tools/testing/radix-tree/bitmap.c

/* lib/bitmap.c pulls in at least two other files. */

#include <linux/bitmap.h>

void bitmap_clear(unsigned long *map, unsigned int start, int len)
{
	unsigned long *p = map + BIT_WORD(start);
	const unsigned int size = start + len;
	int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
	unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);

	while (len - bits_to_clear >= 0) {
		*p &= ~mask_to_clear;
		len -= bits_to_clear;
		bits_to_clear = BITS_PER_LONG;
		mask_to_clear = ~0UL;
		p++;
	}
	if (len) {
		mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
		*p &= ~mask_to_clear;
	}
}