root/include/asm-generic/bitops/ffs.h

INCLUDED FROM

DEFINITIONS

1. ffs

#ifndef _ASM_GENERIC_BITOPS_FFS_H_
#define _ASM_GENERIC_BITOPS_FFS_H_

/**
 * ffs - find first bit set
 * @x: the word to search
 *
 * This is defined the same way as
 * the libc and compiler builtin ffs routines, therefore
 * differs in spirit from the above ffz (man ffs).
 */
static inline int ffs(int x)
{
        int r = 1;

        if (!x)
                return 0;
        if (!(x & 0xffff)) {
                x >>= 16;
                r += 16;
        }
        if (!(x & 0xff)) {
                x >>= 8;
                r += 8;
        }
        if (!(x & 0xf)) {
                x >>= 4;
                r += 4;
        }
        if (!(x & 3)) {
                x >>= 2;
                r += 2;
        }
        if (!(x & 1)) {
                x >>= 1;
                r += 1;
        }
        return r;
}

#endif /* _ASM_GENERIC_BITOPS_FFS_H_ */