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pico_synth_ex.c
408 lines (355 loc) · 18 KB
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pico_synth_ex.c
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////////////////////////////////////////////////////////////
//////// pico_synth_ex v0.1.0 (2021-09-02) /////////////////
////////////////////////////////////////////////////////////
#include <stdio.h>
#include <math.h>
#include "pico/stdlib.h"
#include "pico/float.h"
#include "hardware/gpio.h"
#include "hardware/irq.h"
#include "hardware/pwm.h"
typedef int32_t Q28; // 小数部28ビットの符号付き固定小数点数
typedef int16_t Q14; // 小数部14ビットの符号付き固定小数点数
#define ONE_Q28 ((Q28) (1 << 28)) // Q28型の1.0
#define ONE_Q14 ((Q14) (1 << 14)) // Q14型の1.0
#define PI ((float) M_PI) // float型の円周率
#define FCLKSYS (120000000) // システムクロック周波数（Hz）
#define FS (48000) // サンプリング周波数（Hz）
#define FA (440.0F) // 基準周波数（Hz）
//////// オシレータ群 ////////////////////////////
static uint32_t Osc_freq_table[122]; // 周波数テーブル
static Q14 Osc_tune_table[256]; // 周波数調整テーブル
static Q14 Osc_wave_tables[2][31][512]; // 波形テーブル群
static Q14 Osc_mix_table[65]; // ミックス用テーブル
static volatile uint8_t Osc_waveform = 0; // 波形設定値
static volatile int8_t Osc_2_coarse_pitch = +0; // オシレータ2粗ピッチ設定値
static volatile int8_t Osc_2_fine_pitch = +4; // オシレータ2微ピッチ設定値
static volatile uint8_t Osc_1_2_mix = 16; // オシレータのミックス設定値
static void Osc_init() {
for (uint8_t pitch = 0; pitch < 122; ++pitch) {
uint32_t freq = (FA * powf(2, (pitch - 69.0F) / 12)) * (1LL << 32) / FS;
freq = ((freq >> 4) << 4) + 1; // 少し半端な値にする
Osc_freq_table[pitch] = freq;
}
for (uint16_t tune = 0; tune < 256; ++tune) {
Osc_tune_table[tune] =
(powf(2, (tune - 128.0F) / (12 * 256)) * ONE_Q14) - ONE_Q14;
}
// TODO: 4半音毎にテーブルを持っているが、2または3半音毎のほうが良いかも
// TODO: 参照テーブルを追加して、Osc_wave_tablesの重複データを無くしたい
for (uint8_t pitch_div_4 = 0; pitch_div_4 < 31; ++pitch_div_4) {
// TODO: ((FS - 0.1F) / 2) 以下という制約は不自然，改善の余地アリ
uint16_t harm_max = // 最大倍音次数
(((FS - 1.0F) / 2) * (1LL << 32) / FS) /
Osc_freq_table[(pitch_div_4 << 2) + 1];
if (harm_max > 127) { harm_max = 127; }
// 下降ノコギリ波，矩形波を生成
for (uint16_t i = 0; i < 512; ++i) {
float sum_saw = 0.0F;
float sum_square = 0.0F;
for (uint16_t k = 1; k <= harm_max; ++k) {
sum_saw += (2 / PI) * (sinf(2 * PI * k * i / 512) / k);
if ((k % 2) == 1) {
sum_square += (4 / PI) * (sinf(2 * PI * k * i / 512) / k);
}
}
sum_saw *= 0.5F; // Osc_process() でオーバ・フローしないように必要
sum_square *= 0.25F;
Osc_wave_tables[0][pitch_div_4][i] = float2fix(sum_saw, 14);
Osc_wave_tables[1][pitch_div_4][i] = float2fix(sum_square, 14);
}
}
for (uint8_t i = 0; i < 65; ++i) {
Osc_mix_table[i] = sqrtf((64 - i) / 64.0F) * ONE_Q14;
}
}
static inline Q28 Osc_phase_to_audio(uint32_t phase, uint8_t pitch) {
Q14* wave_table = Osc_wave_tables[Osc_waveform][(pitch + 3) >> 2];
uint16_t curr_index = phase >> 23;
uint16_t next_index = (curr_index + 1) & 0x000001FF;
Q14 curr_sample = wave_table[curr_index];
Q14 next_sample = wave_table[next_index];
Q14 next_weight = (phase >> 9) & 0x3FFF;
return (curr_sample << 14) + ((next_sample - curr_sample) * next_weight);
}
