| 1 | # round.m4 serial 16 |
| 2 | dnl Copyright (C) 2007, 2009-2014 Free Software Foundation, Inc. |
| 3 | dnl This file is free software; the Free Software Foundation |
| 4 | dnl gives unlimited permission to copy and/or distribute it, |
| 5 | dnl with or without modifications, as long as this notice is preserved. |
| 6 | |
| 7 | AC_DEFUN([gl_FUNC_ROUND], |
| 8 | [ |
| 9 | m4_divert_text([DEFAULTS], [gl_round_required=plain]) |
| 10 | AC_REQUIRE([gl_MATH_H_DEFAULTS]) |
| 11 | |
| 12 | dnl Persuade glibc <math.h> to declare round(). |
| 13 | AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) |
| 14 | |
| 15 | gl_CHECK_MATH_LIB([ROUND_LIBM], [x = round (x);], |
| 16 | [extern |
| 17 | #ifdef __cplusplus |
| 18 | "C" |
| 19 | #endif |
| 20 | double round (double); |
| 21 | ]) |
| 22 | if test "$ROUND_LIBM" != missing; then |
| 23 | HAVE_ROUND=1 |
| 24 | dnl Also check whether it's declared. |
| 25 | dnl IRIX 6.5 has round() in libm but doesn't declare it in <math.h>. |
| 26 | AC_CHECK_DECLS([round], , [HAVE_DECL_ROUND=0], [[#include <math.h>]]) |
| 27 | |
| 28 | dnl Test whether round() produces correct results. On NetBSD 3.0, for |
| 29 | dnl x = 1/2 - 2^-54, the system's round() returns a wrong result. |
| 30 | AC_REQUIRE([AC_PROG_CC]) |
| 31 | AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
| 32 | AC_CACHE_CHECK([whether round works], [gl_cv_func_round_works], |
| 33 | [ |
| 34 | save_LIBS="$LIBS" |
| 35 | LIBS="$LIBS $ROUND_LIBM" |
| 36 | AC_RUN_IFELSE([AC_LANG_SOURCE([[ |
| 37 | #include <float.h> |
| 38 | #include <math.h> |
| 39 | extern |
| 40 | #ifdef __cplusplus |
| 41 | "C" |
| 42 | #endif |
| 43 | double round (double); |
| 44 | #ifdef _MSC_VER |
| 45 | # pragma fenv_access (off) |
| 46 | #endif |
| 47 | int main() |
| 48 | { |
| 49 | /* 2^DBL_MANT_DIG. */ |
| 50 | static const double TWO_MANT_DIG = |
| 51 | /* Assume DBL_MANT_DIG <= 5 * 31. |
| 52 | Use the identity |
| 53 | n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ |
| 54 | (double) (1U << (DBL_MANT_DIG / 5)) |
| 55 | * (double) (1U << ((DBL_MANT_DIG + 1) / 5)) |
| 56 | * (double) (1U << ((DBL_MANT_DIG + 2) / 5)) |
| 57 | * (double) (1U << ((DBL_MANT_DIG + 3) / 5)) |
| 58 | * (double) (1U << ((DBL_MANT_DIG + 4) / 5)); |
| 59 | volatile double x = 0.5 - 0.5 / TWO_MANT_DIG; |
| 60 | exit (x < 0.5 && round (x) != 0.0); |
| 61 | }]])], [gl_cv_func_round_works=yes], [gl_cv_func_round_works=no], |
| 62 | [case "$host_os" in |
| 63 | netbsd* | aix*) gl_cv_func_round_works="guessing no";; |
| 64 | *) gl_cv_func_round_works="guessing yes";; |
| 65 | esac |
| 66 | ]) |
| 67 | LIBS="$save_LIBS" |
| 68 | ]) |
| 69 | case "$gl_cv_func_round_works" in |
| 70 | *no) REPLACE_ROUND=1 ;; |
| 71 | esac |
| 72 | |
| 73 | m4_ifdef([gl_FUNC_ROUND_IEEE], [ |
| 74 | if test $gl_round_required = ieee && test $REPLACE_ROUND = 0; then |
| 75 | AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
| 76 | AC_CACHE_CHECK([whether round works according to ISO C 99 with IEC 60559], |
| 77 | [gl_cv_func_round_ieee], |
| 78 | [ |
| 79 | save_LIBS="$LIBS" |
| 80 | LIBS="$LIBS $ROUND_LIBM" |
| 81 | AC_RUN_IFELSE( |
| 82 | [AC_LANG_SOURCE([[ |
| 83 | #ifndef __NO_MATH_INLINES |
| 84 | # define __NO_MATH_INLINES 1 /* for glibc */ |
| 85 | #endif |
| 86 | #include <math.h> |
| 87 | extern |
| 88 | #ifdef __cplusplus |
| 89 | "C" |
| 90 | #endif |
| 91 | double round (double); |
| 92 | ]gl_DOUBLE_MINUS_ZERO_CODE[ |
| 93 | ]gl_DOUBLE_SIGNBIT_CODE[ |
| 94 | static double dummy (double f) { return 0; } |
| 95 | int main (int argc, char *argv[]) |
| 96 | { |
| 97 | double (*my_round) (double) = argc ? round : dummy; |
| 98 | /* Test whether round (-0.0) is -0.0. */ |
| 99 | if (signbitd (minus_zerod) && !signbitd (my_round (minus_zerod))) |
| 100 | return 1; |
| 101 | return 0; |
| 102 | } |
| 103 | ]])], |
| 104 | [gl_cv_func_round_ieee=yes], |
| 105 | [gl_cv_func_round_ieee=no], |
| 106 | [case "$host_os" in |
| 107 | # Guess yes on glibc systems. |
| 108 | *-gnu*) gl_cv_func_round_ieee="guessing yes" ;; |
| 109 | # If we don't know, assume the worst. |
| 110 | *) gl_cv_func_round_ieee="guessing no" ;; |
| 111 | esac |
| 112 | ]) |
| 113 | LIBS="$save_LIBS" |
| 114 | ]) |
| 115 | case "$gl_cv_func_round_ieee" in |
| 116 | *yes) ;; |
| 117 | *) REPLACE_ROUND=1 ;; |
| 118 | esac |
| 119 | fi |
| 120 | ]) |
| 121 | else |
| 122 | HAVE_ROUND=0 |
| 123 | HAVE_DECL_ROUND=0 |
| 124 | fi |
| 125 | if test $HAVE_ROUND = 0 || test $REPLACE_ROUND = 1; then |
| 126 | dnl Find libraries needed to link lib/round.c. |
| 127 | gl_FUNC_FLOOR_LIBS |
| 128 | gl_FUNC_CEIL_LIBS |
| 129 | ROUND_LIBM= |
| 130 | dnl Append $FLOOR_LIBM to ROUND_LIBM, avoiding gratuitous duplicates. |
| 131 | case " $ROUND_LIBM " in |
| 132 | *" $FLOOR_LIBM "*) ;; |
| 133 | *) ROUND_LIBM="$ROUND_LIBM $FLOOR_LIBM" ;; |
| 134 | esac |
| 135 | dnl Append $CEIL_LIBM to ROUND_LIBM, avoiding gratuitous duplicates. |
| 136 | case " $ROUND_LIBM " in |
| 137 | *" $CEIL_LIBM "*) ;; |
| 138 | *) ROUND_LIBM="$ROUND_LIBM $CEIL_LIBM" ;; |
| 139 | esac |
| 140 | fi |
| 141 | AC_SUBST([ROUND_LIBM]) |
| 142 | ]) |