root/arch/x86/boot/bitops.h

INCLUDED FROM

DEFINITIONS

1. constant_test_bit
2. variable_test_bit
3. set_bit

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 /* -*- linux-c -*- ------------------------------------------------------- *
   3  *
   4  *   Copyright (C) 1991, 1992 Linus Torvalds
   5  *   Copyright 2007 rPath, Inc. - All Rights Reserved
   6  *
   7  * ----------------------------------------------------------------------- */
   8 
   9 /*
  10  * Very simple bitops for the boot code.
  11  */
  12 
  13 #ifndef BOOT_BITOPS_H
  14 #define BOOT_BITOPS_H
  15 #define _LINUX_BITOPS_H         /* Inhibit inclusion of <linux/bitops.h> */
  16 
  17 #include <linux/types.h>
  18 #include <asm/asm.h>
  19 
  20 static inline bool constant_test_bit(int nr, const void *addr)
  21 {
  22         const u32 *p = (const u32 *)addr;
  23         return ((1UL << (nr & 31)) & (p[nr >> 5])) != 0;
  24 }
  25 static inline bool variable_test_bit(int nr, const void *addr)
  26 {
  27         bool v;
  28         const u32 *p = (const u32 *)addr;
  29 
  30         asm("btl %2,%1" CC_SET(c) : CC_OUT(c) (v) : "m" (*p), "Ir" (nr));
  31         return v;
  32 }
  33 
  34 #define test_bit(nr,addr) \
  35 (__builtin_constant_p(nr) ? \
  36  constant_test_bit((nr),(addr)) : \
  37  variable_test_bit((nr),(addr)))
  38 
  39 static inline void set_bit(int nr, void *addr)
  40 {
  41         asm("btsl %1,%0" : "+m" (*(u32 *)addr) : "Ir" (nr));
  42 }
  43 
  44 #endif /* BOOT_BITOPS_H */