arch/cris/include/arch-v10/arch/bitops.h

/* SPDX-License-Identifier: GPL-2.0 */
/* asm/arch/bitops.h for Linux/CRISv10 */

#ifndef _CRIS_ARCH_BITOPS_H
#define _CRIS_ARCH_BITOPS_H

/*
 * Helper functions for the core of the ff[sz] functions, wrapping the
 * syntactically awkward asms.  The asms compute the number of leading
 * zeroes of a bits-in-byte and byte-in-word and word-in-dword-swapped
 * number.  They differ in that the first function also inverts all bits
 * in the input.
 */
static inline unsigned long cris_swapnwbrlz(unsigned long w)
{
	/* Let's just say we return the result in the same register as the
	   input.  Saying we clobber the input but can return the result
	   in another register:
	   !  __asm__ ("swapnwbr %2\n\tlz %2,%0"
	   !	      : "=r,r" (res), "=r,X" (dummy) : "1,0" (w));
	   confuses gcc (core.c, gcc from cris-dist-1.14).  */

	unsigned long res;
	__asm__ ("swapnwbr %0 \n\t"
		 "lz %0,%0"
		 : "=r" (res) : "0" (w));
	return res;
}

static inline unsigned long cris_swapwbrlz(unsigned long w)
{
	unsigned res;
	__asm__ ("swapwbr %0 \n\t"
		 "lz %0,%0"
		 : "=r" (res)
		 : "0" (w));
	return res;
}

/*
 * ffz = Find First Zero in word. Undefined if no zero exists,
 * so code should check against ~0UL first..
 */
static inline unsigned long ffz(unsigned long w)
{
	return cris_swapnwbrlz(w);
}

/**
 * __ffs - find first bit in word.
 * @word: The word to search
 *
 * Undefined if no bit exists, so code should check against 0 first.
 */
static inline unsigned long __ffs(unsigned long word)
{
	return cris_swapnwbrlz(~word);
}

/**
 * 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 unsigned long kernel_ffs(unsigned long w)
{
	return w ? cris_swapwbrlz (w) + 1 : 0;
}

#endif