cptr-int: allow full unsigned range.

The cptr-int function requries an address to be expressed as a
signed integer, which is incovenient. E.g. -2147483648 to
2147483647 in a 32 bit address space. Let's fix it to accept
an extended range.

* lib.c (cptr_int): Convert the argument value to a ucnum if it
is positive according to plusp, otherwise to cnum. Then either
one to the mem_t * pointer. Thus we can accept either signed
or unsigned values.

* txr.1: Document the extended range of cptr-int.

2 files changed, 18 insertions, 2 deletions

diff --git a/lib.c b/lib.c
index fa03e7c0..91768c3a 100644
--- a/lib.c
+++ b/lib.c
@@ -9817,7 +9817,10 @@ val cptr_int(val n, val type_sym_in)
 {
   val self = lit("cptr-int");
   val type_sym = default_null_arg(type_sym_in);
-  return cptr_typed(coerce(mem_t *, c_num(n, self)), type_sym, 0);
+  return cptr_typed(if3(plusp(n),
+                        coerce(mem_t *, c_unum(n, self)),
+                        coerce(mem_t *, c_num(n, self))),
+                    type_sym, 0);
 }
 
 val cptr_obj(val obj, val type_sym_in)
diff --git a/txr.1 b/txr.1
index ef9f7f5e..6ef01d69 100644
--- a/txr.1
+++ b/txr.1
@@ -62058,13 +62058,26 @@ object.
 
 The
 .meta integer
-parameter must be an integer which is in range for a pointer value.
+argument must be an integer which is in range for a pointer value.
 Note: this range is wider than the
 .code fixnum
 range; a portion of the range of
 .code bignum
 integers can denote pointers.
 
+An extended range of values is accepted. The entire addressable space may be
+expressed by non-negative values. A range of negative values also expresses a
+portion of the address space, in accordance with the platform's concept of a
+signed integer.
+
+For instance, on a system with 32 bit addresses, the values 0 to 4294967295
+express all of the addresses as a pure binary value. Furthermore, the values
+-2147483648 to -1 also express the upper part of this range, corresponding,
+respectively, to the addresses 2147483648 to 4294967295. On that platform,
+values of
+.meta integer
+outside of the range -2147483648 to 4294967295 are invalid.
+
 The
 .meta type-symbol
 argument should be a symbol. If omitted, it defaults to