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/* File: utf8stringbuf.c; Copyright and License: see below */
#include <inttypes.h>
#include "utf8stringbuf/utf8stringbuf.h"
/* utf8stringbuf_private_empty_buf is constantly 0, but may be overwritten by a 0 - therefore stored in a read-writeable memory page */
char utf8stringbuf_private_empty_buf[1] = "";
const char *utf8stringbuf_private_format_signed_64_bit_int = "%" PRIi64;
const char *utf8stringbuf_private_format_64_bit_hex = "%" PRIx64;
/*!
* \fn utf8stringbuf_private_write_char( char *destination, unsigned int max_size, const uint32_t source )
* \private
*/
/* function to write a code point as utf8, returns the number of bytes written and an error code */
static inline utf8error_t utf8stringbuf_private_write_char( char *destination, unsigned int max_size, const uint32_t source, int *out_len );
/* utf8 sequences longer or equal 2 bytes start with a byte with 2 highest bits set: 0xc0 */
/* utf8 sequences longer or equal 3 bytes start with a byte with 3 highest bits set: 0xe0 */
/* utf8 sequences equal 4 bytes start with a byte with 4 highest bits set: 0xf0 */
static const unsigned char utf8stringbuf_private_pattern_to_detect_half_utf8_sequences[5] = { 0, 0, 0xc0, 0xe0, 0xf0 };
/* Note: There is some magic in the design of utf8 which makes the implementation of this function quite short */
unsigned int utf8_string_buf_private_make_null_termination( utf8stringbuf_t *this_ ) {
unsigned int truncatedLength;
int clearAtEnd = 1;
for ( int searchBackwards = 2; searchBackwards <= 4; searchBackwards ++ ) {
if ( searchBackwards > (*this_).size ) {
break;
}
const char pattern = utf8stringbuf_private_pattern_to_detect_half_utf8_sequences[searchBackwards];
if ( ( (*this_).buf[(*this_).size-searchBackwards] & pattern ) == pattern ) {
clearAtEnd = searchBackwards;
break;
}
}
truncatedLength = (*this_).size - clearAtEnd;
/* (*this_).buf[truncatedLength] = '\0'; */ /* Note: some functions like splitIn2 require complete zeroed trailings */
memset( &((*this_).buf[truncatedLength]), '\0', clearAtEnd );
return truncatedLength;
}
utf8error_t utf8stringbuf_append_char( utf8stringbuf_t *this_, const uint32_t appendix ) {
utf8error_t result;
const unsigned int start = utf8stringbuf_get_length( this_ );
int appendLen;
result = utf8stringbuf_private_write_char( &((*this_).buf[start]), (*this_).size - start - 1, appendix, &appendLen );
if ( result == UTF8ERROR_SUCCESS ) {
(*this_).buf[start+appendLen] = '\0';
}
return result;
}
utf8error_t utf8stringbuf_append_wstr( utf8stringbuf_t *this_, const wchar_t *appendix ) {
utf8error_t result = UTF8ERROR_NULL_PARAM;
if ( appendix != NULL ) {
unsigned int start = utf8stringbuf_get_length( this_ );
result = UTF8ERROR_SUCCESS;
for( ; appendix[0]!=L'\0'; appendix = &(appendix[1]) ) {
int appendLen;
result |= utf8stringbuf_private_write_char( &((*this_).buf[start]), (*this_).size - start - 1, appendix[0], &appendLen );
if ( result != UTF8ERROR_SUCCESS ) {
if ( ( result & UTF8ERROR_TRUNCATED ) != 0 ) {
break;
}
}
start = start + appendLen;
}
(*this_).buf[start] = '\0';
}
return result;
}
static inline utf8error_t utf8stringbuf_private_write_char( char *destination, unsigned int max_size, const uint32_t source, int *out_len ) {
*out_len = 0;
utf8error_t result = UTF8ERROR_TRUNCATED;
if ( source <= 0x7ff ) {
if ( source <= 0x7f ) {
/* 1 byte character */
/* check if there is enough space for the character */
if ( max_size >= 1 ) {
destination[0] = source;
*out_len = 1;
result = UTF8ERROR_SUCCESS;
}
}
else {
/* 2 byte character */
if ( max_size >= 2 ) {
destination[0] = 0xc0 | ( source >> 6 );
destination[1] = 0x80 | ( source & 0x3f );
*out_len = 2;
result = UTF8ERROR_SUCCESS;
}
}
}
else {
if ( source <= 0x10ffff ) {
if ( source <= 0xffff ) {
/* 3 byte character */
if ( max_size >= 3 ) {
destination[0] = 0xe0 | ( source >> 12 );
destination[1] = 0x80 | (( source >> 6 ) & 0x3f );
destination[2] = 0x80 | ( source & 0x3f );
*out_len = 3;
result = UTF8ERROR_SUCCESS;
}
}
else {
/* 4 byte character */
if ( max_size >= 4 ) {
destination[0] = 0xf0 | ( source >> 18 );
destination[1] = 0x80 | (( source >> 12 ) & 0x3f );
destination[2] = 0x80 | (( source >> 6 ) & 0x3f );
destination[3] = 0x80 | ( source & 0x3f );
*out_len = 4;
result = UTF8ERROR_SUCCESS;
}
}
}
else {
/* note: utf8 can not encode more than 21 bits per character, and even there only 0-0x10ffff is allowed. */
result = UTF8ERROR_NOT_A_CODEPOINT;
}
}
return result;
}
/*
* Copyright 2012-2025 Andreas Warnke
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
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