There doesn't seem to be anywhere in Slick-C that exposes an interface to encoding/decoding base64.
If your platform has a command line tool to do the encoding/decoding, you could use filter-command to encode/decode selections. For instance, on linux, there's a 'base64' command you can call out to. Ex:
#pragma option(pedantic,on)
#include "slick.sh"
#import "util.e"
_command void b64_encode() name_info(',')
{
filter_command('base64');
}
_command void b64_decode() name_info(',')
{
filter_command('base64 -d');
}
With that loaded, you could select the text, and then run b64-decode to decode it. If you're just decoding files that are all base64, you could add a call to `select_all()` in the b64_decode function so you don't have to do a manual selection.