本文介绍了汇编语言:cbw的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我不确定cbw命令的实际作用.我有一段代码:
I am unsure of what the cbw command actually does. I have a snippet of code:
mov ax,0FF0h
cbw
idiv ah
cbw之后ax的值如何变化?
How does the value of ax change after cbw?
推荐答案
cbw指令将一个字节扩展为一个单词.在这种情况下，它将使用AL的符号位(恰好是1)并将其复制到AH的每一位.
The cbw instruction sign-extends a byte into a word. In this case, it'll take the sign bit of AL (which happens to be 1) and copy it into every bit of AH.
这意味着AX的二进制补码值将相同，但是二进制表示形式将不同.
This means that the two's-complement value of AX will be the same, but the binary representation will be different.
cbw指令后的AX值将为FFF0h(16位-16值，就像AL最初是8位-16一样)
The value of AX after the cbw instruction will be FFF0h (a 16-bit -16 value, just like AL was originally an 8-bit -16)
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