bytevectors have internal parent field

* libguile/bytevectors.h (SCM_BYTEVECTOR_HEADER_SIZE): Bump, giving
  bytevectors another word: a parent pointer.  Will allow for
  sub-bytevectors and efficient mmap bindings.

* libguile/bytevectors.c (make_bytevector):
  (make_bytevector_from_buffer): Init parent to #f.
  (scm_c_take_bytevector, scm_c_take_typed_bytevector): Another
  argument, the parent, which gets set in the bytevector.

* libguile/foreign.c (scm_pointer_to_bytevector): Use the parent field
  instead of registering a weak reference from bytevector to foreign
  pointer.

* libguile/objcodes.c (scm_objcode_to_bytecode): Use the parent field to
  avoid copying the objcode.

* libguile/srfi-4.c (DEFINE_SRFI_4_C_FUNCS):
* libguile/strings.c (scm_from_stringn):
* libguile/vm.c (really_make_boot_program):
* libguile/r6rs-ports.c (scm_get_bytevector_some)
  (scm_get_bytevector_all, bytevector_output_port_procedure): Set the
  parent to #f.

1 files changed, 23 insertions, 6 deletions

diff --git a/libguile/bytevectors.c b/libguile/bytevectors.c
index a969e3bb4..4ca3c4e25 100644
--- a/libguile/bytevectors.c
+++ b/libguile/bytevectors.c
@@ -193,6 +193,9 @@
   SCM_SET_BYTEVECTOR_FLAGS ((bv),					\
                             (hint)					\
                             | (SCM_BYTEVECTOR_CONTIGUOUS_P (bv) << 8UL))
+#define SCM_BYTEVECTOR_SET_PARENT(_bv, _parent)	\
+  SCM_SET_CELL_OBJECT_3 ((_bv), (_parent))
+
 #define SCM_BYTEVECTOR_TYPE_SIZE(var)                           \
   (scm_i_array_element_type_sizes[SCM_BYTEVECTOR_ELEMENT_TYPE (var)]/8)
 #define SCM_BYTEVECTOR_TYPED_LENGTH(var)                        \
@@ -233,6 +236,7 @@ make_bytevector (size_t len, scm_t_array_element_type element_type)
       SCM_BYTEVECTOR_SET_CONTENTS (ret, contents);
       SCM_BYTEVECTOR_SET_CONTIGUOUS_P (ret, 1);
       SCM_BYTEVECTOR_SET_ELEMENT_TYPE (ret, element_type);
+      SCM_BYTEVECTOR_SET_PARENT (ret, SCM_BOOL_F);
     }
 
   return ret;
@@ -262,6 +266,7 @@ make_bytevector_from_buffer (size_t len, void *contents,
       SCM_BYTEVECTOR_SET_CONTENTS (ret, contents);
       SCM_BYTEVECTOR_SET_CONTIGUOUS_P (ret, 0);
       SCM_BYTEVECTOR_SET_ELEMENT_TYPE (ret, element_type);
+      SCM_BYTEVECTOR_SET_PARENT (ret, SCM_BOOL_F);
     }
 
   return ret;
@@ -282,19 +287,31 @@ scm_i_make_typed_bytevector (size_t len, scm_t_array_element_type element_type)
   return make_bytevector (len, element_type);
 }
 
-/* Return a bytevector of size LEN made up of CONTENTS.  The area pointed to
-   by CONTENTS must have been allocated using `scm_gc_malloc ()'.  */
+/* Return a bytevector of size LEN made up of CONTENTS.  The area
+   pointed to by CONTENTS must be protected from GC somehow: either
+   because it was allocated using `scm_gc_malloc ()', or because it is
+   part of PARENT.  */
 SCM
-scm_c_take_bytevector (signed char *contents, size_t len)
+scm_c_take_bytevector (signed char *contents, size_t len, SCM parent)
 {
-  return make_bytevector_from_buffer (len, contents, SCM_ARRAY_ELEMENT_TYPE_VU8);
+  SCM ret;
+
+  ret = make_bytevector_from_buffer (len, contents, SCM_ARRAY_ELEMENT_TYPE_VU8);
+  SCM_BYTEVECTOR_SET_PARENT (ret, parent);
+
+  return ret;
 }
 
 SCM
 scm_c_take_typed_bytevector (signed char *contents, size_t len,
-                             scm_t_array_element_type element_type)
+                             scm_t_array_element_type element_type, SCM parent)
 {
-  return make_bytevector_from_buffer (len, contents, element_type);
+  SCM ret;
+
+  ret = make_bytevector_from_buffer (len, contents, element_type);
+  SCM_BYTEVECTOR_SET_PARENT (ret, parent);
+
+  return ret;
 }
 
 /* Shrink BV to C_NEW_LEN (which is assumed to be smaller than its current