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<a name='TOP'><h2><a href='../mains.html'>root</a>/<a href='../files/99.html'>include</a>/<a href='../files/100.html'>asm</a>/memory.h</h2>
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<h2><a href='59.html#L26' title='Included from 26 in kernel/blk_drv/ramdisk.c.'>INCLUDED FROM</a></h2>
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<a name='L1'><i><font color='green'>/*</font></i>
<a name='L2'><i><font color='green'>* NOTE!!! memcpy(dest,src,n) assumes ds=es=normal data segment. This</font></i>
<a name='L3'><i><font color='green'>* goes for all kernel functions (ds=es=kernel space, fs=local data,</font></i>
<a name='L4'><i><font color='green'>* gs=null), as well as for all well-behaving user programs (ds=es=</font></i>
<a name='L5'><i><font color='green'>* user data space). This is NOT a bug, as any user program that changes</font></i>
<a name='L6'><i><font color='green'>* es deserves to die if it isn't careful.</font></i>
<a name='L7'><i><font color='green'>*/</font></i>
<a name='L8'><i><font color='green'>/*</font></i>
<a name='L9'><i><font color='green'>* 注意!!!memcpy(dest,src,n)假设段寄存器ds=es=通常数据段。在内核中使用的</font></i>
<a name='L10'><i><font color='green'>* 所有函数都基于该假设（ds=es=内核空间，fs=局部数据空间，gs=null）,具有良好</font></i>
<a name='L11'><i><font color='green'>* 行为的应用程序也是这样（ds=es=用户数据空间）。如果任何用户程序随意改动了</font></i>
<a name='L12'><i><font color='green'>* es 寄存器而出错，则并不是由于系统程序错误造成的。</font></i>
<a name='L13'><i><font color='green'>*/</font></i>
<a name='L14'><i><font color='green'>//// 内存块复制。从源地址src 处开始复制n 个字节到目的地址dest 处。</font></i>
<a name='L15'><i><font color='green'>// 参数：dest - 复制的目的地址，src - 复制的源地址，n - 复制字节数。</font></i>
<a name='L16'><i><font color='green'>// %0 - edi(目的地址dest)，%1 - esi(源地址src)，%2 - ecx(字节数n)，</font></i>
<a name='L17'><font color='darkred'>#define</font> <a href='../R/529.html' title='Multiple refered from 3 places.'>memcpy</a>(dest,src,n) (<font color='red'>{</font> \
<a name='L18'><b>void</b> * _res = dest; \
<a name='L19'><b>__asm__</b> ( "cld;rep;movsb" \ <i><font color='green'>// 从ds:[esi]复制到es:[edi]，并且esi++，edi++。</font></i>
<a name='L20'><i><font color='green'>// 共复制ecx(n)字节。</font></i>
<a name='L21'>:: "D" ((<b>long</b>)(_res)), "S" ((<b>long</b>)(src)), "c" ((<b>long</b>) (n)) \
<a name='L22'>: "di", "si", "cx"); \
<a name='L23'>_res; \
<a name='L24'><font color='red'>}</font>)
<a name='L25'>
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