static inline Q28 Osc_process(uint8_t id,
uint16_t full_pitch, Q14 pitch_mod_in) {
static uint32_t phase_1[4]; // オシレータ1の位相
int32_t full_pitch_1 = full_pitch + ((256 * pitch_mod_in) >> 14);
full_pitch_1 += (full_pitch_1 < 0) * (0 - full_pitch_1);
full_pitch_1 -= (full_pitch_1 > (120 << 8)) * (full_pitch_1 - (120 << 8));
uint8_t pitch_1 = (full_pitch_1 + 128) >> 8;
uint8_t tune_1 = (full_pitch_1 + 128) & 0xFF;
uint32_t freq_1 = Osc_freq_table[pitch_1];
phase_1[id] += freq_1 + ((id - 1) << 8); // ボイス毎にずらす
phase_1[id] += ((int32_t) (freq_1 >> 8) * Osc_tune_table[tune_1]) >> 6;
static uint32_t phase_2[4]; // オシレータ2の位相
int32_t full_pitch_2 =
full_pitch_1 + (Osc_2_coarse_pitch << 8) + (Osc_2_fine_pitch << 2);
full_pitch_2 += (full_pitch_2 < 0) * (0 - full_pitch_2);
full_pitch_2 -= (full_pitch_2 > (120 << 8)) * (full_pitch_2 - (120 << 8));
uint8_t pitch_2 = (full_pitch_2 + 128) >> 8;
uint8_t tune_2 = (full_pitch_2 + 128) & 0xFF;
uint32_t freq_2 = Osc_freq_table[pitch_2];
phase_2[id] += freq_2 + ((id - 1) << 8); // ボイス毎にずらす
phase_2[id] += ((int32_t) (freq_2 >> 8) * Osc_tune_table[tune_2]) >> 6;
// TODO: wave_table切替えをスムーズにしたい（周期の頭で切替えるのが良い？）
return ((Osc_phase_to_audio(phase_1[id], pitch_1) >> 14) *
Osc_mix_table[Osc_1_2_mix - 0]) +
((Osc_phase_to_audio(phase_2[id], pitch_2) >> 14) *
Osc_mix_table[64 - Osc_1_2_mix]);
}
//////// フィルタ ////////////////////////////////
struct FILTER_COEFS { Q28 b0_a0, a1_a0, a2_a0; }; // フィルタ係数群
static struct FILTER_COEFS Filter_coefs_table[6][481]; // フィルタ係数群テーブル
static volatile uint8_t Filter_cutoff = 60; // カットオフ設定値
static volatile uint8_t Filter_resonance = 3; // レゾナンス設定値
static volatile int8_t Filter_mod_amount = +60; // カットオフ変調量設定値
static void Filter_init() {
for (uint8_t resonance = 0; resonance < 6; ++resonance) {
for (uint16_t cutoff = 0; cutoff < 481; ++cutoff) {
float f0 = FA * powf(2, ((cutoff / 4.0F) - 54) / 12);
float w0 = 2 * PI * f0 / FS;
float q = powf(sqrtf(2), resonance - 1.0F);
float alpha = sinf(w0) / (2 * q);
float b0 = (1 - cosf(w0)) / 2;
float a0 = 1 + alpha;
float a1 = -2 * cosf(w0);
float a2 = 1 - alpha;
Filter_coefs_table[resonance][cutoff].b0_a0 = float2fix(b0 / a0, 28);
Filter_coefs_table[resonance][cutoff].a1_a0 = float2fix(a1 / a0, 28);
Filter_coefs_table[resonance][cutoff].a2_a0 = float2fix(a2 / a0, 28);
}
}
}
static inline int32_t mul_s32_s32_h32(int32_t x, int32_t y) {
// 符号付き32ビット同士の乗算結果の上位32ビット
int32_t x1 = x >> 16; uint32_t x0 = x & 0xFFFF;
int32_t y1 = y >> 16; uint32_t y0 = y & 0xFFFF;
int32_t x0_y1 = x0 * y1;
int32_t z = ((x0 * y0) >> 16) + (x1 * y0) + (x0_y1 & 0xFFFF);
return (z >> 16) + (x0_y1 >> 16) + (x1 * y1);
}
static inline Q28 Filter_process(uint8_t id, Q28 audio_in, Q14 cutoff_mod_in) {
static uint16_t curr_cutoff[4]; // カットオフ現在値
int32_t targ_cutoff = Filter_cutoff << 2; // カットオフ目標値
targ_cutoff += (Filter_mod_amount * cutoff_mod_in) >> (14 - 2);
targ_cutoff += (targ_cutoff < 0) * (0 - targ_cutoff);
targ_cutoff -= (targ_cutoff > 480) * (targ_cutoff - 480);
curr_cutoff[id] += (curr_cutoff[id] < targ_cutoff);
curr_cutoff[id] -= (curr_cutoff[id] > targ_cutoff);
struct FILTER_COEFS* coefs_ptr =
