230 lines
6.1 KiB
C++
230 lines
6.1 KiB
C++
// morse.cxx -- Morse code generation class
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//
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// Written by Curtis Olson, started March 2001.
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//
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// Copyright (C) 2001 Curtis L. Olson - curt@flightgear.org
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//
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// This program is free software; you can redistribute it and/or
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// modify it under the terms of the GNU General Public License as
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// published by the Free Software Foundation; either version 2 of the
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// License, or (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful, but
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// WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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//
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// $Id$
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#include <simgear/constants.h>
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#include "morse.hxx"
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static const char alphabet[26][4] = {
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{ DI, DAH, end, end }, /* A */
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{ DA, DI, DI, DIT }, /* B */
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{ DA, DI, DA, DIT }, /* C */
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{ DA, DI, DIT, end }, /* D */
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{ DIT, end, end, end }, /* E */
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{ DI, DI, DA, DIT }, /* F */
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{ DA, DA, DIT, end }, /* G */
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{ DI, DI, DI, DIT }, /* H */
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{ DI, DIT, end, end }, /* I */
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{ DI, DA, DA, DAH }, /* J */
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{ DA, DI, DAH, end }, /* K */
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{ DI, DA, DI, DIT }, /* L */
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{ DA, DAH, end, end }, /* M */
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{ DA, DIT, end, end }, /* N */
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{ DA, DA, DAH, end }, /* O */
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{ DI, DA, DA, DIT }, /* P */
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{ DA, DA, DI, DAH }, /* Q */
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{ DI, DA, DIT, end }, /* R */
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{ DI, DI, DIT, end }, /* S */
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{ DAH, end, end, end }, /* T */
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{ DI, DI, DAH, end }, /* U */
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{ DI, DI, DI, DAH }, /* V */
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{ DI, DA, DAH, end }, /* W */
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{ DA, DI, DI, DAH }, /* X */
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{ DA, DI, DA, DAH }, /* Y */
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{ DA, DA, DI, DIT } /* Z */
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};
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// constructor
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FGMorse::FGMorse() {
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}
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// destructor
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FGMorse::~FGMorse() {
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}
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// Make a tone of specified freq and total_len with trans_len ramp in
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// and out and only the first len bytes with sound, the rest with
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// silence
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void make_tone( unsigned char *buf, int freq,
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int len, int total_len, int trans_len )
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{
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int i, j;
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for ( i = 0; i < trans_len; ++i ) {
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float level = ( sin( (double) i * 2.0 * SGD_PI / (8000.0 / freq) ) )
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* ((double)i / trans_len) / 2.0 + 0.5;
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/* Convert to unsigned byte */
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buf[ i ] = (unsigned char) ( level * 255.0 ) ;
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}
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for ( i = trans_len; i < len - trans_len; ++i ) {
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float level = ( sin( (double) i * 2.0 * SGD_PI / (8000.0 / freq) ) )
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/ 2.0 + 0.5;
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/* Convert to unsigned byte */
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buf[ i ] = (unsigned char) ( level * 255.0 ) ;
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}
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j = trans_len;
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for ( i = len - trans_len; i < len; ++i ) {
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float level = ( sin( (double) i * 2.0 * SGD_PI / (8000.0 / freq) ) )
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* ((double)j / trans_len) / 2.0 + 0.5;
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--j;
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/* Convert to unsigned byte */
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buf[ i ] = (unsigned char) ( level * 255.0 ) ;
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}
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for ( i = len; i < total_len; ++i ) {
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buf[ i ] = (unsigned char) ( 0.5 * 255.0 ) ;
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}
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}
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// allocate and initialize sound samples
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bool FGMorse::init() {
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// Make Low DIT
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make_tone( lo_dit, LO_FREQUENCY, DIT_SIZE - COUNT_SIZE, DIT_SIZE,
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TRANSITION_BYTES );
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// Make High DIT
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make_tone( hi_dit, HI_FREQUENCY, DIT_SIZE - COUNT_SIZE, DIT_SIZE,
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TRANSITION_BYTES );
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// Make Low DAH
