| [444] | 1 | /* idp-inbyte.c -- |
|---|
| 2 | * Copyright (c) 1995 Cygnus Support |
|---|
| 3 | * |
|---|
| 4 | * The authors hereby grant permission to use, copy, modify, distribute, |
|---|
| 5 | * and license this software and its documentation for any purpose, provided |
|---|
| 6 | * that existing copyright notices are retained in all copies and that this |
|---|
| 7 | * notice is included verbatim in any distributions. No written agreement, |
|---|
| 8 | * license, or royalty fee is required for any of the authorized uses. |
|---|
| 9 | * Modifications to this software may be copyrighted by their authors |
|---|
| 10 | * and need not follow the licensing terms described here, provided that |
|---|
| 11 | * the new terms are clearly indicated on the first page of each file where |
|---|
| 12 | * they apply. |
|---|
| 13 | */ |
|---|
| 14 | |
|---|
| 15 | #include <_ansi.h> |
|---|
| 16 | #include "mc68681reg.h" |
|---|
| 17 | |
|---|
| 18 | /* |
|---|
| 19 | * The DUART is mapped into the IDP address space in an unusual |
|---|
| 20 | * manner. The mc68681 is an 8 bit device located on the least |
|---|
| 21 | * significant byte (byte0) of the data bus. Bytes 3, 2, and |
|---|
| 22 | * one have nothing in them and writes to these locations are |
|---|
| 23 | * not valid. |
|---|
| 24 | */ |
|---|
| 25 | |
|---|
| 26 | #define DUART_ADDR 0x00B00000 |
|---|
| 27 | #define READREG(x) (*((volatile char *) DUART_ADDR + (x * 4) + 3)) |
|---|
| 28 | #define WRITEREG(x, y) (*((char *) DUART_ADDR + (x * 4) + 3) = y) |
|---|
| 29 | |
|---|
| 30 | /* |
|---|
| 31 | * inbyte -- get a byte from the DUART RX buffer. This only reads |
|---|
| 32 | * from channel A |
|---|
| 33 | */ |
|---|
| 34 | char |
|---|
| 35 | inbyte (void) |
|---|
| 36 | { |
|---|
| 37 | while ((READREG (DUART_SRA) & 0x01) == 0x00) |
|---|
| 38 | ; |
|---|
| 39 | |
|---|
| 40 | return (READREG (DUART_RBA)); /* read the byte */ |
|---|
| 41 | } |
|---|
