source: trunk/libs/newlib/src/libgloss/m68k/idp-outbyte.c @ 474

Last change on this file since 474 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc

File size: 2.5 KB
Line 
1/* idp-outbyte.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 * raw_outbyte -- send a byte to the DUART buffer. This only sends
32 *           to channel A.
33 */
34static void
35raw_outbyte (char byte)
36{
37  /* First, wait for the UART to finish clocking out the last
38     character we sent, if any.  Then, give it the next character to
39     work on.  By waiting first, then handing off a new character, we
40     allow the UART to work while the processor (perhaps) does other
41     things; if we waited after sending each character, there'd be no
42     opportunity for parallelism.  */
43  while ((READREG (DUART_SRA) & 0x04) == 0x00)
44    ;
45
46  WRITEREG (DUART_TBA, byte);           /* write the byte */
47}
48
49
50/*
51 * outbyte -- send BYTE out the DUART's channel A, for display to
52 *      the user.
53 *
54 *      Normally, this is identical to raw_outbyte, but if
55 *      GDB_MONITOR_OUTPUT is #defined, we prefix each byte we send
56 *      with a ^O character (ASCII 15).  This is a signal to GDB's
57 *      `rom68k' target to pass the character directly on to the user;
58 *      it allows programs to do console output under GDB.
59 *
60 *      We compile this file twice: once with GDB_MONITOR_OUTPUT
61 *      #defined, and once without.  The former .o file we put in
62 *      libidpgdb.a, which is included in the link by idpgdb.ld; the
63 *      latter we put in libidp.a, which is selected by idp.ld.
64 */
65void
66outbyte (char byte)
67{
68#ifdef GDB_MONITOR_OUTPUT
69  raw_outbyte (0x0f);
70#endif
71  raw_outbyte (byte);
72}
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