BIT_TEST位检测

unsigned char BIT_TEST(void *aptr, unsigned char p_nmb)
{
    unsigned char *mem_byte;
    unsigned char byte_nu, bit_nu, i;
    mem_byte = (unsigned char *)aptr;
    byte_nu = p_nmb / 8;
    i = p_nmb % 8;
    bit_nu = 1 << i;
    if ((mem_byte[byte_nu] & bit_nu) != 0) return 0xff;
    else return 0;
}