Mercurial > gnulib
view m4/exponentl.m4 @ 40177:dcd889592b62
dtoastr,ftoastr,ldtoastr: port to c-strtod changes
Decouple these modules from c-strtod. Nowadays it’s reasonable to
assume the C99 signatures for strtod and strtold. Programs that
require stricter adherence to C99 should also use the strtod and
strtold modules as needed, and we no longer need the
HAVE_C99_STRTOLD macro.
* NEWS: Mention this.
* lib/ftoastr.c (STRTOF) [LENGTH == 3]: Assume strtold.
* m4/c-strtod.m4 (gl_C_STRTOLD): Do not define HAVE_C99_STRTOLD.
* modules/dtoastr, modules/ftoastr, modules/ldtoastr:
(Files): Remove m4/c-strtod.m4.
(configure.ac): Do not require gl_C99_STRTOLD, which no longer
exists.
author | Paul Eggert <eggert@cs.ucla.edu> |
---|---|
date | Sat, 02 Feb 2019 13:01:55 -0800 |
parents | b06060465f09 |
children |
line wrap: on
line source
# exponentl.m4 serial 4 dnl Copyright (C) 2007-2019 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_LONG_DOUBLE_EXPONENT_LOCATION], [ AC_REQUIRE([gl_BIGENDIAN]) AC_REQUIRE([AC_CANONICAL_HOST]) dnl for cross-compiles AC_CACHE_CHECK([where to find the exponent in a 'long double'], [gl_cv_cc_long_double_expbit0], [ AC_RUN_IFELSE( [AC_LANG_SOURCE([[ #include <float.h> #include <stddef.h> #include <stdio.h> #include <string.h> #define NWORDS \ ((sizeof (long double) + sizeof (unsigned int) - 1) / sizeof (unsigned int)) typedef union { long double value; unsigned int word[NWORDS]; } memory_long_double; static unsigned int ored_words[NWORDS]; static unsigned int anded_words[NWORDS]; static void add_to_ored_words (long double x) { memory_long_double m; size_t i; /* Clear it first, in case sizeof (long double) < sizeof (memory_long_double). */ memset (&m, 0, sizeof (memory_long_double)); m.value = x; for (i = 0; i < NWORDS; i++) { ored_words[i] |= m.word[i]; anded_words[i] &= m.word[i]; } } int main () { size_t j; FILE *fp = fopen ("conftest.out", "w"); if (fp == NULL) return 1; for (j = 0; j < NWORDS; j++) anded_words[j] = ~ (unsigned int) 0; add_to_ored_words (0.25L); add_to_ored_words (0.5L); add_to_ored_words (1.0L); add_to_ored_words (2.0L); add_to_ored_words (4.0L); /* Remove bits that are common (e.g. if representation of the first mantissa bit is explicit). */ for (j = 0; j < NWORDS; j++) ored_words[j] &= ~anded_words[j]; /* Now find the nonzero word. */ for (j = 0; j < NWORDS; j++) if (ored_words[j] != 0) break; if (j < NWORDS) { size_t i; for (i = j + 1; i < NWORDS; i++) if (ored_words[i] != 0) { fprintf (fp, "unknown"); return (fclose (fp) != 0); } for (i = 0; ; i++) if ((ored_words[j] >> i) & 1) { fprintf (fp, "word %d bit %d", (int) j, (int) i); return (fclose (fp) != 0); } } fprintf (fp, "unknown"); return (fclose (fp) != 0); } ]])], [gl_cv_cc_long_double_expbit0=`cat conftest.out`], [gl_cv_cc_long_double_expbit0="unknown"], [ dnl When cross-compiling, in general we don't know. It depends on the dnl ABI and compiler version. There are too many cases. gl_cv_cc_long_double_expbit0="unknown" case "$host_os" in mingw*) # On native Windows (little-endian), we know the result # in two cases: mingw, MSVC. AC_EGREP_CPP([Known], [ #ifdef __MINGW32__ Known #endif ], [gl_cv_cc_long_double_expbit0="word 2 bit 0"]) AC_EGREP_CPP([Known], [ #ifdef _MSC_VER Known #endif ], [gl_cv_cc_long_double_expbit0="word 1 bit 20"]) ;; esac ]) rm -f conftest.out ]) case "$gl_cv_cc_long_double_expbit0" in word*bit*) word=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word //' -e 's/ bit.*//'` bit=`echo "$gl_cv_cc_long_double_expbit0" | sed -e 's/word.*bit //'` AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_WORD], [$word], [Define as the word index where to find the exponent of 'long double'.]) AC_DEFINE_UNQUOTED([LDBL_EXPBIT0_BIT], [$bit], [Define as the bit index in the word where to find bit 0 of the exponent of 'long double'.]) ;; esac ])