include/asm-generic/bitops.h

   1 #ifndef _ASM_GENERIC_BITOPS_H_
   2 #define _ASM_GENERIC_BITOPS_H_
   3
   4 /*
   5  * For the benefit of those who are trying to port Linux to another
   6  * architecture, here are some C-language equivalents.  You should
   7  * recode these in the native assembly language, if at all possible.
   8  * To guarantee atomicity, these routines call cli() and sti() to
   9  * disable interrupts while they operate.  (You have to provide inline
  10  * routines to cli() and sti().)
  11  *
  12  * Also note, these routines assume that you have 32 bit integers.
  13  * You will have to change this if you are trying to port Linux to the
  14  * Alpha architecture or to a Cray.  :-)
  15  *
  16  * C language equivalents written by Theodore Ts'o, 9/26/92
  17  */
  18
  19 extern __inline__ int set_bit(int nr,int * addr)
  20 {
  21         int     mask, retval;
  22
  23         addr += nr >> 5;
  24         mask = 1 << (nr & 0x1f);
  25         cli();
  26         retval = (mask & *addr) != 0;
  27         *addr |= mask;
  28         sti();
  29         return retval;
  30 }
  31
  32 extern __inline__ int clear_bit(int nr, int * addr)
  33 {
  34         int     mask, retval;
  35
  36         addr += nr >> 5;
  37         mask = 1 << (nr & 0x1f);
  38         cli();
  39         retval = (mask & *addr) != 0;
  40         *addr &= ~mask;
  41         sti();
  42         return retval;
  43 }
  44
  45 extern __inline__ int test_bit(int nr, int * addr)
  46 {
  47         int     mask;
  48
  49         addr += nr >> 5;
  50         mask = 1 << (nr & 0x1f);
  51         return ((mask & *addr) != 0);
  52 }
  53
  54 #ifdef __KERNEL__
  55
  56 /*
  57  * ffs: find first bit set. This is defined the same way as
  58  * the libc and compiler builtin ffs routines, therefore
  59  * differs in spirit from the above ffz (man ffs).
  60  */
  61
  62 #define ffs(x) generic_ffs(x)
  63
  64 /*
  65  * hweightN: returns the hamming weight (i.e. the number
  66  * of bits set) of a N-bit word
  67  */
  68
  69 #define hweight32(x) generic_hweight32(x)
  70 #define hweight16(x) generic_hweight16(x)
  71 #define hweight8(x) generic_hweight8(x)
  72
  73 #endif /* __KERNEL__ */
  74
  75 #endif /* _ASM_GENERIC_BITOPS_H */