#include <iostream.h>
#include <stdlib.h>
#include "common.h"

extern double drand48();
inline bool isOdd(int x);
inline int square (int x);

// Returns true if x is odd, false if it is even
inline bool isOdd(int x)
{
	return x & 0x01;
}

// Returns the square of x
inline int square (int x)
{
	return x * x;
}

// Returns what the change in the x-coordinate will be of an object
// moving in direction dir
int xChange (int dir)
{
	switch (dir)
	{
	case N:
	case S:
		return 0;
	case W:
		return -1;
	case E:
		return 1;
	default:
		cerr << "Direction " << dir << " passed to xChange" << endl;
		return 0;
	}
}

// Returns what the change in the y-coordinate will be of an object
// moving in direction dir
int yChange (int dir)
{
	switch (dir)
	{
	case N:
		return -1;
	case S:
		return 1;
	case W:
	case E:
		return 0;
	default:
		cerr << "Direction " << dir << " passed to yChange" << endl;
		doNothing();
		return 1;
	}
}

// Returns a random direction
int randomDirection ()
{
	return int(drand48() * NUM_DIRECTIONS);
}

// Returns the next direction (to the right) of dir
int nextDir (int dir)
{
	return (dir + 1) % NUM_DIRECTIONS;
}

// Returns the opposite direction of dir
int backDir (int dir)
{
	return (dir + 2) % NUM_DIRECTIONS;
}

// Returns the previous direction before dir
int prevDir (int dir)
{
	return (dir + 3) % NUM_DIRECTIONS;
}

// Returns 10^p
int expTen (int p)
{
	int val = 1;

	while (p > 0)
	{
		if (isOdd(p))
		{
			p--;
			val *= 10;
		}
		else
		{
			val >>= 1;
			val = square(val);
		}
	};

	return val;
}

// Returns the numerical value of a character digit
int digitVal (char c)
{
	return c - 0x30;
}

template <class T>
void Swap (T& a, T& b)
{
	T temp;
	temp = a;
	a = b;
	b = temp;
}

// Randomly returns true or false
bool coinFlip ()
{
	return drand48() * 2;
}

// Randoms a random integer between low and high, inclusive
int randomBetween (int low, int high)
{
	return low + int(drand48() * (high - low + 1));
}