AWK - Fast Urlencoder - Handles Multibytes

#!/bin/bash
function urlencode() { 
LC_ALL=C awk 'BEGIN {
  for (i = 0; i <= 255; i++)
    hex[sprintf("%c", i)] = sprintf("%%%02X", i)
  safe = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.:/!~*@$&[]+=,;?"
  split(safe, safechars, "")
  for (i in safechars)
    hex[safechars[i]] = safechars[i]
}
{
  encoded = ""
  for (i = 1; i <= length($0); i++)
    encoded = encoded hex[substr($0, i, 1)]
  print encoded
}
'
}

 This little bad boy rivals the speed of my C implementation below! 
 Slower by less than 10%.
 
 [Btw: this example is wrapped in a Bash function for ease of use]