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/*
* Copyright (c) 2009 Petri Lehtinen <petri@digip.org>
*
* Jansson is free software; you can redistribute it and/or modify
* it under the terms of the MIT license. See LICENSE for details.
*/
#include <string.h>
#include <stdint.h>
int utf8_encode(int32_t codepoint, char *buffer, int *size)
{
if(codepoint < 0)
return -1;
else if(codepoint < 0x80)
{
buffer[0] = (char)codepoint;
*size = 1;
}
else if(codepoint < 0x800)
{
buffer[0] = 0xC0 + ((codepoint & 0x7C0) >> 6);
buffer[1] = 0x80 + ((codepoint & 0x03F));
*size = 2;
}
else if(codepoint < 0x10000)
{
buffer[0] = 0xE0 + ((codepoint & 0xF000) >> 12);
buffer[1] = 0x80 + ((codepoint & 0x0FC0) >> 6);
buffer[2] = 0x80 + ((codepoint & 0x003F));
*size = 3;
}
else if(codepoint <= 0x10FFFF)
{
buffer[0] = 0xF0 + ((codepoint & 0x1C0000) >> 18);
buffer[1] = 0x80 + ((codepoint & 0x03F000) >> 12);
buffer[2] = 0x80 + ((codepoint & 0x000FC0) >> 6);
buffer[3] = 0x80 + ((codepoint & 0x00003F));
*size = 4;
}
else
return -1;
return 0;
}
int utf8_check_first(char byte)
{
unsigned char u = (unsigned char)byte;
if(u < 0x80)
return 1;
if(0x80 <= u && u <= 0xBF) {
/* second, third or fourth byte of a multi-byte
sequence, i.e. a "continuation byte" */
return 0;
}
else if(u == 0xC0 || u == 0xC1) {
/* overlong encoding of an ASCII byte */
return 0;
}
else if(0xC2 <= u && u <= 0xDF) {
/* 2-byte sequence */
return 2;
}
else if(0xE0 <= u && u <= 0xEF) {
/* 3-byte sequence */
return 3;
}
else if(0xF0 <= u && u <= 0xF4) {
/* 4-byte sequence */
return 4;
}
else { /* u >= 0xF5 */
/* Restricted (start of 4-, 5- or 6-byte sequence) or invalid
UTF-8 */
return 0;
}
}
int utf8_check_full(const char *buffer, int size, int32_t *codepoint)
{
int i;
int32_t value = 0;
unsigned char u = (unsigned char)buffer[0];
if(size == 2)
{
value = u & 0x1F;
}
else if(size == 3)
{
value = u & 0xF;
}
else if(size == 4)
{
value = u & 0x7;
}
else
return 0;
for(i = 1; i < size; i++)
{
u = (unsigned char)buffer[i];
if(u < 0x80 || u > 0xBF) {
/* not a continuation byte */
return 0;
}
value = (value << 6) + (u & 0x3F);
}
if(value > 0x10FFFF) {
/* not in Unicode range */
return 0;
}
else if(0xD800 <= value && value <= 0xDFFF) {
/* invalid code point (UTF-16 surrogate halves) */
return 0;
}
else if((size == 2 && value < 0x80) ||
(size == 3 && value < 0x800) ||
(size == 4 && value < 0x10000)) {
/* overlong encoding */
return 0;
}
if(codepoint)
*codepoint = value;
return 1;
}
const char *utf8_iterate(const char *buffer, int32_t *codepoint)
{
int count;
int32_t value;
if(!*buffer)
return buffer;
count = utf8_check_first(buffer[0]);
if(count <= 0)
return NULL;
if(count == 1)
value = (unsigned char)buffer[0];
else
{
if(!utf8_check_full(buffer, count, &value))
return NULL;
}
if(codepoint)
*codepoint = value;
return buffer + count;
}
int utf8_check_string(const char *string, int length)
{
int i;
if(length == -1)
length = strlen(string);
for(i = 0; i < length; i++)
{
int count = utf8_check_first(string[i]);
if(count == 0)
return 0;
else if(count > 1)
{
if(i + count > length)
return 0;
if(!utf8_check_full(&string[i], count, NULL))
return 0;
i += count - 1;
}
}
return 1;
}
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