| From nobody Mon Sep 17 00:00:00 2001 |
| From: Dan Amelang <dan@amelang.net> |
| Date: Sun Oct 29 21:30:08 2006 -0800 |
| Subject: [PATCH] Add autoconf macro AX_C_FLOAT_WORDS_BIGENDIAN |
| |
| The symbol that this macro defines (FLOAT_WORDS_BIGENDIAN) can be used |
| to make double arithmetic tricks portable. |
| |
| --- |
| |
| acinclude.m4 | 65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
| configure.in | 1 + |
| 2 files changed, 66 insertions(+), 0 deletions(-) |
| |
| 3231d91b59a6c2e1c40bbaa8b143694b6c693662 |
| diff --git a/acinclude.m4 b/acinclude.m4 |
| index af73800..a0eb13a 100644 |
| --- a/acinclude.m4 |
| +++ b/acinclude.m4 |
| @@ -51,3 +51,68 @@ ifelse([$1],[],, |
| AM_CONDITIONAL(ENABLE_GTK_DOC, test x$enable_gtk_doc = xyes) |
| AM_CONDITIONAL(GTK_DOC_USE_LIBTOOL, test -n "$LIBTOOL") |
| ]) |
| + |
| +# AX_C_FLOAT_WORDS_BIGENDIAN ([ACTION-IF-TRUE], [ACTION-IF-FALSE], |
| +# [ACTION-IF-UNKNOWN]) |
| +# |
| +# Checks the ordering of words within a multi-word float. This check |
| +# is necessary because on some systems (e.g. certain ARM systems), the |
| +# float word ordering can be different from the byte ordering. In a |
| +# multi-word float context, "big-endian" implies that the word containing |
| +# the sign bit is found in the memory location with the lowest address. |
| +# This implemenation was inspired by the AC_C_BIGENDIAN macro in autoconf. |
| +# ------------------------------------------------------------------------- |
| +AC_DEFUN([AX_C_FLOAT_WORDS_BIGENDIAN], |
| + [AC_CACHE_CHECK(whether float word ordering is bigendian, |
| + ax_cv_c_float_words_bigendian, [ |
| + |
| +# The endianess is detected by first compiling C code that contains a special |
| +# double float value, then grepping the resulting object file for certain |
| +# strings of ascii values. The double is specially crafted to have a |
| +# binary representation that corresponds with a simple string. In this |
| +# implementation, the string "noonsees" was selected because the individual |
| +# word values ("noon" and "sees") are palindromes, thus making this test |
| +# byte-order agnostic. If grep finds the string "noonsees" in the object |
| +# file, the target platform stores float words in big-endian order. If grep |
| +# finds "seesnoon", float words are in little-endian order. If neither value |
| +# is found, the user is instructed to specify the ordering. |
| + |
| +ax_cv_c_float_words_bigendian=unknown |
| +AC_COMPILE_IFELSE([AC_LANG_SOURCE([[ |
| + |
| +double d = 90904234967036810337470478905505011476211692735615632014797120844053488865816695273723469097858056257517020191247487429516932130503560650002327564517570778480236724525140520121371739201496540132640109977779420565776568942592.0; |
| + |
| +]])], [ |
| + |
| +if grep noonsees conftest.$ac_objext >/dev/null ; then |
| + ax_cv_c_float_words_bigendian=yes |
| +fi |
| +if grep seesnoon conftest.$ac_objext >/dev/null ; then |
| + if test "$ax_cv_c_float_words_bigendian" = unknown; then |
| + ax_cv_c_float_words_bigendian=no |
| + else |
| + ax_cv_c_float_words_bigendian=unknown |
| + fi |
| +fi |
| + |
| +])]) |
| + |
| +case $ax_cv_c_float_words_bigendian in |
| + yes) |
| + m4_default([$1], |
| + [AC_DEFINE([FLOAT_WORDS_BIGENDIAN], 1, |
| + [Define to 1 if your system stores words within floats |
| + with the most significant word first])]) ;; |
| + no) |
| + $2 ;; |
| + *) |
| + m4_default([$3], |
| + [AC_MSG_ERROR([ |
| + |
| +Unknown float word ordering. You need to manually preset |
| +ax_cv_c_float_words_bigendian=no (or yes) according to your system. |
| + |
| + ])]) ;; |
| +esac |
| + |
| +])# AX_C_FLOAT_WORDS_BIGENDIAN |
| diff --git a/configure.in b/configure.in |
| index 2d2bf9f..797c7ce 100644 |
| --- a/configure.in |
| +++ b/configure.in |
| @@ -55,6 +55,7 @@ AC_PROG_CPP |
| AC_PROG_LIBTOOL dnl required version (1.4) DON'T REMOVE! |
| AC_STDC_HEADERS |
| AC_C_BIGENDIAN |
| +AX_C_FLOAT_WORDS_BIGENDIAN |
| |
| dnl =========================================================================== |
| dnl === Local macros |
| -- |
| 1.2.6 |
| |