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//Source: http://golubenco.org/atomic-operations.html
#ifndef __ATOMIC_H__
#define __ATOMIC_H__
/* Check GCC version, just to be safe */
#if !defined(__GNUC__) || (__GNUC__ < 4) || (__GNUC_MINOR__ < 1)
# error atomic.h works only with GCC newer than version 4.1
#endif /* GNUC >= 4.1 */
/**
* Atomic type.
*/
typedef struct {
volatile long counter;
} atomic_long_t;
#define ATOMIC_INIT(i) { (i) }
/**
* Read atomic variable
* @param v pointer of type atomic_long_t
*
* Atomically reads the value of @v.
*/
#define atomic_long_read(v) ((v)->counter)
/**
* Set atomic variable
* @param v pointer of type atomic_long_t
* @param i required value
*/
#define atomic_long_set(v,i) (((v)->counter) = (i))
/**
* Add to the atomic variable
* @param i integer value to add
* @param v pointer of type atomic_long_t
*/
static inline void atomic_long_add( int i, atomic_long_t *v )
{
(void)__sync_add_and_fetch(&v->counter, i);
}
/**
* Subtract the atomic variable
* @param i integer value to subtract
* @param v pointer of type atomic_long_t
*
* Atomically subtracts @i from @v.
*/
static inline void atomic_long_sub( int i, atomic_long_t *v )
{
(void)__sync_sub_and_fetch(&v->counter, i);
}
/**
* Subtract value from variable and test result
* @param i integer value to subtract
* @param v pointer of type atomic_long_t
*
* Atomically subtracts @i from @v and returns
* true if the result is zero, or false for all
* other cases.
*/
static inline int atomic_long_sub_and_test( int i, atomic_long_t *v )
{
return !(__sync_sub_and_fetch(&v->counter, i));
}
/**
* Increment atomic variable
* @param v pointer of type atomic_long_t
*
* Atomically increments @v by 1.
*/
static inline void atomic_long_inc( atomic_long_t *v )
{
(void)__sync_fetch_and_add(&v->counter, 1);
}
/**
* @brief decrement atomic variable
* @param v: pointer of type atomic_long_t
*
* Atomically decrements @v by 1. Note that the guaranteed
* useful range of an atomic_long_t is only 24 bits.
*/
static inline void atomic_long_dec( atomic_long_t *v )
{
(void)__sync_fetch_and_sub(&v->counter, 1);
}
/**
* @brief Decrement and test
* @param v pointer of type atomic_long_t
*
* Atomically decrements @v by 1 and
* returns true if the result is 0, or false for all other
* cases.
*/
static inline int atomic_long_dec_and_test( atomic_long_t *v )
{
return !(__sync_sub_and_fetch(&v->counter, 1));
}
/**
* @brief Increment and test
* @param v pointer of type atomic_long_t
*
* Atomically increments @v by 1
* and returns true if the result is zero, or false for all
* other cases.
*/
static inline int atomic_long_inc_and_test( atomic_long_t *v )
{
return !(__sync_add_and_fetch(&v->counter, 1));
}
/**
* @brief add and test if negative
* @param v pointer of type atomic_long_t
* @param 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.
*/
static inline int atomic_long_add_negative( int i, atomic_long_t *v )
{
return (__sync_add_and_fetch(&v->counter, i) < 0);
}
#endif
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