src/mlibc/stdlib/itoa.c


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43

#include <mlibc/math.h>
#include <stdint.h>
#include <mlibc/string.h>
#include <mlibc/stdlib.h>

static const char __ITOA_TABLE[] = "0123456789";

char *itoa(int n) {
    // Special cases
    if (!n) {
        char *ret = kmalloc(2);
        ret[0] = '0';
        ret[1] = 0;
        return ret;
    }
    uint8_t negative = (uint8_t) (n < 0);
    if (negative) n *= -1;

    // First get the number of digits.
    int sz;
    for (sz = 0; n % pow(10, sz) != n; sz++) {}

    char *ret = kmalloc(sz + 1);

    // Iterate all digits again.
    for (int i = 0; i < sz; i++) {
        int digit = (n % pow(10, i + 1)) / pow(10, i);
        ret[i] = __ITOA_TABLE[digit];
    }
    ret[sz] = 0;

    if (negative) {
        char *aux = kmalloc(sz + 2);
        strcpy(aux, ret);
        aux[sz] = '-';
        aux[sz + 1] = 0;
        kfree(ret);
        ret = aux;
    }

    strinv(ret);
    return ret;
}