root/include/asm-generic/bitops.h

/* */

INCLUDED FROM

DEFINITIONS

1. set_bit
2. clear_bit
3. test_bit

   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 #endif /* _ASM_GENERIC_BITOPS_H */

/* */