charset.c
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/*
* charset conversion utils
*
* Copyright (c) 2017 Rob Clark
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <charset.h>
#include <malloc.h>
/*
* utf8/utf16 conversion mostly lifted from grub
*/
size_t utf16_strlen(const uint16_t *in)
{
size_t i;
for (i = 0; in[i]; i++);
return i;
}
size_t utf16_strnlen(const uint16_t *in, size_t count)
{
size_t i;
for (i = 0; count-- && in[i]; i++);
return i;
}
uint16_t *utf16_strcpy(uint16_t *dest, const uint16_t *src)
{
uint16_t *tmp = dest;
while ((*dest++ = *src++) != '\0')
/* nothing */;
return tmp;
}
uint16_t *utf16_strdup(const uint16_t *s)
{
uint16_t *new;
if (!s || !(new = malloc((utf16_strlen(s) + 1) * 2)))
return NULL;
utf16_strcpy(new, s);
return new;
}
/* Convert UTF-16 to UTF-8. */
uint8_t *utf16_to_utf8(uint8_t *dest, const uint16_t *src, size_t size)
{
uint32_t code_high = 0;
while (size--) {
uint32_t code = *src++;
if (code_high) {
if (code >= 0xDC00 && code <= 0xDFFF) {
/* Surrogate pair. */
code = ((code_high - 0xD800) << 10) + (code - 0xDC00) + 0x10000;
*dest++ = (code >> 18) | 0xF0;
*dest++ = ((code >> 12) & 0x3F) | 0x80;
*dest++ = ((code >> 6) & 0x3F) | 0x80;
*dest++ = (code & 0x3F) | 0x80;
} else {
/* Error... */
*dest++ = '?';
/* *src may be valid. Don't eat it. */
src--;
}
code_high = 0;
} else {
if (code <= 0x007F) {
*dest++ = code;
} else if (code <= 0x07FF) {
*dest++ = (code >> 6) | 0xC0;
*dest++ = (code & 0x3F) | 0x80;
} else if (code >= 0xD800 && code <= 0xDBFF) {
code_high = code;
continue;
} else if (code >= 0xDC00 && code <= 0xDFFF) {
/* Error... */
*dest++ = '?';
} else if (code < 0x10000) {
*dest++ = (code >> 12) | 0xE0;
*dest++ = ((code >> 6) & 0x3F) | 0x80;
*dest++ = (code & 0x3F) | 0x80;
} else {
*dest++ = (code >> 18) | 0xF0;
*dest++ = ((code >> 12) & 0x3F) | 0x80;
*dest++ = ((code >> 6) & 0x3F) | 0x80;
*dest++ = (code & 0x3F) | 0x80;
}
}
}
return dest;
}
uint16_t *utf8_to_utf16(uint16_t *dest, const uint8_t *src, size_t size)
{
while (size--) {
int extension_bytes;
uint32_t code;
extension_bytes = 0;
if (*src <= 0x7f) {
code = *src++;
/* Exit on zero byte */
if (!code)
size = 0;
} else if (*src <= 0xbf) {
/* Illegal code */
code = '?';
} else if (*src <= 0xdf) {
code = *src++ & 0x1f;
extension_bytes = 1;
} else if (*src <= 0xef) {
code = *src++ & 0x0f;
extension_bytes = 2;
} else if (*src <= 0xf7) {
code = *src++ & 0x07;
extension_bytes = 3;
} else {
/* Illegal code */
code = '?';
}
for (; extension_bytes && size; --size, --extension_bytes) {
if ((*src & 0xc0) == 0x80) {
code <<= 6;
code |= *src++ & 0x3f;
} else {
/* Illegal code */
code = '?';
++src;
--size;
break;
}
}
if (code < 0x10000) {
*dest++ = code;
} else {
/*
* Simplified expression for
* (((code - 0x10000) >> 10) & 0x3ff) | 0xd800
*/
*dest++ = (code >> 10) + 0xd7c0;
*dest++ = (code & 0x3ff) | 0xdc00;
}
}
return dest;
}