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kvisc/vm/pc/DECD

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# The OS/K Team licenses this file to you under the MIT license.
# See the LICENSE file in the project root for more information.
Instruction encoding:
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Byte 1: Instruction number
Byte 2:
xx0xxxxx
|| └───┘
RL CND
Values for ModRMs:
000xxxxx xxxxx = reg
(for memory accesses, xxxxx = access size)
001xxxxx [reg]
010xxxxx [reg+reg]
011xxxxx [reg+reg+imm16]
100xxxxx [reg+reg+imm32]
101xxxxx [reg+reg*imm8+imm32]
110xxxxx [reg+imm64]
11100001 imm8 (zero extended)
11100010 imm16 (zero extended)
11100100 imm32 (zero extended)
11101000 imm64 (zero extended)
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Values for COND:
00000 (none)
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00001 .C .B
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00010 .O
00011 .Z .E
00100 .S
00101 .P
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00110 .BE
00111 .L
01000 .LE
01001 .AXZ
01010 .BXZ
01011 .CXZ
01100 .DXZ
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Highest (6th) bit of COND indicates negation