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[metaconfig.git] / dist / U / alignbytes.U

?RCS: $Id$
?RCS:
?RCS: Copyright (c) 1991-1997, 2004-2006, Raphael Manfredi
?RCS: 
?RCS: You may redistribute only under the terms of the Artistic Licence,
?RCS: as specified in the README file that comes with the distribution.
?RCS: You may reuse parts of this distribution only within the terms of
?RCS: that same Artistic Licence; a copy of which may be found at the root
?RCS: of the source tree for dist 4.0.
?RCS:
?RCS: $Log: alignbytes.U,v $
?RCS: Revision 3.0.1.2  1994/10/29  16:02:28  ram
?RCS: patch36: added ?F: line for metalint file checking
?RCS:
?RCS: Revision 3.0.1.1  1994/05/06  14:25:20  ram
?RCS: patch23: avoid ALIGNBYTES, since it conflicts on NetBSD
?RCS:
?RCS: Revision 3.0  1993/08/18  12:05:23  ram
?RCS: Baseline for dist 3.0 netwide release.
?RCS:
?MAKE:alignbytes: Assert Myread Trylink cat i_inttypes i_limits i_math
?MAKE:	-pick add $@ %<
?S:alignbytes:
?S:	This variable holds the number of bytes required to align an
?S:	arbitrary standard type. Usual values are 2, 4 and 8.
?S:.
?X: This used to be called ALIGNBYTES, but that conflicts with
?X: <machines/param.h> in NetBSD.
?C:MEM_ALIGNBYTES (ALIGNBYTES):
?C:	This symbol contains the number of bytes required to align a
?C:	double. Usual values are 2, 4 and 8.
?C:.
?H:#define MEM_ALIGNBYTES $alignbytes	/**/
?H:.
?T:alignment result
: check for alignment requirements
echo " "
case "$alignbytes" in
'')
	echo "Checking alignment constraints..." >&4

	for alignment in 8 4 2 1 16 32 error
	do
		$cat >try.c <<EOCP
#$i_inttypes I_INTTYPES
#ifdef I_INTTYPES
#include <inttypes.h>
#endif
#$i_limits I_LIMITS
#ifdef I_LIMITS
#include <limits.h>
#endif
#$i_math I_MATH
#ifdef I_MATH
#include <math.h>
#endif

union u {
	void *void_ptr;
	void (*func_ptr)(void);
	char c;
	short s;
	int i;
	long l;
	float f;
	double d;
#ifdef LLONG_MAX
	long long ll;
#else
#warning "LLONG_MAX undefined"
#endif
#if defined(HUGE_VALL)
	long double ld;
#else
#warning "HUGE_VALL undefined"
#endif
#ifdef UINT32_MAX
	uint32_t u32;
#else
#warning "UINT32_MAX undefined"
#endif
#ifdef UINT16_MAX
	uint16_t u16;
#else
#warning "UINT32_MAX undefined"
#endif
#ifdef UINT64_MAX
	uint64_t u64;
#else
#warning "UINT64_MAX undefined"
#endif
#ifdef UINTMAX_MAX
	uintmax_t m;
#else
#warning "UINTMAX_MAX undefined"
#endif
#ifdef UINTPTR_MAX
	uintptr_t up;
#else
#warning "UINTPTR_MAX undefined"
#endif
};

struct s {
	char a;
	union u b;
};

#include "static_assert.h"

int
main(void)
{
	STATIC_ASSERT($alignment == ((sizeof (struct s) - (sizeof (union u)))));
	return 0;
}
EOCP

		result=''
		set result
		eval $trylink
		case "$result" in
		"$define") break;;
		esac
	done

	case "$alignment" in
	error)	dflt='8'
		echo "(I can't seem to compile the test program...)" >&4
		;;
	*)	dflt=$alignment
		;;
	esac
;;
*) dflt="$alignbytes"
	;;
esac
rp="What is the maximum alignment in bytes required for a standard type?"
. ./myread
alignbytes="$ans"