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Documentation Index

Fetch the complete documentation index at: https://mintlify.com/CryZe/asr-assemblyscript/llms.txt

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The runtime module configures the auto splitting runtime environment and provides essential debugging and introspection utilities. It controls how frequently your update() function is invoked, exposes a logging helper for development, and lets your code inspect the host operating system and CPU architecture so you can branch on platform-specific behaviour (for example, choosing between a 32-bit and 64-bit game executable). Beyond its exported functions, this module also registers a custom abort handler that replaces AssemblyScript’s default error behaviour with an explicit WebAssembly unreachable trap. This side-effect import is required in your entry file. Without it, runtime errors may not be surfaced correctly by the LiveSplit One host. 
import 'asr-assemblyscript/runtime';              // required side-effect import
import * as Runtime from 'asr-assemblyscript/runtime'; // for using the exported functions
Both imports can coexist in the same file — the side-effect import simply ensures the abort handler is registered, while the namespace import gives you access to the functions below.

​
setTickRate

function setTickRate(ticks_per_second: f64): void
Sets how many times per second the LiveSplit One host will call your auto splitter’s update() function. This applies globally to the runtime — it is not scoped to a single auto splitter module.
​
ticks_per_second
f64
required
The desired number of update() calls per second. Must be a positive value. Common choices are 60.0 (default) for responsive splitting, or lower values such as 30.0 or 10.0 to reduce CPU usage for simpler auto splitters.
setTickRate affects the entire auto splitting runtime — a common default is 60 ticks per second. Lowering the rate reduces CPU usage and is recommended for auto splitters that only need to poll memory infrequently. Changes take effect on the next tick cycle.
import 'asr-assemblyscript/runtime';
import * as Runtime from 'asr-assemblyscript/runtime';

let initialized = false;

export function update(): void {
  if (!initialized) {
    Runtime.setTickRate(30.0); // poll 30 times per second
    initialized = true;
  }
}

​
printMessage

function printMessage(text: string): void
Prints a debug log message to the LiveSplit One debug console. The message is encoded as UTF-8 before being passed to the host. Use this during development to inspect values and trace execution — it has no effect on timer behaviour.
​
text
string
required
The message string to print. Accepts any valid UTF-8 content, including interpolated values.
import * as Runtime from 'asr-assemblyscript/runtime';

Runtime.printMessage("Auto splitter loaded!");
Runtime.printMessage("Current level: " + levelName);

​
getOS

function getOS(): string
Returns the name of the operating system that the LiveSplit One runtime is running on. The string is valid UTF-8 and not null-terminated. Returns an empty string "" if the OS name cannot be determined. Returns: string — the OS identifier. Example values:
ValuePlatform
"windows"Microsoft Windows
"linux"Linux
"macos"macOS / OS X

​
getArch

function getArch(): string
Returns the name of the CPU architecture that the LiveSplit One runtime is running on. The string is valid UTF-8 and not null-terminated. Returns an empty string "" if the architecture cannot be determined. Returns: string — the architecture identifier. Example values:
ValueArchitecture
"x86"32-bit x86
"x86_64"64-bit x86 (amd64)
"arm"32-bit ARM
"aarch64"64-bit ARM (Apple Silicon)

​
Combined Example

import 'asr-assemblyscript/runtime';
import * as Runtime from 'asr-assemblyscript/runtime';

let initialized = false;

export function update(): void {
  if (!initialized) {
    const os   = Runtime.getOS();
    const arch = Runtime.getArch();

    Runtime.printMessage("Running on " + os + " / " + arch);

    // Choose the right process name based on the host OS
    if (os === "windows") {
      // attach to Celeste.exe
    } else if (os === "linux") {
      // attach to Celeste (no extension)
    }

    initialized = true;
  }
}

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