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refactor: Replace LFSR with Xorshift PRNG, store menu strings in PROGMEM, and ensure atomic CV value updates.

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This commit is contained in:
Adam Wonak
2026-03-18 13:00:19 -07:00
parent 59fbd37524
commit e363c05823
1 changed files with 90 additions and 73 deletions
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163
firmware/Rhythm/Rhythm.ino
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@ -81,8 +81,16 @@ volatile int cv1_val = 0;
volatile int cv2_val = 0; volatile int cv2_val = 0;
int last_mapped_slot = -1; int last_mapped_slot = -1;
// LFSR State for Chaos // PRNG State for Chaos
uint16_t lfsr = 0xACE1; uint16_t xorshift_seed = 0xACE1;
// Fast 16-bit xorshift PRNG
uint16_t xorshift16() {
xorshift_seed ^= xorshift_seed << 7;
xorshift_seed ^= xorshift_seed >> 9;
xorshift_seed ^= xorshift_seed << 8;
return xorshift_seed;
}
// Math Helper: 1D Linear Interpolation between two bytes // Math Helper: 1D Linear Interpolation between two bytes
uint8_t lerp(uint8_t a, uint8_t b, uint8_t t) { uint8_t lerp(uint8_t a, uint8_t b, uint8_t t) {
@ -95,21 +103,17 @@ uint8_t GetThreshold(int inst, int step, int x_pos, int y_pos) {
// x_pos is 0-255 mapped across 4 nodes (0, 1, 2, 3). Distance is 85 (255 / 3) // x_pos is 0-255 mapped across 4 nodes (0, 1, 2, 3). Distance is 85 (255 / 3)
// y_pos is 0-255 mapped across 4 nodes (0, 1, 2, 3). Distance is 85 (255 / 3) // y_pos is 0-255 mapped across 4 nodes (0, 1, 2, 3). Distance is 85 (255 / 3)
int x_idx = x_pos / 85; int x_idx = 0;
int y_idx = y_pos / 85; uint8_t x_frac = 0;
if (x_pos < 85) { x_idx = 0; x_frac = x_pos * 3; }
else if (x_pos < 170) { x_idx = 1; x_frac = (x_pos - 85) * 3; }
else { x_idx = 2; x_frac = x_pos == 255 ? 255 : (x_pos - 170) * 3; }
uint8_t x_frac = (x_pos % 85) * 3; // scale remainder 0-84 up to 0-255 int y_idx = 0;
uint8_t y_frac = (y_pos % 85) * 3; uint8_t y_frac = 0;
if (y_pos < 85) { y_idx = 0; y_frac = y_pos * 3; }
// Guard against out of bounds if exactly 255 else if (y_pos < 170) { y_idx = 1; y_frac = (y_pos - 85) * 3; }
if (x_idx >= 3) { else { y_idx = 2; y_frac = y_pos == 255 ? 255 : (y_pos - 170) * 3; }
x_idx = 2;
x_frac = 255;
}
if (y_idx >= 3) {
y_idx = 2;
y_frac = 255;
}
// Read 4 corners from PROGMEM // Read 4 corners from PROGMEM
uint8_t p00 = pgm_read_byte(&PATTERN_MAPS[x_idx][y_idx][inst][step]); uint8_t p00 = pgm_read_byte(&PATTERN_MAPS[x_idx][y_idx][inst][step]);
@ -138,20 +142,13 @@ void SaveState() {
EEPROM.put(EEPROM_PATTERNS, patterns); EEPROM.put(EEPROM_PATTERNS, patterns);
} }
// LFSR random bit generator (returns 0 or 1, fast)
uint8_t GetRandomBit() { uint8_t GetRandomBit() {
uint8_t bit = ((lfsr >> 0) ^ (lfsr >> 2) ^ (lfsr >> 3) ^ (lfsr >> 5)) & 1; return xorshift16() & 1;
lfsr = (lfsr >> 1) | (bit << 15);
return bit;
} }
// Get 8-bit pseudo-random number // Get 8-bit pseudo-random number
uint8_t GetRandomByte() { uint8_t GetRandomByte() {
uint8_t r = 0; return xorshift16() & 0xFF;
for (int i = 0; i < 8; i++) {
r = (r << 1) | GetRandomBit();
}
return r;
} }
void ProcessSequencerTick(uint32_t tick) { void ProcessSequencerTick(uint32_t tick) {
@ -428,7 +425,21 @@ void drawMainSelection() {
gravity.display.drawLine(0, mainHeight, 0, mainHeight - tickSize); gravity.display.drawLine(0, mainHeight, 0, mainHeight - tickSize);
} }
