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判断指令集 #26

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Mars-GZ opened this issue Mar 20, 2019 · 1 comment
Open

判断指令集 #26

Mars-GZ opened this issue Mar 20, 2019 · 1 comment

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@Mars-GZ
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Mars-GZ commented Mar 20, 2019

求问大佬目标地址值的bit[0]为什么能确定目标地址的指令类型？
@yongyecc
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ARM指令集切换到Thumb是通过分支执行条内存地址为奇数的指令，当然这条指令存储的位置还是偶数的，只是将这个奇数减一就可以得到指令真实地址。之后如果通过PC寄存器每次加2来得到奇数的内存地址来执行指令，所以一直都是Thumb模式，如果出现分支跳转到一个偶数指令，就会切回ARM指令集，可能是这样吧

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@Mars-GZ @yongyecc