181 lines
5.2 KiB
Plaintext
181 lines
5.2 KiB
Plaintext
# log2.m4
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# serial 15
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dnl Copyright (C) 2010-2024 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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dnl This file is offered as-is, without any warranty.
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AC_DEFUN([gl_FUNC_LOG2],
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[
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m4_divert_text([DEFAULTS], [gl_log2_required=plain])
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AC_REQUIRE([gl_MATH_H_DEFAULTS])
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dnl Persuade glibc <math.h> to declare log2().
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AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
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dnl Determine LOG2_LIBM.
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gl_COMMON_DOUBLE_MATHFUNC([log2])
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dnl Test whether log2() exists.
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saved_LIBS="$LIBS"
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LIBS="$LIBS $LOG2_LIBM"
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gl_CHECK_FUNCS_ANDROID([log2], [[#include <math.h>]])
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LIBS="$saved_LIBS"
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if test $ac_cv_func_log2 = yes; then
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HAVE_LOG2=1
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dnl Also check whether it's declared.
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dnl IRIX 6.5 has log2() in libm but doesn't declare it in <math.h>.
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AC_CHECK_DECL([log2], , [HAVE_DECL_LOG2=0], [[#include <math.h>]])
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saved_LIBS="$LIBS"
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LIBS="$LIBS $LOG2_LIBM"
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gl_FUNC_LOG2_WORKS
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LIBS="$saved_LIBS"
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case "$gl_cv_func_log2_works" in
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*yes) ;;
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*) REPLACE_LOG2=1 ;;
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esac
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m4_ifdef([gl_FUNC_LOG2_IEEE], [
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if test $gl_log2_required = ieee && test $REPLACE_LOG2 = 0; then
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AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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AC_CACHE_CHECK([whether log2 works according to ISO C 99 with IEC 60559],
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[gl_cv_func_log2_ieee],
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[
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saved_LIBS="$LIBS"
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LIBS="$LIBS $LOG2_LIBM"
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AC_RUN_IFELSE(
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[AC_LANG_SOURCE([[
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#ifndef __NO_MATH_INLINES
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# define __NO_MATH_INLINES 1 /* for glibc */
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#endif
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#include <math.h>
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#ifndef log2 /* for Cygwin 1.7.x */
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extern
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#ifdef __cplusplus
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"C"
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#endif
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double log2 (double);
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#endif
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/* Compare two numbers with ==.
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This is a separate function because IRIX 6.5 "cc -O" miscompiles an
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'x == x' test. */
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static int
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numeric_equal (double x, double y)
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{
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return x == y;
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}
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static double dummy (double x) { return 0; }
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int main (int argc, char *argv[])
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{
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double (* volatile my_log2) (double) = argc ? log2 : dummy;
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/* Test log2(negative).
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This test fails on NetBSD 5.1 and Solaris 10/x86_64. */
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double y = my_log2 (-1.0);
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if (numeric_equal (y, y))
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return 1;
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return 0;
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}
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]])],
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[gl_cv_func_log2_ieee=yes],
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[gl_cv_func_log2_ieee=no],
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[case "$host_os" in
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# Guess yes on glibc systems.
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*-gnu* | gnu*) gl_cv_func_log2_ieee="guessing yes" ;;
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# Guess yes on musl systems.
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*-musl* | midipix*) gl_cv_func_log2_ieee="guessing yes" ;;
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# Guess yes on native Windows.
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mingw* | windows*) gl_cv_func_log2_ieee="guessing yes" ;;
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# If we don't know, obey --enable-cross-guesses.
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*) gl_cv_func_log2_ieee="$gl_cross_guess_normal" ;;
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esac
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])
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LIBS="$saved_LIBS"
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])
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case "$gl_cv_func_log2_ieee" in
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*yes) ;;
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*) REPLACE_LOG2=1 ;;
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esac
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fi
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])
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else
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HAVE_LOG2=0
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HAVE_DECL_LOG2=0
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case "$gl_cv_onwards_func_log2" in
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future*) REPLACE_LOG2=1 ;;
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esac
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fi
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if test $HAVE_LOG2 = 0 || test $REPLACE_LOG2 = 1; then
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dnl Find libraries needed to link lib/log2.c.
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AC_REQUIRE([gl_FUNC_ISNAND])
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AC_REQUIRE([gl_FUNC_FREXP])
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AC_REQUIRE([gl_FUNC_LOG])
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LOG2_LIBM=
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dnl Append $ISNAND_LIBM to LOG2_LIBM, avoiding gratuitous duplicates.
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case " $LOG2_LIBM " in
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*" $ISNAND_LIBM "*) ;;
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*) LOG2_LIBM="$LOG2_LIBM $ISNAND_LIBM" ;;
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esac
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dnl Append $FREXP_LIBM to LOG2_LIBM, avoiding gratuitous duplicates.
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case " $LOG2_LIBM " in
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*" $FREXP_LIBM "*) ;;
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*) LOG2_LIBM="$LOG2_LIBM $FREXP_LIBM" ;;
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esac
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dnl Append $LOG_LIBM to LOG2_LIBM, avoiding gratuitous duplicates.
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case " $LOG2_LIBM " in
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*" $LOG_LIBM "*) ;;
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*) LOG2_LIBM="$LOG2_LIBM $LOG_LIBM" ;;
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esac
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fi
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])
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dnl Test whether log2() works.
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dnl On OSF/1 5.1, log2(-0.0) is NaN.
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dnl On Cygwin 1.7.9, log2(2^29) is not exactly 29.
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AC_DEFUN([gl_FUNC_LOG2_WORKS],
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[
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AC_REQUIRE([AC_PROG_CC])
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AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles
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AC_CACHE_CHECK([whether log2 works], [gl_cv_func_log2_works],
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[
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AC_RUN_IFELSE(
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[AC_LANG_SOURCE([[
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#include <math.h>
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#ifndef log2 /* for Cygwin 1.7.x */
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extern
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#ifdef __cplusplus
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"C"
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#endif
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double log2 (double);
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#endif
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volatile double x;
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volatile double y;
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int main ()
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{
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int result = 0;
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/* This test fails on OSF/1 5.1. */
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x = -0.0;
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y = log2 (x);
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if (!(y + y == y))
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result |= 1;
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/* This test fails on Cygwin 1.7.9. */
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x = 536870912.0;
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y = log2 (x);
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if (!(y == 29.0))
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result |= 2;
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return result;
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}
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]])],
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[gl_cv_func_log2_works=yes],
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[gl_cv_func_log2_works=no],
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[case "$host_os" in
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cygwin* | osf*) gl_cv_func_log2_works="guessing no" ;;
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# Guess yes on native Windows.
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mingw* | windows*) gl_cv_func_log2_works="guessing yes" ;;
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*) gl_cv_func_log2_works="guessing yes" ;;
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esac
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])
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])
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])
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