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- 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
|
