On Tue, 24 Apr 2007 10:54:27 +0900 Hisashi Hifumi <[EMAIL PROTECTED]> wrote: > In the case that changing the same bit concurrently, lock prefix or other > spinlock is needed. But, I think that concurrent bit operation on different > bits > is just like OR operation , so lock prefix is not needed. > > AMD instruction manual says about bts that , > > "Copies a bit, specified by bit index in a register or 8-bit immediate > value (second operand), from a bit > string (first operand), also called the bit base, to the carry flag (CF) of > the rFLAGS register, and then > sets the bit in the bit string to 1." > > BTS instruction is read-modify-write instruction on bit unit. So concurrent > bit operation on different > bits may be possible. > This is ia64's __set_bit() hehe.. == static __inline__ void __set_bit (int nr, volatile void *addr) { *((__u32 *) addr + (nr >> 5)) |= (1 << (nr & 31)); } ==
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