> For the complete documentation index, see [llms.txt](https://guide.cronuszen.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://guide.cronuszen.com/gpcscripting/gpc-script-guide/reference/additional-built-ins/device-timing-remapper-and-bvar-built-ins.md).

# Device, timing, remapper, and BVAR built-ins

These functions affect VM timing, active slots, device settings, LEDs, or persistent binary-variable storage. Treat slot changes and persistent writes as deliberate user actions, never background work at the base of `main`.

***

#### `get_rtime`

Returns the elapsed time between the current and previous `main` iterations.

**Syntax**

```gpc
elapsed_ms = get_rtime();
```

**Parameters**

None.

**Returns**

Elapsed milliseconds. The usual value is near the VM interval, but it can change with timing control and runtime conditions.

**Example**

{% code title="get-rtime.gpc" %}

```gpc
int elapsed_ms;

main {
    elapsed_ms = elapsed_ms + get_rtime();
    if(elapsed_ms >= 1000) elapsed_ms = elapsed_ms - 1000;
    set_val(TRACE_1, elapsed_ms);
}
```

{% endcode %}

Subtract the threshold instead of resetting to zero when accumulated timing should retain overshoot.

***

#### `get_slot`

Returns the currently active Zen memory slot.

**Syntax**

```gpc
slot = get_slot();
```

**Parameters**

None.

**Returns**

The active slot number.

**Example**

{% code title="get-slot.gpc" %}

```gpc
int active_slot;

init {
    active_slot = get_slot();
}

main {
    set_val(TRACE_1, active_slot);
}
```

{% endcode %}

Refresh the cached value only when the script design has a reason to expect a slot-state change.

***

#### `load_slot`

Immediately attempts to load a slot. Slot `0` unloads the current programmed slot; the accepted range is `0..8`.

**Syntax**

```gpc
load_slot(slot);
```

**Parameters**

* `slot`: `0..8`.

**Returns**

Nothing. Loading occurs immediately, so code after the call must not be relied on.

**Example**

{% code title="load-slot.gpc" %}

```gpc
main {
    if(get_ival(PS5_L2) && event_press(PS5_OPTIONS)) {
        load_slot(2);
    }
}
```

{% endcode %}

Use an intentional chord to prevent accidental slot changes.

***

#### `get_ctrlbutton`

Returns the configured remote slot-control button mode from the Zen device settings.

**Syntax**

```gpc
control_mode = get_ctrlbutton();
```

**Parameters**

None.

**Returns**

The configured control-button mode; the supplied Live documentation identifies values `0`, `1`, and `8`.

**Example**

{% code title="get-ctrlbutton.gpc" %}

```gpc
int control_mode;

init {
    control_mode = get_ctrlbutton();
}

main {
    set_val(TRACE_1, control_mode);
}
```

{% endcode %}

Treat the result as device configuration data, not as a controller report identifier.

***

#### `vm_tctrl`

Applies an offset to the VM interval for the next iteration.

**Syntax**

```gpc
vm_tctrl(timeout_offset);
```

**Parameters**

* `timeout_offset`: compiler-accepted range `-9..30` relative to the normal interval.

**Returns**

Nothing.

**Example**

{% code title="vm-tctrl.gpc" %}

```gpc
main {
    vm_tctrl(-5);
    set_val(TRACE_1, get_rtime());
}
```

{% endcode %}

Shorter intervals increase VM work and may reduce stability. Measure VM load and controller behavior before keeping a non-default value.

***

#### `set_rgb`

Sets the Zen or controller LED color with red, green, and blue components.

**Syntax**

```gpc
set_rgb(red, green, blue);
```

**Parameters**

* `red`, `green`, `blue`: each `0..255`.

**Returns**

Nothing.

**Example**

{% code title="set-rgb.gpc" %}

```gpc
int feedback_dirty = TRUE;

main {
    if(feedback_dirty) {
        set_rgb(87, 151, 209);
        feedback_dirty = FALSE;
    }
}
```

{% endcode %}

Render on a state change instead of rewriting the same color every cycle.

***

#### `set_hsb`

Sets the Zen or controller LED color using hue, saturation, and brightness.

