关于sbbl的问题
wyfwx 2011-08-15 03:32:45 static inline int test_and_set_bit(int nr, volatile unsigned long * addr)
{
int oldbit;
__asm__ __volatile__( LOCK_PREFIX
"btsl %2,%1\n\tsbbl %0,%0"
:"=r" (oldbit),"=m" (ADDR)
:"Ir" (nr) : "memory");
return oldbit;
}
若btsl %2,%1使CF标志为1,那么sbbl %0,%0让oldbit等于 -1 吗?
sbbl是怎么工作的,请各位大虾指点下!!!