Performs an 'encode step', only encodes blocks of 3 characters from in into the output out at a time, saves
left-over state in state and save (initialise to 0 on first invocation).
| len |
max length of data to decode |
| break_lines |
Whether to use line breaks |
| state |
holds the number of bits that are stored in |
| save |
leftover bits that have not yet been decoded |
| in |
input stream |
| out |
output stream |
|
the number of bytes encoded |