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/* 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 */
}
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