ppi.c

这是一个非常有价值的参考代码

/*
 * avrdude - A Downloader/Uploader for AVR device programmers
 * Copyright (C) 2000-2004  Brian S. Dean <[e-mail]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* $Id: ppi.c,v 1.23 2004/12/22 01:52:45 bdean Exp $ */

#if defined(__FreeBSD__) || defined(__linux__)

#include "ac_cfg.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>

#if defined(__FreeBSD__)
#include <dev/ppbus/ppi.h>
#elif defined(__linux__)
#include "linux_ppdev.h"
#endif

#include "avr.h"
#include "pindefs.h"
#include "pgm.h"
#include "ppi.h"

extern char * progname;

enum {
  PPI_READ,
  PPI_WRITE,
  PPI_SHADOWREAD
};

int ppi_shadow_access(int fd, int reg, unsigned char *v, unsigned char action)
{
  static unsigned char shadow[3];
  int shadow_num;
  unsigned long set, get;

  switch (reg) {
    case PPIDATA:
      set = PPISDATA;
      get = PPIGDATA;
      shadow_num = 0;
      break;
    case PPICTRL:
      set = PPISCTRL;
      get = PPIGCTRL;
      shadow_num = 1;
      break;
    case PPISTATUS:
      set = PPISSTATUS;
      get = PPIGSTATUS;
      shadow_num = 2;
      break;
    default:
      fprintf(stderr, "%s: avr_set(): invalid register=%d\n",
              progname, reg);
      return -1;
      break;
  }

  switch (action) {
    case PPI_SHADOWREAD:
      *v = shadow[shadow_num];
      break;
    case PPI_READ:
      ioctl(fd, get, v);
      shadow[shadow_num]=*v;
      break;
    case PPI_WRITE:
      shadow[shadow_num]=*v;
      ioctl(fd, set, v);
      break;
  }
  return 0;
}

/*
 * set the indicated bit of the specified register.
 */
int ppi_set(int fd, int reg, int bit)
{
  unsigned char v;
  int rc;

  rc = ppi_shadow_access(fd, reg, &v, PPI_SHADOWREAD);
  v |= bit;
  rc |= ppi_shadow_access(fd, reg, &v, PPI_WRITE);

  if (rc)
    return -1;

  return 0;
}


/*
 * clear the indicated bit of the specified register.
 */
int ppi_clr(int fd, int reg, int bit)
{
  unsigned char v;
  int rc;

  rc = ppi_shadow_access(fd, reg, &v, PPI_SHADOWREAD);
  v &= ~bit;
  rc |= ppi_shadow_access(fd, reg, &v, PPI_WRITE);

  if (rc)
    return -1;

  return 0;
}


/*
 * get the indicated bit of the specified register.
 */
int ppi_get(int fd, int reg, int bit)
{
  unsigned char v;
  int rc;

  rc = ppi_shadow_access(fd, reg, &v, PPI_READ);
  v &= bit;

  if (rc)
    return -1;

  return v; /* v == bit */
}

/*
 * toggle the indicated bit of the specified register.
 */
int ppi_toggle(int fd, int reg, int bit)
{
  unsigned char v;
  int rc;

  rc = ppi_shadow_access(fd, reg, &v, PPI_SHADOWREAD);
  v ^= bit;
  rc |= ppi_shadow_access(fd, reg, &v, PPI_WRITE);

  if (rc)
    return -1;

  return 0;
}


/*
 * get all bits of the specified register.
 */
int ppi_getall(int fd, int reg)
{
  unsigned char v;
  int rc;

  rc = ppi_shadow_access(fd, reg, &v, PPI_READ);

  if (rc)
    return -1;

  return v; /* v == bit */
}

/*
 * set all bits of the specified register to val.
 */
int ppi_setall(int fd, int reg, int val)
{
  unsigned char v;
  int rc;

  v = val;
  rc = ppi_shadow_access(fd, reg, &v, PPI_WRITE);

  if (rc)
    return -1;

  return 0;
}


int ppi_open(char * port)
{
  int fd;
  unsigned char v;

  fd = open(port, O_RDWR);
  if (fd < 0) {
    fprintf(stderr, "%s: can't open device \"%s\": %s\n",
              progname, port, strerror(errno));
    return -1;
  }

  /*
   * Initialize shadow registers
   */

  ppi_shadow_access (fd, PPIDATA, &v, PPI_READ);
  ppi_shadow_access (fd, PPICTRL, &v, PPI_READ);
  ppi_shadow_access (fd, PPISTATUS, &v, PPI_READ);

  return fd;
}


void ppi_close(int fd)
{
  close(fd);
}


#elif defined(__POWERPC__) && defined(__APPLE__)

int ppi_shadow_access(int fd, int reg, unsigned char *v, unsigned char action)
{
  return -1;
}

/*
 * set the indicated bit of the specified register.
 */
int ppi_set(int fd, int reg, int bit)
{
  return -1;
}


/*
 * clear the indicated bit of the specified register.
 */
int ppi_clr(int fd, int reg, int bit)
{
  return -1;
}


/*
 * get the indicated bit of the specified register.
 */
int ppi_get(int fd, int reg, int bit)
{
  return -1;
}

/*
 * toggle the indicated bit of the specified register.
 */
int ppi_toggle(int fd, int reg, int bit)
{
  return -1;
}


/*
 * get all bits of the specified register.
 */
int ppi_getall(int fd, int reg)
{
  return -1;
}

/*
 * set all bits of the specified register to val.
 */
int ppi_setall(int fd, int reg, int val)
{
  return -1;
}


int ppi_open(char * port)
{
  return -1;
}


void ppi_close(int fd)
{
}


#endif