// SPDX-License-Identifier: GPL-2.0
/*
 * MSB0 numbered special bitops handling.
 *
 * The bits are numbered:
 *   |0..............63|64............127|128...........191|192...........255|
 *
 * The reason for this bit numbering is the fact that the hardware sets bits
 * in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap
 * from the 'wrong end'.
 */

#include <linux/compiler.h>
#include <linux/bitops.h>
#include <linux/export.h>

unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size)
{
        const unsigned long *p = addr;
        unsigned long result = 0;
        unsigned long tmp;

        while (size & ~(BITS_PER_LONG - 1)) {
                if ((tmp = *(p++)))
                        goto found;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
        tmp = (*p) & (~0UL << (BITS_PER_LONG - size));
        if (!tmp)               /* Are any bits set? */
                return result + size;   /* Nope. */
found:
        return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_first_bit_inv);

unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size,
                                unsigned long offset)
{
        const unsigned long *p = addr + (offset / BITS_PER_LONG);
        unsigned long result = offset & ~(BITS_PER_LONG - 1);
        unsigned long tmp;

        if (offset >= size)
                return size;
        size -= result;
        offset %= BITS_PER_LONG;
        if (offset) {
                tmp = *(p++);
                tmp &= (~0UL >> offset);
                if (size < BITS_PER_LONG)
                        goto found_first;
                if (tmp)
                        goto found_middle;
                size -= BITS_PER_LONG;
                result += BITS_PER_LONG;
        }
        while (size & ~(BITS_PER_LONG-1)) {
                if ((tmp = *(p++)))
                        goto found_middle;
                result += BITS_PER_LONG;
                size -= BITS_PER_LONG;
        }
        if (!size)
                return result;
        tmp = *p;
found_first:
        tmp &= (~0UL << (BITS_PER_LONG - size));
        if (!tmp)               /* Are any bits set? */
                return result + size;   /* Nope. */
found_middle:
        return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
}
EXPORT_SYMBOL(find_next_bit_inv);