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binbinyouliiii
V2EX  ›  程序员

Arm 指令如何匹配不同的格式

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  •   binbinyouliiii · 2020-08-18 17:23:56 +08:00 · 698 次点击
    这是一个创建于 1351 天前的主题,其中的信息可能已经有所发展或是发生改变。

    今天看 ARM7 相关的文档的时候,看到 Arm 指令格式区分的表格,但是发现格式并不是完全各自独立的,同一个指令可能会匹配到多种格式。

    比如: xxxx_0000_10xx_xxxx_xxxx_0000_1001_xxxx 这条指令会匹配到 Multiply Long 和 Halfword Data Transfer:register offset 这两种格式。

    // 没问题
    xxxx_100x_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx  Block Data Transfer
    xxxx_101x_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx  Branch
    xxxx_110x_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx  Coprocessor Data      Transfer
    xxxx_1110_xxxx_xxxx_xxxx_xxxx_xxx0_xxxx  Coprocessor Data      Operation
    xxxx_1110_xxxx_xxxx_xxxx_xxxx_xxx1_xxxx  Coprocessor Register  Transfer
    xxxx_1111_xxxx_xxxx_xxxx_xxxx_xxx1_xxxx  Software Interrupt
    //
    xxxx_0000_1xxx_xxxx_xxxx_xxxx_1001_xxxx  Multiply Long
    xxxx_000x_x0xx_xxxx_xxxx_0000_1xx1_xxxx  Halfword Data Transfer:register offset
    xxxx_0000_00xx_xxxx_xxxx_xxxx_1001_xxxx  Multiply
    xxxx_000x_x1xx_xxxx_xxxx_xxxx_1xx1_xxxx  Halfword Data Transfer:immediate offset
    xxxx_0001_0010_1111_1111_1111_0001_xxxx  Branch and Exchange
    xxxx_0001_0x00_xxxx_xxxx_0000_1001_xxxx  Single Data Swap
    xxxx_00xx_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx  Data Processing / PSR Transfer
    
    xxxx_011x_xxxx_xxxx_xxxx_xxxx_xxx1_xxxx  Undefined
    xxxx_01xx_xxxx_xxxx_xxxx_xxxx_xxxx_xxxx  Single Data Transfer
    

    Snipaste_2020-08-18_17-14-21.png

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