utils.c

/*
 * The MIT License (MIT)
 * 
 * Copyright (c) <year> <copyright holders>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

#include <stdio.h>
#include <string.h>

/**
 * @brief Converts a string containing to its binary counterpart. The string is
 *        expected to hold 2 characters for each byte, in hexdecimal notation.
 */
size_t hexstring_to_bin(char *buf, size_t bsiz, const char *str, size_t ssiz)
{
	size_t i;

	for (i = 0; i < bsiz && i*2 < ssiz; i++)
		sscanf(&str[i*2], "%2hhx", &buf[i]);
	return i;
}

/**
 * @brief Print a number in binary. Keep aware of recursiveness
 */
void printbin(int i)
{
        if (i > 1)
                printbin(i/2);
        printf("%d", i % 2);
}

/**
 * An average with no need of arrays :)
 *
 * @param  y       The current point
 * @param  factor  From 0.0 to 1.0. Smaller values will retain old points.
 * @param  ema     The current expential moving average value
 * @return         A new exponential moving average value
 */
double exponential_moving_average(double y, double factor, double ema)
{
        return factor * y + (1.0 - factor) * ema;
}

/**
 * Return system clock in us
 */
unsigned long clock_gettime_us(void)
{
    struct timespec ts;
    unsigned long value;

    clock_gettime(CLOCK_MONOTONIC, &ts);
    value = (ts.tv_sec * 1e6 + ts.tv_nsec / 1e3);
    return value;
}