//
// Copyright (c) 2012 Ian Cowburn
//
using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

namespace Noddybox.Emulation.EightBit.Z80
{
    public partial class Z80Cpu
    {
        #region Status register helpers
        
        /// <summary>
        /// Set a flag in the status register.
        /// </summary>
        /// <param name="flag">The flag.</param>
        private void SetFlag(Z80Flags flag)
        {
            F |= flag;
        }

        /// <summary>
        /// Clear a flag in the status register.
        /// </summary>
        /// <param name="flag">The flag.</param>
        private void ClearFlag(Z80Flags flag)
        {
            F &= ~flag;
        }

        #endregion

        #region Stack commands

        /// <summary>
        /// Push a value on the stack.
        /// </summary>
        /// <param name="val">The value.</param>
        private void PUSH(ushort val)
        {
            memory.Write(--SP, (byte)(val & 0xff));
            memory.Write(--SP, (byte)(Binary.ShiftRight(val, 8) & 0xff));
        }

        /// <summary>
        /// Pop a value from the stack.
        /// </summary>
        /// <returns></returns>
        private ushort POP()
        {
            SP = (ushort)((SP + 2) & 0xffff);
            return (ushort)(memory.Read((ushort)(SP-2)) |
                             (memory.Read((ushort)(SP - 1)) >> 8));
        }

        #endregion

        #region ALU arithmetic and comparison

        /// <summary>
        /// Add an 8-bit value to the accumulator without carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Add8(byte b)
        {
            int w = A + b;

            F = SZtable[w] | H35table[w & 0xff];

            if (((A ^ w ^ b) & (int)Z80Flags.HalfCarry) == (int)Z80Flags.HalfCarry)
            {
                F |= Z80Flags.HalfCarry;
            }

            if (((b ^ A) & (b ^ w) & 0x80) > 0)
            {
                F |= Z80Flags.PV;
            }

            A = (byte)(w & 0xff);
        }

        /// <summary>
        /// Add an 8-bit value to the accumulator with carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Adc8(byte b)
        {
            int w = A + b + (int)(F & Z80Flags.Carry);

            F = SZtable[w] | H35table[w & 0xff];

            if (((A ^ w ^ b) & (int)Z80Flags.HalfCarry) == (int)Z80Flags.HalfCarry)
            {
                F |= Z80Flags.HalfCarry;
            }

            if (((b ^ A) & (b ^ w) & 0x80) > 0)
            {
                F |= Z80Flags.PV;
            }

            A = (byte)(w & 0xff);
        }

        /// <summary>
        /// Subtract an 8-bit value from the accumulator without carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Sub8(byte b)
        {
            int w = A - b;

            if (w < 0)
            {
                w += 0x200;
            }

            F = SZtable[w] | H35table[w & 0xff] | Z80Flags.Neg;

            if (((A ^ w ^ b) & (int)Z80Flags.HalfCarry) == (int)Z80Flags.HalfCarry)
            {
                F |= Z80Flags.HalfCarry;
            }

            if (((b ^ A) & (b ^ w) & 0x80) > 0)
            {
                F |= Z80Flags.PV;
            }

            A = (byte)(w & 0xff);
        }

        /// <summary>
        /// Compare an 8-bit value with the accumulator.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Cmp8(byte b)
        {
            int w = A - b;

            if (w < 0)
            {
                w += 0x200;
            }

            F = SZtable[w] | H35table[w & 0xff] | Z80Flags.Neg;

            if (((A ^ w ^ b) & (int)Z80Flags.HalfCarry) == (int)Z80Flags.HalfCarry)
            {
                F |= Z80Flags.HalfCarry;
            }

            if (((b ^ A) & (b ^ w) & 0x80) > 0)
            {
                F |= Z80Flags.PV;
            }
        }

        /// <summary>
        /// Subtract an 8-bit value from the accumulator with carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Sbc8(byte b)
        {
            int w = A - b - (int)(F & Z80Flags.Carry);

            if (w < 0)
            {
                w += 0x200;
            }

            F = SZtable[w] | H35table[w & 0xff] | Z80Flags.Neg;

            if (((A ^ w ^ b) & (int)Z80Flags.HalfCarry) == (int)Z80Flags.HalfCarry)
            {
                F |= Z80Flags.HalfCarry;
            }

            if (((b ^ A) & (b ^ w) & 0x80) > 0)
            {
                F |= Z80Flags.PV;
            }

