The number of ASCII code points in the input array.
const char  input
An array of ASCII code points (0..7F).
size_t * output_length
The caller passes in the maximum number of code
points that it can receive into the output array (which is also
the maximum number of flags that it can receive into the
case_flags array, if case_flags is not a NULL pointer). On
successful return it will contain the number of code points
actually output (which is also the number of flags actually
output, if case_flags is not a null pointer). The decoder will
never need to output more code points than the number of ASCII
code points in the input, because of the way the encoding is
defined. The number of code points output cannot exceed the
maximum possible value of a punycode_uint, even if the supplied
output_length is greater than that.
punycode_uint  output
An array of code points like the input argument of
punycode_encode() (see above).
unsigned char  case_flags
A NULL pointer (if the flags are not needed by the
caller) or an array of boolean values parallel to the output
array. Nonzero (true, flagged) suggests that the corresponding
Unicode character be forced to uppercase by the caller (if
possible), and zero (false, unflagged) suggests that it be forced
to lowercase (if possible). ASCII code points (0..7F) are output
already in the proper case, but their flags will be set
appropriately so that applying the flags would be harmless.