6502/CLK
1
0
Fork 0
mirror of https://github.com/TomHarte/CLK.git synced 2024-11-22 12:33:29 +00:00
Code Issues Projects Releases Wiki Activity

Add some extra notes, implement correct mapping to only 18 operators. Not 22.

Browse Source
This commit is contained in:
Thomas Harte 2020-04-05 14:32:55 -04:00
parent 335a68396f
commit 0ed7d257e1
2 changed files with 76 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

89
Components/OPL2/OPL2.cpp
View File

@ -112,6 +112,30 @@ bool OPL2::is_zero_level() {
void OPL2::get_samples(std::size_t number_of_samples, std::int16_t *target) {
// TODO.
// out = exp(logsin(phase2 + exp(logsin(phase1) + gain1)) + gain2)
/*
Melodic channels are:
Channel Operator 1 Operator 2
0 0 3
1 1 4
2 2 5
3 6 9
4 7 10
5 8 11
6 12 15
7 13 16
8 14 17
In percussion mode, only channels 0–5 are use as melodic, with 6 7 and 8 being
replaced by:
Bass drum, using operators 12 and 15;
Snare, using operator 16;
Tom tom, using operator 14,
Cymbal, using operator 17; and
Symbol, using operator 13.
*/
}
void OPL2::set_sample_volume_range(std::int16_t range) {
@ -127,7 +151,10 @@ void OPL2::write(uint16_t address, uint8_t value) {
}
uint8_t OPL2::read(uint16_t address) {
// TODO.
// TODO. There's a status register where:
// b7 = IRQ status (set if interrupt request ongoing)
// b6 = timer 1 flag (set if timer 1 expired)
// b5 = timer 2 flag
return 0xff;
}
@ -139,6 +166,10 @@ void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
case 0x02: timers_[0] = value; return;
case 0x03: timers_[1] = value; return;
case 0x04: timer_control_ = value; return;
// TODO from register 4:
// b7 = IRQ reset;
// b6/b5 = timer 1/2 mask (irq enabling flags, I think?)
// b4/b3 = timer 2/1 start (seemingly the opposite order to b6/b5?)
default: break;
}
@ -150,35 +181,58 @@ void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
// Operator modifications.
//
// The 18 operators are spreat out across 22 addresses; each group of
// six is framed within an eight-byte area thusly:
constexpr int operator_by_address[] = {
0, 1, 2, 3, 4, 5, -1, -1,
6, 7, 8, 9, 10, 11, -1, -1,
12, 13, 14, 15, 16, 17, -1, -1
};
if(location >= 0x20 && location <= 0x35) {
operators_[location - 0x20].apply_amplitude_modulation = value & 0x80;
operators_[location - 0x20].apply_vibrato = value & 0x40;
operators_[location - 0x20].hold_sustain_level = value & 0x20;
operators_[location - 0x20].keyboard_scaling_rate = value & 0x10;
operators_[location - 0x20].frequency_multiple = value & 0xf;
const auto index = operator_by_address[location - 0x20];
if(index == -1) return;
operators_[index].apply_amplitude_modulation = value & 0x80;
operators_[index].apply_vibrato = value & 0x40;
operators_[index].hold_sustain_level = value & 0x20;
operators_[index].keyboard_scaling_rate = value & 0x10;
operators_[index].frequency_multiple = value & 0xf;
return;
}
if(location >= 0x40 && location <= 0x55) {
operators_[location - 0x40].scaling_level = value >> 6;
operators_[location - 0x40].output_level = value & 0x3f;
const auto index = operator_by_address[location - 0x40];
if(index == -1) return;
operators_[index].scaling_level = value >> 6;
operators_[index].output_level = value & 0x3f;
return;
}
if(location >= 0x60 && location <= 0x75) {
operators_[location - 0x60].attack_rate = value >> 5;
operators_[location - 0x60].decay_rate = value & 0xf;
const auto index = operator_by_address[location - 0x60];
if(index == -1) return;
operators_[index].attack_rate = value >> 5;
operators_[index].decay_rate = value & 0xf;
return;
}
if(location >= 0x80 && location <= 0x95) {
operators_[location - 0x60].sustain_level = value >> 5;
operators_[location - 0x60].release_rate = value & 0xf;
const auto index = operator_by_address[location - 0x80];
if(index == -1) return;
operators_[index].sustain_level = value >> 5;
operators_[index].release_rate = value & 0xf;
return;
}
if(location >= 0xe0 && location <= 0xf5) {
operators_[location - 0xe0].waveform = value & 3;
const auto index = operator_by_address[location - 0xe0];
if(index == -1) return;
operators_[index].waveform = value & 3;
return;
}
@ -201,7 +255,7 @@ void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
if(location >= 0xc0 && location <= 0xc8) {
channels_[location - 0xc0].feedback_strength = (value >> 1) & 0x7;
channels_[location - 0xc0].two_operator = value & 1;
channels_[location - 0xc0].use_fm_synthesis = value & 1;
return;
}
@ -211,7 +265,12 @@ void OPL2::set_opl2_register(uint8_t location, uint8_t value) {
//
switch(location) {
case 0x01: waveform_enable_ = value & 0x20; break;
case 0x08: csm_keyboard_split_ = value; break;
case 0x08:
// b7: "composite sine wave mode on/off"?
csm_keyboard_split_ = value;
// b6: "Controls the split point of the keyboard. When 0, the keyboard split is the
// second bit from the bit 8 of the F-Number. When 1, the MSB of the F-Number is used."
break;
case 0xbd: depth_rhythm_control_ = value; break;
default: break;

4
Components/OPL2/OPL2.hpp
View File

@ -64,14 +64,14 @@ class OPL2: public ::Outputs::Speaker::SampleSource {
int sustain_level = 0;
int release_rate = 0;
int waveform = 0;
} operators_[22];
} operators_[18];
struct Channel {
int frequency;
int octave;
bool key_on;
int feedback_strength;
bool two_operator;
bool use_fm_synthesis;
} channels_[9];
uint8_t depth_rhythm_control_;