51 lines
1.8 KiB
C#
51 lines
1.8 KiB
C#
// <copyright file="StatusBits.cs" company="Adrian Conlon">
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// Copyright (c) Adrian Conlon. All rights reserved.
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// </copyright>
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namespace EightBit
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{
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using System;
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[Flags]
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public enum StatusBits : byte
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{
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None = 0,
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// Carry: set if there was a carry from the bit 7 during last add
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// operation, or if there was a borrow from last subtract operation,
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// or if bit 7 of the A register was set during last MUL operation.
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CF = Bits.Bit0,
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// Overflow: set if there was an overflow during last result calculation.
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// Logical, load and store operations clear this bit.
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VF = Bits.Bit1,
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// Zero: set if the result is zero. Like the N bit, this bit can be
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// set not only by arithmetic and logical operations, but also
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// by load / store operations.
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ZF = Bits.Bit2,
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// Negative: set if the most significant bit of the result is set.
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// This bit can be set not only by arithmetic and logical operations,
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// but also by load / store operations.
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NF = Bits.Bit3,
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// Interrupt mask: set if the IRQ interrupt is disabled.
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IF = Bits.Bit4,
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// Half carry: set if there was a carry from bit 3 to bit 4 of the result
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// during the last add operation.
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HF = Bits.Bit5,
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// Fast interrupt mask: set if the FIRQ interrupt is disabled.
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FF = Bits.Bit6,
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// Entire flag: set if the complete machine state was saved in the stack.
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// If this bit is not set then only program counter and condition code
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// registers were saved in the stack. This bit is used by interrupt
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// handling routines only.
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// The bit is cleared by fast interrupts, and set by all other interrupts.
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EF = Bits.Bit7,
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}
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}
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