39 lines
1.5 KiB
Plaintext
39 lines
1.5 KiB
Plaintext
#serial 1003
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dnl Copyright (C) 2003 Free Software Foundation, Inc.
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dnl This file is free software; the Free Software Foundation
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dnl gives unlimited permission to copy and/or distribute it,
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dnl with or without modifications, as long as this notice is preserved.
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# This macro can be removed once we can rely on Autoconf 2.57a or later,
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# since we can then use its AC_C_RESTRICT.
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# gl_C_RESTRICT
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# --------------
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# Determine whether the C/C++ compiler supports the "restrict" keyword
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# introduced in ANSI C99, or an equivalent. Do nothing if the compiler
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# accepts it. Otherwise, if the compiler supports an equivalent,
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# define "restrict" to be that. Here are some variants:
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# - GCC supports both __restrict and __restrict__
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# - older DEC Alpha C compilers support only __restrict
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# - _Restrict is the only spelling accepted by Sun WorkShop 6 update 2 C
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# Otherwise, define "restrict" to be empty.
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AC_DEFUN([gl_C_RESTRICT],
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[AC_CACHE_CHECK([for C/C++ restrict keyword], gl_cv_c_restrict,
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[gl_cv_c_restrict=no
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# Try the official restrict keyword, then gcc's __restrict, and
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# the less common variants.
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for ac_kw in restrict __restrict __restrict__ _Restrict; do
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AC_COMPILE_IFELSE([AC_LANG_SOURCE(
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[float * $ac_kw x;])],
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[gl_cv_c_restrict=$ac_kw; break])
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done
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])
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case $gl_cv_c_restrict in
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restrict) ;;
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no) AC_DEFINE(restrict,,
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[Define to equivalent of C99 restrict keyword, or to nothing if this
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is not supported. Do not define if restrict is supported directly.]) ;;
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*) AC_DEFINE_UNQUOTED(restrict, $gl_cv_c_restrict) ;;
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esac
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])
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