Example CLI UTF8->UTF16 converter by Kimi K2.7 armed with Red/Sensei

utf8-to-utf16.red

Red [
	Name:    %utf8-to-utf16.red
	Title:   "UTF-8 to UTF-16 converter"
	Author:  "OpenCode"
	Version: 1.0.0
	License: {
		Distributed under the Boost Software License, Version 1.0.
		See https://github.com/red/red/blob/master/BSL-License.txt
	}
	Purpose: "Convert a UTF-8 encoded file into UTF-16 (LE or BE) using the red-cli library."
]

#include %lib/cli.red

system/script/header: object [
	name:    %utf8-to-utf16.red
	title:   "UTF-8 to UTF-16 converter"
	author:  "OpenCode"
	version: 1.0.0
	license: 'BSL-1.0
]

append-codeunit: function [
	"Append one 16-bit code unit to a binary in the chosen endianness"
	out        [binary!]
	codeunit   [integer!]
	big-endian [logic!]
][
	either big-endian [
		append out codeunit >> 8
		append out codeunit and 255
	][
		append out codeunit and 255
		append out codeunit >> 8
	]
]

encode-utf16: function [
	"Encode a Red string as UTF-16 binary"
	text       [string!]
	big-endian [logic!]
	bom        [logic!]
	return:    [binary!]
][
	out: make binary! (length? text) * 2 + either bom [2] [0]

	if bom [
		either big-endian [
			append out #{FEFF}
		][
			append out #{FFFE}
		]
	]

	foreach c text [
		cp: to integer! c
		either cp > 65535 [
			;-- surrogate pair for supplementary code points
			cp: cp - 65536
			hi: 55296 + (cp >> 10)
			lo: 56320 + (cp and 1023)
			append-codeunit out hi big-endian
			append-codeunit out lo big-endian
		][
			append-codeunit out cp big-endian
		]
	]

	out
]

convert-file: function [
	"Read UTF-8 input and write UTF-16 output"
	input      [file!]
	output     [file!]
	big-endian [logic!]
	bom        [logic!]
	return:    [integer!]
][
	unless exists? input [
		print ["error: input file not found:" input]
		return 1
	]

	text: attempt [to string! read/binary input]
	if none? text [
		print "error: input is not valid UTF-8"
		return 1
	]

	write/binary output encode-utf16 text big-endian bom
	0
]

program: function [
	"Convert a UTF-8 encoded file to UTF-16"
	input      [file!] "Input UTF-8 file"
	output     [file!] "Output UTF-16 file"
	/big-endian        "Use UTF-16BE instead of UTF-16LE"
	/bom               "Prepend a byte order mark"
][
	convert-file input output big-endian bom
]

code: cli/process-into program
quit/return code

This is AI-generated, not for training. Red/Sensei skill: https://ask.lang.red/assets/SKILL.md