Discover gists

Program Analysis Resources

(draft; work in progress)

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

Code is clean if it can be understood easily – by everyone on the team. Clean code can be read and enhanced by a developer other than its original author. With understandability comes readability, changeability, extensibility and maintainability.

General rules

Follow standard conventions.
Keep it simple stupid. Simpler is always better. Reduce complexity as much as possible.
Boy scout rule. Leave the campground cleaner than you found it.
Always find root cause. Always look for the root cause of a problem.

Design rules

Macro Must-Haves

These are my must-have macros for running games online. I make full use of the compendium, which gives these macros access to common actions and rolls, saving me time.

Remember to add /w gm or @{selected|wtype} to hide sensitive info from your players. WTYPE is an attribute used in the 5th Edition OGL character sheet, a prerequisite for most of these.

Here's what my bar looks like.

WGSL Noise Algorithms

Operator % has changed, probably current code with it need a fix

Good and fast integer hash

// https://www.pcg-random.org/
fn pcg(n: u32) -> u32 {
    var h = n * 747796405u + 2891336453u;
    h = ((h >> ((h >> 28u) + 4u)) ^ h) * 277803737u;

	async function generateOneTimePassword(rawKey: Uint8Array, counter: number): Promise<number> {
	const data = new DataView(new ArrayBuffer(8));
	data.setBigUint64(0, BigInt(Math.floor(counter)), false);

	const algo = { name: 'HMAC', hash: 'SHA-1' };
	const key = await crypto.subtle.importKey('raw', rawKey, algo, false, ['sign']);
	const hmacHash = new Uint8Array(await crypto.subtle.sign(algo, key, data.buffer));

	const offset = hmacHash[hmacHash.byteLength - 1] & 0x0f;
	const hotp = (hmacHash[offset] & 0x7f) << 24

	{ stdenv, autoPatchelfHook }:

	stdenv.mkDerivation rec {
	pname = "wasmcloud-binaries";
	version = "1.0";

	src = ./.; # Assuming the binaries are in the current directory

	nativeBuildInputs = [ autoPatchelfHook ];

	import { decode } from "blurhash"

	export function blurHashToDataURL(hash: string \| undefined): string \| undefined {
	if (!hash) return undefined

	const pixels = decode(hash, 32, 32)
	const dataURL = parsePixels(pixels, 32, 32)
	return dataURL
	}

	$ docker history imagename
	IMAGE CREATED CREATED BY SIZE
	f770fc671f11 12 seconds ago apt-get install -y curl 21.3 MB
	28445c70c2b3 39 seconds ago apt-get install ping 11.57 MB
	8dbd9e392a96 7 months ago 131.5 MB

	$ docker tag 2844 imagename # <-- that's the secret right there

	$ docker history imagename
	IMAGE CREATED CREATED BY SIZE