cwtones.c

/* cwtones.c */
/*
This file is part of a program that implements a Software-Defined Radio.

Copyright (C) 2005 by Frank Brickle, AB2KT and Bob McGwier, N4HY

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

The authors can be reached by email at

ab2kt@arrl.net
or
rwmcgwier@comcast.net

or by paper mail at

The DTTS Microwave Society
6 Kathleen Place
Bridgewater, NJ 08807
*/

#include <cwtones.h>

//------------------------------------------------------------------------
// An ASR envelope on a complex phasor,
// with asynchronous trigger for R stage.
// A/R use sine shaping.
//------------------------------------------------------------------------

BOOLEAN
CWTone(CWToneGen cwt)
{
    int i, n = cwt->size;

    ComplexOSC(cwt->osc.gen);

    for (i = 0; i < n; i++)
    {

        // in an envelope stage?

        if(cwt->stage == CWTone_RISE)
        {

            // still going?
            if(cwt->rise.have++ < cwt->rise.want)
            {
                cwt->curr += cwt->rise.incr;
                cwt->mul = cwt->scl * (REAL)sin(cwt->curr * M_PI / 2.0);
            } else
            {
                // no, assert steady-state, force level
                cwt->curr = 1.0;
                cwt->mul = cwt->scl;
                cwt->stage = CWTone_STDY;
                // won't come back into envelopes
                // until FALL asserted from outside
            }

        } else if(cwt->stage == CWTone_FALL)
        {

            // still going?
            if(cwt->fall.have++ < cwt->fall.want)
            {
                cwt->curr -= cwt->fall.incr;
                cwt->mul = cwt->scl * (REAL)sin(cwt->curr * M_PI / 2.0);
            } else
            {
                // no, assert trailing, force level
                cwt->curr = 0.0;
                cwt->mul = 0.0;
                cwt->stage = CWTone_HOLD;
                // won't come back into envelopes hereafter
            }
        }
        // apply envelope
        // (same base as osc.gen internal buf)
        CXBdata(cwt->buf, i) = Cscl(CXBdata(cwt->buf, i), cwt->mul);
    }
    CXBhave(cwt->buf) = n; /* kd5tfd added - set have field of buf so correctIQ works */

    // indicate whether it's turned itself off
    // sometime during this pass

    return (cwt->stage != CWTone_HOLD);
}

//------------------------------------------------------------------------
// turn tone on with current settings

void
CWToneOn(CWToneGen cwt)
{

    // gain is in dB

    cwt->scl = (REAL)pow(10.0, cwt->gain / 20.0);
    cwt->curr = cwt->mul = 0.0;

    // A/R times are in msec

    cwt->rise.want = (int)(0.5 + cwt->sr * (cwt->rise.dur / 1e3));
    cwt->rise.have = 0;
    if(cwt->rise.want <= 1) cwt->rise.incr = 1.0;
    else cwt->rise.incr = 1.0f / (cwt->rise.want - 1);

    cwt->fall.want = (int)(0.5 + cwt->sr * (cwt->fall.dur / 1e3));
    cwt->fall.have = 0;
    if(cwt->fall.want <= 1) cwt->fall.incr = 1.0;
    else cwt->fall.incr = 1.0f / (cwt->fall.want - 1);

    // freq is in Hz

    OSCfreq(cwt->osc.gen) = 2.0 * M_PI * cwt->osc.freq / cwt->sr;
    OSCphase(cwt->osc.gen) = 0.0;

    cwt->stage = CWTone_RISE;
}

//------------------------------------------------------------------------
// initiate turn-off

void
CWToneOff(CWToneGen cwt)
{
    cwt->stage = CWTone_FALL;
}

//------------------------------------------------------------------------

void
setCWToneGenVals(CWToneGen cwt, REAL gain, REAL freq, REAL rise, REAL fall)
{
    cwt->gain = gain;
    cwt->osc.freq = freq;
    cwt->rise.dur = rise;
    cwt->fall.dur = fall;
}

CWToneGen
newCWToneGen(REAL gain,    // dB
             REAL freq, REAL rise, // ms
             REAL fall,    // ms
             int size, REAL samplerate)
{

    CWToneGen cwt = (CWToneGen)safealloc(1, sizeof(CWToneGenDesc),
                                         "CWToneGenDesc");

    setCWToneGenVals(cwt, gain, freq, rise, fall);
    cwt->size = size;
    cwt->sr = samplerate;

    cwt->osc.gen = newOSC(cwt->size,
                          ComplexTone,
                          (double)cwt->osc.freq, 0.0, cwt->sr, "CWTone osc");

    // overload oscillator buf
    cwt->buf = newCXB(cwt->size, OSCCbase(cwt->osc.gen), "CWToneGen buf");

    return (cwt);
}

void
delCWToneGen(CWToneGen cwt)
{
    if(cwt)
    {
        delCXB(cwt->buf);
        delOSC(cwt->osc.gen);
        safefree((char *)cwt);
    }
}