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/*
* Atomic operations that C can't guarantee us. Useful for
* resource counting etc..
*
* But use these as seldom as possible since they are much more slower
* than regular operations.
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1996, 1997, 2000 by Ralf Baechle
*/
#ifndef __ASM_ATOMIC_H
#define __ASM_ATOMIC_H
#include <linux/config.h>
typedef struct { volatile int counter; } atomic_t;
#ifdef __KERNEL__
#define ATOMIC_INIT(i) { (i) }
/*
* atomic_read - read atomic variable
* @v: pointer of type atomic_t
*
* Atomically reads the value of @v. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_read(v) ((v)->counter)
/*
* atomic_set - set atomic variable
* @v: pointer of type atomic_t
* @i: required value
*
* Atomically sets the value of @v to @i. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_set(v,i) ((v)->counter = (i))
#if !defined(CONFIG_CPU_HAS_LLSC)
#include <asm/system.h>
/*
* The MIPS I implementation is only atomic with respect to
* interrupts. R3000 based multiprocessor machines are rare anyway ...
*
* atomic_add - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v. Note that the guaranteed useful range
* of an atomic_t is only 24 bits.
*/
extern __inline__ void atomic_add(int i, atomic_t * v)
{
int flags;
save_flags(flags);
cli();
v->counter += i;
restore_flags(flags);
}
/*
* atomic_sub - subtract the atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
extern __inline__ void atomic_sub(int i, atomic_t * v)
{
int flags;
save_flags(flags);
cli();
v->counter -= i;
restore_flags(flags);
}
extern __inline__ int atomic_add_return(int i, atomic_t * v)
{
int temp, flags;
save_flags(flags);
cli();
temp = v->counter;
temp += i;
v->counter = temp;
restore_flags(flags);
return temp;
}
extern __inline__ int atomic_sub_return(int i, atomic_t * v)
{
int temp, flags;
save_flags(flags);
cli();
temp = v->counter;
temp -= i;
v->counter = temp;
restore_flags(flags);
return temp;
}
#else
/*
* ... while for MIPS II and better we can use ll/sc instruction. This
* implementation is SMP safe ...
*/
/*
* atomic_add - add integer to atomic variable
* @i: integer value to add
* @v: pointer of type atomic_t
*
* Atomically adds @i to @v. Note that the guaranteed useful range
* of an atomic_t is only 24 bits.
*/
extern __inline__ void atomic_add(int i, atomic_t * v)
{
unsigned long temp;
__asm__ __volatile__(
"1: ll %0, %1 # atomic_add\n"
" addu %0, %2 \n"
" sc %0, %1 \n"
" beqz %0, 1b \n"
: "=&r" (temp), "=m" (v->counter)
: "Ir" (i), "m" (v->counter));
}
/*
* atomic_sub - subtract the atomic variable
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
extern __inline__ void atomic_sub(int i, atomic_t * v)
{
unsigned long temp;
__asm__ __volatile__(
"1: ll %0, %1 # atomic_sub\n"
" subu %0, %2 \n"
" sc %0, %1 \n"
" beqz %0, 1b \n"
: "=&r" (temp), "=m" (v->counter)
: "Ir" (i), "m" (v->counter));
}
/*
* Same as above, but return the result value
*/
extern __inline__ int atomic_add_return(int i, atomic_t * v)
{
unsigned long temp, result;
__asm__ __volatile__(
".set push # atomic_add_return\n"
".set noreorder \n"
"1: ll %1, %2 \n"
" addu %0, %1, %3 \n"
" sc %0, %2 \n"
" beqz %0, 1b \n"
" addu %0, %1, %3 \n"
".set pop \n"
: "=&r" (result), "=&r" (temp), "=m" (v->counter)
: "Ir" (i), "m" (v->counter)
: "memory");
return result;
}
extern __inline__ int atomic_sub_return(int i, atomic_t * v)
{
unsigned long temp, result;
__asm__ __volatile__(
".set push \n"
".set noreorder # atomic_sub_return\n"
"1: ll %1, %2 \n"
" subu %0, %1, %3 \n"
" sc %0, %2 \n"
" beqz %0, 1b \n"
" subu %0, %1, %3 \n"
".set pop \n"
: "=&r" (result), "=&r" (temp), "=m" (v->counter)
: "Ir" (i), "m" (v->counter)
: "memory");
return result;
}
#endif
#define atomic_dec_return(v) atomic_sub_return(1,(v))
#define atomic_inc_return(v) atomic_add_return(1,(v))
/*
* atomic_sub_and_test - test variable then subtract
* @i: integer value to subtract
* @v: pointer of type atomic_t
*
* Atomically subtracts @i from @v and returns
* true if the result is zero, or false for all
* other cases. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_sub_and_test(i,v) (atomic_sub_return((i), (v)) == 0)
/*
* atomic_inc_and_test - increment by 1 and test
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1
* and returns true if the result is zero, or false for all
* other cases. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_inc_and_test(v) (atomic_inc_return(1, (v)) == 0)
/*
* atomic_dec_and_test - decrement by 1 and test
* @v: pointer of type atomic_t
*
* Atomically decrements @v by 1 and
* returns true if the result is 0, or false for all other
* cases. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
/*
* atomic_inc - increment atomic variable
* @v: pointer of type atomic_t
*
* Atomically increments @v by 1. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_inc(v) atomic_add(1,(v))
/*
* atomic_dec - decrement the atomic variable
* @v: pointer of type atomic_t
*
* Atomically decrements @v by 1. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*/
#define atomic_dec(v) atomic_sub(1,(v))
/*
* atomic_add_negative - add and test if negative
* @v: pointer of type atomic_t
* @i: integer value to add
*
* Atomically adds @i to @v and returns true
* if the result is negative, or false when
* result is greater than or equal to zero. Note that the guaranteed
* useful range of an atomic_t is only 24 bits.
*
* Currently not implemented for MIPS.
*/
#endif /* defined(__KERNEL__) */
#endif /* __ASM_ATOMIC_H */
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