146 lines
3.1 KiB
C++
146 lines
3.1 KiB
C++
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// Meteor - A Nintendo Gameboy Advance emulator
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// Copyright (C) 2009-2011 Philippe Daouadi
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (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, see <http://www.gnu.org/licenses/>.
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#include "ameteor/audio/sound2.hpp"
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#include "../globals.hpp"
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#include <cmath>
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namespace AMeteor
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{
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namespace Audio
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{
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Sound2::Sound2 (uint16_t& cntl, uint16_t& cnth, uint16_t freq) :
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m_cntl(cntl),
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m_cnth(cnth),
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m_on(false),
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m_posP(0),
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m_posE(0),
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m_sample(0),
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m_speriod(16*1024*1024/freq),
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m_envelope(0),
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m_length(0),
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m_timed(false)
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{
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}
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void Sound2::Reset ()
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{
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m_on = false;
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m_timed = false;
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m_length = 0;
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m_envelope = 0;
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m_posP = m_posE = 0;
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m_sample = 0;
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}
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void Sound2::ResetSound ()
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{
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m_on = true;
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m_timed = (m_cnth & (0x1 << 14));
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m_length = (64 - (m_cntl & 0x3F)) * ((16*1024*1024)/256);
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m_envelope = m_cntl >> 12;
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m_posE = 0;
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}
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void Sound2::SoundTick ()
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{
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// refer at sound1 to know how sound2 works
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m_posP += m_speriod;
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m_posE += m_speriod;
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if (m_length > m_speriod)
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m_length -= m_speriod;
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else
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{
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if (m_timed)
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m_on = false;
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m_length = 0;
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}
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uint32_t period =
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((16*1024*1024) / (128*1024)) * (2048 - (m_cnth & 0x7FF));
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m_posP %= period;
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uint32_t steptime = ((m_cntl >> 8) & 0x7) * ((16*1024*1024)/64);
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if (steptime && m_posE > steptime)
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{
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if (m_cntl & (0x1 << 11))
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{
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if (m_envelope < 15)
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++m_envelope;
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}
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else
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{
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if (m_envelope > 0)
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--m_envelope;
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}
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m_posE -= steptime;
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}
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if (m_on && m_envelope)
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{
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switch ((m_cntl >> 6) & 0x3)
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{
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case 0: // 12.5%
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m_sample = m_posP < period/8 ? 112 : -16;
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break;
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case 1: // 25%
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m_sample = m_posP < period/4 ? 96 : -32;
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break;
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case 2: // 50%
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m_sample = m_posP < period/2 ? 64 : -64;
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break;
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case 3: // 75%
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m_sample = m_posP < (3*period)/4 ? 32 : -96;
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break;
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}
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m_sample = (((int16_t)m_sample) * m_envelope)/15;
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}
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else
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m_sample = 0;
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}
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bool Sound2::SaveState (std::ostream& stream)
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{
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SS_WRITE_VAR(m_on);
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SS_WRITE_VAR(m_posP);
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SS_WRITE_VAR(m_posE);
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SS_WRITE_VAR(m_sample);
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SS_WRITE_VAR(m_envelope);
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SS_WRITE_VAR(m_length);
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SS_WRITE_VAR(m_timed);
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return true;
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}
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bool Sound2::LoadState (std::istream& stream)
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{
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SS_READ_VAR(m_on);
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SS_READ_VAR(m_posP);
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SS_READ_VAR(m_posE);
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SS_READ_VAR(m_sample);
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SS_READ_VAR(m_envelope);
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SS_READ_VAR(m_length);
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SS_READ_VAR(m_timed);
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return true;
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}
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}
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}
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