console.c

一个C源代码分析器

/* Copyright (C) 1994 Free Software Foundation, Inc.
   Contributed by Joel Sherrill ([e-mail]),
     On-Line Applications Research Corporation.
 
This file is part of the GNU C Library.
 
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
 
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Library General Public License for more details.
 
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <ansidecl.h>
#include <standalone.h>
#include "__m68020.h"

/* Console IO routines for a Motorola MVME135/MVME136 board.
   
They currently use the B port.  It should be possible to
use the A port by filling in the reset of the chip structure,
adding an ifdef for PORTA/PORTB, and switching the addresses,
and maybe the macroes based on the macro. */

/* M68681 DUART chip register structures and constants */

typedef struct {
  volatile unsigned char fill1[ 5 ];     /* channel A regs ( not used ) */
  volatile unsigned char isr;            /* interrupt status reg */
  volatile unsigned char fill2[ 2 ];     /* counter regs (not used) */
  volatile unsigned char mr1mr2b;        /* MR1B and MR2B regs */
  volatile unsigned char srb;            /* status reg channel B */
  volatile unsigned char fill3;          /* do not access */
  volatile unsigned char rbb;            /* receive buffer channel B */
  volatile unsigned char ivr;            /* interrupt vector register */
} r_m681_info;

typedef struct {
  volatile unsigned char fill1[ 4 ];     /* channel A regs (not used) */
  volatile unsigned char acr;            /* auxillary control reg */
  volatile unsigned char imr;            /* interrupt mask reg */
  volatile unsigned char fill2[ 2 ];     /* counter regs (not used) */
  volatile unsigned char mr1mr2b;        /* MR1B and MR2B regs */
  volatile unsigned char csrb;           /* clock select reg */
  volatile unsigned char crb;            /* command reg */
  volatile unsigned char tbb;            /* transmit buffer channel B */
  volatile unsigned char ivr;            /* interrupt vector register */
} w_m681_info;

#define RD_M68681     ((r_m681_info *)0xfffb0040)   /* ptr to the M68681 */
#define WR_M68681     ((w_m681_info *)0xfffb0040)   /* ptr to the M68681 */
#define RXRDYB        0x01               /* status reg recv ready mask */
#define TXRDYB        0x04               /* status reg trans ready mask */

/* _Console_Putc

This routine transmits a character out the M68681.  It supports
XON/XOFF flow control.  */

#define XON             0x11            /* control-Q */
#define XOFF            0x13            /* control-S */

int
DEFUN( _Console_Putc, (ch), char ch )
{
  while ( ! (RD_M68681->srb & TXRDYB) ) ;
  while ( RD_M68681->srb & RXRDYB )        /* must be an XOFF */
    if ( RD_M68681->rbb == XOFF ) 
      do {
        while ( ! (RD_M68681->srb & RXRDYB) ) ;
      } while ( RD_M68681->rbb != XON ); 

  WR_M68681->tbb = ch;
  return( 0 );
}

/* _Console_Getc

This routine reads a character from the UART and returns it. */

int
DEFUN( _Console_Getc, (poll), int poll )
{
  if ( poll ) {
    if ( !(RD_M68681->srb & RXRDYB) ) 
      return -1;
    else
      return RD_M68681->rbb;
  } else {
    while ( !(RD_M68681->srb & RXRDYB) );
    return RD_M68681->rbb;
  }
}