- toString("latin1"): counts the high bytes eight at a time, copies
words of ASCII bytes, and writes other bytes from a table of their
UTF-8 pairs without branches. ASCII-only results are marked ASCII, and
other results record their UTF-16 length (one unit per byte), so
`.length` does not walk the string.
- Buffer.from(text, "latin1" | "ascii" | "binary"): copies text known to
be ASCII, copies words of ASCII bytes, and decodes eight bytes of one-
and two-byte sequences in one word, storing each output byte without
branches. Longer sequences take the previous path.
- Buffer.from(text, "hex"): reads digit values from a table.
- toString("hex") and toString("base64"/"base64url") mark their results
ASCII, so a later decode, length or index read skips the scan for
non-ASCII bytes.
