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+/* %W% %G% %U% - (c) Copyright 1987, 1988 Chuck Simmons */
+
+/*
+ *    Copyright (C) 1987, 1988 Chuck Simmons
+ * 
+ * See the file COPYING, distributed with empire, for restriction
+ * and warranty information.
+ */
+
+/*
+math.c -- various mathematical routines.
+
+This file contains routines used to create random integers.  The
+initialization routine 'rndini' should be called at program startup.
+The flavors of random integers that can be generated are:
+
+    irand(n) -- returns a random integer in the range 0..n-1
+    rndint(a,b) -- returns a random integer in the range a..b
+
+Other routines include:
+
+    dist (a, b) -- returns the straight-line distance between two locations.
+*/
+
+#include "empire.h"
+#include "extern.h"
+
+void rndini()
+{
+       srand((unsigned)(time(0) & 0xFFFF));
+}
+
+long irand(high)
+long high;
+{
+       if (high < 2) {
+               return (0);
+       }
+       return (rand() % high);
+}
+
+int rndint(minp, maxp)
+int minp, maxp;
+{
+       int size;
+
+       size = maxp - minp + 1;
+       return ((rand() % size) + minp);
+}
+
+/*
+Return the distance between two locations.  This is simply
+the max of the absolute differnce between the x and y coordinates.
+*/
+
+#define MIN(a,b) ((a)<(b) ? (a) : (b))
+#define MAX(a,b) ((a)>(b) ? (a) : (b))
+#define ABS(a) ((a) < 0 ? -(a) : (a))
+
+dist (a, b)
+long a, b;
+{
+       int ax, ay, bx, by;
+
+       ax = loc_row (a);
+       ay = loc_col (a);
+       bx = loc_row (b);
+       by = loc_col (b);
+
+       return (MAX (ABS (ax-bx), ABS (ay-by)));
+}
+
+/*
+Find the square root of an integer.  We actually return the floor
+of the square root using Newton's method.
+*/
+
+int sqrt (n)
+int n;
+{
+       int guess;
+       
+       ASSERT (n >= 0); /* can't take sqrt of negative number */
+
+       if (n <= 1) return (n); /* do easy cases and avoid div by zero */
+               
+       guess = 2; /* gotta start somewhere */
+       guess = (guess + n/guess) / 2;
+       guess = (guess + n/guess) / 2;
+       guess = (guess + n/guess) / 2;
+       guess = (guess + n/guess) / 2;
+       guess = (guess + n/guess) / 2;
+       
+       if (guess * guess > n) guess -= 1; /* take floor */
+       return (guess);
+}