&Filter_coefs_table[Filter_resonance][curr_cutoff[id]];
static Q28 x1[4], x2[4], y1[4], y2[4];
Q28 x0 = audio_in;
Q28 x3 = x0 + (x1[id] << 1) + x2[id];
Q28 y0 = mul_s32_s32_h32(coefs_ptr->b0_a0, x3) << 4;
y0 -= mul_s32_s32_h32(coefs_ptr->a1_a0, y1[id]) << 4;
y0 -= mul_s32_s32_h32(coefs_ptr->a2_a0, y2[id]) << 4;
x2[id] = x1[id]; y2[id] = y1[id]; x1[id] = x0; y1[id] = y0;
return y0;
}
//////// アンプ //////////////////////////////////
static inline Q28 Amp_process(uint8_t id, Q28 audio_in, Q14 gain_in) {
return (audio_in >> 14) * gain_in; // 計算を簡略化
}
//////// EG（Envelope Generator） ////////////////
static uint32_t EG_exp_table[65]; // 指数関数テーブル
static volatile uint8_t EG_decay_time = 40; // ディケイ・タイム設定値
static volatile uint8_t EG_sustain_level = 0; // サスティン・レベル設定値
static inline void EG_init() {
for (uint8_t index = 0; index < 65; ++index) {
EG_exp_table[index] = 100 * powf(10, (index - 32.0F) / 16);
}
}
static inline Q14 EG_process(uint8_t id, uint8_t gate_in) {
static int32_t curr_level[4]; // EG出力レベル現在値
static uint8_t curr_gate[4]; // ゲート入力レベル現在値
static uint8_t curr_attack_phase[4]; // 現在アタック・フェーズかどうか
curr_attack_phase[id] |= (curr_gate[id] == 0) & gate_in;
curr_attack_phase[id] &= (curr_level[id] < (1 << 24)) & gate_in;
curr_gate[id] = gate_in;
if (curr_attack_phase[id]) {
int32_t attack_targ_level = (1 << 24) + (1 << 23);
curr_level[id] += ((attack_targ_level - curr_level[id]) >> 5);
} else {
static uint32_t decay_counter[4]; // ディケイ用カウンター
++decay_counter[id];
decay_counter[id] =
(decay_counter[id] < EG_exp_table[EG_decay_time]) * decay_counter[id];
int32_t decay_targ_level = (EG_sustain_level << 18) * curr_gate[id];
int32_t to_decay = (curr_level[id] > decay_targ_level) &
(decay_counter[id] == 0);
curr_level[id] += to_decay *
((decay_targ_level - curr_level[id]) >> 5);
}
return curr_level[id] >> 10;
}
//////// LFO（Low Frequency Oscillator） /////////
static uint32_t LFO_freq_table[65]; // 周波数テーブル
static volatile uint8_t LFO_depth = 16; // 深さ設定値
static volatile uint8_t LFO_rate = 48; // 速さ設定値
static void LFO_init() {
for (uint8_t rate = 0; rate < 65; ++rate) {
LFO_freq_table[rate] =
2 * powf(10, (rate - 32.0F) / 32) * (1LL << 32) / FS;
}
}
static inline Q14 LFO_process(uint8_t id) {
static uint32_t phase[4]; // 位相
phase[id] += LFO_freq_table[LFO_rate] + ((id - 1) << 8); // ボイス毎にずらす
// 三角波を生成
uint16_t phase_h16 = phase[id] >> 16;
uint16_t out = phase_h16;
out += (phase_h16 >= 32768) * (65536 - (phase_h16 << 1));
return ((out - 16384) * LFO_depth) >> 7;
}
//////// PWMオーディオ出力部 /////////////////////
#define PWMA_L_GPIO (28) // PWM出力するGPIO番号（左チャンネル）
#define PWMA_L_SLICE (6) // PWMスライス番号（左チャンネル）
#define PWMA_L_CHAN (PWM_CHAN_A) // PWMチャンネル（左チャンネル）
#define PWMA_R_GPIO (27) // PWM出力するGPIO番号（右チャンネル）
#define PWMA_R_SLICE (5) // PWMスライス番号（右チャンネル）
#define PWMA_R_CHAN (PWM_CHAN_B) // PWMチャンネル（右チャンネル）
#define PWMA_CYCLE (FCLKSYS / FS) // PWM周期
static void pwm_irq_handler();
static void PWMA_init() {
gpio_set_function(PWMA_R_GPIO, GPIO_FUNC_PWM);
gpio_set_function(PWMA_L_GPIO, GPIO_FUNC_PWM);
irq_set_exclusive_handler(PWM_IRQ_WRAP, pwm_irq_handler);
