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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)
{
// Weak consistency notes:
// Since this is a lock, we do not need to ensure that all writes
// are globally visible prior to execution (lwsync) but we do need
// to ensure that all instructions finish completion prior to
// leaving (isync). Both __sync_val_compare_and_swap and
// __sync_lock_test_and_set have an implied isync.
uint64_t l_count = __sync_val_compare_and_swap(&(i_mutex->iv_val),0,1);
if(unlikely(l_count != 0))
{
if (likely(l_count != 2))
{
l_count = __sync_lock_test_and_set(&(i_mutex->iv_val), 2);
}
while( l_count != 0 )
{
futex_wait( &(i_mutex->iv_val), 2);
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.
}
}
return;
}
//-----------------------------------------------------------------------------
void mutex_unlock(mutex_t * i_mutex)
{
// Weak consistency notes:
// Since this is an unlock we need to ensure that all writes are
// globally visible prior to execution (lwsync). The
// __sync_fetch_and_sub has an implied lwsync. If we need to
// release a task, due to a contended mutex, the write to iv_val
// and futex_wake pair will appear globally ordered due to the
// context synchronizing nature of the 'sc' instruction.
uint64_t l_count = __sync_fetch_and_sub(&(i_mutex->iv_val),1);
if(unlikely(2 <= l_count))
{
i_mutex->iv_val = 0;
futex_wake(&(i_mutex->iv_val), 1); // wake one thread
}
return;
}
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