            A = (byte)(w & 0xff);
        }

        /// <summary>
        /// Add a 16-bit value to a register without carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Add16(ref ushort reg, ushort b)
        {
            int w = reg + b;

            F &= Z80Flags.Sign | Z80Flags.Zero | Z80Flags.PV;

            if (w > 0xffff)
            {
                F |= Z80Flags.Carry;
            }

            if ((reg ^ w ^ b) == 0x1000)
            {
                F |= Z80Flags.HalfCarry;
            }

            reg = (ushort)(w & 0xffff);

            F |= H35table[reg >> 8];
        }

        /// <summary>
        /// Add a 16-bit value to a register with carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Adc16(ref ushort reg, ushort b)
        {
            int w = reg + b + (int)(F & Z80Flags.Carry);

            F = Z80Flags.None;

            if ((w & 0xffff) == 0)
            {
                F |= Z80Flags.Zero;
            }

            if ((w & 0x8000) == 0x8000)
            {
                F |= Z80Flags.Sign;
            }

            if (w > 0xffff)
            {
                F |= Z80Flags.Carry;
            }

            if (((b ^ reg ^ 0x8000) & ((reg ^ w) & 0x8000)) == 0x8000)
            {
                F |= Z80Flags.PV;
            }

            if ((reg ^ w ^ b) == 0x1000)
            {
                F |= Z80Flags.HalfCarry;
            }

            reg = (ushort)(w & 0xffff);

            F |= H35table[reg >> 8];
        }


        /// <summary>
        /// Subtract a 16-bit value from a register with carry.
        /// </summary>
        /// <param name="b">The vakue.</param>
        private void Sbc16(ref ushort reg, ushort b)
        {
            int w = reg - b - (int)(F & Z80Flags.Carry);

            F = Z80Flags.Neg;

            if (w < 0)
            {
                w += 0x10000;
                F |= Z80Flags.Carry;
            }

            if ((w & 0xffff) == 0)
            {
                F |= Z80Flags.Zero;
            }

            if ((w & 0x8000) == 0x8000)
            {
                F |= Z80Flags.Sign;
            }

            if (((b ^ reg) & ((reg ^ w) & 0x8000)) == 0x8000)
            {
                F |= Z80Flags.PV;
            }

            if ((reg ^ w ^ b) == 0x1000)
            {
                F |= Z80Flags.HalfCarry;
            }

            reg = (ushort)(w & 0xffff);

            F |= H35table[reg >> 8];
        }

        /// <summary>
        /// Increment an 8-bit register.
        /// </summary>
        /// <param name="reg">The register to increment.</param>
        void Inc8(ref byte reg)
        {
            reg++;

            F = Z80Flags.Carry;

            if (reg == 0x80)
            {
                F |= Z80Flags.PV;
            }

            if ((reg & 0x0f) == 0x00)
            {
                F |= Z80Flags.HalfCarry;
            }
        }

        /// <summary>
        /// Decrement an 8-bit register.
        /// </summary>
        /// <param name="reg">The register to decrement.</param>
        void Dec8(ref byte reg)
        {
            reg--;

            F = Z80Flags.Carry | Z80Flags.Neg;

            if (reg == 0x7f)
            {
                F |= Z80Flags.PV;
            }

            if ((reg & 0x0f) == 0x0f)
            {
                F |= Z80Flags.HalfCarry;
            }
        }

        #endregion

        #region ALU rotate and shift operations

        /// <summary>
        /// Do RRCA.
        /// </summary>
        private void RRCA()
        {
            F &= Z80Flags.Sign | Z80Flags.Zero | Z80Flags.PV;
            F |= (Z80Flags)(A & 1);
            A = (byte)(Binary.ShiftRight(A, 1) | Binary.ShiftLeft(A, 7));
            F |= H35table[A];
        }

