make initial memory smaller and let it grow

i also enabled lto building which should make performance better.

Makefile

@@ -1,6 +1,6 @@
 LIBRARY=src/blurhash-decode.wasm
 $(LIBRARY): blurhash/decode.c
-	emcc -ffast-math -O3 --no-entry -Wl,--export,decodeToArray -Wl,--export,malloc -Wl,--export,free -Wl,--export,isValidBlurhash -o $@ blurhash/decode.c
+	emcc -flto -ffast-math -O3 --no-entry -Wl,--export,decodeToArray -Wl,--export,malloc -Wl,--export,free -Wl,--export,isValidBlurhash -s ALLOW_MEMORY_GROWTH -s INITIAL_MEMORY=128KB -o $@ blurhash/decode.c
 
 .PHONY: clean
 clean:

package.json

@@ -1,7 +1,7 @@
 {
 	"type": "module",
 	"name": "@fries/blurhash-c-wasm",
-	"version": "0.1.0",
+	"version": "0.1.1",
 	"description": "A WASM module using the Blurhash C library",
 	"main": "dist/blurhash-c-wasm.cjs",
 	"module": "dist/blurhash-c-wasm.js",

src/library.ts

@@ -46,7 +46,13 @@ function encodeStringToWasmArray(string: string): number {
  */
 export async function initWasm() {
 	wasmInstance = await WebAssembly.instantiate(
-		(await wasm()) as WebAssembly.Module
+		(await wasm()) as WebAssembly.Module,
+		{
+			env: {
+				// stub for a emscripten import
+				emscripten_notify_memory_growth: () => {},
+			},
+		}
 	);
 	instance = wasmInstance.exports as InstanceType;
 }
@@ -77,11 +83,6 @@ export function decode(
 
 	const pixelsPtrSize = width * 4 * width;
 	const pixelsPtr = instance.malloc(pixelsPtrSize);
-	const pixelsBuf = new Uint8ClampedArray(
-		instance.memory.buffer,
-		pixelsPtr,
-		pixelsPtrSize
-	);
 
 	const stringPtr = encodeStringToWasmArray(blurhashString);
 
@@ -99,6 +100,11 @@ export function decode(
 		throw Error("Decoding the Blurhash string has failed.");
 	}
 
+	const pixelsBuf = new Uint8ClampedArray(
+		instance.memory.buffer,
+		pixelsPtr,
+		pixelsPtrSize
+	);
 	const clonedBuffer = pixelsBuf.slice(0);
 
 	instance.free(stringPtr);