circuitpython/shared-module/usb/utf16le.c

75 lines
2.5 KiB
C

/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2022 Scott Shawcroft for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "shared-module/usb/utf16le.h"
typedef struct {
const uint16_t *buf;
size_t len;
} utf16_str;
STATIC uint32_t utf16str_peek_unit(utf16_str *utf) {
if (!utf->len) {
return 0;
}
return *utf->buf;
}
STATIC uint32_t utf16str_next_unit(utf16_str *utf) {
uint32_t result = utf16str_peek_unit(utf);
if (utf->len) {
utf->len--;
utf->buf++;
}
return result;
}
STATIC uint32_t utf16str_next_codepoint(utf16_str *utf) {
uint32_t unichr = utf16str_next_unit(utf);
if (unichr >= 0xd800 && unichr < 0xdc00) {
uint32_t low_surrogate = utf16str_peek_unit(utf);
if (low_surrogate >= 0xdc00 && low_surrogate < 0xe000) {
(void)utf16str_next_unit(utf);
unichr = (unichr - 0xd800) * 0x400 + low_surrogate - 0xdc00 + 0x10000;
}
}
return unichr;
}
STATIC void _convert_utf16le_to_utf8(vstr_t *vstr, utf16_str *utf) {
while (utf->len) {
vstr_add_char(vstr, utf16str_next_codepoint(utf));
}
}
mp_obj_t utf16le_to_string(const uint16_t *buf, size_t utf16_len) {
// will grow if necessary, but will never grow for an all-ASCII descriptor
vstr_t vstr;
vstr_init(&vstr, utf16_len);
utf16_str utf = {buf, utf16_len};
_convert_utf16le_to_utf8(&vstr, &utf);
return mp_obj_new_str_from_vstr(&vstr);
}