include/asm/bitops.h

/* */
This source file includes following definitions.
set_bit
clear_bit
test_bit
set_bit
clear_bit
test_bit
   1 #ifndef _ASM_BITOPS_H
   2 #define _ASM_BITOPS_H
   3 /*
   4  * Copyright 1992, Linus Torvalds.
   5  */
   6 
   7 #ifdef i386
   8 /*
   9  * These have to be done with inline assembly: that way the bit-setting
  10  * is guaranteed to be atomic. All bitoperations return 0 if the bit
  11  * was cleared before the operation and != 0 if it was not.
  12  *
  13  * bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
  14  */
  15 
  16 /*
  17  * Some hacks to defeat gcc over-optimizations..
  18  */
  19 struct __dummy { unsigned long a[100]; };
  20 #define ADDR (*(struct __dummy *) addr)
  21 
  22 extern __inline__ int set_bit(int nr, void * addr)
     /*  */
  23 {
  24         int oldbit;
  25 
  26         __asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
  27                 :"=r" (oldbit),"=m" (ADDR)
  28                 :"r" (nr));
  29         return oldbit;
  30 }
  31 
  32 extern __inline__ int clear_bit(int nr, void * addr)
     /*  */
  33 {
  34         int oldbit;
  35 
  36         __asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
  37                 :"=r" (oldbit),"=m" (ADDR)
  38                 :"r" (nr));
  39         return oldbit;
  40 }
  41 
  42 /*
  43  * This routine doesn't need to be atomic, but it's faster to code it
  44  * this way.
  45  */
  46 extern __inline__ int test_bit(int nr, void * addr)
     /*  */
  47 {
  48         int oldbit;
  49 
  50         __asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
  51                 :"=r" (oldbit)
  52                 :"m" (ADDR),"r" (nr));
  53         return oldbit;
  54 }
  55 
  56 #else
  57 /*
  58  * For the benefit of those who are trying to port Linux to another
  59  * architecture, here are some C-language equivalents.  You should
  60  * recode these in the native assmebly language, if at all possible.
  61  * To guarantee atomicity, these routines call cli() and sti() to
  62  * disable interrupts while they operate.  (You have to provide inline
  63  * routines to cli() and sti().)
  64  *
  65  * Also note, these routines assume that you have 32 bit integers.
  66  * You will have to change this if you are trying to port Linux to the
  67  * Alpha architecture or to a Cray.  :-)
  68  * 
  69  * C language equivalents written by Theodore Ts'o, 9/26/92
  70  */
  71 
  72 extern __inline__ int set_bit(int nr,int * addr)
     /*  */
  73 {
  74         int     mask, retval;
  75 
  76         addr += nr >> 5;
  77         mask = 1 << (nr & 0x1f);
  78         cli();
  79         retval = (mask & *addr) != 0;
  80         *addr |= mask;
  81         sti();
  82         return retval;
  83 }
  84 
  85 extern __inline__ int clear_bit(int nr, int * addr)
     /*  */
  86 {
  87         int     mask, retval;
  88 
  89         addr += nr >> 5;
  90         mask = 1 << (nr & 0x1f);
  91         cli();
  92         retval = (mask & *addr) == 0;
  93         *addr &= ~mask;
  94         sti();
  95         return retval;
  96 }
  97 
  98 extern __inline__ int test_bit(int nr, int * addr)
     /*  */
  99 {
 100         int     mask;
 101 
 102         addr += nr >> 5;
 103         mask = 1 << (nr & 0x1f);
 104         return ((mask & *addr) != 0);
 105 }
 106 #endif  /* i386 */
 107 #endif /* _ASM_BITOPS_H */
/* */
root/include/asm/bitops.h

INCLUDED FROM

DEFINITIONS