void drawMenuItems(String menu_items[], int menu_size, int current_item) { const char str_kick[] PROGMEM = "KICK";
const char str_snare[] PROGMEM = "SNARE";
const char str_hhat[] PROGMEM = "HHAT";
const char str_chaos[] PROGMEM = "CHAOS";
const char str_mapx[] PROGMEM = "MAP X";
const char str_mapy[] PROGMEM = "MAP Y";
const char* const param_menu_items[] PROGMEM = {str_kick, str_snare, str_hhat, str_chaos, str_mapx, str_mapy};
const char str_source[] PROGMEM = "SOURCE";
const char str_tempo[] PROGMEM = "TEMPO";
const char str_cv1dest[] PROGMEM = "CV1 DEST";
const char str_cv2dest[] PROGMEM = "CV2 DEST";
const char* const global_menu_items[] PROGMEM = {str_source, str_tempo, str_cv1dest, str_cv2dest};
void drawMenuItems(const char* const menu_items[], int menu_size, int current_item) {
gravity.display.setFont(TEXT_FONT); gravity.display.setFont(TEXT_FONT);
int selectedBoxY = 0; int selectedBoxY = 0;
@ -461,8 +472,9 @@ void drawMenuItems(String menu_items[], int menu_size, int current_item) {
for (int i = 0; i < min(menu_size, (int)VISIBLE_MENU_ITEMS); ++i) { for (int i = 0; i < min(menu_size, (int)VISIBLE_MENU_ITEMS); ++i) {
int idx = start_index + i; int idx = start_index + i;
drawRightAlignedText(menu_items[idx].c_str(), char buffer[16];
MENU_ITEM_HEIGHT * (i + 1) - 1); strcpy_P(buffer, (char*)pgm_read_ptr(&(menu_items[idx])));
drawRightAlignedText(buffer, MENU_ITEM_HEIGHT * (i + 1) - 1);
} }
} }
@ -470,8 +482,8 @@ void DisplayMainArea() {
gravity.display.setFontMode(1); gravity.display.setFontMode(1);
gravity.display.setDrawColor(2); gravity.display.setDrawColor(2);
String mainText; char mainText[16] = "";
String subText; char subText[16] = "";
if (selected_slot > 0) { if (selected_slot > 0) {
PatternState &p = patterns[active_pattern]; PatternState &p = patterns[active_pattern];
@ -494,96 +506,96 @@ void DisplayMainArea() {
switch (current_param) { switch (current_param) {
case PARAM_KICK_DENS: case PARAM_KICK_DENS:
mainText = String(map(act_val, 0, 255, 0, 100)) + "%"; itoa(map(act_val, 0, 255, 0, 100), mainText, 10);
subText = "KICK DENS"; strcat(mainText, "%");
strcpy(subText, "KICK DENS");
break; break;
case PARAM_SNARE_DENS: case PARAM_SNARE_DENS:
mainText = String(map(act_val, 0, 255, 0, 100)) + "%"; itoa(map(act_val, 0, 255, 0, 100), mainText, 10);
subText = "SNAR DENS"; strcat(mainText, "%");
strcpy(subText, "SNAR DENS");
break; break;
case PARAM_HIHAT_DENS: case PARAM_HIHAT_DENS:
mainText = String(map(act_val, 0, 255, 0, 100)) + "%"; itoa(map(act_val, 0, 255, 0, 100), mainText, 10);
subText = "HHAT DENS"; strcat(mainText, "%");
strcpy(subText, "HHAT DENS");
break; break;
case PARAM_CHAOS: case PARAM_CHAOS:
mainText = String(map(act_val, 0, 255, 0, 100)) + "%"; itoa(map(act_val, 0, 255, 0, 100), mainText, 10);
subText = "CHAOS"; strcat(mainText, "%");
strcpy(subText, "CHAOS");
break; break;
case PARAM_MAP_X: case PARAM_MAP_X:
mainText = String(act_val); itoa(act_val, mainText, 10);
subText = "MAP X"; strcpy(subText, "MAP X");
break; break;
case PARAM_MAP_Y: case PARAM_MAP_Y:
mainText = String(act_val); itoa(act_val, mainText, 10);
subText = "MAP Y"; strcpy(subText, "MAP Y");
break; break;
default: default:
break; break;
} }
drawCenteredText(mainText.c_str(), MAIN_TEXT_Y, LARGE_FONT); drawCenteredText(mainText, MAIN_TEXT_Y, LARGE_FONT);
drawCenteredText(subText.c_str(), SUB_TEXT_Y, TEXT_FONT); drawCenteredText(subText, SUB_TEXT_Y, TEXT_FONT);
String menu_items[PARAM_LAST] = { drawMenuItems(param_menu_items, PARAM_LAST, (int)current_param);
