gr_file_descriptor_source.cc

gnuradio软件无线电源程序.现在的手机多基于软件无线电

/* -*- c++ -*- */
/*
 * Copyright 2004,2005 Free Software Foundation, Inc.
 * 
 * This file is part of GNU Radio
 * 
 * GNU Radio 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, or (at your option)
 * any later version.
 * 
 * GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 * Boston, MA 02111-1307, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <gr_file_descriptor_source.h>
#include <gr_io_signature.h>
#include <cstdio>
#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdexcept>


gr_file_descriptor_source::gr_file_descriptor_source (size_t itemsize,
						      int fd,
						      bool repeat)
  : gr_sync_block ("file_descriptor_source",
		   gr_make_io_signature (0, 0, 0),
		   gr_make_io_signature (1, 1, itemsize)),
    d_itemsize (itemsize), d_fd (fd), d_repeat (repeat),
    d_residue (new unsigned char[itemsize]), d_residue_len (0)
{
}

// public constructor that returns a shared_ptr

gr_file_descriptor_source_sptr
gr_make_file_descriptor_source (size_t itemsize, int fd, bool repeat)
{
  return gr_file_descriptor_source_sptr (
	       new gr_file_descriptor_source (itemsize, fd, repeat));
}

gr_file_descriptor_source::~gr_file_descriptor_source ()
{
  close (d_fd);
  delete [] d_residue;
}

int
gr_file_descriptor_source::work (int noutput_items,
				 gr_vector_const_void_star &input_items,
				 gr_vector_void_star &output_items)
{
  assert (noutput_items > 0);

  char *o = (char *) output_items[0];
  int nread = 0;

  while (1){
    int r = read_items (o, noutput_items - nread);
    if (r == -1){
      if (errno == EINTR)
	continue;
      else {
	perror ("file_descriptor_source[read]");
	return -1;
      }
    }
    else if (r == 0){	  // end of file
      if (!d_repeat)
	break;
      else {
	flush_residue ();
	if (lseek (d_fd, 0, SEEK_SET) == -1){
	  perror ("file_descriptor_source[lseek]");
	  return -1;
	}
      }
    }
    else {
      o += r * d_itemsize;
      nread += r;
      break;
    }
  }

  if (nread == 0)	// EOF
    return -1;

  return nread;
}

int
gr_file_descriptor_source::read_items (char *buf, int nitems)
{
  assert (nitems > 0);
  assert (d_residue_len < d_itemsize);

  int nbytes_read = 0;

  if (d_residue_len > 0){
    memcpy (buf, d_residue, d_residue_len);
    nbytes_read = d_residue_len;
    d_residue_len = 0;
  }

  int r = read (d_fd, buf + nbytes_read, nitems * d_itemsize - nbytes_read);
  if (r <= 0){
    handle_residue (buf, nbytes_read);
    return r;
  }

  r = handle_residue (buf, r + nbytes_read);

  if (r == 0)			// block until we get something
    return read_items (buf, nitems);
  
  return r;
}  

int
gr_file_descriptor_source::handle_residue (char *buf, int nbytes_read)
{
  assert (nbytes_read >= 0);
  int nitems_read = nbytes_read / d_itemsize;
  d_residue_len = nbytes_read % d_itemsize;
  if (d_residue_len > 0){
    // fprintf (stderr, "handle_residue: %d\n", d_residue_len);
    memcpy (d_residue, buf + nbytes_read - d_residue_len, d_residue_len);
  }
  return nitems_read;
}