Slow exp for ppc64/power4 with FPU.
authordrepper <drepper>
Sun, 3 Jun 2007 21:15:32 +0000 (21:15 +0000)
committerdrepper <drepper>
Sun, 3 Jun 2007 21:15:32 +0000 (21:15 +0000)
sysdeps/powerpc/powerpc64/power4/fpu/slowexp.c [new file with mode: 0644]

diff --git a/sysdeps/powerpc/powerpc64/power4/fpu/slowexp.c b/sysdeps/powerpc/powerpc64/power4/fpu/slowexp.c
new file mode 100644 (file)
index 0000000..b22b0df
--- /dev/null
@@ -0,0 +1,66 @@
+/*
+ * IBM Accurate Mathematical Library
+ * written by International Business Machines Corp.
+ * Copyright (C) 2001, 2007 Free Software Foundation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+/**************************************************************************/
+/*  MODULE_NAME:slowexp.c                                                 */
+/*                                                                        */
+/*  FUNCTION:slowexp                                                      */
+/*                                                                        */
+/*  FILES NEEDED:mpa.h                                                    */
+/*               mpa.c mpexp.c                                            */
+/*                                                                        */
+/*Converting from double precision to Multi-precision and calculating     */
+/* e^x                                                                    */
+/**************************************************************************/
+#include "math_private.h"
+
+#ifdef NO_LONG_DOUBLE
+#include "mpa.h"
+void __mpexp(mp_no *x, mp_no *y, int p);
+#endif
+
+/*Converting from double precision to Multi-precision and calculating  e^x */
+double __slowexp(double x) {
+#ifdef NO_LONG_DOUBLE
+  double w,z,res,eps=3.0e-26;
+  int p;
+  mp_no mpx, mpy, mpz,mpw,mpeps,mpcor;
+
+  p=6;
+  __dbl_mp(x,&mpx,p); /* Convert a double precision number  x               */
+                    /* into a multiple precision number mpx with prec. p. */
+  __mpexp(&mpx, &mpy, p); /* Multi-Precision exponential function */
+  __dbl_mp(eps,&mpeps,p);
+  __mul(&mpeps,&mpy,&mpcor,p);
+  __add(&mpy,&mpcor,&mpw,p);
+  __sub(&mpy,&mpcor,&mpz,p);
+  __mp_dbl(&mpw, &w, p);
+  __mp_dbl(&mpz, &z, p);
+  if (w == z) return w;
+  else  {                   /* if calculating is not exactly   */
+    p = 32;
+    __dbl_mp(x,&mpx,p);
+    __mpexp(&mpx, &mpy, p);
+    __mp_dbl(&mpy, &res, p);
+    return res;
+  }
+#else
+  return (double) __ieee754_expl((long double)x);
+#endif
+}