718 	register unsigned int head, tail;  in pc_write()  local
780 		tail = bc->tout;  in pc_write()
784 		if (tail != bc->tout)  in pc_write()
785 			tail = bc->tout;  in pc_write()
794 		tail &= (size - 1);  in pc_write()
861 		dataLen = (head >= tail) ? (size - (head - tail) - 1) : (tail - head - 1);  in pc_write()
932 	tail = bc->tout;  in pc_write()
934 	if (tail != bc->tout)  in pc_write()
935 		tail = bc->tout;  in pc_write()
936 	tail &= (size - 1);  in pc_write()
939 	if (head >= tail)   in pc_write()
951 		remain = size - (head - tail) - 1;  in pc_write()
957 		remain = tail - head - 1;  in pc_write()
988 			dataLen = tail;  in pc_write()
1028 	unsigned int head, tail;  in pc_write_room()  local
1046 		tail = bc->tout;  in pc_write_room()
1048 		if (tail != bc->tout)  in pc_write_room()
1049 			tail = bc->tout;  in pc_write_room()
1051 		tail &= (ch->txbufsize - 1);  in pc_write_room()
1053 		if ((remain = tail - head - 1) < 0 )  in pc_write_room()
1076 	unsigned int ctail, head, tail;  in pc_chars_in_buffer()  local
1096 	tail = bc->tout;  in pc_chars_in_buffer()
1100 	if (tail == head && ch->mailbox->cin == ctail && bc->tbusy == 0)  in pc_chars_in_buffer()
1106 		tail &= (ch->txbufsize - 1);  in pc_chars_in_buffer()
1114 		if ((remain = tail - head - 1) < 0 )  in pc_chars_in_buffer()
1145 	unsigned int tail;  in pc_flush_buffer()  local
1165 	tail = bc->tout;  in pc_flush_buffer()
1169 	fepcmd(ch, STOUT, (unsigned) tail, 0, 0, 0);  in pc_flush_buffer()
2213 	volatile unsigned int head, tail;  in epcapoll()  local
2253 		tail = ch->mailbox->eout;  in epcapoll()
2257 		if (head != tail)  in epcapoll()
2279 	register volatile unsigned int tail, head;  in doevent()  local
2295 	while ((tail = chan0->mailbox->eout) != (head = chan0->mailbox->ein))   in doevent()
2300 		eventbuf = (volatile unchar *)bus_to_virt((ulong)(bd->re_map_membase + tail + ISTART));  in doevent()
2413 		chan0->mailbox->eout = (tail + 4) & (IMAX - ISTART - 4);  in doevent()
2834 	register unsigned int tail, head;  in receive_data()  local
2870 	tail = bc->rout & wrapmask;  in receive_data()
2872 	bytesAvailable = (head - tail) & wrapmask;  in receive_data()
2903 		wrapgap = (head >= tail) ? head - tail : ch->rxbufsize - tail;  in receive_data()
2928 		if ((memcpy(rptr, ch->rxptr + tail, dataToRead)) != rptr)  in receive_data()
2933 		tail = (tail + dataToRead) & wrapmask;  in receive_data()
2942 	bc->rout = tail;  in receive_data()