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1 # logbf.m4 serial 1 |
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2 dnl Copyright (C) 2012-2015 Free Software Foundation, Inc. |
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3 dnl This file is free software; the Free Software Foundation |
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4 dnl gives unlimited permission to copy and/or distribute it, |
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5 dnl with or without modifications, as long as this notice is preserved. |
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6 |
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7 AC_DEFUN([gl_FUNC_LOGBF], |
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8 [ |
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9 AC_REQUIRE([gl_MATH_H_DEFAULTS]) |
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10 |
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11 dnl Persuade glibc <math.h> to declare logbf(). |
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12 AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) |
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13 |
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14 dnl Determine LOGBF_LIBM. |
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15 gl_MATHFUNC([logbf], [float], [(float)]) |
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16 if test $gl_cv_func_logbf_no_libm = yes \ |
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17 || test $gl_cv_func_logbf_in_libm = yes; then |
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18 save_LIBS="$LIBS" |
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19 LIBS="$LIBS $LOGBF_LIBM" |
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20 gl_FUNC_LOGBF_WORKS |
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21 LIBS="$save_LIBS" |
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22 case "$gl_cv_func_logbf_works" in |
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23 *yes) ;; |
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24 *) REPLACE_LOGBF=1 ;; |
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25 esac |
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26 else |
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27 HAVE_LOGBF=0 |
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28 fi |
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29 if test $HAVE_LOGBF = 0 || test $REPLACE_LOGBF = 1; then |
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30 dnl Find libraries needed to link lib/logbf.c. |
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31 AC_REQUIRE([gl_FUNC_FREXPF]) |
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32 AC_REQUIRE([gl_FUNC_ISNANF]) |
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33 LOGBF_LIBM= |
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34 dnl Append $FREXPF_LIBM to LOGBF_LIBM, avoiding gratuitous duplicates. |
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35 case " $LOGBF_LIBM " in |
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36 *" $FREXPF_LIBM "*) ;; |
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37 *) LOGBF_LIBM="$LOGBF_LIBM $FREXPF_LIBM" ;; |
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38 esac |
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39 dnl Append $ISNANF_LIBM to LOGBF_LIBM, avoiding gratuitous duplicates. |
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40 case " $LOGBF_LIBM " in |
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41 *" $ISNANF_LIBM "*) ;; |
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42 *) LOGBF_LIBM="$LOGBF_LIBM $ISNANF_LIBM" ;; |
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43 esac |
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44 fi |
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45 AC_SUBST([LOGBF_LIBM]) |
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46 ]) |
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47 |
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48 dnl Test whether logbf() works. |
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49 dnl On glibc 2.11/ppc, glibc 2.7/sparc, glibc 2.7/hppa, Solaris 10/SPARC, |
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50 dnl the return value for subnormal (denormalized) arguments is too large. |
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51 AC_DEFUN([gl_FUNC_LOGBF_WORKS], |
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52 [ |
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53 AC_REQUIRE([AC_PROG_CC]) |
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54 AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles |
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55 AC_CACHE_CHECK([whether logbf works], [gl_cv_func_logbf_works], |
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56 [ |
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57 AC_RUN_IFELSE( |
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58 [AC_LANG_SOURCE([[ |
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59 #include <float.h> |
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60 #include <math.h> |
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61 volatile float x; |
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62 int main () |
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63 { |
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64 int i; |
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65 for (i = 1, x = 1.0f; i >= FLT_MIN_EXP; i--, x *= 0.5f) |
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66 ; |
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67 /* Here i = FLT_MIN_EXP - 1. Either x = 2^(i-1) is subnormal or x = 0.0. */ |
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68 if (x > 0.0f && !(logbf (x) == (float)(i - 1))) |
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69 return 1; |
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70 return 0; |
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71 } |
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72 ]])], |
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73 [gl_cv_func_logbf_works=yes], |
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74 [gl_cv_func_logbf_works=no], |
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75 [case "$host_os" in |
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76 *gnu* | solaris*) gl_cv_func_logbf_works="guessing no";; |
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77 *) gl_cv_func_logbf_works="guessing yes";; |
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78 esac |
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79 ]) |
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80 ]) |
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81 ]) |