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make_tone( lo_dah, LO_FREQUENCY, DAH_SIZE - COUNT_SIZE, DAH_SIZE,
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TRANSITION_BYTES );
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// Make High DAH
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make_tone( hi_dah, HI_FREQUENCY, DAH_SIZE - COUNT_SIZE, DAH_SIZE,
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TRANSITION_BYTES );
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// Make SPACE
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int i;
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for ( i = 0; i < SPACE_SIZE; ++i ) {
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space[ i ] = (unsigned char) ( 0.5 * 255 ) ;
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}
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return true;
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}
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// allocate and initialize sound samples
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bool FGMorse::cust_init(const int freq ) {
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int i;
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// Make DIT
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make_tone( cust_dit, freq, DIT_SIZE - COUNT_SIZE, DIT_SIZE,
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TRANSITION_BYTES );
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// Make DAH
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make_tone( cust_dah, freq, DAH_SIZE - COUNT_SIZE, DAH_SIZE,
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TRANSITION_BYTES );
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// Make SPACE
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for ( i = 0; i < SPACE_SIZE; ++i ) {
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space[ i ] = (unsigned char) ( 0.5 * 255 ) ;
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}
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return true;
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}
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// make a FGSimpleSound morse code transmission for the specified string
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FGSimpleSound *FGMorse::make_ident( const string& id, const int freq ) {
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char *idptr = (char *)id.c_str();
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int length = 0;
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int i, j;
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// 0. Select the frequency. If custom frequency, generate the
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// sound fragments we need on the fly.
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unsigned char *dit_ptr, *dah_ptr;
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if ( freq == LO_FREQUENCY ) {
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dit_ptr = lo_dit;
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dah_ptr = lo_dah;
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} else if ( freq == HI_FREQUENCY ) {
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dit_ptr = hi_dit;
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dah_ptr = hi_dah;
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} else {
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cust_init( freq );
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dit_ptr = cust_dit;
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dah_ptr = cust_dah;
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}
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// 1. Determine byte length of message
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for ( i = 0; i < (int)id.length(); ++i ) {
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if ( idptr[i] >= 'A' && idptr[i] <= 'Z' ) {
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char c = idptr[i] - 'A';
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for ( j = 0; j < 4 || alphabet[c][j] == end; ++j ) {
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if ( alphabet[c][j] == DIT ) {
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length += DIT_SIZE;
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} else if ( alphabet[c][j] == DAH ) {
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length += DAH_SIZE;
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}
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}
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length += SPACE_SIZE;
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} else {
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// skip unknown character
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}
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}
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// add 2x more space to the end of the string
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length += 2 * SPACE_SIZE;
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// 2. Allocate space for the message
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unsigned char *buffer = new unsigned char[length];
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// 3. Assemble the message;
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unsigned char *buf_ptr = buffer;
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for ( i = 0; i < (int)id.length(); ++i ) {
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if ( idptr[i] >= 'A' && idptr[i] <= 'Z' ) {
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char c = idptr[i] - 'A';
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for ( j = 0; j < 4 || alphabet[c][j] == end; ++j ) {
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if ( alphabet[c][j] == DIT ) {
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memcpy( buf_ptr, dit_ptr, DIT_SIZE );
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buf_ptr += DIT_SIZE;
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} else if ( alphabet[c][j] == DAH ) {
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memcpy( buf_ptr, dah_ptr, DAH_SIZE );
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buf_ptr += DAH_SIZE;
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}
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}
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memcpy( buf_ptr, space, SPACE_SIZE );
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buf_ptr += SPACE_SIZE;
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} else {
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// skip unknown character
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}
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}
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memcpy( buf_ptr, space, SPACE_SIZE );
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buf_ptr += SPACE_SIZE;
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memcpy( buf_ptr, space, SPACE_SIZE );
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buf_ptr += SPACE_SIZE;
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// 4. create the simple sound and return
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FGSimpleSound *sample = new FGSimpleSound( buffer, length );
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return sample;
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}
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