# round.m4 serial 5 dnl Copyright (C) 2007 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_ROUND], [ AC_REQUIRE([gl_MATH_H_DEFAULTS]) dnl Persuade glibc to declare round(). AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS]) AC_CHECK_DECLS([round], , , [#include ]) if test "\$ac_cv_have_decl_round" = yes; then gl_CHECK_MATH_LIB([ROUND_LIBM], [x = round (x);]) fi if test "\$ac_cv_have_decl_round" = yes && test "\$ROUND_LIBM" != missing; then dnl Test whether round() produces correct results. On NetBSD 3.0, for dnl x = 1/2 - 2^-54, the system's round() returns a wrong result. AC_REQUIRE([AC_PROG_CC]) AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([whether round works], [gl_cv_func_round_works], [ save_LIBS="\$LIBS" LIBS="\$LIBS \$ROUND_LIBM" AC_TRY_RUN([ #include #include int main() { /* 2^DBL_MANT_DIG. */ static const double TWO_MANT_DIG = /* Assume DBL_MANT_DIG <= 5 * 31. Use the identity n = floor(n/5) + floor((n+1)/5) + ... + floor((n+4)/5). */ (double) (1U << (DBL_MANT_DIG / 5)) * (double) (1U << ((DBL_MANT_DIG + 1) / 5)) * (double) (1U << ((DBL_MANT_DIG + 2) / 5)) * (double) (1U << ((DBL_MANT_DIG + 3) / 5)) * (double) (1U << ((DBL_MANT_DIG + 4) / 5)); volatile double x = 0.5 - 0.5 / TWO_MANT_DIG; exit (x < 0.5 && round (x) != 0.0); }], [gl_cv_func_round_works=yes], [gl_cv_func_round_works=no], [case "\$host_os" in netbsd*) gl_cv_func_round_works="guessing no";; *) gl_cv_func_round_works="guessing yes";; esac ]) LIBS="\$save_LIBS" ]) case "\$gl_cv_func_round_works" in *no) ROUND_LIBM=missing ;; esac fi if test "\$ac_cv_have_decl_round" != yes || test "\$ROUND_LIBM" = missing; then REPLACE_ROUND=1 AC_LIBOBJ([round]) gl_FUNC_FLOOR_LIBS gl_FUNC_CEIL_LIBS ROUND_LIBM="\$FLOOR_LIBM \$CEIL_LIBM" fi AC_SUBST([ROUND_LIBM]) ])