math: add exception handling functionality

According to standards SVID and SYSV.
Modified lgamma calling in case when 'signgam' variable should not be used.

Signed-off-by: Waldemar Brodkorb <wbx@uclibc-ng.org>

1 files changed, 47 insertions, 0 deletions

diff --git a/libm/w_tgamma.c b/libm/w_tgamma.c
new file mode 100644
index 000000000..0bacff16b
--- /dev/null
+++ b/libm/w_tgamma.c
@@ -0,0 +1,47 @@
+/* @(#)w_gamma.c 5.1 93/09/24 */
+/*
+ * ====================================================
+ * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+ *
+ * Developed at SunPro, a Sun Microsystems, Inc. business.
+ * Permission to use, copy, modify, and distribute this
+ * software is freely granted, provided that this notice
+ * is preserved.
+ * ====================================================
+ */
+
+/* double gamma(double x)
+ * Return  the logarithm of the Gamma function of x or the Gamma function of x,
+ * depending on the library mode.
+ */
+
+#include <math.h>
+#include "math_private.h"
+#if __UCLIBC_HAS_FENV__
+#include <errno.h>
+#endif
+
+double
+tgamma(double x)
+{
+#if __UCLIBC_HAS_FENV__
+	double y = __ieee754_tgamma(x);
+
+	if(__builtin_expect (!isfinite (y) || y == 0, 0)
+	   && (isfinite (x) || (isinf (x) && x < 0.0))
+	   && _LIB_VERSION != _IEEE_) {
+	  if (x == 0.0)
+	    return __kernel_standard(x,x,50); /* tgamma pole */
+	  else if(floor(x)==x&&x<0.0)
+	    return __kernel_standard(x,x,41); /* tgamma domain */
+	  else if (y == 0)
+	    __set_errno (ERANGE); /* tgamma underflow */
+	  else
+	    return __kernel_standard(x,x,40); /* tgamma overflow */
+	}
+	return y;
+#else
+	return __ieee754_tgamma(x);
+#endif
+}
+libm_hidden_def(tgamma);