firebird-mirror/src/misc/align.cpp

/*
 * The contents of this file are subject to the Interbase Public
 * License Version 1.0 (the "License"); you may not use this file
 * except in compliance with the License. You may obtain a copy
 * of the License at http://www.Inprise.com/IPL.html
 *
 * Software distributed under the License is distributed on an
 * "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express
 * or implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * The Original Code was created by Inprise Corporation
 * and its predecessors. Portions created by Inprise Corporation are
 * Copyright (C) Inprise Corporation.
 *
 * All Rights Reserved.
 * Contributor(s): ______________________________________.
 */


#include "firebird.h"
#include <signal.h>
#include <stdio.h>

struct xyz
{
	char a;
	double b;
};
typedef xyz* XYZ;

#define MAJOR_MINOR	"((n + b - 1) & ~(b - 1))"
#define EVEN		"((n + 1) & ~1)"
#define NO_OP		"(n)"

struct alignment
{
	short rule_offset;
	short rule_length;
	short rule_faults;
	short rule_base_align;
	short rule_double_align;
	const char *rule_rule;
	const char *rule_system;
};

static const alignment rules[] =
{
	1, 9, 0, 4, 4, NO_OP, "VMS",	/* VMS */
	2, 10, 0, 4, 4, EVEN, "MC 68K",	/* Generic Motorola */
	4, 12, 0, 4, 4, MAJOR_MINOR, "VAX Ultrix, 386i, RT",	/* VAX Ultrix */
	8, 16, 1, 8, 8, MAJOR_MINOR, "HP Precision",	/* HP Precision */
	8, 16, 0, 4, 8, MAJOR_MINOR, "Sparc",	/* MIPS, Sun Sparc */
	0, 0, 0, 0, 0
};

static void check_byte_order();
static int check_double();
static void handler();


int main(int argc, char *argv[])
{
#if SIZEOF_LONG == 8
	int vector[3];
#else
	long vector[3];
#endif

	const short offset = (int) &((XYZ) NULL)->b;
	const short length = sizeof(xyz);
	const short faults = check_double();

	for (const alignment* rule = rules; rule->rule_offset; ++rule)
		if (rule->rule_offset == offset &&
			rule->rule_length == length && rule->rule_faults == faults)
		{
			printf("\n/* %s */\n\n", rule->rule_system);
			printf("#define FB_ALIGNMENT\t%d\n", rule->rule_base_align);
			printf("#define FB_DOUBLE_ALIGN\t%d\n", rule->rule_double_align);
			printf("#define FB_ALIGN(n, b)\t%s\n", rule->rule_rule);
			check_byte_order();
			printf("\n");
			return 1;
		}

	printf("Unknown system, double offset %d, structure length %d\n",
			  offset, length);
	check_byte_order();

	return 1;
}

static void check_byte_order()
{
	union {
		short s;
		char c[2];
	} order_test;

	order_test.c[0] = 1;
	order_test.c[1] = 2;

	if (order_test.s == 0x0102)
		printf("#define WORDS_BIGENDIAN\t\t1\n");
}

static int check_double()
{
	double *p;
#if SIZEOF_LONG == 8
	int vector[3];
#else
	long vector[3];
#endif

	try {
		signal(SIGBUS, handler);
		signal(SIGSEGV, handler);
		p = (double *) &vector[0];
		*p = 3;
		*p *= 2.5;
		p = (double *) &vector[1];
		*p = 3;
		*p *= 2.5;
	}
	catch (const Firebird::Exception&) {
		return 1;
	}

	return 0;
}

static void handler()
{
	Firebird::status_exception::raise();
}