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LDM 和STM编码时有一个参数P,官方文档里的解释如下:<br />P==1<br />indicates that the word addressed by Rn is included in the range of memory locations accessed, lying at the top (U==0) or bottom (U==1) of that range.<br />P==0 <br />indicates that the word addressed by Rn is excluded from the range of memory locations accessed, and lies one word beyond the top of the range (U==0) or one word below the bottom of the range (U==1).<br />我理解是P==1时为类似空栈的方式( Rn指的内存单元将会被使用 )<br />P==0时为类似满栈的方式( Rn指的内存单元将不会被使用 )<br /><br />可是我又发现当LDMIA时显示P==0 (INCREASE AFTER,类似空栈)<br />LDMIB时P==1(INCREASE BEFORE,类似满栈)<br /><br />越看越晕,不知道到底是怎样了,请大家释疑,谢谢 |
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