if (!current_SC->SCp.this_residual && current_SC->SCp.buffers_residual) {
--current_SC->SCp.buffers_residual;
++current_SC->SCp.buffer;
if (!current_SC->SCp.this_residual && current_SC->SCp.buffers_residual) {
--current_SC->SCp.buffers_residual;
++current_SC->SCp.buffer;