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

   1/* SPDX-License-Identifier: GPL-2.0 */
   2/* asm/arch/bitops.h for Linux/CRISv10 */
   3
   4#ifndef _CRIS_ARCH_BITOPS_H
   5#define _CRIS_ARCH_BITOPS_H
   6
   7/*
   8 * Helper functions for the core of the ff[sz] functions, wrapping the
   9 * syntactically awkward asms.  The asms compute the number of leading
  10 * zeroes of a bits-in-byte and byte-in-word and word-in-dword-swapped
  11 * number.  They differ in that the first function also inverts all bits
  12 * in the input.
  13 */
  14static inline unsigned long cris_swapnwbrlz(unsigned long w)
  15{
  16        /* Let's just say we return the result in the same register as the
  17           input.  Saying we clobber the input but can return the result
  18           in another register:
  19           !  __asm__ ("swapnwbr %2\n\tlz %2,%0"
  20           !          : "=r,r" (res), "=r,X" (dummy) : "1,0" (w));
  21           confuses gcc (core.c, gcc from cris-dist-1.14).  */
  22
  23        unsigned long res;
  24        __asm__ ("swapnwbr %0 \n\t"
  25                 "lz %0,%0"
  26                 : "=r" (res) : "0" (w));
  27        return res;
  28}
  29
  30static inline unsigned long cris_swapwbrlz(unsigned long w)
  31{
  32        unsigned res;
  33        __asm__ ("swapwbr %0 \n\t"
  34                 "lz %0,%0"
  35                 : "=r" (res)
  36                 : "0" (w));
  37        return res;
  38}
  39
  40/*
  41 * ffz = Find First Zero in word. Undefined if no zero exists,
  42 * so code should check against ~0UL first..
  43 */
  44static inline unsigned long ffz(unsigned long w)
  45{
  46        return cris_swapnwbrlz(w);
  47}
  48
  49/**
  50 * __ffs - find first bit in word.
  51 * @word: The word to search
  52 *
  53 * Undefined if no bit exists, so code should check against 0 first.
  54 */
  55static inline unsigned long __ffs(unsigned long word)
  56{
  57        return cris_swapnwbrlz(~word);
  58}
  59
  60/**
  61 * ffs - find first bit set
  62 * @x: the word to search
  63 *
  64 * This is defined the same way as
  65 * the libc and compiler builtin ffs routines, therefore
  66 * differs in spirit from the above ffz (man ffs).
  67 */
  68
  69static inline unsigned long kernel_ffs(unsigned long w)
  70{
  71        return w ? cris_swapwbrlz (w) + 1 : 0;
  72}
  73
  74#endif
  75