        /// <summary>
        /// Do RRA.
        /// </summary>
        private void RRA()
        {
            byte carry = (byte)(F & Z80Flags.Carry);
            F &= Z80Flags.Sign | Z80Flags.Zero | Z80Flags.PV;
            F |= (Z80Flags)(A & 1);
            A = (byte)(Binary.ShiftRight(A, 1) | Binary.ShiftLeft(carry, 7));
            F |= H35table[A];
        }

        /// <summary>
        /// Do RRC.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void RRC(ref byte reg)
        {
            F = (Z80Flags)(reg & (int)Z80Flags.Carry);
            reg = (byte)(Binary.ShiftRight(reg, 1) | Binary.ShiftLeft(reg, 7));
            F |= PSZtable[reg] | H35table[reg];
        }

        /// <summary>
        /// Do RR.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void RR(ref byte reg)
        {
            byte carry = (byte)(F & Z80Flags.Carry);
            F = (Z80Flags)(reg & (int)Z80Flags.Carry);
            reg = (byte)(Binary.ShiftRight(reg, 1) | Binary.ShiftLeft(carry, 7));
            F |= PSZtable[reg] | H35table[reg];
        }

        /// <summary>
        /// Do RLCA.
        /// </summary>
        private void RLCA()
        {
            F = (F & Z80Flags.PV | Z80Flags.Sign | Z80Flags.Zero)
                     | (Z80Flags)Binary.ShiftRight(A, 7);

            A = (byte)(Binary.ShiftLeft(A, 1) | Binary.ShiftRight(A, 7));

            F |= H35table[A];
        }

        /// <summary>
        /// Do RLA.
        /// </summary>
        private void RLA()
        {
            byte carry = (byte)(F & Z80Flags.Carry);
            F = (F & Z80Flags.PV | Z80Flags.Sign | Z80Flags.Zero)
                     | (Z80Flags)Binary.ShiftRight(A, 7);
            A = (byte)(Binary.ShiftRight(A, 1) | carry);
            F |= H35table[A];
        }

        /// <summary>
        /// Do RLC.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void RLC(ref byte reg)
        {
            byte carry = Binary.ShiftRight(reg, 7);
            reg = (byte)(Binary.ShiftLeft(reg, 1) | carry);
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        /// <summary>
        /// Do RL.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void RL(ref byte reg)
        {
            byte carry = Binary.ShiftRight(reg, 7);
            reg = (byte)(Binary.ShiftLeft(reg, 1) | (int)(F & Z80Flags.Carry));
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        /// <summary>
        /// Do SRL.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void SRL(ref byte reg)
        {
            byte carry = (byte)(reg & 1);
            reg = Binary.ShiftLeft(reg, 1);
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        /// <summary>
        /// Do SRA.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void SRA(ref byte reg)
        {
            byte carry = (byte)(reg & 1);
            reg = (byte)(Binary.ShiftLeft(reg, 1) | (reg & 0x80));
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        /// <summary>
        /// Do SLL.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void SLL(ref byte reg)
        {
            byte carry = Binary.ShiftRight(reg, 7);
            reg = (byte)(Binary.ShiftRight(reg, 1) | 0x01);
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        /// <summary>
        /// Do SLA.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        private void SLA(ref byte reg)
        {
            byte carry = Binary.ShiftRight(reg, 7);
            reg = Binary.ShiftRight(reg, 1);
            F = PSZtable[reg] | (Z80Flags)carry | H35table[reg];
        }

        #endregion

        #region ALU boolean operations

        /// <summary>
        /// AND a value with the accumulator.
        /// </summary>
        /// <param name="val">The value.</param>
        void AND(byte val)
        {
            A &= val;
            F = PSZtable[A] | Z80Flags.HalfCarry | H35table[A];
        }

        /// <summary>
        /// OR a value with the accumulator.
        /// </summary>
        /// <param name="val">The value.</param>
        void OR(byte val)
        {
            A |= val;
            F = PSZtable[A] | Z80Flags.HalfCarry | H35table[A];
        }

        /// <summary>
        /// XOR a value with the accumulator.
        /// </summary>
        /// <param name="val">The value.</param>
        void XOR(byte val)
        {
            A ^= val;
            F = PSZtable[A] | Z80Flags.HalfCarry | H35table[A];
        }

