CIRC_SPACE_TO_END
(CIRC_SPACE_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))
(CIRC_SPACE_TO_END((circ)->head, (circ)->tail, BUF_SZ))
c = CIRC_SPACE_TO_END(head, tail, XMIT_SIZE);
seg = CIRC_SPACE_TO_END(cons->tx_buf.head, cons->tx_buf.tail,
c = CIRC_SPACE_TO_END(info->xmit.head,
len = CIRC_SPACE_TO_END(bc->head, bc->tail, BUF_SIZE);
(CIRC_SPACE_TO_END((circ)->head, (circ)->tail, ACPI_AML_BUF_SIZE))