tagotip-codec 0.1.1

/// Format a `u32` as decimal into a byte buffer.
/// Returns the number of bytes written, or `None` if the buffer is too small.
/// Maximum output is 10 digits for u32.
pub fn format_u32(value: u32, out: &mut [u8]) -> Option<usize> {
  if value == 0 {
    if out.is_empty() {
      return None;
    }
    out[0] = b'0';
    return Some(1);
  }

  // Max u32 = 4294967295 = 10 digits
  let mut buf = [0u8; 10];
  let mut pos = buf.len();
  let mut v = value;

  while v > 0 {
    pos -= 1;
    buf[pos] = b'0' + (v % 10) as u8;
    v /= 10;
  }

  let len = buf.len() - pos;
  if out.len() < len {
    return None;
  }
  out[..len].copy_from_slice(&buf[pos..]);
  Some(len)
}

/// Format a `u64` as decimal into a byte buffer.
/// Returns the number of bytes written, or `None` if the buffer is too small.
/// Maximum output is 20 digits for u64.
pub fn format_u64(value: u64, out: &mut [u8]) -> Option<usize> {
  if value == 0 {
    if out.is_empty() {
      return None;
    }
    out[0] = b'0';
    return Some(1);
  }

  // Max u64 = 18446744073709551615 = 20 digits
  let mut buf = [0u8; 20];
  let mut pos = buf.len();
  let mut v = value;

  while v > 0 {
    pos -= 1;
    buf[pos] = b'0' + (v % 10) as u8;
    v /= 10;
  }

  let len = buf.len() - pos;
  if out.len() < len {
    return None;
  }
  out[..len].copy_from_slice(&buf[pos..]);
  Some(len)
}