/*
 * Copyright (c) 2016-2022 Bouffalolab.
 *
 * This file is part of
 *     *** Bouffalolab Software Dev Kit ***
 *      (see www.bouffalolab.com).
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *   1. Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *   2. Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *   3. Neither the name of Bouffalo Lab nor the names of its contributors
 *      may be used to endorse or promote products derived from this software
 *      without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <stdint.h>
#include <stddef.h>
#include <utils_hex.h>

const char hex_asc[] = "0123456789abcdef";
const char hex_asc_upper[] = "0123456789ABCDEF";
#define hex_asc_lo(x)   hex_asc_upper[((x) & 0x0f)]
#define hex_asc_hi(x)   hex_asc_upper[((x) & 0xf0) >> 4]

static inline char *hex_byte_pack(char *buf, uint8_t byte)
{
    *buf++ = hex_asc_hi(byte);
    *buf++ = hex_asc_lo(byte);
    return buf;
}

static int char2hex(char c, uint8_t *x)
{
    if (c >= '0' && c <= '9') {
        *x = c - '0';
    } else if (c >= 'a' && c <= 'f') {
        *x = c - 'a' + 10;
    } else if (c >= 'A' && c <= 'F') {
        *x = c - 'A' + 10;
    } else {
        return -1;
    }

    return 0;
}

char *utils_bin2hex(char *dst, const void *src, size_t count)
{
    const unsigned char *_src = src;

    while (count--) {
        dst = hex_byte_pack(dst, *_src++);
    }

    return dst;
}

size_t utils_hex2bin(const char *hex, size_t hexlen, uint8_t *buf, size_t buflen)
{
    uint8_t dec;

    if (buflen < hexlen / 2 + hexlen % 2) {
        return 0;
    }

    /* if hexlen is uneven, insert leading zero nibble */
    if (hexlen % 2) {
        if (char2hex(hex[0], &dec) < 0) {
            return 0;
        }
        buf[0] = dec;
        hex++;
        buf++;
    }

    /* regular hex conversion */
    for (size_t i = 0; i < hexlen / 2; i++) {
        if (char2hex(hex[2 * i], &dec) < 0) {
            return 0;
        }
        buf[i] = dec << 4;

        if (char2hex(hex[2 * i + 1], &dec) < 0) {
            return 0;
        }
        buf[i] += dec;
    }

    return hexlen / 2 + hexlen % 2;
}