Control Flow

If Statement

Basic conditional:

gpc

if (get_val(BUTTON_10) > 50) {
    set_val(BUTTON_10, 100);
}

With else:

gpc

if (get_val(BUTTON_9)) {
    set_val(BUTTON_15, 100);
} else {
    set_val(BUTTON_15, 0);
}

Else-if chain:

gpc

int value = get_val(BUTTON_10);

if (value > 80) {
    // Heavy press
} else if (value > 40) {
    // Medium press
} else if (value > 0) {
    // Light press
} else {
    // Not pressed
}

While Loop

Repeats while condition is true:

gpc

int i = 0;
while (i < 10) {
    set_val(i, 0);
    i++;
}

Warning: Avoid infinite loops in main block - use combos with wait() for timing.

Do-While Loop

A do-while loop runs its body once before checking the condition:

gpc

int attempts = 0;

do {
    attempts++;
} while (attempts < 3);

Keep loops short; wait() belongs in a combo, not a loop in main.

For Loop

Standard C-style for loop:

gpc

for (int i = 0; i < 10; i++) {
    set_val(i, 0);
}

Iterating arrays:

gpc

int values[5];
for (int i = 0; i < 5; i++) {
    values[i] = i * 10;
}

Counting down:

gpc

for (int i = 9; i >= 0; i--) {
    set_val(i, 100 - (i * 10));
}

Switch Statement

Multi-way branching:

gpc

int mode = 2;

switch (mode) {
    case 0:
        // Mode 0 logic
        break;
    case 1:
        // Mode 1 logic
        break;
    case 2:
        // Mode 2 logic
        break;
    default:
        // Default logic
        break;
}

Important: Use break to prevent fall-through.

Break Statement

Exits the current loop or switch:

gpc

for (int i = 0; i < 100; i++) {
    if (get_val(i) > 50) {
        break;  // Exit loop early
    }
}

Continue Statement

Skips to next loop iteration:

gpc

for (int i = 0; i < 10; i++) {
    if (i == 5) {
        continue;  // Skip i=5
    }
    set_val(i, 100);
}

Return Statement

Exits a function with optional value:

gpc

function int calculate_value(int base, int multiplier) {
    if (multiplier == 0) {
        return 0;  // Early exit
    }
    return base * multiplier;
}

Practical Examples

State Machine

gpc

int state = 0;

main {
    switch (state) {
        case 0:  // Idle
            if (event_active(BUTTON_15)) {
                state = 1;
            }
            break;

        case 1:  // Active
            combo_run(MyCombo);
            if (event_active(BUTTON_14)) {
                combo_stop(MyCombo);
                state = 0;
            }
            break;
    }
}

combo MyCombo {
    set_val(BUTTON_15, 100);
    wait(250);
    set_val(BUTTON_15, 0);
    wait(100);
}

Button Combination Detection

gpc

main {
    // Detect BUTTON_11 + BUTTON_12 held together
    if (get_val(BUTTON_11) && get_val(BUTTON_12)) {
        // Both pressed
    }

    // Detect either button
    if (get_val(BUTTON_15) || get_val(BUTTON_14)) {
        // At least one pressed
    }
}

Timed Hold Detection

gpc

main {
    // Check if button held for 500ms
    if (check_active(BUTTON_1, 500)) {
        // Long press detected
    }
}