add SCM_{PACK,UNPACK}_POINTER

* libguile/tags.h (SCM_UNPACK_POINTER, SCM_PACK_POINTER): New macros.
  The old SCM2PTR and PTR2SCM were defined in such a way that
  round-tripping through a pointer could lose precision, even in the
  case in which you weren't interested in actually dereferencing the
  pointer, it was simply that you needed to plumb a SCM through APIs
  that take pointers.  These new macros are more like SCM_PACK and
  SCM_UNPACK, but for pointer types.  The bit representation of the
  pointer should be the same as the scm_t_bits representation.

* libguile/gc.h (PTR2SCM, SCM2PTR): Remove support for (old) UNICOS
  pointers.  We are going to try tagging the SCM object itself in the
  future, and I don't think that keeping this support is worth its
  cost.  It probably doesn't work anyway.

* libguile/backtrace.c:
* libguile/bytevectors.c:
* libguile/continuations.c:
* libguile/fluids.c:
* libguile/foreign.c:
* libguile/gc.h:
* libguile/guardians.c:
* libguile/hashtab.c:
* libguile/load.c:
* libguile/numbers.c:
* libguile/ports.c:
* libguile/smob.c:
* libguile/strings.c:
* libguile/symbols.c:
* libguile/vm.c:
* libguile/weak-set.c:
* libguile/weak-table.c:
* libguile/weak-vector.c: Update many sites to use the new macros.

1 files changed, 2 insertions, 2 deletions

diff --git a/libguile/backtrace.c b/libguile/backtrace.c
index db22c17e9..a9b37fd7c 100644
--- a/libguile/backtrace.c
+++ b/libguile/backtrace.c
@@ -511,7 +511,7 @@ display_backtrace_body (struct display_backtrace_args *a)
 static SCM
 error_during_backtrace (void *data, SCM tag, SCM throw_args)
 {
-  SCM port = PTR2SCM (data);
+  SCM port = SCM_PACK_POINTER (data);
   
   scm_puts ("Exception thrown while printing backtrace:\n", port);
   scm_print_exception (port, SCM_BOOL_F, tag, throw_args);
@@ -544,7 +544,7 @@ SCM_DEFINE (scm_display_backtrace_with_highlights, "display-backtrace", 2, 3, 0,
 
   scm_internal_catch (SCM_BOOL_T,
 		      (scm_t_catch_body) display_backtrace_body, &a,
-		      (scm_t_catch_handler) error_during_backtrace, SCM2PTR (port));
+		      (scm_t_catch_handler) error_during_backtrace, SCM_UNPACK_POINTER (port));
 
   return SCM_UNSPECIFIED;
 }