INNER CODE UNIT · TypeScript
avail
paulmillr/noble-ciphers · src/_arx.ts:399
const avail = this.pos < this.blockLen ? this.blockLen - this.pos : 0;
const blocks = Math.ceil(Math.max(0, len - avail) / this.blockLen);
// Preflight overflow so failed reads don't partially consume keystream
// and leave the PRG repeating blocks.
if (blocks > 0 && this.ctr > MAX_COUNTER - blocks) throw new Error('arx: counter overflow');
const out = new Uint8Array(len);
let outPos = 0;
// `out` starts zero-filled, and `buf.fill(0)` below does the same for leftovers: XOR-stream
// ciphers then emit raw keystream bytes directly into those buffers.
// Serve buffered leftovers first so split reads stay identical to one larger read.
if (this.pos < this.blockLen) {
const take = Math.min(len, this.blockLen - this.pos);
out.set(this.buf.subarray(this.pos, this.pos + take), 0);
this.pos += take;
outPos += take;
if (outPos === len) return out as TRet<Uint8Array>; // fast path
}
// Full blocks directly to out