Add useful sys:bits function.

sys:bits converts a Lisp value to an integer whose value is
the object's bit pattern interpreted as a pure binary number.
(Only the "unboxed" part of the object that is stored in
variables or passed into functions, not any "boxded" heap part
which is referenced.)

this holds:

  (eq a b)  <-->  (= (sys:bits a) (sys:bits b))

Two values a and b are the same object iff their sys:bits
values are the same integer.

* arith.c (bits): New static function.
(arith_init): Register bits as sys:bits.

1 files changed, 8 insertions, 0 deletions

diff --git a/arith.c b/arith.c
index d5932acb..e1d105e8 100644
--- a/arith.c
+++ b/arith.c
@@ -2468,6 +2468,12 @@ val width(val obj)
   uw_throwf(error_s, lit("integer-length: ~s isn't an integer"), obj, nao);
 }
 
+static val bits(val obj)
+{
+  return normalize(bignum_from_uintptr(coerce(uint_ptr_t, obj)));
+}
+
+
 void arith_init(void)
 {
   mp_init(&NUM_MAX_MP);
@@ -2500,6 +2506,8 @@ void arith_init(void)
 #endif
   reg_varl(intern(lit("*e*"), user_package), flo(M_E));
   reg_varl(intern(lit("%e%"), user_package), flo(M_E));
+
+  reg_fun(intern(lit("bits"), system_package), func_n1(bits));
 }
 
 void arith_free_all(void)