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/*
* Copyright (c) 2021 Andrew Lelechenko <andrew.lelechenko@gmail.com>
*/
#include <string.h>
#include <stdint.h>
/*
_hs_text_reverse takes a UTF-8 encoded buffer, specified by (src0, off, len),
and reverses it, writing output starting from dst0.
The input buffer (src0, off, len) must be a valid UTF-8 sequence,
this condition is not checked.
*/
void _hs_text_reverse(uint8_t *dst0, const uint8_t *src0, size_t off, size_t len)
{
const uint8_t *src = src0 + off;
const uint8_t *srcend = src + len;
uint8_t *dst = dst0 + len - 1;
while (src < srcend){
uint8_t leadByte = *src++;
if (leadByte < 0x80){
*dst-- = leadByte;
} else if (leadByte < 0xe0){
*(dst-1) = leadByte;
*dst = *src++;
dst-=2;
} else if (leadByte < 0xf0){
*(dst-2) = leadByte;
*(dst-1) = *src++;
*dst = *src++;
dst-=3;
} else {
*(dst-3) = leadByte;
*(dst-2) = *src++;
*(dst-1) = *src++;
*dst = *src++;
dst-=4;
}
}
}
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