HelenOS sources

CTRL_FRCDPLX      409 uspace/drv/nic/e1k/e1k.c 	ctrl |= CTRL_FRCDPLX;
CTRL_FRCDPLX      451 uspace/drv/nic/e1k/e1k.c 	ctrl &= ~(CTRL_FRCDPLX);
CTRL_FRCDPLX      479 uspace/drv/nic/e1k/e1k.c 	ctrl |= CTRL_FRCDPLX;
HelenOS homepage, sources at GitHub