107 lines
2.3 KiB
C
107 lines
2.3 KiB
C
#ifndef _ASM_BITOPS_H
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#define _ASM_BITOPS_H
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/*
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* Copyright 1992, Linus Torvalds.
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*/
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#ifdef i386
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/*
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* These have to be done with inline assembly: that way the bit-setting
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* is guaranteed to be atomic. All bitoperations return 0 if the bit
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* was cleared before the operation and != 0 if it was not.
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*
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* bit 0 is the LSB of addr; bit 32 is the LSB of (addr+1).
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*/
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/*
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* Some hacks to defeat gcc over-optimizations..
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*/
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struct __dummy { unsigned long a[100]; };
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#define ADDR (*(struct __dummy *) addr)
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extern __inline__ int set_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btsl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit),"=m" (ADDR)
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:"r" (nr));
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return oldbit;
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}
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extern __inline__ int clear_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btrl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit),"=m" (ADDR)
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:"r" (nr));
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return oldbit;
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}
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/*
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* This routine doesn't need to be atomic, but it's faster to code it
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* this way.
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*/
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extern __inline__ int test_bit(int nr, void * addr)
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{
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int oldbit;
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__asm__ __volatile__("btl %2,%1\n\tsbbl %0,%0"
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:"=r" (oldbit)
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:"m" (ADDR),"r" (nr));
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return oldbit;
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}
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#else
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/*
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* For the benefit of those who are trying to port Linux to another
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* architecture, here are some C-language equivalents. You should
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* recode these in the native assmebly language, if at all possible.
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* To guarantee atomicity, these routines call cli() and sti() to
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* disable interrupts while they operate. (You have to provide inline
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* routines to cli() and sti().)
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*
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* Also note, these routines assume that you have 32 bit integers.
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* You will have to change this if you are trying to port Linux to the
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* Alpha architecture or to a Cray. :-)
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*
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* C language equivalents written by Theodore Ts'o, 9/26/92
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*/
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extern __inline__ int set_bit(int nr,int * addr)
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{
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int mask, retval;
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addr += nr >> 5;
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mask = 1 << (nr & 0x1f);
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cli();
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retval = (mask & *addr) != 0;
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*addr |= mask;
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sti();
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return retval;
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}
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extern __inline__ int clear_bit(int nr, int * addr)
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{
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int mask, retval;
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addr += nr >> 5;
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mask = 1 << (nr & 0x1f);
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cli();
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retval = (mask & *addr) == 0;
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*addr &= ~mask;
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sti();
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return retval;
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}
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extern __inline__ int test_bit(int nr, int * addr)
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{
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int mask;
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addr += nr >> 5;
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mask = 1 << (nr & 0x1f);
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return ((mask & *addr) != 0);
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}
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#endif /* i386 */
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#endif /* _ASM_BITOPS_H */
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