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authorUlrich Drepper <drepper@redhat.com>2001-02-17 16:54:13 +0000
committerUlrich Drepper <drepper@redhat.com>2001-02-17 16:54:13 +0000
commit63640cb777a26b684f44a1786c1384d3a96a8825 (patch)
tree9ed7ce04cdc72dd2a25d903adfc5333514c68bb7 /sysdeps/ieee754
parentd313277ad2a2a7a292705a5d9c9a47709e759f42 (diff)
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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.
Diffstat (limited to 'sysdeps/ieee754')
-rw-r--r--sysdeps/ieee754/dbl-64/e_exp2.c130
-rw-r--r--sysdeps/ieee754/flt-32/e_exp2f.c128
2 files changed, 258 insertions, 0 deletions
diff --git a/sysdeps/ieee754/dbl-64/e_exp2.c b/sysdeps/ieee754/dbl-64/e_exp2.c
new file mode 100644
index 0000000000..d02af15ecc
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/e_exp2.c
@@ -0,0 +1,130 @@
+/* Double-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.
+ */
+#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_exp2.h"
+
+static const volatile double TWO1023 = 8.988465674311579539e+307;
+static const volatile double TWOM1000 = 9.3326361850321887899e-302;
+
+double
+__ieee754_exp2 (double x)
+{
+ static const double himark = (double) DBL_MAX_EXP;
+ static const double lomark = (double) (DBL_MIN_EXP - DBL_MANT_DIG - 1) - 1.0;
+
+ /* Check for usual case. */
+ if (isless (x, himark) && isgreater (x, lomark))
+ {
+ static const double THREEp42 = 13194139533312.0;
+ int tval, unsafe;
+ double rx, x22, result;
+ union ieee754_double 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, -256 <= t < 256, and some real
+ -1/1024 <= x1 <= 1024 so that
+ x = ex + t/512 + x1.
+
+ First, calculate rx = ex + t/512. */
+ rx = x + THREEp42;
+ rx -= THREEp42;
+ x -= rx; /* Compute x=x1. */
+ /* Compute tval = (ex*512 + t)+256.
+ Now, t = (tval mod 512)-256 and ex=tval/512 [that's mod, NOT %; and
+ /-round-to-nearest not the usual c integer /]. */
+ tval = (int) (rx * 512.0 + 256.0);
+
+ /* 2. Adjust for accurate table entry.
+ Find e so that
+ x = ex + t/512 + e + x2
+ where -1e6 < e < 1e6, and
+ (double)(2^(t/512+e))
+ is accurate to one part in 2^-64. */
+
+ /* 'tval & 511' is the same as 'tval%512' except that it's always
+ positive.
+ Compute x = x2. */
+ x -= exp2_deltatable[tval & 511];
+
+ /* 3. Compute ex2 = 2^(t/512+e+ex). */
+ ex2_u.d = exp2_accuratetable[tval & 511];
+ tval >>= 9;
+ unsafe = abs(tval) >= -DBL_MIN_EXP - 1;
+ ex2_u.ieee.exponent += tval >> unsafe;
+ scale_u.d = 1.0;
+ scale_u.ieee.exponent += tval - (tval >> unsafe);
+
+ /* 4. Approximate 2^x2 - 1, using a fourth-degree polynomial,
+ with maximum error in [-2^-10-2^-30,2^-10+2^-30]
+ less than 10^-19. */
+
+ x22 = (((.0096181293647031180
+ * x + .055504110254308625)
+ * x + .240226506959100583)
+ * x + .69314718055994495) * ex2_u.d;
+
+ /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex). */
+ fesetenv (&oldenv);
+
+ result = x22 * x + ex2_u.d;
+
+ if (!unsafe)
+ return result;
+ else
+ return result * scale_u.d;
+ }
+ /* Exceptional cases: */
+ else if (isless (x, himark))
+ {
+ if (__isinf (x))
+ /* e^-inf == 0, with no error. */
+ return 0;
+ else
+ /* Underflow */
+ return TWOM1000 * TWOM1000;
+ }
+ else
+ /* Return x, if x is a NaN or Inf; or overflow, otherwise. */
+ return TWO1023*x;
+}
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;
+}