Motorola 68000模拟器ADD.b指令(d8,AX,Xn)寻址测试问题

开发Motorola 68000模拟器时，卡在了首个使用(d8, AX, Xn)寻址模式的ADD.b指令测试上。无法手动计算出内存地址13367077的由来——虽然确定该地址经过24位掩码处理，但推导不出未掩码的原始值。根据第二个预取值15214的第8位可知需要处理全扩展字，但其I/IS位属于保留组合，按索引尺寸读取长字后相加仍无法得到目标地址。

以下为测试用例的初始、终态寄存器与内存数据：

d133 [ADD.b D0, (d8, A3, Xn)] 1
Len = 18

==== Initial ====
D0 = 2308435391     0x8997edbf  0b10001001 10010111 11101101 10111111 
D1 = 1060694383     0x3f38e96f  0b00111111 00111000 11101001 01101111 
D2 = 144798559      0x8a1735f   0b00001000 10100001 01110011 01011111 
D3 = 1114670029     0x427083cd  0b01000010 01110000 10000011 11001101 
D4 = 3546817942     0xd3682596  0b11010011 01101000 00100101 10010110 
D5 = 3017016069     0xb3d40305  0b10110011 11010100 00000011 00000101 
D6 = 157945861      0x96a1005   0b00001001 01101010 00010000 00000101 
D7 = 3531664314     0xd280ebba  0b11010010 10000000 11101011 10111010 
A0 = 1707790453     0x65cad075  0b01100101 11001010 11010000 01110101 
A1 = 3858677903     0xe5fec08f  0b11100101 11111110 11000000 10001111 
A2 = 3797006336     0xe251b800  0b11100010 01010001 10111000 00000000 
A3 = 2874897130     0xab5b72ea  0b10101011 01011011 01110010 11101010 
A4 = 3126142618     0xba55269a  0b10111010 01010101 00100110 10011010 
A5 = 271034980      0x1027aa64  0b00010000 00100111 10101010 01100100 
A6 = 2663102061     0x9ebbb66d  0b10011110 10111011 10110110 01101101 
SSP = 2048      0x800   0b00000000000000000000100000000000
USP = 2048      0x800   0b00000000000000000000100000000000
PC = 3072       0xc00   0b00000000000000000000110000000000
SR = 9993       0x2709  0b00000000000000000010011100001001
Prefetch: 53555, 15214  0x3B6E      0b00111011 01101110
[MEMORY]
3079 = 160  A0  41206
3078 = 246  F6  
13367077 = 228  E4
3077 = 181  B5
3076 = 237  ED  46573   87779   175558

==== Final ====
D0 = 2308435391     0x8997edbf  0b10001001 10010111 11101101 10111111 
D1 = 1060694383     0x3f38e96f  0b00111111 00111000 11101001 01101111 
D2 = 144798559      0x8a1735f   0b00001000 10100001 01110011 01011111 
D3 = 1114670029     0x427083cd  0b01000010 01110000 10000011 11001101 
D4 = 3546817942     0xd3682596  0b11010011 01101000 00100101 10010110 
D5 = 3017016069     0xb3d40305  0b10110011 11010100 00000011 00000101 
D6 = 157945861      0x96a1005   0b00001001 01101010 00010000 00000101 
D7 = 3531664314     0xd280ebba  0b11010010 10000000 11101011 10111010 
A0 = 1707790453     0x65cad075  0b01100101 11001010 11010000 01110101 
A1 = 3858677903     0xe5fec08f  0b11100101 11111110 11000000 10001111 
A2 = 3797006336     0xe251b800  0b11100010 01010001 10111000 00000000 
A3 = 2874897130     0xab5b72ea  0b10101011 01011011 01110010 11101010 
A4 = 3126142618     0xba55269a  0b10111010 01010101 00100110 10011010 
A5 = 271034980      0x1027aa64  0b00010000 00100111 10101010 01100100 
A6 = 2663102061     0x9ebbb66d  0b10011110 10111011 10110110 01101101 
SSP = 2048      0x800   0b00000000000000000000100000000000
USP = 2048      0x800   0b00000000000000000000100000000000
PC = 3076       0xc04   0b00000000000000000000110000000100
SR = 10009      0x2719  0b00000000000000000010011100011001
Prefetch: 60853, 63136
[MEMORY]
3079 = 160
3078 = 246
13367077 [0xCBF725] = 163
3077 = 181
3076 = 237

测试用例来自ProcessorTests项目的680x0/68000/v1测试集。

内容的提问来源于stack exchange，提问作者Javid