__bitmap

void __bitmap_set(unsigned long *map, unsigned int start, int len)
{
    unsigned long *p = map + BIT_WORD(start);
    const unsigned int size = start + len;
    int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
    unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
 
    while (len - bits_to_set >= 0) {
        *p |= mask_to_set;
        len -= bits_to_set;
        bits_to_set = BITS_PER_LONG;
        mask_to_set = ~0UL;
        p++;
    }
    if (len) {
        mask_to_set &= BITMAP_LAST_WORD_MASK(size);
        *p |= mask_to_set;
    }
}
函数源码
