, 0x00, 0x00,	// [4] LDA $0000
			0xbd, 0x00, 0x00,	// [4] LDA $0000, x (no wrap)
			0xbd, 0x02, 0x00,	// [5] LDA $0002, x (wrap)
			0xb9, 0x00, 0x00,	// [4] LDA $0000, y (no wrap)
			0xb9, 0x10, 0x00,	// [5] LDA $0010, y (wrap)
			0xa1, 0x44,			// [6] LDA ($44, x)
			0xb1, 0x00,			// [5] LDA ($00), y (no wrap)
			0xb1, 0x02,			// [6] LDA ($01), y (wrap)
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 48)
	}

	func testBIT() {
		let code: [UInt8] = [
			0x24, 0x2a,			// [3] BIT $2a
			0x2c, 0x2a, 0x2b,	// [4] BIT $2b2a
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 7)
	}

	func testSTA() {
		let code: [UInt8] = [
			0x85, 0x00,			// [3] STA $00
			0x95, 0x00,			// [4] STA $00,X
			0x8d, 0x00, 0x00,	// [4] STA $0000
			0x9d, 0x00, 0x00,	// [5] STA $0000, x (no wrap)
			0x9d, 0x02, 0x00,	// [5] STA $0002, x (wrap)
			0x99, 0x00, 0x00,	// [5] STA $0000, y (no wrap)
			0x99, 0x10, 0x00,	// [5] STA $0010, y (wrap)
			0x81, 0x44,			// [6] STA ($44, x)
			0x91, 0x00,			// [6] STA ($00), y (no wrap)
			0x91, 0x02,			// [6] STA ($01), y (wrap)
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 49)
	}

	func testINC() {
		let code: [UInt8] = [
			0xe6, 0x00,			// [5] INC $00
			0xf6, 0x00,			// [6] INC $00,X
			0xee, 0x00, 0x00,	// [6] INC $0000
			0xfe, 0x00, 0x00,	// [7] INC $0000, x (no wrap)
			0xfe, 0x02, 0x00,	// [7] INC $0002, x (wrap)
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 31)
	}

	func testJSR() {
		let code: [UInt8] = [
			0x20, 0x04, 0x02,	// [6] JSR $0204
			CSTestMachineJamOpcode,
			0x60,				// [6] RTS
			]
		self.runTest(code, expectedRunLength: 12)
	}

	func testJMP() {
		let code: [UInt8] = [
			0x6c, 0x04, 0x00,	// [5] JMP ($0004)
			0x00, 0x00, 0x00, 0x00, 0x00,
			0x4c, 0x0b, 0x02,	// [3] JMP 020b
			CSTestMachineJamOpcode,
			]
		self.runTest(code, expectedRunLength: 8)
	}

	func testPHAPLA() {
		let code: [UInt8] = [
			0x48, // [3] PHA
			0x48, // [3] PHA
			0x68, // [4] PLA
			CSTestMachineJamOpcode,
			]
		self.runTest(code, expectedRunLength: 10)
	}

	func testBCS() {
		let code: [UInt8] = [
			0x18,				// [2] CLC
			0xb0, 0xff,			// [2] BCS -1 (not taken)
			0x90, 0x7f,			// [3] BCC +7f (taken)
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x90, 0x00,			// [3] BCC 0 (taken)
			0x90, 0x7f,			// [4] BCC +6f (taken, page wrap)
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 14)
	}

	func testSnippet1() {
		let code: [UInt8] = [
			0x8d, 0x08, 0x00,	// [4] STA $0008
			0xc6, 0xb4,			// [5] DEC $B4
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 9)
	}

	func testSnippet2() {
		let code: [UInt8] = [
			0x16, 0x16,			// [6] ASL $16, x
			0x46, 0x46,			// [5] LSR $46
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 11)
	}

	func testSnippet3() {
		let code: [UInt8] = [
			0x20, 0x04, 0x02,	// [6] JSR $0204
			CSTestMachineJamOpcode,
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x85, 0x09,			// [3] STA $09
			0x85, 0x09,			// [3] STA $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x85, 0x09,			// [3] STA $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x85, 0x09,			// [3] STA $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x86, 0x09,			// [3] STX $09
			0x87, 0x09,			// [3] SAX $09
			0x60,				// [6] RTS
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 66)
	}

	func testNOP() {
		let code: [UInt8] = [
			0x04, 0x00,	// [3] NOP zpg
			0x14, 0x00,	// [4] NOP zpg, x
			0x34, 0x00,	// [4] NOP zpg, x
			0x44, 0x00,	// [3] NOP zpg
			0x54, 0x00,	// [4] NOP zpg, x
			0x64, 0x00,	// [3] NOP zpg
			0x74, 0x00,	// [4] NOP zpg, x
			0x80, 0x00,	// [2] NOP #
			0x82, 0x00,	// [2] NOP #
			0x89, 0x00,	// [2] NOP #
			0xc2, 0x00,	// [2] NOP #
			0xd4, 0x00,	// [4] NOP zpg, x
			0xe2, 0x00,	// [2] NOP #
			0xf4, 0x00,	// [4] NOP zpg, x
			CSTestMachineJamOpcode]
		self.runTest(code, expectedRunLength: 43)
	}

	func runTest(_ code: [UInt8], expectedRunLength: UInt32) {
		let machine = CSTestMachine()

		machine.jamHandler = self

		let immediateCode = Data(bytes: UnsafePointer<UInt8>(code), count: code.count)
		machine.setData(immediateCode, atAddress: 0x200)
		machine.setValue(0x00, forAddress: 0x0000)
		machine.setValue(0x00, forAddress: 0x0001)
		machine.setValue(0xff, forAddress: 0x0002)
		machine.setValue(0x00, forAddress: 0x0003)
		machine.setValue(0x08, forAddress: 0x0004)
		machine.setValue(0x02, forAddress: 0x0005)
		machine.setValue(0x200, for: CSTestMachineRegister.programCounter)
		machine.setValue(0xff, for: CSTestMachineRegister.X)
		machine.setValue(0xfe, for: CSTestMachineRegister.Y)

		self.endTime = 0
		while self.endTime == 0 {
			machine.runForNumber(ofCycles: 10)
		}

		XCTAssert(self.endTime == expectedRunLength, "Took \(self.endTime) cycles to perform rather than \(expectedRunLength)")
	}

	func testMachine(_ machine: CSTestMachine!, didJamAtAddress address: UInt16) {
		if self.endTime == 0 {
			self.endTime = machine.timestamp - 9
		}
	}
}