parser: batched read operation for speed.

As a result of this change, the startup time is reduced.
The command txr -e '(compile-toplevel nil)' shows a 54%
speedup: around 110 milliseconds down from around 170.

Programs that read large amounts of TXR Lisp data will
benefit.

* parser.l (YY_INPUT): Use new get_bytes function instead of
get_byte to read a buffer at a time.

* stream.c (get_bytes): New function.

* stream.h (get_bytes): Declared.

1 files changed, 8 insertions, 0 deletions

diff --git a/stream.c b/stream.c
index 7120fd78..d264da16 100644
--- a/stream.c
+++ b/stream.c
@@ -2972,6 +2972,14 @@ val get_byte(val stream_in)
   return ops->get_byte(stream);
 }
 
+val get_bytes(val self, val stream_in, mem_t *ptr, ucnum len)
+{
+  val stream = default_arg(stream_in, std_input);
+  struct strm_ops *ops = coerce(struct strm_ops *,
+                                cobj_ops(self, stream, stream_s));
+  return unum(ops->fill_buf(stream, ptr, len, 0));
+}
+
 val unget_char(val ch, val stream_in)
 {
   val self = lit("unget-char");