1 files changed, 95 insertions, 0 deletions
diff --git a/src/utils.ts b/src/utils.ts
new file mode 100644
index 0000000..f47f584
--- /dev/null
+++ b/src/utils.ts
@@ -0,0 +1,95 @@
+
+export function readUint8(buffer: Uint8Array, index: number) {
+  return buffer[index];
+}
+export function readUint16(buffer: Uint8Array, index: number) {
+  return (buffer[index] << 8) + buffer[index + 1];
+}
+export function readUint24(buffer: Uint8Array, index: number) {
+  return (buffer[index] << 16) + (buffer[index + 1] << 8) + buffer[index + 2];
+}
+export function readUint32(buffer: Uint8Array, index: number) {
+  return ((buffer[index] << 24) + (buffer[index + 1] << 16) + (buffer[index + 2] << 8) + buffer[index + 3]) >>> 0;
+}
+export function readUint64(buffer: Uint8Array, index: number) {
+  const left = readUint32(buffer, index);
+  const right = readUint32(buffer, index+4);
+  return (BigInt(left) << 32n) + BigInt(right);
+}
+export function readUintN(buffer: Uint8Array, index: number, n: number) {
+  switch (n) {
+    case 1: return readUint8(buffer, index);
+    case 2: return readUint16(buffer, index);
+    case 3: return readUint24(buffer, index);
+    case 4: return readUint32(buffer, index);
+    default: throw new Error('Unsupported UInt size');
+  }
+}
+
+export function writeUint8(uint: number, buffer: Uint8Array, index: number) {
+  buffer[index] = uint & 255;
+}
+export function writeUint16(uint: number, buffer: Uint8Array, index: number) {
+  buffer[index] = (uint & 65280) >> 8;
+  buffer[index + 1] = uint & 255;
+}
+export function writeUint24(uint: number, buffer: Uint8Array, index: number) {
+  buffer[index] = (uint & 16711680) >> 16;
+  buffer[index + 1] = (uint & 65280) >> 8;
+  buffer[index + 2] = uint & 255;
+}
+export function writeUint32(uint: number, buffer: Uint8Array, index: number) {
+  buffer[index] = (uint & 4278190080) >> 24;
+  buffer[index + 1] = (uint & 16711680) >> 16;
+  buffer[index + 2] = (uint & 65280) >> 8;
+  buffer[index + 3] = uint & 255;
+}
+export function writeUint64(uint: bigint, buffer: Uint8Array, index: number) {
+  const left = (uint & 0xffffffff00000000n) >> 32n;
+  const right = uint & 0xffffffffn;
+  writeUint32(Number(left), buffer, index);
+  writeUint32(Number(right), buffer, index+4);
+}
+export function writeUintN(uint: number, buffer: Uint8Array, index: number, size: number) {
+  switch (size) {
+    case 1: return writeUint8(uint, buffer, index);
+    case 2: return writeUint16(uint, buffer, index);
+    case 3: return writeUint24(uint, buffer, index);
+    case 4: return writeUint32(uint, buffer, index);
+    default: throw new Error('Unsupported UInt size');
+  }
+}
+
+export function minUInt(uint: number) {
+  if (uint < 256) return 1;
+  if (uint < 65536) return 2;
+  if (uint < 16777216) return 3;
+  if (uint < 4294967296) return 4;
+  throw new Error('Unsupported UInt size');
+}
+
+export function concatUint8Array(arrays: Uint8Array[]): Uint8Array {
+  let size = 0;
+  for (const array of arrays) {
+    size += array.length;
+  }
+  const buffer = new Uint8Array(size);
+  let index = 0;
+  for (const array of arrays) {
+    buffer.set(array, index);
+    index += array.length;
+  }
+  return buffer;
+}
+
+const decoder = new TextDecoder('utf8');
+const encoder = new TextEncoder();
+export function readString(buffer: Uint8Array, index: number, length: number) {
+  return decoder.decode(buffer.subarray(index, index+length));
+}
+export function writeString(str: string, buffer: Uint8Array, index: number) {
+  buffer.set(encoder.encode(str), index);
+}
+export function encodeString(str: string) {
+  return encoder.encode(str);
+}
+\ No newline at end of file