UTF-16 sandbox (encode)

Step-by-step breakdown

1. 01

   Pick the endianness

   The low-order byte of each code unit comes first (Little Endian).

   Little Endian (LE)
2. 02

   Pick the UTF-16 form

   Range U+10000 → U+10FFFF - beyond the BMP, in the supplementary planes (emojis, historic scripts, rare CJK...). Encoded as a surrogate pair: 2 code units = 4 bytes.

   2 code units · surrogate pair
3. 03

   Convert to binary

   Subtract 0x10000 and keep the remaining 20 bits.

   00001111001110001001
4. 04

   Split for the surrogates

   Split the 20 bits into 2 packets of 10 bits.
   The left 10 bits (high-order) form the high surrogate, the right 10 bits (low-order) form the low surrogate.
   Each 10-bit packet represents an integer between 0 and 1,023 (10 bits = 2¹⁰ = 1,024 values). Add it to the surrogate base: 0xD800 for the high, 0xDC00 for the low.

   0000111100 | 1110001001
5. 05

   Convert to hexadecimal

   The 2 code units (high + low surrogate) yield 4 bytes, each code unit ordered by endianness.

   0x3C 0xD8 0x89 0xDF