using System;
using System.Collections.Generic;
using System.Text;

namespace smallEmulator
{
    class CPUemulator
    {
        const UInt16 LDX = 0x01; //Load x
        const UInt16 LDY = 0x02; //Load y
        const UInt16 IOX = 0x03; //IO, 0x01 for output, 0x02 for input
        const UInt16 HLT = 0x04; //Halt the processor

        UInt16 p = 0, regX = 0, regY = 0;
        UInt16[] memory = new UInt16[] { LDX, 0x01, LDY, 0x06, IOX, HLT, 'J','u','s','t',' ','a',' ','t','e','s','t', '!', '\n', '\0' };
        public void ldx(UInt16 xData)
        {
            regX = xData;
        }
        public void ldy(UInt16 yData)
        {
            regY = yData;
        }
        public void iox()
        {
            UInt16 walk;
            switch (regX)
            {
                case 0x01:
                    //Console out
                    walk = regY;
                    while (memory[walk] != '\0')
                    {
                        Console.Write((char)memory[walk]);
                        walk++;
                    }
                    break;
            }
        }
        public void run()
        {
            bool running = true;
            while (running)
            {
                switch(memory[p])
                {
                    case LDX:
                        ldx(memory[p+1]);
                        p+=2;
                        break;
                    case LDY:
                        ldy(memory[p+1]);
                        p+=2;
                        break;
                    case IOX:
                        iox();
                        p++;
                        break;
                    case HLT:
                        Console.Write("Emulator halted, HLT.\n");
                        running = false;
                        break;
                }
            }
        }
    }
    class driverApp
    {
        static void Main(string[] args)
        {
            CPUemulator temp = new CPUemulator();
            temp.run();
        }
    }
}