ASYNC_SW_IN_FLOW
async->async_flags |= ASYNC_SW_IN_FLOW |
~ASYNC_SW_IN_FLOW) | ASYNC_SW_IN_NEEDED;
async->async_flags & ASYNC_SW_IN_FLOW ?
async->async_flags |= ASYNC_SW_IN_FLOW |
~ASYNC_SW_IN_FLOW) | ASYNC_SW_IN_NEEDED;
c = (async->async_flags & ASYNC_SW_IN_FLOW) ?