"KICK", "SNARE", "HHAT", "CHAOS", "MAP X", "MAP Y"};
drawMenuItems(menu_items, PARAM_LAST, (int)current_param);
} else { } else {
switch (current_global_param) { switch (current_global_param) {
case PARAM_GLOBAL_CLK_SRC: case PARAM_GLOBAL_CLK_SRC:
switch (selected_source) { switch (selected_source) {
case Clock::SOURCE_INTERNAL: case Clock::SOURCE_INTERNAL:
mainText = F("INT"); strcpy_P(mainText, PSTR("INT"));
subText = F("CLOCK"); strcpy_P(subText, PSTR("CLOCK"));
break; break;
case Clock::SOURCE_EXTERNAL_PPQN_24: case Clock::SOURCE_EXTERNAL_PPQN_24:
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
subText = F("24 PPQN"); strcpy_P(subText, PSTR("24 PPQN"));
break; break;
case Clock::SOURCE_EXTERNAL_PPQN_4: case Clock::SOURCE_EXTERNAL_PPQN_4:
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
subText = F("4 PPQN"); strcpy_P(subText, PSTR("4 PPQN"));
break; break;
case Clock::SOURCE_EXTERNAL_PPQN_2: case Clock::SOURCE_EXTERNAL_PPQN_2:
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
subText = F("2 PPQN"); strcpy_P(subText, PSTR("2 PPQN"));
break; break;
case Clock::SOURCE_EXTERNAL_PPQN_1: case Clock::SOURCE_EXTERNAL_PPQN_1:
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
subText = F("1 PPQN"); strcpy_P(subText, PSTR("1 PPQN"));
break; break;
case Clock::SOURCE_EXTERNAL_MIDI: case Clock::SOURCE_EXTERNAL_MIDI:
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
subText = F("MIDI"); strcpy_P(subText, PSTR("MIDI"));
break; break;
} }
break; break;
case PARAM_GLOBAL_BPM: case PARAM_GLOBAL_BPM:
if (gravity.clock.ExternalSource()) { if (gravity.clock.ExternalSource()) {
mainText = F("EXT"); strcpy_P(mainText, PSTR("EXT"));
} else { } else {
mainText = String(gravity.clock.Tempo()); itoa(gravity.clock.Tempo(), mainText, 10);
} }
subText = F("BPM"); strcpy_P(subText, PSTR("BPM"));
break; break;
case PARAM_GLOBAL_CV1_DEST: case PARAM_GLOBAL_CV1_DEST:
mainText = F("CV1"); strcpy_P(mainText, PSTR("CV1"));
subText = GetCvDestName(cv1_dest); strcpy(subText, GetCvDestName(cv1_dest));
break; break;
case PARAM_GLOBAL_CV2_DEST: case PARAM_GLOBAL_CV2_DEST:
mainText = F("CV2"); strcpy_P(mainText, PSTR("CV2"));
subText = GetCvDestName(cv2_dest); strcpy(subText, GetCvDestName(cv2_dest));
break; break;
default: default:
break; break;
} }
drawCenteredText(mainText.c_str(), MAIN_TEXT_Y, LARGE_FONT); drawCenteredText(mainText, MAIN_TEXT_Y, LARGE_FONT);
drawCenteredText(subText.c_str(), SUB_TEXT_Y, TEXT_FONT); drawCenteredText(subText, SUB_TEXT_Y, TEXT_FONT);
String menu_items[PARAM_GLOBAL_LAST] = { drawMenuItems(global_menu_items, PARAM_GLOBAL_LAST, (int)current_global_param);
"SOURCE", "TEMPO", "CV1 DEST", "CV2 DEST"};
drawMenuItems(menu_items, PARAM_GLOBAL_LAST, (int)current_global_param);
} }
} }
@ -653,8 +665,13 @@ void loop() {
static int last_cv1_val = 0; static int last_cv1_val = 0;
static int last_cv2_val = 0; static int last_cv2_val = 0;
cv1_val = gravity.cv1.Read(); // -512 to 512 int cv1_temp = gravity.cv1.Read(); // -512 to 512
cv2_val = gravity.cv2.Read(); int cv2_temp = gravity.cv2.Read();
noInterrupts();
cv1_val = cv1_temp;
cv2_val = cv2_temp;
interrupts();
// Trigger redraw if we're not editing and the CV modulating the selected param changes // Trigger redraw if we're not editing and the CV modulating the selected param changes
if (!editing_param && selected_slot > 0) { if (!editing_param && selected_slot > 0) {