| /* idp-inbyte.c -- |
| * Copyright (c) 1995 Cygnus Support |
| * |
| * The authors hereby grant permission to use, copy, modify, distribute, |
| * and license this software and its documentation for any purpose, provided |
| * that existing copyright notices are retained in all copies and that this |
| * notice is included verbatim in any distributions. No written agreement, |
| * license, or royalty fee is required for any of the authorized uses. |
| * Modifications to this software may be copyrighted by their authors |
| * and need not follow the licensing terms described here, provided that |
| * the new terms are clearly indicated on the first page of each file where |
| * they apply. |
| */ |
| |
| #include <_ansi.h> |
| #include "mc68681reg.h" |
| |
| /* |
| * The DUART is mapped into the IDP address space in an unusual |
| * manner. The mc68681 is an 8 bit device located on the least |
| * significant byte (byte0) of the data bus. Bytes 3, 2, and |
| * one have nothing in them and writes to these locations are |
| * not valid. |
| */ |
| |
| #define DUART_ADDR 0x00B00000 |
| #define READREG(x) (*((volatile char *) DUART_ADDR + (x * 4) + 3)) |
| #define WRITEREG(x, y) (*((char *) DUART_ADDR + (x * 4) + 3) = y) |
| |
| /* |
| * inbyte -- get a byte from the DUART RX buffer. This only reads |
| * from channel A |
| */ |
| char |
| _DEFUN_VOID (inbyte) |
| { |
| while ((READREG (DUART_SRA) & 0x01) == 0x00) |
| ; |
| |
| return (READREG (DUART_RBA)); /* read the byte */ |
| } |