HEXBuilder.cpp

/*
  Copyright (c) 2015 Hristo Gochkov. All rights reserved.
  This file is part of the esp32 core for Arduino environment.

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include <Arduino.h>
#include <HEXBuilder.h>

static uint8_t hex_char_to_byte(uint8_t c)
{
    return  (c >= 'a' && c <= 'f') ? (c - ((uint8_t)'a' - 0xa)) :
            (c >= 'A' && c <= 'F') ? (c - ((uint8_t)'A' - 0xA)) :
            (c >= '0' &&  c<= '9') ? (c - (uint8_t)'0') : 0x10; // unknown char is 16
}

size_t HEXBuilder::hex2bytes(unsigned char * out, size_t maxlen, String &in) {
    return hex2bytes(out, maxlen, in.c_str());
}

size_t HEXBuilder::hex2bytes(unsigned char * out, size_t maxlen, const char * in) {
    size_t len = 0;
    for(;*in;in++) {
        uint8_t c = hex_char_to_byte(*in);
        // Silently skip anything unknown.
        if (c > 15)
            continue;

        if (len & 1) {
            if (len/2 < maxlen)
                out[len/2] |= c;
        } else {
            if (len/2 < maxlen)
                 out[len/2] = c<<4;
        }
        len++;
    }
    return (len + 1)/2;
}

size_t HEXBuilder::bytes2hex(char * out, size_t maxlen, const unsigned char * in, size_t len) {
    for(size_t i = 0; i < len; i++) {
        if (i*2 + 1 < maxlen) {
            sprintf(out + (i * 2), "%02x", in[i]);
        }
    }
    return len * 2 + 1;
}

String HEXBuilder::bytes2hex(const unsigned char * in, size_t len) {
    size_t maxlen = len * 2 + 1;
    char * out = (char *) malloc(maxlen);
    if (!out) return String();
    bytes2hex(out, maxlen, in, len);
    String ret = String(out);
    free(out);
    return ret;
}