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The m6502 intermediate variable should really be of type Register16

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Signed-off-by: Adrian Conlon <Adrian.conlon@gmail.com>
This commit is contained in:
Adrian Conlon 2019-02-18 22:14:11 +00:00
parent 999bdf71ff
commit 9ac2c53685
1 changed files with 19 additions and 20 deletions
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39
M6502/M6502.cs
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@ -12,7 +12,7 @@ namespace EightBit
private const byte RSTvector = 0xfc; // RST vector private const byte RSTvector = 0xfc; // RST vector
private const byte NMIvector = 0xfa; // NMI vector private const byte NMIvector = 0xfa; // NMI vector
private ushort intermediate; private Register16 intermediate;
private bool handlingRESET = false; private bool handlingRESET = false;
private bool handlingNMI = false; private bool handlingNMI = false;
@ -658,8 +658,8 @@ namespace EightBit
private ushort Address_relative_byte() private ushort Address_relative_byte()
{ {
var offset = (sbyte)this.FetchByte(); var offset = (sbyte)this.FetchByte();
this.intermediate = (ushort)(this.PC().Word + offset); this.intermediate.Word = (ushort)(this.PC().Word + offset);
return this.intermediate; return this.intermediate.Word;
} }
private byte AM_Immediate() => this.FetchByte(); private byte AM_Immediate() => this.FetchByte();
@ -760,10 +760,9 @@ namespace EightBit
{ {
var returned = this.SUB(operand, data, ~this.P & (int)StatusBits.CF); var returned = this.SUB(operand, data, ~this.P & (int)StatusBits.CF);
var difference = this.intermediate; this.AdjustNZ(this.intermediate.Low);
this.AdjustNZ(Chip.LowByte(difference)); this.P = SetFlag(this.P, StatusBits.VF, (operand ^ data) & (operand ^ this.intermediate.Low) & (int)StatusBits.NF);
this.P = SetFlag(this.P, StatusBits.VF, (operand ^ data) & (operand ^ Chip.LowByte(difference)) & (int)StatusBits.NF); this.P = ClearFlag(this.P, StatusBits.CF, this.intermediate.High);
this.P = ClearFlag(this.P, StatusBits.CF, Chip.HighByte(difference));
return returned; return returned;
} }
@ -775,13 +774,13 @@ namespace EightBit
private byte SUB_b(byte operand, byte data, int borrow) private byte SUB_b(byte operand, byte data, int borrow)
{ {
this.intermediate = (ushort)(operand - data - borrow); this.intermediate.Word = (ushort)(operand - data - borrow);
return Chip.LowByte(this.intermediate); return this.intermediate.Low;
} }
private byte SUB_d(byte operand, byte data, int borrow) private byte SUB_d(byte operand, byte data, int borrow)
{ {
this.intermediate = (ushort)(operand - data - borrow); this.intermediate.Word = (ushort)(operand - data - borrow);
var low = (byte)(LowNibble(operand) - LowNibble(data) - borrow); var low = (byte)(LowNibble(operand) - LowNibble(data) - borrow);
var lowNegative = low & (byte)StatusBits.NF; var lowNegative = low & (byte)StatusBits.NF;
@ -803,7 +802,7 @@ namespace EightBit
private byte ADC(byte operand, byte data) private byte ADC(byte operand, byte data)
{ {
var returned = this.ADD(operand, data, this.Carry); var returned = this.ADD(operand, data, this.Carry);
this.AdjustNZ(Chip.LowByte(this.intermediate)); this.AdjustNZ(this.intermediate.Low);
return returned; return returned;
} }
@ -814,17 +813,17 @@ namespace EightBit
private byte ADD_b(byte operand, byte data, int carry) private byte ADD_b(byte operand, byte data, int carry)
{ {
this.intermediate = (ushort)(operand + data + carry); this.intermediate.Word = (ushort)(operand + data + carry);
this.P = SetFlag(this.P, StatusBits.VF, ~(operand ^ data) & (operand ^ Chip.LowByte(this.intermediate)) & (int)StatusBits.NF); this.P = SetFlag(this.P, StatusBits.VF, ~(operand ^ data) & (operand ^ this.intermediate.Low) & (int)StatusBits.NF);
this.P = SetFlag(this.P, StatusBits.CF, Chip.HighByte(this.intermediate) & (int)StatusBits.CF); this.P = SetFlag(this.P, StatusBits.CF, this.intermediate.High & (int)StatusBits.CF);
return Chip.LowByte(this.intermediate); return this.intermediate.Low;
} }
private byte ADD_d(byte operand, byte data, int carry) private byte ADD_d(byte operand, byte data, int carry)
{ {
this.intermediate = (ushort)(operand + data + carry); this.intermediate.Word = (ushort)(operand + data + carry);
var low = (byte)(LowNibble(operand) + LowNibble(data) + carry); var low = (byte)(LowNibble(operand) + LowNibble(data) + carry);
if (low > 9) if (low > 9)
@ -862,9 +861,9 @@ namespace EightBit
private void CMP(byte first, byte second) private void CMP(byte first, byte second)
{ {
this.intermediate = (ushort)(first - second); this.intermediate.Word = (ushort)(first - second);
this.AdjustNZ(Chip.LowByte(this.intermediate)); this.AdjustNZ(this.intermediate.Low);
this.P = ClearFlag(this.P, StatusBits.CF, Chip.HighByte(this.intermediate)); this.P = ClearFlag(this.P, StatusBits.CF, this.intermediate.High);
} }
private byte DEC(byte value) => this.Through(--value); private byte DEC(byte value) => this.Through(--value);
@ -948,7 +947,7 @@ namespace EightBit
private void AXS(byte value) private void AXS(byte value)
{ {
this.X = this.Through(this.SUB((byte)(this.A & this.X), value)); this.X = this.Through(this.SUB((byte)(this.A & this.X), value));
this.P = ClearFlag(this.P, StatusBits.CF, Chip.HighByte(this.intermediate)); this.P = ClearFlag(this.P, StatusBits.CF, this.intermediate.High);
} }
private void DCP(byte value) private void DCP(byte value)