**Syntax**

```gpc
set_hsb(hue, saturation, brightness);
```

**Parameters**

* `hue`: `0..360` degrees.
* `saturation`: `0..100` percent.
* `brightness`: `0..100` percent.

**Returns**

Nothing.

**Example**

{% code title="set-hsb.gpc" %}

```gpc
init {
    set_hsb(210, 60, 80);
}
```

{% endcode %}

***

#### `get_info`

Queries a value from the active mouse-and-keyboard profile or related Live device state.

**Syntax**

```gpc
value = get_info(selector);
```

**Parameters**

* `selector`: numeric selector accepted by the exact Live build.

**Returns**

The selected information value.

**Example**

{% code title="get-info.gpc" %}

```gpc
int profile_value;

main {
    profile_value = get_info(0);
    set_val(TRACE_1, profile_value);
}
```

{% endcode %}

Use the documented Zen Studio Live selector constants whenever possible. Confirm any raw numeric selector against the intended Live build before relying on its meaning.

***

#### `set_remapper`

Changes one entry in the device-level remapper. This is different from a script `remap` declaration because it modifies device configuration.

**Syntax**

```gpc
set_remapper(identifier_from, identifier_to);
```

**Parameters**

* `identifier_from`: `BUTTON_MIN..BUTTON_MAX`.
* `identifier_to`: `BUTTON_MIN..BUTTON_MAX`.

**Returns**

Nothing.

**Example**

{% code title="set-remapper.gpc" %}

```gpc
int remap_saved;

main {
    if(!remap_saved && get_ival(PS5_L2) && event_press(PS5_OPTIONS)) {
        set_remapper(PS5_CROSS, PS5_CIRCLE);
        save_eeprom();
        remap_saved = TRUE;
    }
}
```

{% endcode %}

Use a guarded, explicit action. A device remapper change can affect scripts beyond the current slot.

***

#### `save_eeprom`

Persists changed device settings to EEPROM.

**Syntax**

```gpc
save_eeprom();
```

**Parameters**

None.

**Returns**

Nothing.

**Example**

{% code title="save-eeprom.gpc" %}

```gpc
int device_setting_dirty;

main {
    if(event_press(PS5_CROSS)) device_setting_dirty = TRUE;

    if(device_setting_dirty && event_press(PS5_OPTIONS)) {
        save_eeprom();
        device_setting_dirty = FALSE;
    }
}
```

{% endcode %}

{% hint style="warning" %}
EEPROM has a finite write life. Never call this unconditionally in `main`.
{% endhint %}

***

#### `get_bvar`

Reads one indexed BVAR value on the 32-bit target.

**Syntax**

```gpc
value = get_bvar(index);
```

**Parameters**

* `index`: `0..1023`.

**Returns**

The value stored at the selected index.

**Example**

{% code title="get-bvar.gpc" %}

```gpc
define PROFILE_GAIN_INDEX = 40;

int profile_gain;

init {
    profile_gain = get_bvar(PROFILE_GAIN_INDEX);
    if(profile_gain < 0 || profile_gain > 200) profile_gain = 100;
}
```

{% endcode %}

Validate loaded data before using it, and reserve index ranges so unrelated records cannot overlap.

***

#### `set_bvar`

Writes one indexed BVAR value on the 32-bit target.

**Syntax**

```gpc
set_bvar(index, value);
```

**Parameters**

* `index`: `0..1023`.
* `value`: current-target signed integer expression. Device-test storage width and signed round trips for the intended firmware.

**Returns**

Nothing.

**Example**

{% code title="set-bvar.gpc" %}

```gpc
define PROFILE_GAIN_INDEX = 40;

int profile_gain = 100;
int dirty;

main {
    if(event_press(PS5_UP)) {
        profile_gain = min(profile_gain + 1, 200);
        dirty = TRUE;
    }

    if(dirty && event_press(PS5_OPTIONS)) {
        set_bvar(PROFILE_GAIN_INDEX, profile_gain);
        dirty = FALSE;
    }
}
```

{% endcode %}

Use named schema constants, bounds-check computed indexes, and write only on an explicit save/change event.


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