module strconv

// write_dec writes the decimal representation of `n` into `buf`.
// It returns the number of bytes written, or `-1` if `buf` is too small.
@[direct_array_access]
pub fn write_dec(n i64, mut buf []u8) int {
    mut mag := u64(n)
    if n < 0 {
        mag = u64(0) - mag
        ndigits := dec_digits(mag)
        if buf.len < ndigits + 1 {
            return -1
        }
        buf[0] = `-`
        write_dec_u_digits(mag, mut buf, 1, ndigits)
        return ndigits + 1
    }
    ndigits := dec_digits(mag)
    if buf.len < ndigits {
        return -1
    }
    write_dec_u_digits(mag, mut buf, 0, ndigits)
    return ndigits
}

// write_dec_u writes the decimal representation of `n` into `buf`.
// It returns the number of bytes written, or `-1` if `buf` is too small.
@[direct_array_access]
pub fn write_dec_u(n u64, mut buf []u8) int {
    ndigits := dec_digits(n)
    if buf.len < ndigits {
        return -1
    }
    write_dec_u_digits(n, mut buf, 0, ndigits)
    return ndigits
}

@[direct_array_access]
fn write_dec_u_digits(n u64, mut buf []u8, offset int, ndigits int) {
    mut x := n
    mut i := offset + ndigits
    for {
        i--
        buf[i] = u8(x % 10) + `0`
        x /= 10
        if x == 0 {
            break
        }
    }
}