base64 funtions: factor out stream filtering internals.

The base64_encode and base64_decode functions internally work
with streams. This change factors out those internals into
separate functions (with the intent that these will be
usefully exposed, in another commit).

* filter.c (base64_stream_enc): New function, made out of
the internals of base64_encode.
(base64_encode): Simple wrapper for base64_stream_enc.
(base64_stream_dec): New function, made out of
the internals of base64_decode.
(base64_decode): Simple wrapper for base64_stream_dec.

* filter.h (base64_stream_enc, base64_stream_dec): Declared.

1 files changed, 3 insertions, 0 deletions

diff --git a/filter.h b/filter.h
index a8507b9c..6aaae66c 100644
--- a/filter.h
+++ b/filter.h
@@ -44,6 +44,9 @@ val register_filter(val sym, val table);
 val url_encode(val str, val space_plus);
 val url_decode(val str, val space_plus);
 
+val base64_stream_enc(val out_stream, val in_stream, val nbytes, val wrap_cols);
+val base64_stream_dec(val out_stream, val in_stream, val nchars);
+
 val base64_encode(val str, val wrap_cols);
 val base64_decode(val str);