root/include/asm/memory.h

/* */

DEFINITIONS

1. f_memcpy

   1 /*
   2  *  NOTE!!! memcpy(dest,src,n) assumes ds=es=normal data segment. This
   3  *  goes for all kernel functions (ds=es=kernel space, fs=local data,
   4  *  gs=null), as well as for all well-behaving user programs (ds=es=
   5  *  user data space). This is NOT a bug, as any user program that changes
   6  *  es deserves to die if it isn't careful.
   7  */
   8 #if 0
   9 #define memcpy(dest,src,n) ({ \
  10 void * _res = dest; \
  11 __asm__ __volatile__ ("cld;rep;movsb" \
  12         ::"D" ((long)(_res)),"S" ((long)(src)),"c" ((long) (n)) \
  13         :"di","si","cx"); \
  14 _res; \
  15 })
  16 #else
  17 
  18 /* this is basically memcpy_tofs.  It should be faster.
  19    I've reorder it.  This should be a little faster. -RAB */
  20 
  21 #define memcpy(dest, src, n) f_memcpy(dest, src, n)
  22 extern inline void * f_memcpy(void * to, void * from, unsigned long n)
     /*  */
  23 {
  24 __asm__("cld\n\t"
  25         "movl %%edx, %%ecx\n\t"
  26         "shrl $2,%%ecx\n\t"
  27         "rep ; movsl\n\t"
  28         "testb $1,%%dl\n\t"
  29         "je 1f\n\t"
  30         "movsb\n"
  31         "1:\ttestb $2,%%dl\n\t"
  32         "je 2f\n\t"
  33         "movsw\n"
  34         "2:\n"
  35         ::"d" (n),"D" ((long) to),"S" ((long) from)
  36         : "cx","di","si");
  37 return (to);
  38 }
  39 #endif

/* */