[pypy-svn] pypy default: Try another approach to isinf.

[alex_gaynor]

Author: Alex Gaynor <alex.gaynor at gmail.com>
Branch: 
Changeset: r43295:55888b692fe7
Date: 2011-04-11 09:10 -0400
http://bitbucket.org/pypy/pypy/changeset/55888b692fe7/

Log:	Try another approach to isinf.

diff --git a/pypy/rpython/lltypesystem/module/test/test_ll_math.py b/pypy/rpython/lltypesystem/module/test/test_ll_math.py
--- a/pypy/rpython/lltypesystem/module/test/test_ll_math.py
+++ b/pypy/rpython/lltypesystem/module/test/test_ll_math.py
@@ -11,6 +11,7 @@
         nan = inf / inf
         assert not ll_math.ll_math_isinf(0)
         assert ll_math.ll_math_isinf(inf)
+        assert ll_math.ll_math_isinf(-inf)
         assert not ll_math.ll_math_isinf(nan)
 
     def test_isnan(self):

diff --git a/pypy/rpython/lltypesystem/module/ll_math.py b/pypy/rpython/lltypesystem/module/ll_math.py
--- a/pypy/rpython/lltypesystem/module/ll_math.py
+++ b/pypy/rpython/lltypesystem/module/ll_math.py
@@ -94,7 +94,7 @@
     return y != y
 
 def ll_math_isinf(y):
-    return not isnan(y) and isnan(y - y)
+    return y != 0 and y * .5 == y
 
 
 ll_math_copysign = math_copysign