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  */
  14 static 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
  30 static 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  */
  44 static 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  */
  55 static 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
  69 static inline unsigned long kernel_ffs(unsigned long w)
  70 {
  71         return w ? cris_swapwbrlz (w) + 1 : 0;
  72 }
  73
  74 #endif