ujson_utf.h

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// SPDX-License-Identifier: LGPL-2.1-or-later
/*
 * Copyright (C) 2022-2024 Cyril Hrubis <metan@ucw.cz>
 */
 
#ifndef UJSON_UTF_H
#define UJSON_UTF_H
 
#include <stdint.h>
#include <stddef.h>
 
#define UJSON_UTF8_IS_ASCII(ch) (!((ch) & 0x80))
#define UJSON_UTF8_IS_NBYTE(ch) (((ch) & 0xc0) == 0x80)
#define UJSON_UTF8_IS_2BYTE(ch) (((ch) & 0xe0) == 0xc0)
#define UJSON_UTF8_IS_3BYTE(ch) (((ch) & 0xf0) == 0xe0)
#define UJSON_UTF8_IS_4BYTE(ch) (((ch) & 0xf8) == 0xf0)
 
#define UJSON_UTF8_NBYTE_MASK 0x3f
 
static inline uint32_t ujson_utf8_next(const char **str)
{
        uint32_t s0 = *str[0];
 
        (*str)++;
 
        if (UJSON_UTF8_IS_ASCII(s0))
                return s0;
 
        uint32_t s1 = *str[0];
 
        if (!UJSON_UTF8_IS_NBYTE(s1))
                return 0;
 
        s1 &= UJSON_UTF8_NBYTE_MASK;
 
        (*str)++;
 
        if (UJSON_UTF8_IS_2BYTE(s0))
                return (s0 & 0x1f)<<6 | s1;
 
        uint32_t s2 = *str[0];
 
        if (!UJSON_UTF8_IS_NBYTE(s2))
                return 0;
 
        s2 &= UJSON_UTF8_NBYTE_MASK;
 
        (*str)++;
 
        if (UJSON_UTF8_IS_3BYTE(s0))
                return (s0 & 0x0f)<<12 | s1<<6 | s2;
 
        (*str)++;
 
        uint32_t s3 = *str[0];
 
        if (!UJSON_UTF8_IS_NBYTE(s2))
                return 0;
 
        s3 &= UJSON_UTF8_NBYTE_MASK;
 
        if (UJSON_UTF8_IS_4BYTE(s0))
                return (s0 & 0x07)<<18 | s1<<12 | s2<<6 | s3;
 
        return 0;
}
 
int8_t ujson_utf8_next_chsz(const char *str, size_t off);
 
int8_t ujson_utf8_prev_chsz(const char *str, size_t off);
 
size_t ujson_utf8_strlen(const char *str);
 
static inline unsigned int ujson_utf8_bytes(uint32_t unicode)
{
        if (unicode < 0x0080)
                return 1;
 
        if (unicode < 0x0800)
                return 2;
 
        if (unicode < 0x10000)
                return 3;
 
        return 4;
}
 
static inline int ujson_to_utf8(uint32_t unicode, char *buf)
{
        if (unicode < 0x0080) {
                buf[0] = unicode & 0x007f;
                return 1;
        }
 
        if (unicode < 0x0800) {
                buf[0] = 0xc0 | (0x1f & (unicode>>6));
                buf[1] = 0x80 | (0x3f & unicode);
                return 2;
        }
 
        if (unicode < 0x10000) {
                buf[0] = 0xe0 | (0x0f & (unicode>>12));
                buf[1] = 0x80 | (0x3f & (unicode>>6));
                buf[2] = 0x80 | (0x3f & unicode);
                return 3;
        }
 
        buf[0] = 0xf0 | (0x07 & (unicode>>18));
        buf[1] = 0x80 | (0x3f & (unicode>>12));
        buf[2] = 0x80 | (0x3f & (unicode>>6));
        buf[3] = 0x80 | (0x3f & unicode);
        return 4;
}
 
#endif /* UJSON_UTF_H */