        /// <summary>
        /// Perform the BIT operation.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        /// <param name="bit">The bit to test.</param>
        void BIT(ref byte reg, int bit)
        {
            F &= Z80Flags.Carry;
            F |= Z80Flags.HalfCarry;

            if ((reg & (1 << bit)) != 0)
            {
                if (bit == 7 && (reg & (int)Z80Flags.Sign) != 0)
                {
                    F |= Z80Flags.Sign;
                }

                if (bit == 5 && (reg & (int)Z80Flags.Hidden5) != 0)
                {
                    F |= Z80Flags.Hidden5;
                }

                if (bit == 3 && (reg & (int)Z80Flags.Hidden3) != 0)
                {
                    F |= Z80Flags.Hidden3;
                }
            }
            else
            {
                F |= Z80Flags.Zero | Z80Flags.PV;
            }
        }

        /// <summary>
        /// Perform the bit set operation.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        /// <param name="bit">The bit to test.</param>
        void BIT_SET(ref byte reg, int bit)
        {
            reg |= (byte)(1 << bit);
        }

        /// <summary>
        /// Perform the bit clear operation.
        /// </summary>
        /// <param name="reg">The register to operate on.</param>
        /// <param name="bit">The bit to test.</param>
        void BIT_RES(ref byte reg, int bit)
        {
            reg &= (byte)~(1 << bit);
        }

        #endregion

        #region Jump operations

        /// <summary>
        /// The call operation.
        /// </summary>
        private void CALL()
        {
            PUSH((ushort)(PC + 2));
            PC = (ushort)(memory.Read(PC) | memory.Read((ushort)(PC+1)) >> 8);
        }

        /// <summary>
        /// The jump operation.
        /// </summary>
        private void JP()
        {
            PC = (ushort)(memory.Read(PC) | memory.Read((ushort)(PC+1)) >> 8);
        }

        /// <summary>
        /// The jump relative operation.
        /// </summary>
        private void JR()
        {
            PC = (ushort)(PC + (sbyte)memory.Read(PC) + 1);
        }

        /// <summary>
        /// Jump relative if the passed condition flag ANDed with the flag
        /// register equals the passed check value.
        /// </summary>
        /// <param name="cond">The condition flag.</param>
        /// <param name="val">The check value.</param>
        private void JR_COND(Z80Flags cond, Z80Flags val)
        {
            if ((F & cond) == val)
            {
                clock.Add(12);
                JR();
            }
            else
            {
                clock.Add(7);
                PC++;
            }
        }

        /// <summary>
        /// Jump if the passed condition flag ANDed with the flag
        /// register equals the passed check value.
        /// </summary>
        /// <param name="cond">The condition flag.</param>
        /// <param name="val">The check value.</param>
        private void JP_COND(Z80Flags cond, Z80Flags val)
        {
            clock.Add(10);

            if ((F & cond) == val)
            {
                JP();
            }
            else
            {
                PC+=2;
            }
        }

        /// <summary>
        /// Call if the passed condition flag ANDed with the flag
        /// register equals the passed check value.
        /// </summary>
        /// <param name="cond">The condition flag.</param>
        /// <param name="val">The check value.</param>
        private void CALL_COND(Z80Flags cond, Z80Flags val)
        {
            if ((F & cond) == val)
            {
                clock.Add(17);
                CALL();
            }
            else
            {
                clock.Add(10);
                PC+=2;
            }
        }

        /// <summary>
        /// Return if the passed condition flag ANDed with the flag
        /// register equals the passed check value.
        /// </summary>
        /// <param name="cond">The condition flag.</param>
        /// <param name="val">The check value.</param>
        private void RET_COND(Z80Flags cond, Z80Flags val)
        {
            if ((F & cond) == val)
            {
                clock.Add(11);
                PC = POP();
            }
            else
            {
                clock.Add(5);
            }
        }

        /// <summary>
        /// Reset the PC to an address
        /// register equals the passed check value.
        /// </summary>
        /// <param name="addr">The address.</param>
        private void RST(ushort addr)
        {
            clock.Add(11);
            PUSH(PC);
            PC = addr;
        }

        #endregion
    }
}