Move bignump, fixnump from C to Lisp

* doc/lispref/objects.texi (Integer Type): Mention
most-negative-fixnum and most-positive-fixnum as alternatives
to fixnump and bignump.
* lisp/subr.el (fixnump, bignump): Now written in Lisp.
* src/data.c (Ffixnump, Fbignump): No longer written in C,
as these new functions are not crucial for performance.

doc/lispref/objects.texi

@@ -190,9 +190,10 @@ but many machines provide a wider range.
 fixnum will return a bignum instead.
 
   Fixnums can be compared with @code{eq}, but bignums require
-@code{eql} or @code{=}.  The @code{fixnump} predicate can be used to
-detect such small integers, and @code{bignump} can be used to detect
-large integers.
+@code{eql} or @code{=}.  To test whether an integer is a fixnum or a
+bignum, you can compare it to @code{most-negative-fixnum} and
+@code{most-positive-fixnum}, or you can use the convenience predicates
+@code{fixnump} and @code{bignump} on any object.
 
   The read syntax for integers is a sequence of (base ten) digits with an
 optional sign at the beginning and an optional period at the end.  The

lisp/subr.el

@@ -366,6 +366,15 @@ was called."
   (declare (compiler-macro (lambda (_) `(= 0 ,number))))
   (= 0 number))
 
+(defun fixnump (object)
+  "Return t if OBJECT is a fixnum."
+  (and (integerp object)
+       (<= most-negative-fixnum object most-positive-fixnum)))
+
+(defun bignump (object)
+  "Return t if OBJECT is a bignum."
+  (and (integerp object) (not (fixnump object))))
+
 (defun lsh (value count)
   "Return VALUE with its bits shifted left by COUNT.
 If COUNT is negative, shifting is actually to the right.

src/data.c

@@ -511,16 +511,6 @@ DEFUN ("integerp", Fintegerp, Sintegerp, 1, 1, 0,
   return Qnil;
 }
 
-DEFUN ("fixnump", Ffixnump, Sfixnump, 1, 1, 0,
-       doc: /* Return t if OBJECT is an fixnum.  */
-       attributes: const)
-  (Lisp_Object object)
-{
-  if (FIXNUMP (object))
-    return Qt;
-  return Qnil;
-}
-
 DEFUN ("integer-or-marker-p", Finteger_or_marker_p, Sinteger_or_marker_p, 1, 1, 0,
        doc: /* Return t if OBJECT is an integer or a marker (editor pointer).  */)
   (register Lisp_Object object)
@@ -598,15 +588,6 @@ DEFUN ("condition-variable-p", Fcondition_variable_p, Scondition_variable_p,
     return Qt;
   return Qnil;
 }
-
-DEFUN ("bignump", Fbignump, Sbignump, 1, 1, 0,
-       doc: /* Return t if OBJECT is a bignum.  */)
-  (Lisp_Object object)
-{
-  if (BIGNUMP (object))
-    return Qt;
-  return Qnil;
-}
 
 /* Extract and set components of lists.  */
 
@@ -4153,7 +4134,6 @@ syms_of_data (void)
   defsubr (&Sconsp);
   defsubr (&Satom);
   defsubr (&Sintegerp);
-  defsubr (&Sfixnump);
   defsubr (&Sinteger_or_marker_p);
   defsubr (&Snumberp);
   defsubr (&Snumber_or_marker_p);
@@ -4179,7 +4159,6 @@ syms_of_data (void)
   defsubr (&Sthreadp);
   defsubr (&Smutexp);
   defsubr (&Scondition_variable_p);
-  defsubr (&Sbignump);
   defsubr (&Scar);
   defsubr (&Scdr);
   defsubr (&Scar_safe);