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From: darrell@sdcsvax.UUCP (Darrell Long)
Newsgroups: net.arch,net.lang.c,net.micro,net.micro.pc,net.micro.68k
Subject: Re: Re: Re: Need 286 "C" benchmark
Message-ID: <894@sdcsvax.UUCP>
Date: Wed, 29-May-85 00:20:15 EDT
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Posted: Wed May 29 00:20:15 1985
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Organization: EECS Dept. U.C. San Diego
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Xref: watmath net.arch:1287 net.lang.c:5328 net.micro:10595 net.micro.pc:4093 net.micro.68k:842

Here's a little program that makes a good benchmark.  It especially
exercises the CALL instruction, clearly on of the most used of all
instructions.

This program finds the Knight's tour on an n*n chess board, I
suggest you start with n=5.  The running times grow exponentially
in n.

I have run this program on 68010's (SUN), WE-3200x (3B-2) and VAXen
with interesting results.  Let's see how the 80286 fares.

#include <stdio.h>

#define	TRUE	1
#define	FALSE	!TRUE
#define	n	5
#define	n_sqr	n*n

int a[8]={2,1,-1,-2,-2,-1,1,2};
int b[8]={1,2,2,1,-1,-2,-2,-1};

int chess_board[n][n];

int count = 0;

main()
{ 
	int i,j;
	for (i = 0; i < n; i++)
		for (j = 0; j < n; j++)
			chess_board[i][j] = 0;
	chess_board[0][0] = 1;
	if (try(2,0,0))
		for (i = 0; i < n; i++)
		{ 
			for (j = 0; j < n; j++)
				printf("\t%d",chess_board[i][j]);
			printf("\n"); 
		}
	else
		printf("no solution in %d tries.\n", count);

}

try(i,x,y)
int i,x,y;
{ 
	int k,u,v,q_1;
	k = 0;
	do {
		count++;
		q_1 = FALSE; 
		u = x + a[k]; 
		v = y + b[k];
		if (((u < n) && (u >= 0)) && ((v < n) && (v >= 0)))
			if (chess_board[u][v] == 0) { 
				chess_board[u][v] = i; 
				if (i < n_sqr) 
				{ 
					q_1 = try((i + 1),u,v); 
					if (!q_1) chess_board[u][v] = 0; 
				} 
				else
					q_1 = TRUE; 
			};
	} 
	while ((!q_1) && (++k < 8)); 
	return(q_1);
}
-- 
Darrell Long
Department of Electrical Engineering and Computer Science
University of California, San Diego

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