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/* copyright (c) 2022 - 2026 grunfink et al. / MIT license */
#ifndef _XS_HEX_H
#define _XS_HEX_H
int xs_is_hex_digit(char str);
void xs_hex_enc_1(char **dst, const char **src);
int xs_hex_dec_1(char **dst, const char **src);
char *_xs_hex_enc(char *dst, const char *src, int src_size);
char *_xs_hex_dec(char *dst, const char *src, int src_size);
#ifdef _XS_H
xs_str *xs_hex_enc(const xs_val *data, int size);
xs_val *xs_hex_dec(const xs_str *hex, int *size);
int xs_is_hex(const char *str);
#endif /* _XS_H */
#ifdef XS_IMPLEMENTATION
#include <string.h>
/** hex **/
static char rev_hex_digits[] = "fedcba9876543210FEDCBA";
int xs_is_hex_digit(char str)
/* checks if the char is an hex digit */
{
return strchr(rev_hex_digits, str) != NULL;
}
void xs_hex_enc_1(char **dst, const char **src)
/* decodes one character into two hex digits */
{
const char *i = *src;
char *o = *dst;
*o++ = rev_hex_digits[0xf - (*i >> 4 & 0xf)];
*o++ = rev_hex_digits[0xf - (*i & 0xf)];
*src = i + 1;
*dst = o;
}
int xs_hex_dec_1(char **dst, const char **src)
/* decodes two hex digits (returns 0 on error) */
{
const char *i = *src;
char *o = *dst;
char *d1 = strchr(rev_hex_digits, *i++);
char *d2 = strchr(rev_hex_digits, *i++);
if (!d1 || !d2) {
/* decoding error */
return 0;
}
*o++ = (0xf - ((d1 - rev_hex_digits) & 0xf)) << 4 |
(0xf - ((d2 - rev_hex_digits) & 0xf));
*src = i;
*dst = o;
return 1;
}
char *_xs_hex_enc(char *dst, const char *src, int src_size)
/* hex-encodes the src buffer into dst, which has enough size */
{
const char *e = src + src_size;
while (src < e)
xs_hex_enc_1(&dst, &src);
return dst;
}
char *_xs_hex_dec(char *dst, const char *src, int src_size)
/* hex-decodes the src string int dst, which has enough size.
return NULL on decoding errors or the final position of dst */
{
if (src_size % 2)
return NULL;
const char *e = src + src_size;
while (src < e) {
if (!xs_hex_dec_1(&dst, &src))
return NULL;
}
return dst;
}
#ifdef _XS_H
xs_str *xs_hex_enc(const xs_val *data, int size)
/* returns an hexdump of data */
{
xs_str *s = xs_realloc(NULL, _xs_blk_size(size * 2 + 1));
char *q = _xs_hex_enc(s, data, size);
*q = '\0';
return s;
}
xs_val *xs_hex_dec(const xs_str *hex, int *size)
/* decodes an hexdump into data */
{
int sz = strlen(hex);
xs_val *s = NULL;
*size = sz / 2;
s = xs_realloc(NULL, _xs_blk_size(*size + 1));
if (!_xs_hex_dec(s, hex, sz))
return xs_free(s);
s[*size] = '\0';
return s;
}
int xs_is_hex(const char *str)
/* returns 1 if str is an hex string */
{
if (strlen(str) % 2)
return 0;
while (*str) {
if (!xs_is_hex_digit(*str++))
return 0;
}
return 1;
}
#endif /* _XS_H */
#endif /* XS_IMPLEMENTATION */
#endif /* _XS_HEX_H */
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