HelenOS sources

ANAR_PAUSE       1482 uspace/drv/nic/rtl8139/driver.c 		if (anar_lp & ANAR_PAUSE)
ANAR_PAUSE       1637 uspace/drv/nic/rtl8139/driver.c 		anar |= ANAR_PAUSE;
ANAR_PAUSE       1693 uspace/drv/nic/rtl8139/driver.c 	if (anar & ANAR_PAUSE)
ANAR_PAUSE        626 uspace/drv/nic/rtl8169/driver.c 		anar |= ANAR_PAUSE;
HelenOS homepage, sources at GitHub