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6d93bddbd6
Found via `codespell -i 3 -w -I ../cairo-word-whitelist.txt -L tim,ned,uint`
Follow up of 12cb59be7d
Reviewed-by: Bryce Harrington <bryce@bryceharrington.org>
65 lines
2.6 KiB
Text
65 lines
2.6 KiB
Text
# AX_C_FLOAT_WORDS_BIGENDIAN ([ACTION-IF-TRUE], [ACTION-IF-FALSE],
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# [ACTION-IF-UNKNOWN])
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#
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# Checks the ordering of words within a multi-word float. This check
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# is necessary because on some systems (e.g. certain ARM systems), the
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# float word ordering can be different from the byte ordering. In a
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# multi-word float context, "big-endian" implies that the word containing
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# the sign bit is found in the memory location with the lowest address.
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# This implementation was inspired by the AC_C_BIGENDIAN macro in autoconf.
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# -------------------------------------------------------------------------
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AC_DEFUN([AX_C_FLOAT_WORDS_BIGENDIAN],
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[AC_CACHE_CHECK(whether float word ordering is bigendian,
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ax_cv_c_float_words_bigendian, [
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# The endianness is detected by first compiling C code that contains a special
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# double float value, then grepping the resulting object file for certain
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# strings of ascii values. The double is specially crafted to have a
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# binary representation that corresponds with a simple string. In this
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# implementation, the string "noonsees" was selected because the individual
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# word values ("noon" and "sees") are palindromes, thus making this test
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# byte-order agnostic. If grep finds the string "noonsees" in the object
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# file, the target platform stores float words in big-endian order. If grep
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# finds "seesnoon", float words are in little-endian order. If neither value
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# is found, the user is instructed to specify the ordering.
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ax_cv_c_float_words_bigendian=unknown
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AC_LINK_IFELSE([AC_LANG_SOURCE([[
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double d __attribute__((used)) = 90904234967036810337470478905505011476211692735615632014797120844053488865816695273723469097858056257517020191247487429516932130503560650002327564517570778480236724525140520121371739201496540132640109977779420565776568942592.0;
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int main() { return 0; }
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]])], [
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if strings -a conftest$ac_exeext | grep noonsees >/dev/null ; then
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ax_cv_c_float_words_bigendian=yes
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fi
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if strings -a conftest$ac_exeext | grep seesnoon >/dev/null ; then
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if test "$ax_cv_c_float_words_bigendian" = unknown; then
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ax_cv_c_float_words_bigendian=no
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else
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ax_cv_c_float_words_bigendian=unknown
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fi
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fi
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])])
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case $ax_cv_c_float_words_bigendian in
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yes)
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m4_default([$1],
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[AC_DEFINE([FLOAT_WORDS_BIGENDIAN], 1,
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[Define to 1 if your system stores words within floats
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with the most significant word first])]) ;;
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no)
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$2 ;;
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*)
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m4_default([$3],
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[AC_MSG_ERROR([
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Unknown float word ordering. You need to manually preset
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ax_cv_c_float_words_bigendian=no (or yes) according to your system.
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])]) ;;
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esac
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])# AX_C_FLOAT_WORDS_BIGENDIAN
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