From 650425ceb40e840b2123b6c8cc65389589f41218 Mon Sep 17 00:00:00 2001 From: Ulrich Drepper Date: Wed, 24 Sep 1997 23:03:42 +0000 Subject: Update. 1997-09-25 00:23 Ulrich Drepper * elf/dl-profile.c: Correct implementation. * io/ftwtest-sh: Don't depend on TMPDIR == /tmp. * locale/setlocale.c: Rewrite a bit for more clarity. * math/Makefile (libm-calls): Add w_exp2. * math/math_private.h: Add prototypes for __ieee754_exp2{,f,l}. * sysdeps/libm-i387/s_exp2.S: Change name to __ieee754_exp2. * sysdeps/libm-i387/s_exp2f.S: Likewise. * sysdeps/libm-i387/s_exp2l.S: Likewise. * sysdeps/libm-ieee754/k_standard.c: Add error cases for exp2. * string/bits/string2.h (__strcpy_small): Optimize. (__stpcpy_small): Likewise. (strncpy): Use variable for dest argument since it's used more than once. (strncat): Likewise. (strcmp): Add optimization for this function. * sysdeps/i386/i486/string.h (strlen): Correctly use __builtin_strlen. (__strcpy_small): Optimize. (__stpcpy_small): Likewise. (__stpcpy_c): Correctly use __mempcpy_* macros. (__mempcpy_by2, __mempcpy_by4, __mempcpy_byn): Return pointer to byte following last copied. (strncat): Use variable for dest argument since it's used more than once. (strcmp): Add optimization for this function. * sysdeps/i386/dl-machine.h (ELF_MACHINE_RUNTIME_TRAMPOLINE): Use .text and .previous to select correct section. 1997-09-23 19:56 Philip Blundell * configure.in: Add `--disable-versioning' option to suppress the use of symbol versions even if binutils claims to support it. 1997-09-24 20:10 Philip Blundell * csu/Makefile (before-compile): Don't try to build abi-tags.h if not using ELF. 1997-09-21 Andreas Schwab * elf/sofini.c [HAVE_DWARF2_UNWIND_INFO]: Supply termination for the frame unwind info section. * elf/soinit.c [HAVE_DWARF2_UNWIND_INFO]: Register and unregister the frame unwind info. * config.h.in (HAVE_DWARF2_UNWIND_INFO): Add #undef. * configure.in: Check whether gcc supports DWARF2 unwind info. * libc.map: Export frame handling tables. 1997-09-10 06:56 Geoff Keating * sysdeps/unix/sysv/linux/powerpc/bits/kernel_termios.h: Use the size of the kernel's termios structure for ioctls. * sysdeps/powerpc/dl-machine.h: Prepare for library profiling. * sysdeps/powerpc/bits/mathinline.h: Add slightly slower versions of the C9X FP comparison macros. Delete 'fabs' and 'sqrt' inline routines, because gcc has them as internals. * sysdeps/powerpc/Makefile (pic-ccflags): Define this instead of CFLAGS-.os. * sysdeps/powerpc/bzero.S: New file. * sysdeps/powerpc/strcat.c: New file. * sysdeps/powerpc/strcpy.S: New file. * sysdeps/powerpc/stpcpy.S: New file. * math/Makefile: Add atest_exp2, test-reduce. * math/atest_exp2.c: New file. * math/test-reduce.c: New file. * sysdeps/libm-ieee754/Dist: New file. * sysdeps/libm-ieee754/s_exp2.c: New file. * sysdeps/libm-ieee754/s_exp2f.c: New file. * sysdeps/libm-ieee754/t_exp2.h: New file. * sysdeps/libm-ieee754/t_exp2f.h: New file. * math/libm-test.c (exp2_test): Add some more tests. * Rules: Use empty.os instead of empty.o, since it gets linked into libc.so... * configure.in: Add --disable-static to disable building .a files. * config.make.in: Substitute the new variable. * Makeconfig: Don't build .o files if not building .a files. * elf/dl-runtime.c (fixup): Factor out call to elf_machine_relplt. (profile_fixup): Likewise. 1997-09-23 Andreas Schwab * posix/globtest.c (main): Change to directory passed as first argument. * posix/globtest.sh: Don't cd before running the program, instead pass testdir as argument, so that $common_objpfx remains valid. 1997-09-23 18:01 Thorsten Kukuk * nis/nis_call.c (__do_niscall2): Fix multiple Server support. * nis/nis_findserver.c: Save latest working sockaddr_in. 1997-09-17 22:07 Zack Weinberg * configure.in: Automatically determine whether as and ld are the GNU versions. (options): --with-gnu-{as,ld,binutils} replaced by single option --with-binutils=PATH specifying a -B option to gcc. * aclocal.m4: Two new macros defined, LIBC_PROG_FOO_GNU and LIBC_PROG_BINUTILS. * configure.in: Allow the user to force configuration for unsupported platforms with an undocumented option. 