/* CC0 license (public domain) - see LICENSE file for details */

#include "config.h"

#include "hex.h"

#include <stdio.h>

#include <stdlib.h>

static bool char_to_hex(unsigned char *val, char c)

{

  if (c >= '0' && c <= '9') {

    *val = c - '0';

    return true;

  }

  if (c >= 'a' && c <= 'f') {

    *val = c - 'a' + 10;

    return true;

  }

  if (c >= 'A' && c <= 'F') {

    *val = c - 'A' + 10;

    return true;

  }

  return false;

}

bool hex_decode(const char *str, size_t slen, void *buf, size_t bufsize)

{

  unsigned char v1, v2;

  unsigned char *p = buf;

  while (slen > 1) {

    if (!char_to_hex(&v1, str[0]) || !char_to_hex(&v2, str[1]))

      return false;

    if (!bufsize)

      return false;

    *(p++) = (v1 << 4) | v2;

    str += 2;

    slen -= 2;

    bufsize--;

  }

  return slen == 0 && bufsize == 0;

}

static const char HEX_CHARS[] = "0123456789abcdef";

bool hex_encode(const void *buf, size_t bufsize, char *dest, size_t destsize)

{

  size_t used = 0;

  if (destsize < 1)

    return false;

  while (used < bufsize) {

    unsigned int c = ((const unsigned char *)buf)[used];

    if (destsize < 3)

      return false;

    *(dest++) = HEX_CHARS[(c >> 4) & 0xF];

    *(dest++) = HEX_CHARS[c & 0xF];

    used++;

    destsize -= 2;

  }

  *dest = '\0';

  return used + 1;

}