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8b4460e310
This is a subtle issue associated with the Common::Frac usage. The frac_t type is signed (int32), but the symbols such as FRAC_ONE are defined by an enumeration which will default to unsigned int for members. Unsure if the common code needs changing, but other usages fix the warning by casting the enumeration values to frac_t so doing this for now.
145 lines
3.6 KiB
C++
145 lines
3.6 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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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
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* as published by the Free Software Foundation; either version 2
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* of the 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,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#include "common/system.h"
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#include "audio/mixer.h"
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#include "adl/sound.h"
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namespace Adl {
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// Generic PC-speaker synth
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// This produces more accurate frequencies than Audio::PCSpeaker, but only
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// does square waves.
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class Speaker {
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public:
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Speaker(int sampleRate);
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void startTone(double freq);
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void stopTone();
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void generateSamples(int16 *buffer, int numSamples);
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private:
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int _rate;
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frac_t _halfWaveLen, _halfWaveRem;
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int16 _curSample;
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};
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Speaker::Speaker(int sampleRate) :
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_rate(sampleRate),
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_curSample(32767) {
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stopTone();
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}
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void Speaker::startTone(double freq) {
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_halfWaveLen = _halfWaveRem = doubleToFrac(_rate / freq / 2);
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if (_halfWaveLen < (frac_t)FRAC_ONE) {
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// Tone out of range at this sample rate
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stopTone();
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}
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}
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void Speaker::stopTone() {
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_halfWaveLen = 0;
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_halfWaveRem = intToFrac(32767);
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}
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void Speaker::generateSamples(int16 *buffer, int numSamples) {
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int offset = 0;
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while (offset < numSamples) {
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if (_halfWaveRem >= 0 && _halfWaveRem < (frac_t)FRAC_ONE) {
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// Rising/falling edge
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// Switch level
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_curSample = ~_curSample;
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// Use transition point fraction for current sample value
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buffer[offset++] = _halfWaveRem ^ _curSample;
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// Compute next transition point
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_halfWaveRem += _halfWaveLen - FRAC_ONE;
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} else {
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// Low/high level (incl. silence)
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// Generate as many samples as we can
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const int samples = MIN(numSamples - offset, (int)fracToInt(_halfWaveRem));
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Common::fill(buffer + offset, buffer + offset + samples, _curSample);
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offset += samples;
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// Count down to level transition point, unless we're playing silence
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if (_halfWaveLen > 0)
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_halfWaveRem -= intToFrac(samples);
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}
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}
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}
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Sound::Sound(const Tones &tones) :
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_tones(tones),
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_toneIndex(0),
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_samplesRem(0) {
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_rate = g_system->getMixer()->getOutputRate();
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_speaker = new Speaker(_rate);
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}
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Sound::~Sound() {
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delete _speaker;
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}
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bool Sound::endOfData() const {
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return _samplesRem == 0 && _toneIndex == _tones.size();
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}
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int Sound::readBuffer(int16 *buffer, const int numSamples) {
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int offset = 0;
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while (offset < numSamples) {
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if (_samplesRem == 0) {
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// Set up next tone
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if (_toneIndex == _tones.size()) {
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// No more tones
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return offset;
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}
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if (_tones[_toneIndex].freq == 0.0)
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_speaker->stopTone();
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else
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_speaker->startTone(_tones[_toneIndex].freq);
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// Compute length of tone
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_samplesRem = _rate * _tones[_toneIndex++].len / 1000;
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}
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// Generate as many samples as we can
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const int samples = MIN(numSamples - offset, _samplesRem);
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_speaker->generateSamples(buffer + offset, samples);
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_samplesRem -= samples;
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offset += samples;
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}
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return numSamples;
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}
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} // End of namespace Adl
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