HelenOS sources

DF_DATA_OFFSET_l   86 uspace/srv/net/tcp/inet.c 	data_offset = BIT_RANGE_EXTRACT(uint32_t, DF_DATA_OFFSET_h, DF_DATA_OFFSET_l,
DF_DATA_OFFSET_l  138 uspace/srv/net/tcp/pdu.c 	doff = (sizeof(tcp_header_t) / sizeof(uint32_t)) << DF_DATA_OFFSET_l;