42 lines
1.4 KiB
C
42 lines
1.4 KiB
C
|
/* 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
|
||
|
|
inbyte (void)
|
||
|
|
{
|
||
|
|
while ((READREG (DUART_SRA) & 0x01) == 0x00)
|
||
|
|
;
|
||
|
|
|
||
|
|
return (READREG (DUART_RBA)); /* read the byte */
|
||
|
|
}
|