1997-09-22 16:55 Thorsten Kukuk * sunrpc/get_myaddr.c (get_myaddress): Avoid loopback interfaces, return loopback address only if there is no other interface. * nis/Makefile: Add nis_callback libnsl-routines. * nis/nis_add.c: Use new __do_niscall* interface. * nis/nis_cache.c: Likewise. * nis/nis_checkpoint.c: Likewise. * nis/nis_lookup.c: Likewise. * nis/nis_mkdir.c: Likewise. * nis/nis_modify.c: Likewise. * nis/nis_ping.c: Likewise. * nis/nis_remove.c: Likewise. * nis/nis_rmdir.c: Likewise. * nis/nis_server.c: Likewise. * nis/nis_util.c: Likewise. * nis/rpcsvc/nis.h: Make C++ safe. * nis/nss_nisplus/nisplus-publickey.c (getsecretkey): Fix use of variables. * nis/nis_findserv.c: Make thread safe. * nis/nis_call.c: Add support for callback, Fix use of variables. * nis/nis_table.c: Add support for callback, FOLLOW_PATH and ALL_RESULTS. * nis/nis_callback.c: New, callback functions. * nis/nis_intern.h: Add callback declarations. 1997-09-20 Andreas Schwab * string/bits/string2.h: Fix logic in preprocessor directive. (__strsep_1c, __strsep_g): Don't declare __retval as pointing to const, to save a cast and a possible warning. 1997-09-22 04:12 Ulrich Drepper * sysdeps/i386/i486/atomicity.h (exchange_and_add): Really address memory in xadd not %1. 1997-09-21 13:56 Ulrich Drepper * manual/maint.texi (Supported Configurations): Add SPARC64 to list of supported platforms. --- sysdeps/libm-ieee754/s_exp2f.c | 126 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 126 insertions(+) create mode 100644 sysdeps/libm-ieee754/s_exp2f.c (limited to 'sysdeps/libm-ieee754/s_exp2f.c') diff --git a/sysdeps/libm-ieee754/s_exp2f.c b/sysdeps/libm-ieee754/s_exp2f.c new file mode 100644 index 0000000000..e50ac77792 --- /dev/null +++ b/sysdeps/libm-ieee754/s_exp2f.c @@ -0,0 +1,126 @@ +/* Single-precision floating point 2^x. + Copyright (C) 1997 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Geoffrey Keating + + 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. + */ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include + +#include "t_exp2f.h" + +static const volatile float TWOM100 = 7.88860905e-31; +static const volatile float huge = 1e+30; + +float +__ieee754_exp2f (float x) +{ + static const uint32_t a_inf = 0x7f800000; + /* Check for usual case. */ + if (isless (x, (float) FLT_MAX_EXP) + && isgreater (x, (float) (FLT_MIN_EXP - 1))) + { + static const float TWO16 = 65536.0; + int tval; + float rx, x22; + union ieee754_float ex2_u; + fenv_t oldenv; + + feholdexcept (&oldenv); + fesetround (FE_TONEAREST); + + /* 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. */ + if (x >= 0) + { + rx = x + TWO16; + rx -= TWO16; + } + else + { + rx = x - TWO16; + rx += TWO16; + } + 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 -= exp2_deltatable[tval & 255]; + + /* 3. Compute ex2 = 2^(t/255+e+ex). */ + ex2_u.f = exp2_accuratetable[tval & 255]; + ex2_u.ieee.exponent += tval >> 8; + + /* 4. Approximate 2^x2 - 1, using a second-degree polynomial, + 2^x2 ~= sum(k=0..2 | (x2 * ln(2))^k / k! ) + + so + 2^x2 - 1 ~= sum(k=1..4 | (x2 * ln(2))^k / k! ) + with error less than 2^(1/512+7e-4) * (x2 * ln(2))^3 / 3! < 1.2e-18. */ + + x22 = (.240226507f * x + .6931471806f) * ex2_u.f; + + /* 5. Return (2^x2-1) * 2^(t/512+e+ex) + 2^(t/512+e+ex). */ + fesetenv (&oldenv); + + /* Need to check: does this set FE_INEXACT correctly? */ + return x22 * x + ex2_u.f; + } + /* 2^inf == inf, with no error. */ + else if (x == *(const float *)&a_inf) + { + return x; + } + /* Check for overflow. */ + else if (isgreaterequal (x, (float) FLT_MAX_EXP)) + return huge * huge; + /* And underflow (including -inf). */ + else if (isless (x, (float) (FLT_MIN_EXP - FLT_MANT_DIF))) + return TWOM100 * TWOM100; + /* Maybe the result needs to be a denormalised number... */ + else if (!isnan (x)) + return __ieee754_exp2f (x + 100.0) * TWOM100; + else /* isnan(x) */ + return x + x; +} -- cgit v1.2.3-65-gdbad