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Diffstat (limited to 'engines/sci/sfx/softseq/pcjr.cpp')
| -rw-r--r-- | engines/sci/sfx/softseq/pcjr.cpp | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/engines/sci/sfx/softseq/pcjr.cpp b/engines/sci/sfx/softseq/pcjr.cpp new file mode 100644 index 0000000000..b4afa1c593 --- /dev/null +++ b/engines/sci/sfx/softseq/pcjr.cpp @@ -0,0 +1,196 @@ +/* ScummVM - Graphic Adventure Engine + * + * ScummVM is the legal property of its developers, whose names + * are too numerous to list here. Please refer to the COPYRIGHT + * file distributed with this source distribution. + * + * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + * $URL$ + * $Id$ + * + */ + +#include "sci/sfx/softseq.h" +#include "sci/sfx/sci_midi.h" +#include "sci/sfx/softseq/pcjr.h" + +namespace Sci { + +#define FREQUENCY 44100 +#define VOLUME_SHIFT 3 + +#define BASE_NOTE 129 // A10 +#define BASE_OCTAVE 10 // A10, as I said + +const static int freq_table[12] = { // A4 is 440Hz, halftone map is x |-> ** 2^(x/12) + 28160, // A10 + 29834, + 31608, + 33488, + 35479, + 37589, + 39824, + 42192, + 44701, + 47359, + 50175, + 53159 +}; + +static inline int get_freq(int note) { + int halftone_delta = note - BASE_NOTE; + int oct_diff = ((halftone_delta + BASE_OCTAVE * 12) / 12) - BASE_OCTAVE; + int halftone_index = (halftone_delta + (12 * 100)) % 12 ; + int freq = (!note) ? 0 : freq_table[halftone_index] / (1 << (-oct_diff)); + + return freq; +} + +void MidiDriver_PCJr::send(uint32 b) { + byte command = b & 0xff; + byte op1 = (b >> 8) & 0xff; + byte op2 = (b >> 16) & 0xff; + int i; + int mapped_chan = -1; + int chan_nr = command & 0xf; + + // First, test for channel having been assigned already + if (_channels_assigned & (1 << chan_nr)) { + // Already assigned this channel number: + for (i = 0; i < _channels_nr; i++) + if (_chan_nrs[i] == chan_nr) { + mapped_chan = i; + break; + } + } else if ((command & 0xe0) == 0x80) { + // Assign new channel round-robin + + // Mark channel as unused: + if (_chan_nrs[_channel_assigner] >= 0) + _channels_assigned &= ~(1 << _chan_nrs[_channel_assigner]); + + // Remember channel: + _chan_nrs[_channel_assigner] = chan_nr; + // Mark channel as used + _channels_assigned |= (1 << _chan_nrs[_channel_assigner]); + + // Save channel for use later in this call: + mapped_chan = _channel_assigner; + // Round-ropin iterate channel assigner: + _channel_assigner = (_channel_assigner + 1) % _channels_nr; + } + + if (mapped_chan == -1) + return; + + switch (command & 0xf0) { + + case 0x80: + if (op1 == _notes[mapped_chan]) + _notes[mapped_chan] = 0; + break; + + case 0x90: + if (!op2) { + if (op1 == _notes[mapped_chan]) + _notes[mapped_chan] = 0; + } else { + _notes[mapped_chan] = op1; + _volumes[mapped_chan] = op2; + } + break; + + case 0xb0: + if ((op1 == SCI_MIDI_CHANNEL_NOTES_OFF) || (op1 == SCI_MIDI_CHANNEL_SOUND_OFF)) + _notes[mapped_chan] = 0; + break; + + default: + debug(2, "Unused MIDI command %02x %02x %02x", command, op1, op2); + break; /* ignore */ + } +} + +void MidiDriver_PCJr::generateSamples(int16 *data, int len) { + int i; + int chan; + int freq[kMaxChannels]; + + for (chan = 0; chan < _channels_nr; chan++) + freq[chan] = get_freq(_notes[chan]); + + for (i = 0; i < len; i++) { + int16 result = 0; + + for (chan = 0; chan < _channels_nr; chan++) + if (_notes[chan]) { + int volume = (_global_volume * _volumes[chan]) + >> VOLUME_SHIFT; + + _freq_count[chan] += freq[chan]; + while (_freq_count[chan] >= (FREQUENCY << 1)) + _freq_count[chan] -= (FREQUENCY << 1); + + if (_freq_count[chan] - freq[chan] < 0) { + /* Unclean rising edge */ + int l = volume << 1; + result += -volume + (l * _freq_count[chan]) / freq[chan]; + } else if (_freq_count[chan] >= FREQUENCY + && _freq_count[chan] - freq[chan] < FREQUENCY) { + /* Unclean falling edge */ + int l = volume << 1; + result += volume - (l * (_freq_count[chan] - FREQUENCY)) / freq[chan]; + } else { + if (_freq_count[chan] < FREQUENCY) + result += volume; + else + result += -volume; + } + } + data[i] = result; + } +} + +int MidiDriver_PCJr::open(int channels) { + if (_isOpen) + return MERR_ALREADY_OPEN; + + if (channels > kMaxChannels) + return -1; + + _channels_nr = channels; + _global_volume = 100; + for (int i = 0; i < _channels_nr; i++) { + _volumes[i] = 100; + _notes[i] = 0; + _freq_count[i] = 0; + _chan_nrs[i] = -1; + } + _channel_assigner = 0; + _channels_assigned = 0; + + MidiDriver_Emulated::open(); + + _mixer->playInputStream(Audio::Mixer::kPlainSoundType, &_mixerSoundHandle, this, -1, Audio::Mixer::kMaxChannelVolume * (int) _global_volume / 127); + + return 0; +} + +void MidiDriver_PCJr::close() { + _mixer->stopHandle(_mixerSoundHandle); +} + +} // End of namespace Sci |