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#include <arch/ppc.H>
#include <sys/sync.h>
#include <sys/syscall.h>
#include <assert.h>
using namespace Systemcalls;
//-----------------------------------------------------------------------------
uint64_t futex_wait(uint64_t * i_addr, uint64_t i_val)
{
return (uint64_t) _syscall2(FUTEX_WAIT,i_addr, (void *)i_val);
}
//-----------------------------------------------------------------------------
uint64_t futex_wake(uint64_t * i_addr, uint64_t i_count)
{
return (uint64_t) _syscall2(FUTEX_WAKE, i_addr, (void *)i_count);
}
//-----------------------------------------------------------------------------
void barrier_init (barrier_t * o_barrier, uint64_t i_count)
{
mutex_init(&(o_barrier->iv_mutex));
o_barrier->iv_event = 0;
o_barrier->iv_count = i_count;
o_barrier->iv_missing = i_count;
return;
}
//-----------------------------------------------------------------------------
void barrier_destroy (barrier_t * i_barrier)
{
crit_assert(i_barrier->iv_missing == i_barrier->iv_count);
return;
}
//-----------------------------------------------------------------------------
void barrier_wait (barrier_t * i_barrier)
{
mutex_lock(&(i_barrier->iv_mutex));
--(i_barrier->iv_missing);
if(i_barrier->iv_missing > 0)
{
uint64_t l_event = i_barrier->iv_event;
mutex_unlock(&(i_barrier->iv_mutex));
do
{
futex_wait(&(i_barrier->iv_event), l_event);
} while (i_barrier->iv_event == l_event);
}
else
{
++(i_barrier->iv_event);
i_barrier->iv_missing = i_barrier->iv_count;
// Wake em all up
futex_wake(&(i_barrier->iv_event), UINT64_MAX);
mutex_unlock(&(i_barrier->iv_mutex));
}
return;
}
//-----------------------------------------------------------------------------
void mutex_init(mutex_t * o_mutex)
{
o_mutex->iv_val = 0;
return;
}
//-----------------------------------------------------------------------------
void mutex_destroy(mutex_t *& i_mutex)
{
i_mutex->iv_val = ~0;
return;
}
//-----------------------------------------------------------------------------
void mutex_lock(mutex_t * i_mutex)
{
uint64_t l_count = __sync_val_compare_and_swap(&(i_mutex->iv_val),0,1);
if(l_count != 0)
{
if (l_count != 2)
{
lwsync();
l_count = __sync_lock_test_and_set(&(i_mutex->iv_val), 2);
}
while( l_count != 0 )
{
futex_wait( &(i_mutex->iv_val), 2);
lwsync();
l_count = __sync_lock_test_and_set(&(i_mutex->iv_val),2);
// if more than one thread gets out - one continues while
// the rest get blocked again.
}
}
#ifdef __IDEA_2
// Idea # 2
while(1)
{
uint64_t l_count = __sync_val_compare_and_swap(&(i_mutex->iv_val),0,1);
if( 0 == l_count ) // uncontended lock
{
break;
}
else if ( 2 == l_count ) // already contended
{
futex_wait( &(i_mutex->iv_val), l_count);
}
else if ( 1 == l_count ) // lock now contended
{
if (__sync_bool_compare_and_swap(&(i_mutex->iv_val),1,2))
{
futex_wait( &(i_mutex->iv_val), 2);
}
}
}
#endif
return;
}
//-----------------------------------------------------------------------------
void mutex_unlock(mutex_t * i_mutex)
{
#ifdef __IDEA_1
if (__sync_fetch_and_sub(&(i_mutex->iv_val), 1) != 1)
{
i_mutex->iv_val = 0; // the thread that is started will set this back to 2
futex_wake(&(i_mutex->iv_val), 1); // wake one thread
}
#endif
// #idea 2
lwsync();
uint64_t l_count = __sync_lock_test_and_set(&(i_mutex->iv_val),0);
if(2 == l_count)
{
futex_wake(&(i_mutex->iv_val), 1); // wake one thread
}
return;
}
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