void bt_readlock(BtLatch *latch)
{
ushort prev;
do {
// obtain latch mutex
#ifdef unix
if( __sync_fetch_and_or((ushort *)latch, Mutex) & Mutex )
continue;
#else
if( prev = _InterlockedOr16((ushort *)latch, Mutex) & Mutex )
continue;
#endif
// see if exclusive request is granted or pending
if( prev = !(latch->exclusive | latch->pending) )
#ifdef unix
__sync_fetch_and_add((ushort *)latch, Share);
#else
_InterlockedExchangeAdd16 ((ushort *)latch, Share);
#endif
#ifdef unix
__sync_fetch_and_and ((ushort *)latch, ~Mutex);
#else
_InterlockedAnd16((ushort *)latch, ~Mutex);
#endif
if( prev )
return;
#ifdef unix
} while( sched_yield(), 1 );
#else
} while( SwitchToThread(), 1 );
/* _Atomic_fetch_add_2, _Atomic_fetch_sub_2 */
static _Uint2_t _Fetch_add_seq_cst_2(volatile _Uint2_t *_Tgt,
_Uint2_t _Value)
{ /* add _Value to *_Tgt atomically with
sequentially consistent memory order */
_Value = _InterlockedExchangeAdd16((volatile short *)_Tgt, _Value);
return (_Value);
}
short test_InterlockedExchangeAdd16(short volatile *value, short mask) {
return _InterlockedExchangeAdd16(value, mask);
}
