120 lines
3.6 KiB
C#
120 lines
3.6 KiB
C#
/*
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* Copyright 2007, 2015 Alex Makeev
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*
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* This file is part of ZXMAK2 (ZX Spectrum virtual machine).
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*
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* ZXMAK2 is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* ZXMAK2 is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with ZXMAK2. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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namespace ZXMAK2.Engine.Cpu
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{
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/// <summary>
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/// Represent masks for the Z80 flags register
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/// </summary>
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public static class CpuFlags
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{
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#region Flags
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/// <summary>
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/// Sign Flag
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/// [Set if the 2-complement value is negative (copy of MSB)]
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/// </summary>
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public const byte S = 0x80;
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/// <summary>
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/// Zero Flag
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/// [Set if the value is zero]
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/// </summary>
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public const byte Z = 0x40;
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/// <summary>
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/// Undocumented flag F5
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/// </summary>
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public const byte F5 = 0x20;
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/// <summary>
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/// Half Carry Flag
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/// [Carry from bit 3 to bit 4]
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/// </summary>
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public const byte H = 0x10;
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/// <summary>
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/// Undocumented flag F3
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/// </summary>
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public const byte F3 = 0x08;
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/// <summary>
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/// P/V - Parity/Overflow Flag
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/// [Parity set if even number of bits set.
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/// Overflow set if the 2-complement result does not fit in the register]
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/// </summary>
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public const byte P = 0x04;
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/// <summary>
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/// Add/Subtract Flag
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/// [Set if the last operation was a subtraction]
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/// </summary>
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public const byte N = 0x02;
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/// <summary>
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/// Carry Flag
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/// [Set if the result did not fit in the register]
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/// </summary>
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public const byte C = 0x01;
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#endregion Flags
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#region Inverted Masks
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public const byte NotS = S ^ 0xFF;
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public const byte NotZ = Z ^ 0xFF;
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public const byte NotF5 = F5 ^ 0xFF;
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public const byte NotH = H ^ 0xFF;
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public const byte NotF3 = F3 ^ 0xFF;
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public const byte NotP = P ^ 0xFF;
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public const byte NotN = N ^ 0xFF;
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public const byte NotC = C ^ 0xFF;
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#endregion Inverted Masks
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#region Internal flag sets (used by engine)
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internal const byte F3F5 = F3 | F5;
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internal const byte SF3F5 = S | F3 | F5;
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internal const byte PCF3F5 = P | C | F3 | F5;
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internal const byte HNCF3F5 = H | N | C | F3 | F5;
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internal const byte HPNF3F5 = H | P | N | F3 | F5;
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internal const byte HC = H | C;
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internal const byte SZP = S | Z | P;
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internal const byte SZPC = S | Z | P | C;
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internal const byte HN = H | N;
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internal const byte NotF3F5 = F3F5 ^ 0xFF;
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internal const byte NotSF3F5 = SF3F5 ^ 0xFF;
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internal const byte NotPCF3F5 = PCF3F5 ^ 0xFF;
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internal const byte NotHNCF3F5 = HNCF3F5 ^ 0xFF;
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internal const byte NotHPNF3F5 = HPNF3F5 ^ 0xFF;
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internal const byte NotHC = HC ^ 0xFF;
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internal const byte NotSZP = SZP ^ 0xFF;
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internal const byte NotSZPC = SZPC ^ 0xFF;
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internal const byte NotHN = HN ^ 0xFF;
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#endregion Internal flag sets (used by engine)
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}
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}
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