tools/include/linux/bits.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef __LINUX_BITS_H
   3 #define __LINUX_BITS_H
   4
   5 #include <linux/const.h>
   6 #include <vdso/bits.h>
   7 #include <uapi/linux/bits.h>
   8 #include <asm/bitsperlong.h>
   9
  10 #define BIT_MASK(nr)            (UL(1) << ((nr) % BITS_PER_LONG))
  11 #define BIT_WORD(nr)            ((nr) / BITS_PER_LONG)
  12 #define BIT_ULL_MASK(nr)        (ULL(1) << ((nr) % BITS_PER_LONG_LONG))
  13 #define BIT_ULL_WORD(nr)        ((nr) / BITS_PER_LONG_LONG)
  14 #define BITS_PER_BYTE           8
  15
  16 /*
  17  * Create a contiguous bitmask starting at bit position @l and ending at
  18  * position @h. For example
  19  * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
  20  */
  21 #if !defined(__ASSEMBLY__)
  22 #include <linux/build_bug.h>
  23 #define GENMASK_INPUT_CHECK(h, l) \
  24         (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
  25                 __is_constexpr((l) > (h)), (l) > (h), 0)))
  26 #else
  27 /*
  28  * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
  29  * disable the input check if that is the case.
  30  */
  31 #define GENMASK_INPUT_CHECK(h, l) 0
  32 #endif
  33
  34 #define GENMASK(h, l) \
  35         (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
  36 #define GENMASK_ULL(h, l) \
  37         (GENMASK_INPUT_CHECK(h, l) + __GENMASK_ULL(h, l))
  38
  39 #if !defined(__ASSEMBLY__)
  40 /*
  41  * Missing asm support
  42  *
  43  * __GENMASK_U128() depends on _BIT128() which would not work
  44  * in the asm code, as it shifts an 'unsigned __init128' data
  45  * type instead of direct representation of 128 bit constants
  46  * such as long and unsigned long. The fundamental problem is
  47  * that a 128 bit constant will get silently truncated by the
  48  * gcc compiler.
  49  */
  50 #define GENMASK_U128(h, l) \
  51         (GENMASK_INPUT_CHECK(h, l) + __GENMASK_U128(h, l))
  52 #endif
  53
  54 #endif  /* __LINUX_BITS_H */