* @maxlen: max number of digits in the output string (not counting prefix and units)
* @base: multiplier for num (e.g., if num represents Ki, use 1024)
* @pow2: select unit prefix - 0=power-of-10 decimal SI, nonzero=power-of-2 binary IEC
* @maxlen: max number of digits in the output string (not counting prefix and units)
* @base: multiplier for num (e.g., if num represents Ki, use 1024)
* @pow2: select unit prefix - 0=power-of-10 decimal SI, nonzero=power-of-2 binary IEC