RossComputerGuy/stardustos

/**
    * StardustOS libc - (C) 2019 Tristan Ross
    */
#include <sys/types.h>
#include <math.h>
#include <stdlib.h>
#include <string.h>

static int ntu(int num, int count) {
    int res = 1;
    while (count-- > 0) res *= num;
    return res;
}

int ftoa(float value, char* ptr) {
    if (ptr == NULL) return 0;
    int sign = -1;
    if (value < 0) {
        sign = '-';
        value = -value;
    }
    float num2 = value;
    long long int num = value;
    size_t len = 0;
    size_t len2 = 0;
    while ((num2 - (float)num) != 0.0 && !((num2 - (float)num) < 0.0)) {
        num2 = value * (ntu(10.0, len2 + 1));
        num = num2;
        len2++;
    }
    for (len = (value > 1) ? 0 : 1; value > 1; len++) value /= 10;
    size_t pos = len;
    len = len + 1 + len2;
    num = num2;
    if (sign == '-') {
        len++;
        pos++;
    }
    size_t wl = 0;
    for (int8_t i = len; i >= 0; i--) {
        if (i == len) ptr[i] = 0;
        else if (i == pos) ptr[i] = '.';
        else if (sign == '-' && i == 0) ptr[i] = '-';
        else {
            ptr[i] = (num % 10) + '0';
            num /= 10;
        }
        wl++;
    }
    return wl;
}