1 # define ACE_BIT_ENABLED(WORD, BIT) (((WORD) & (BIT)) != 0 )2 # define ACE_BIT_DISABLED(WORD, BIT) (((WORD) & (BIT)) == 0 )3 # define ACE_BIT_CMP_MASK(WORD, BIT, MASK) (((WORD) & (BIT)) == MASK)4 # define ACE_SET_BITS(WORD, BITS) (WORD |= (BITS))5 # define ACE_CLR_BITS(WORD, BITS) (WORD &= ~ (BITS))
附上C中常用的位运算用法,取自《C Primer Plus》
掩码:即mask,通常为某一个位为1,而其他位都为0的byte,如00000100。1.把byte中除掩码相同的位外,全部置0,掩码位不变flags &= mask
10101111 & 00000100 = 00000100
2.打开位:打开特定的位,其他位不变。flags |= MASK
00001000 | 00000100 = 00001100
3.关闭位:关闭特定位,但不影响其他位flags &= ~MASK
11100101 &= ~10000000 = 01100101
4.转置位:一个位如果打开,则关闭;如果关闭,则打开flags ^= MASK
11100101 ^= 10000000 = 01100101
11100101 ^= 00010000 = 111101015.查看一个位的值:1 if ((flag & MASK) == MASK)2 do_some_work();
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