buffers: improve put-buf and fill-buf.

* stream.h (struct strm_ops): put_buf and fill_buf function
pointers get third argument to indicate starting position
of read and write.
(put_buf, fill_buf): Declarations updated.

* stream.c (unimpl_put_buf, unimpl_fill_buf): Third argument
added.
(generic_put_buf, generic_fill_buf, stdio_put_buf,
stdio_fill_buf): Implement position
argument.
(delegate_put_buf, delegate_fill_buf): Take third argument,
pass it down.
(put_buf, fill_buf): New position argument in second position.
Defaulted to zero. Passed down.
(stream_init): Updated registration of put-buf and fill-buf.

* txr.1: Updated documentation.

1 files changed, 4 insertions, 4 deletions

diff --git a/stream.h b/stream.h
index 2a324ad3..4484d554 100644
--- a/stream.h
+++ b/stream.h
@@ -63,8 +63,8 @@ struct strm_ops {
   val (*get_byte)(val);
   val (*unget_char)(val, val);
   val (*unget_byte)(val, int);
-  val (*put_buf)(val, val);
-  val (*fill_buf)(val, val);
+  val (*put_buf)(val, val, cnum);
+  val (*fill_buf)(val, val, cnum);
   val (*close)(val, val);
   val (*flush)(val);
   val (*seek)(val, val, enum strm_whence);
@@ -180,8 +180,8 @@ val get_char(val);
 val get_byte(val);
 val unget_char(val ch, val stream);
 val unget_byte(val byte, val stream);
-val put_buf(val buf, val stream);
-val fill_buf(val buf, val stream);
+val put_buf(val buf, val pos, val stream);
+val fill_buf(val buf, val pos, val stream);
 val vformat(val stream, val string, va_list);
 val vformat_to_string(val string, va_list);
 val format(val stream, val string, ...);