ffi: support buf objects.

* buf.c (make_duplicate_buf, buf_get, buf_fill): New
functions.

* buf.h (make_duplicate_buf, buf_get, buf_fill): Declared.

* ffi.c (struct txr_ffi_type): New member, nelem.
Keeps track of number of elements, for types that are
FFI pointers. This lets us support the get method so that
a buf can be a C function return value, if its size is
declared in our FFI type system.
(ffi_buf_put, ffi_buf_get, ffi_buf_fill): New functions.
(ffi_type_compile): Handle two new cases of syntax for
buffers: (buf <size>) and buf.

1 files changed, 24 insertions, 0 deletions

diff --git a/buf.c b/buf.c
index 0c1ecf18..58cd4177 100644
--- a/buf.c
+++ b/buf.c
@@ -107,6 +107,18 @@ val make_borrowed_buf(val len, mem_t *data)
   return obj;
 }
 
+val make_duplicate_buf(val len, mem_t *data)
+{
+  val obj = make_obj();
+
+  obj->b.type = BUF;
+  obj->b.data = chk_copy_obj(data, c_num(len));
+  obj->b.len = len;
+  obj->b.size = nil;
+
+  return obj;
+}
+
 static struct buf *buf_handle(val buf, val ctx)
 {
   if (type(buf) == BUF)
@@ -186,6 +198,18 @@ val length_buf(val buf)
   return b->len;
 }
 
+mem_t *buf_get(val buf, val self)
+{
+  struct buf *b = buf_handle(buf, self);
+  return b->data;
+}
+
+void buf_fill(val buf, mem_t *src, val self)
+{
+  struct buf *b = buf_handle(buf, self);
+  memcpy(b->data, src, c_num(b->len));
+}
+
 static void buf_put_bytes(val buf, val pos, mem_t *ptr, cnum size, val self)
 {
   struct buf *b = buf_handle(buf, self);