Implement scm_logbit_p with new integer library

* libguile/integers.c (scm_integer_logbit_ui, scm_integer_logbit_uz):
* libguile/integers.h: Declare the new internal functions.
* libguile/numbers.c (scm_logbit_p): Use new internal functions.

libguile/integers.c

@@ -2008,3 +2008,23 @@ scm_integer_logtest_zz (SCM x, SCM y)
 {
   return scm_is_eq (scm_integer_logand_zz (x, y), SCM_INUM0);
 }
+
+int
+scm_integer_logbit_ui (unsigned long index, scm_t_inum n)
+{
+  if (index < SCM_LONG_BIT)
+    /* Assume two's complement representation.  */
+    return (n >> index) & 1;
+  else
+    return n < 0;
+}
+
+int
+scm_integer_logbit_uz (unsigned long index, SCM n)
+{
+  mpz_t zn;
+  alias_bignum_to_mpz (scm_bignum (n), zn);
+  int val = mpz_tstbit (zn, index);
+  scm_remember_upto_here_1 (n);
+  return val;
+}

libguile/integers.h

@@ -148,6 +148,9 @@ SCM_INTERNAL int scm_integer_logtest_ii (scm_t_inum x, scm_t_inum y);
 SCM_INTERNAL int scm_integer_logtest_zi (SCM x, scm_t_inum y);
 SCM_INTERNAL int scm_integer_logtest_zz (SCM x, SCM y);
 
+SCM_INTERNAL int scm_integer_logbit_ui (unsigned long bit, scm_t_inum n);
+SCM_INTERNAL int scm_integer_logbit_uz (unsigned long bit, SCM n);
+
 
 
 #endif  /* SCM_INTEGERS_H */

libguile/numbers.c

@@ -3155,23 +3155,9 @@ SCM_DEFINE (scm_logbit_p, "logbit?", 2, 0, 0,
   iindex = scm_to_ulong (index);
 
   if (SCM_I_INUMP (j))
-    {
+    return scm_from_bool (scm_integer_logbit_ui (iindex, SCM_I_INUM (j)));
-      if (iindex < SCM_LONG_BIT - 1)
-        /* Arrange for the number to be converted to unsigned before
-           checking the bit, to ensure that we're testing the bit in a
-           two's complement representation (regardless of the native
-           representation.  */
-        return scm_from_bool ((1UL << iindex) & SCM_I_INUM (j));
-      else
-        /* Portably check the sign.  */
-        return scm_from_bool (SCM_I_INUM (j) < 0);
-    }
   else if (SCM_BIGP (j))
-    {
+    return scm_from_bool (scm_integer_logbit_uz (iindex, j));
-      int val = mpz_tstbit (SCM_I_BIG_MPZ (j), iindex);
-      scm_remember_upto_here_1 (j);
-      return scm_from_bool (val);
-    }
   else
     SCM_WRONG_TYPE_ARG (SCM_ARG2, j);
 }