gr_bytes_to_syms.cc

这是用python语言写的一个数字广播的信号处理工具包。利用它

/* -*- c++ -*- */
/*
 * Copyright 2004 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 3, 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., 51 Franklin Street,
 * Boston, MA 02110-1301, USA.
 */

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

#include <gr_bytes_to_syms.h>
#include <gr_io_signature.h>
#include <assert.h>

static const int BITS_PER_BYTE = 8;

gr_bytes_to_syms_sptr 
gr_make_bytes_to_syms ()
{
  return gr_bytes_to_syms_sptr (new gr_bytes_to_syms ());
}

gr_bytes_to_syms::gr_bytes_to_syms ()
  : gr_sync_interpolator ("bytes_to_syms",
			  gr_make_io_signature (1, 1, sizeof (unsigned char)),
			  gr_make_io_signature (1, 1, sizeof (float)),
			  BITS_PER_BYTE)
{
}

int
gr_bytes_to_syms::work (int noutput_items,
			gr_vector_const_void_star &input_items,
			gr_vector_void_star &output_items)
{
  const unsigned char *in = (unsigned char *) input_items[0];
  float *out = (float *) output_items[0];

  assert (noutput_items % BITS_PER_BYTE == 0);

  for (int i = 0; i < noutput_items / BITS_PER_BYTE; i++){
    int x = in[i];

    *out++ = (((x >> 7) & 0x1) << 1) - 1;
    *out++ = (((x >> 6) & 0x1) << 1) - 1;
    *out++ = (((x >> 5) & 0x1) << 1) - 1;
    *out++ = (((x >> 4) & 0x1) << 1) - 1;
    *out++ = (((x >> 3) & 0x1) << 1) - 1;
    *out++ = (((x >> 2) & 0x1) << 1) - 1;
    *out++ = (((x >> 1) & 0x1) << 1) - 1;
    *out++ = (((x >> 0) & 0x1) << 1) - 1;
  }

  return noutput_items;
}