neptunium-firmware/Core/Src/utils.c

#include "utils.h"

// https://stackoverflow.com/questions/23191203/convert-float-to-string-without-sprintf
char *float_to_char(float x, char *p)
{
    char *s = p + FLOAT_CHAR_BUFF_SIZE; // go to end of buffer
    uint16_t decimals;                  // variable to store the decimals
    int units;                          // variable to store the units (part to left of decimal place)
    if (x < 0)
    {                                     // take care of negative numbers
        decimals = (int)(x * -100) % 100; // make 1000 for 3 decimals etc.
        units = (int)(-1 * x);
    }
    else
    { // positive numbers
        decimals = (int)(x * 100) % 100;
        units = (int)x;
    }

    *--s = (decimals % 10) + '0';
    decimals /= 10; // repeat for as many decimal places as you need
    *--s = (decimals % 10) + '0';
    *--s = '.';

    while (units > 0)
    {
        *--s = (units % 10) + '0';
        units /= 10;
    }
    if (x < 0)
        *--s = '-'; // unary minus sign for negative numbers
    return s;
}