irq_set_enabled(PWM_IRQ_WRAP, true);
pwm_set_irq_enabled(PWMA_L_SLICE, true);
pwm_set_wrap(PWMA_R_SLICE, PWMA_CYCLE - 1);
pwm_set_wrap(PWMA_L_SLICE, PWMA_CYCLE - 1);
pwm_set_chan_level(PWMA_R_SLICE, PWMA_R_CHAN, PWMA_CYCLE / 2);
pwm_set_chan_level(PWMA_L_SLICE, PWMA_L_CHAN, PWMA_CYCLE / 2);
pwm_set_enabled(PWMA_R_SLICE, true);
pwm_set_enabled(PWMA_L_SLICE, true);
}
static inline void PWMA_process(Q28 audio_in) {
int32_t level_int32 = (audio_in >> 18) + (PWMA_CYCLE / 2);
uint16_t level = (level_int32 > 0) * level_int32;
pwm_set_chan_level(PWMA_R_SLICE, PWMA_R_CHAN, level);
pwm_set_chan_level(PWMA_L_SLICE, PWMA_L_CHAN, level);
}
//////// 割り込みハンドラとメイン関数 ////////////
static volatile uint16_t start_time = 0; // 開始時間
static volatile uint16_t max_start_time = 0; // 最大開始時間
static volatile uint16_t proc_time = 0; // 処理時間
static volatile uint16_t max_proc_time = 0; // 最大処理時間
static volatile uint8_t gate_voice[4]; // ゲート制御値（ボイス毎）
static volatile uint8_t pitch_voice[4]; // ピッチ制御値（ボイス毎）
static volatile int8_t octave_shift; // キーのオクターブシフト量
static inline Q28 process_voice(uint8_t id) {
Q14 lfo_out = LFO_process(id);
Q14 eg_out = EG_process(id, gate_voice[id]);
Q28 osc_out = Osc_process(id, pitch_voice[id] << 8, lfo_out);
Q28 filter_out = Filter_process(id, osc_out, eg_out);
Q28 amp_out = Amp_process(id, filter_out, eg_out);
return amp_out;
}
static void pwm_irq_handler() {
pwm_clear_irq(PWMA_L_SLICE);
start_time = pwm_get_counter(PWMA_L_SLICE);
Q28 voice_out[4];
voice_out[0] = process_voice(0);
voice_out[1] = process_voice(1);
voice_out[2] = process_voice(2);
voice_out[3] = process_voice(3);
PWMA_process((voice_out[0] + voice_out[1] +
voice_out[2] + voice_out[3]) >> 2);
uint16_t end_time = pwm_get_counter(PWMA_L_SLICE);
proc_time = end_time - start_time; // 計算を簡略化
max_start_time +=
(start_time > max_start_time) * (start_time - max_start_time);
max_proc_time +=
(proc_time > max_proc_time) * (proc_time - max_proc_time);
}
static inline void note_on_off(uint8_t key)
{
uint8_t pitch = key + (octave_shift * 12);
if (pitch_voice[0] == pitch) { gate_voice[0] = (gate_voice[0] == 0); }
else if (pitch_voice[1] == pitch) { gate_voice[1] = (gate_voice[1] == 0); }
else if (pitch_voice[2] == pitch) { gate_voice[2] = (gate_voice[2] == 0); }
else if (pitch_voice[3] == pitch) { gate_voice[3] = (gate_voice[3] == 0); }
else if (gate_voice[0] == 0) { pitch_voice[0] = pitch; gate_voice[0] = 1; }
else if (gate_voice[1] == 0) { pitch_voice[1] = pitch; gate_voice[1] = 1; }
else if (gate_voice[2] == 0) { pitch_voice[2] = pitch; gate_voice[2] = 1; }
else { pitch_voice[3] = pitch; gate_voice[3] = 1; }
}
static inline void all_notes_off()
{
for (uint8_t id = 0; id < 4; ++id) { gate_voice[id] = 0; }
}
int main() {
for (uint8_t id = 0; id < 4; ++id) { pitch_voice[id] = 60; }
#if 1
note_on_off(60); note_on_off(64); note_on_off(67); note_on_off(71);
#endif
set_sys_clock_khz(FCLKSYS / 1000, true);
stdio_init_all();
LFO_init(); EG_init(); Osc_init(); Filter_init(); PWMA_init();
while (true) {
switch (getchar_timeout_us(0)) {
case 'q': note_on_off(60); break; // ド
case '2': note_on_off(61); break; // ド＃
