include/asm-um/system-i386.h

   1 #ifndef __UM_SYSTEM_I386_H
   2 #define __UM_SYSTEM_I386_H
   3
   4 #include "asm/system-generic.h"
   5
   6 static inline unsigned long __cmpxchg(volatile void *ptr, unsigned long old,
   7                                       unsigned long new, int size)
   8 {
   9         unsigned long prev;
  10         switch (size) {
  11         case 1:
  12                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgb %b1,%2"
  13                                      : "=a"(prev)
  14                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
  15                                      : "memory");
  16                 return prev;
  17         case 2:
  18                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgw %w1,%2"
  19                                      : "=a"(prev)
  20                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
  21                                      : "memory");
  22                 return prev;
  23         case 4:
  24                 __asm__ __volatile__(LOCK_PREFIX "cmpxchgl %1,%2"
  25                                      : "=a"(prev)
  26                                      : "q"(new), "m"(*__xg(ptr)), "0"(old)
  27                                      : "memory");
  28                 return prev;
  29         }
  30         return old;
  31 }
  32
  33 #define cmpxchg(ptr,o,n)\
  34         ((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
  35                                         (unsigned long)(n),sizeof(*(ptr))))
  36
  37 #endif