Update.

2001-02-17  Ulrich Drepper  <drepper@redhat.com>

	* sysdeps/generic/s_exp2l.c: Renamed to...
	* sysdeps/generic/s_exp2l.c: ...this.   New file.
	* sysdeps/i386/fpu/s_exp2.S: Renamed to...
	* sysdeps/i386/fpu/s_exp2.S: ...this.   New file.
	* sysdeps/i386/fpu/s_exp2f.S: Renamed to...
	* sysdeps/i386/fpu/s_exp2f.S: ...this.   New file.
	* sysdeps/i386/fpu/s_exp2l.S: Renamed to...
	* sysdeps/i386/fpu/s_exp2l.S: ...this.   New file.
	* sysdeps/ieee754/flt-32/s_exp2f.c: Renamed to...
	* sysdeps/ieee754/flt-32/s_exp2f.c: ...this.   New file.
	* sysdeps/ieee754/dbl-64/s_exp2.c: Renamed to...
	* sysdeps/ieee754/dbl-64/s_exp2.c: ...this.   New file.
	* sysdeps/m68k/fpu/s_exp2.c: Renamed to...
	* sysdeps/m68k/fpu/s_exp2.c: ...this.   New file.
	* sysdeps/m68k/fpu/s_exp2f.c: Renamed to...
	* sysdeps/m68k/fpu/s_exp2f.c: ...this.   New file.
	* sysdeps/m68k/fpu/s_exp2l.c: Renamed to...
	* sysdeps/m68k/fpu/s_exp2l.c: ...this.   New file.

1 files changed, 128 insertions, 0 deletions

diff --git a/sysdeps/ieee754/flt-32/e_exp2f.c b/sysdeps/ieee754/flt-32/e_exp2f.c
new file mode 100644
index 0000000000..4d529ea285
--- /dev/null
+++ b/sysdeps/ieee754/flt-32/e_exp2f.c
@@ -0,0 +1,128 @@
+/* Single-precision floating point 2^x.
+   Copyright (C) 1997, 1998, 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Geoffrey Keating <geoffk@ozemail.com.au>
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+/* The basic design here is from
+   Shmuel Gal and Boris Bachelis, "An Accurate Elementary Mathematical
+   Library for the IEEE Floating Point Standard", ACM Trans. Math. Soft.,
+   17 (1), March 1991, pp. 26-45.
+   It has been slightly modified to compute 2^x instead of e^x, and for
+   single-precision.
+   */
+#ifndef _GNU_SOURCE
+# define _GNU_SOURCE
+#endif
+#include <stdlib.h>
+#include <float.h>
+#include <ieee754.h>
+#include <math.h>
+#include <fenv.h>
+#include <inttypes.h>
+#include <math_private.h>
+
+#include "t_exp2f.h"
+
+static const volatile float TWOM100 = 7.88860905e-31;
+static const volatile float TWO127 = 1.7014118346e+38;
+
+float
+__ieee754_exp2f (float x)
+{
+  static const float himark = (float) FLT_MAX_EXP;
+  static const float lomark = (float) (FLT_MIN_EXP - FLT_MANT_DIG - 1) - 1.0;
+
+  /* Check for usual case.  */
+  if (isless (x, himark) && isgreater (x, lomark))
+    {
+      static const float THREEp14 = 49152.0;
+      int tval, unsafe;
+      float rx, x22, result;
+      union ieee754_float ex2_u, scale_u;
+      fenv_t oldenv;
+
+      feholdexcept (&oldenv);
+#ifdef FE_TONEAREST
+      /* If we don't have this, it's too bad.  */
+      fesetround (FE_TONEAREST);
+#endif
+
+      /* 1. Argument reduction.
+	 Choose integers ex, -128 <= t < 128, and some real
+	 -1/512 <= x1 <= 1/512 so that
+	 x = ex + t/512 + x1.
+
+	 First, calculate rx = ex + t/256.  */
+      rx = x + THREEp14;
+      rx -= THREEp14;
+      x -= rx;  /* Compute x=x1. */
+      /* Compute tval = (ex*256 + t)+128.
+	 Now, t = (tval mod 256)-128 and ex=tval/256  [that's mod, NOT %; and
+	 /-round-to-nearest not the usual c integer /].  */
+      tval = (int) (rx * 256.0f + 128.0f);
+
+      /* 2. Adjust for accurate table entry.
+	 Find e so that
+	 x = ex + t/256 + e + x2
+	 where -7e-4 < e < 7e-4, and
+	 (float)(2^(t/256+e))
+	 is accurate to one part in 2^-64.  */
+
+      /* 'tval & 255' is the same as 'tval%256' except that it's always
+	 positive.
+	 Compute x = x2.  */
+      x -= __exp2f_deltatable[tval & 255];
+
+      /* 3. Compute ex2 = 2^(t/255+e+ex).  */
+      ex2_u.f = __exp2f_atable[tval & 255];
+      tval >>= 8;
+      unsafe = abs(tval) >= -FLT_MIN_EXP - 1;
+      ex2_u.ieee.exponent += tval >> unsafe;
+      scale_u.f = 1.0;
+      scale_u.ieee.exponent += tval - (tval >> unsafe);
+
+      /* 4. Approximate 2^x2 - 1, using a second-degree polynomial,
+	 with maximum error in [-2^-9 - 2^-14, 2^-9 + 2^-14]
+	 less than 1.3e-10.  */
+
+      x22 = (.24022656679f * x + .69314736128f) * ex2_u.f;
+
+      /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex).  */
+      fesetenv (&oldenv);
+
+      result = x22 * x + ex2_u.f;
+
+      if (!unsafe)
+	return result;
+      else
+	return result * scale_u.f;
+    }
+  /* Exceptional cases:  */
+  else if (isless (x, himark))
+    {
+      if (__isinff (x))
+	/* e^-inf == 0, with no error.  */
+	return 0;
+      else
+	/* Underflow */
+	return TWOM100 * TWOM100;
+    }
+  else
+    /* Return x, if x is a NaN or Inf; or overflow, otherwise.  */
+    return TWO127*x;
+}