static void SetVoiceVolume(opl_voice_t *voice, unsigned int volume)
{
genmidi_voice_t *opl_voice;
unsigned int midi_volume;
unsigned int full_volume;
unsigned int car_volume;
unsigned int mod_volume;
voice->note_volume = volume;
opl_voice = &voice->current_instr->voices[voice->current_instr_voice];
// Multiply note volume and channel volume to get the actual volume.
midi_volume = 2 * (volume_mapping_table[(voice->channel->volume
* current_music_volume) / 127] + 1);
full_volume = (volume_mapping_table[voice->note_volume] * midi_volume)
>> 9;
// The volume value to use in the register:
car_volume = 0x3f - full_volume;
// Update the volume register(s) if necessary.
if (car_volume != voice->reg_volume)
{
voice->reg_volume = car_volume | (opl_voice->carrier.scale & 0xc0);
OPL_WriteRegister((OPL_REGS_LEVEL + voice->op2) | voice->array,
voice->reg_volume);
// If we are using non-modulated feedback mode, we must set the
// volume for both voices.
if ((opl_voice->feedback & 0x01) != 0
&& opl_voice->modulator.level != 0x3f)
{
mod_volume = 0x3f - opl_voice->modulator.level;
if (mod_volume >= car_volume)
{
mod_volume = car_volume;
}
OPL_WriteRegister((OPL_REGS_LEVEL + voice->op1) | voice->array,
mod_volume |
(opl_voice->modulator.scale & 0xc0));
}
}
}
static void SetVoiceVolume(opl_voice_t *voice, unsigned int volume)
{
genmidi_voice_t *opl_voice;
unsigned int full_volume;
unsigned int op_volume;
unsigned int reg_volume;
voice->note_volume = volume;
opl_voice = &voice->current_instr->voices[voice->current_instr_voice];
// Multiply note volume and channel volume to get the actual volume.
full_volume = (volume_mapping_table[voice->note_volume]
* volume_mapping_table[voice->channel->volume]
* volume_mapping_table[current_music_volume]) / (127 * 127);
// The volume of each instrument can be controlled via GENMIDI:
op_volume = 0x3f - opl_voice->carrier.level;
// The volume value to use in the register:
reg_volume = (op_volume * full_volume) / 128;
reg_volume = (0x3f - reg_volume) | opl_voice->carrier.scale;
// Update the volume register(s) if necessary.
if (reg_volume != voice->reg_volume)
{
voice->reg_volume = reg_volume;
OPL_WriteRegister(OPL_REGS_LEVEL + voice->op2, reg_volume);
// If we are using non-modulated feedback mode, we must set the
// volume for both voices.
// Note that the same register volume value is written for
// both voices, always calculated from the carrier's level
// value.
if ((opl_voice->feedback & 0x01) != 0)
{
OPL_WriteRegister(OPL_REGS_LEVEL + voice->op1, reg_volume);
}
}
}
static void SetVoicePan(opl_voice_t *voice, unsigned int pan)
{
genmidi_voice_t *opl_voice;
voice->reg_pan = pan;
opl_voice = &voice->current_instr->voices[voice->current_instr_voice];;
OPL_WriteRegister((OPL_REGS_FEEDBACK + voice->index) | voice->array,
opl_voice->feedback | pan);
}
static void LoadOperatorData(int operator, genmidi_op_t *data,
boolean max_level)
{
int level;
// The scale and level fields must be combined for the level register.
// For the carrier wave we always set the maximum level.
level = (data->scale & 0xc0) | (data->level & 0x3f);
if (max_level)
{
level |= 0x3f;
}
OPL_WriteRegister(OPL_REGS_LEVEL + operator, level);
OPL_WriteRegister(OPL_REGS_TREMOLO + operator, data->tremolo);
OPL_WriteRegister(OPL_REGS_ATTACK + operator, data->attack);
OPL_WriteRegister(OPL_REGS_SUSTAIN + operator, data->sustain);
OPL_WriteRegister(OPL_REGS_WAVEFORM + operator, data->waveform);
}
static void SetVoiceInstrument(opl_voice_t *voice,
genmidi_instr_t *instr,
unsigned int instr_voice)
{
genmidi_voice_t *data;
unsigned int modulating;
// Instrument already set for this channel?
if (voice->current_instr == instr
&& voice->current_instr_voice == instr_voice)
{
return;
}
voice->current_instr = instr;
voice->current_instr_voice = instr_voice;
data = &instr->voices[instr_voice];
// Are we usind modulated feedback mode?
modulating = (data->feedback & 0x01) == 0;
// Doom loads the second operator first, then the first.
// The carrier is set to minimum volume until the voice volume
// is set in SetVoiceVolume (below). If we are not using
// modulating mode, we must set both to minimum volume.
LoadOperatorData(voice->op2 | voice->array, &data->carrier, true);
LoadOperatorData(voice->op1 | voice->array, &data->modulator, !modulating);
// Set feedback register that control the connection between the
// two operators. Turn on bits in the upper nybble; I think this
// is for OPL3, where it turns on channel A/B.
OPL_WriteRegister((OPL_REGS_FEEDBACK + voice->index) | voice->array,
data->feedback | voice->reg_pan);
// Hack to force a volume update.
voice->reg_volume = 999;
// Calculate voice priority.
voice->priority = 0x0f - (data->carrier.attack >> 4)
+ 0x0f - (data->carrier.sustain & 0x0f);
}
void OPL_InitRegisters(void)
{
int r;
// Initialize level registers
for (r = OPL_REGS_LEVEL; r <= OPL_REGS_LEVEL + OPL_NUM_OPERATORS; ++r)
{
OPL_WriteRegister(r, 0x3f);
}
// Initialize other registers
// These two loops write to registers that actually don't exist,
// but this is what Doom does ...
// Similarly, the <= is also intenational.
for (r = OPL_REGS_ATTACK; r <= OPL_REGS_WAVEFORM + OPL_NUM_OPERATORS; ++r)
{
OPL_WriteRegister(r, 0x00);
}
// More registers ...
for (r = 1; r < OPL_REGS_LEVEL; ++r)
{
OPL_WriteRegister(r, 0x00);
}
// Re-initialize the low registers:
// Reset both timers and enable interrupts:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60);
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80);
// "Allow FM chips to control the waveform of each operator":
OPL_WriteRegister(OPL_REG_WAVEFORM_ENABLE, 0x20);
// Keyboard split point on (?)
OPL_WriteRegister(OPL_REG_FM_MODE, 0x40);
}
int OPL_Detect(void)
{
int result1, result2;
int i;
// Reset both timers:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60);
// Enable interrupts:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80);
// Read status
result1 = OPL_ReadStatus();
// Set timer:
OPL_WriteRegister(OPL_REG_TIMER1, 0xff);
// Start timer 1:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x21);
// Wait for 80 microseconds
// This is how Doom does it:
for (i=0; i<200; ++i)
{
OPL_ReadStatus();
}
OPL_Delay(1 * OPL_MS);
// Read status
result2 = OPL_ReadStatus();
// Reset both timers:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x60);
// Enable interrupts:
OPL_WriteRegister(OPL_REG_TIMER_CTRL, 0x80);
return (result1 & 0xe0) == 0x00
&& (result2 & 0xe0) == 0xc0;
}
