From f9811f9f2e1369cb3cc70416edced98d6887bc11 Mon Sep 17 00:00:00 2001
From: Kevin Ryde <user42@zip.com.au>
Date: Sat, 30 Aug 2003 00:04:42 +0000
Subject: [PATCH] (scm_lognot): Rewrite using ~ and mpz_com, for directness and
 to have non-integer types rejected as per other logical funcs.

---
 libguile/numbers.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/libguile/numbers.c b/libguile/numbers.c
index 7b65814bb..68d4361ce 100644
--- a/libguile/numbers.c
+++ b/libguile/numbers.c
@@ -1247,7 +1247,22 @@ SCM_DEFINE (scm_lognot, "lognot", 1, 0, 0,
 	    "@end lisp")
 #define FUNC_NAME s_scm_lognot
 {
-  return scm_difference (SCM_MAKINUM (-1L), n);
+  if (SCM_INUMP (n)) {
+    /* No overflow here, just need to toggle all the bits making up the inum.
+       Enhancement: No need to strip the tag and add it back, could just xor
+       a block of 1 bits, if that worked with the various debug versions of
+       the SCM typedef.  */
+    return SCM_MAKINUM (~ SCM_INUM (n));
+
+  } else if (SCM_BIGP (n)) {
+    SCM result = scm_i_mkbig ();
+    mpz_com (SCM_I_BIG_MPZ (result), SCM_I_BIG_MPZ (n));
+    scm_remember_upto_here_1 (n);
+    return result;
+
+  } else {
+    SCM_WRONG_TYPE_ARG (SCM_ARG1, n);
+  }
 }
 #undef FUNC_NAME