case 'w': note_on_off(62); break; // レ
case '3': note_on_off(63); break; // レ＃
case 'e': note_on_off(64); break; // ミ
case 'r': note_on_off(65); break; // ファ
case '5': note_on_off(66); break; // ファ＃
case 't': note_on_off(67); break; // ソ
case '6': note_on_off(68); break; // ソ＃
case 'y': note_on_off(69); break; // ラ
case '7': note_on_off(70); break; // ラ＃
case 'u': note_on_off(71); break; // シ
case 'i': note_on_off(72); break; // ド
case '1': if (octave_shift > -5) { --octave_shift; } break;
case '9': if (octave_shift < +4) { ++octave_shift; } break;
case '0': all_notes_off(); break;
case 'A': if (Osc_waveform > 0) { --Osc_waveform; } break;
case 'a': if (Osc_waveform < 1) { ++Osc_waveform; } break;
case 'S': if (Osc_2_coarse_pitch > +0) { --Osc_2_coarse_pitch; } break;
case 's': if (Osc_2_coarse_pitch < +24) { ++Osc_2_coarse_pitch; } break;
case 'D': if (Osc_2_fine_pitch > +0) { --Osc_2_fine_pitch; } break;
case 'd': if (Osc_2_fine_pitch < +32) { ++Osc_2_fine_pitch; } break;
case 'F': if (Osc_1_2_mix > 0) { --Osc_1_2_mix; } break;
case 'f': if (Osc_1_2_mix < 64) { ++Osc_1_2_mix; } break;
case 'G': if (Filter_cutoff > 0) { --Filter_cutoff; } break;
case 'g': if (Filter_cutoff < 120) { ++Filter_cutoff; } break;
case 'H': if (Filter_resonance > 0) { --Filter_resonance; } break;
case 'h': if (Filter_resonance < 5) { ++Filter_resonance; } break;
case 'J': if (Filter_mod_amount > +0) { --Filter_mod_amount; } break;
case 'j': if (Filter_mod_amount < +60) { ++Filter_mod_amount; } break;
case 'X': if (EG_decay_time > 0) { --EG_decay_time; } break;
case 'x': if (EG_decay_time < 64) { ++EG_decay_time; } break;
case 'C': if (EG_sustain_level > 0) { --EG_sustain_level; } break;
case 'c': if (EG_sustain_level < 64) { ++EG_sustain_level; } break;
case 'B': if (LFO_depth > 0) { --LFO_depth; } break;
case 'b': if (LFO_depth < 64) { ++LFO_depth; } break;
case 'N': if (LFO_rate > 0) { --LFO_rate; } break;
case 'n': if (LFO_rate < 64) { ++LFO_rate; } break;
}
static uint32_t loop_counter = 0; // ループ回数
if ((++loop_counter & 0xFFFFF) == 0) {
printf("Pitch : [ %3hhu, %3hhu, %3hhu, %3hhu ]\n",
pitch_voice[0], pitch_voice[1], pitch_voice[2], pitch_voice[3]);
printf("Gate : [ %3hhu, %3hhu, %3hhu, %3hhu ]\n",
gate_voice[0], gate_voice[1], gate_voice[2], gate_voice[3]);
printf("Octave Shift : %+3hd (1/9)\n", octave_shift);
printf("Osc Waveform : %3hhu (A/a)\n", Osc_waveform);
printf("Osc 2 Coarse Pitch: %+3hd (S/s)\n", Osc_2_coarse_pitch);
printf("Osc 2 Fine Pitch : %+3hd (D/d)\n", Osc_2_fine_pitch);
printf("Osc 1/2 Mix : %3hhu (F/f)\n", Osc_1_2_mix);
printf("Filter Cutoff : %3hhu (G/g)\n", Filter_cutoff);
printf("Filter Resonance : %3hhu (H/h)\n", Filter_resonance);
printf("Filter EG Amount : %+3hd (J/j)\n", Filter_mod_amount);
printf("EG Decay Time : %3hhu (X/x)\n", EG_decay_time);
printf("EG Sustain Level : %3hhu (C/c)\n", EG_sustain_level);
printf("LFO Depth : %3hhu (B/b)\n", LFO_depth);
printf("LFO Rate : %3hhu (N/n)\n", LFO_rate);
printf("Start Time : %4hu/%4hu\n", start_time, max_start_time);
printf("Processing Time : %4hu/%4hu\n\n", proc_time, max_proc_time);
}
}
}