calc.h

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/*
	calc.h
	
	(c) Richard Thrippleton
	Licensing terms are in the 'LICENSE' file
	If that file is not included with this source then permission is not given to use this source in any way whatsoever.
*/

#include <math.h>
#include <SDL_types.h>
#include <SDL_endian.h>

#ifndef M_PI
#define M_PI 3.14159265358979323846
#endif

class vect;
class pol //A polar vector
{
	public:
	inline vect tovect(); //Returns conversion to a vect

        double ang; //Angle
	double rad; //Radius
};

class vect //A vector
{
	public:
	inline pol topol(); //Returns conversion to a pol
	
	double xx;
	double yy; //X and Y components
};

inline vect pol::tovect()
{
	vect out; //Return value
	double cang; //Converted angle

	cang=((ang-90)*M_PI)/180;
	out.xx=rad*cos(cang);
	out.yy=rad*sin(cang);
	return out;
}

inline pol vect::topol()
{
	pol out; //Return value

	out.rad=sqrt(xx*xx+yy*yy);
	if(xx!=0)
	{
		out.ang=atan(yy/xx)*(180/M_PI);
		if(yy>0)
		{
			if(xx>0)
				out.ang=90+out.ang;
			else
				out.ang=270+out.ang;
		}
		else
		{
			if(xx>0)
				out.ang=90+out.ang;
			else
				out.ang=360-(90-out.ang);
		}
	}
	else
	{
		if(yy>0)
			out.ang=180;
		else
			out.ang=0;
	}
	return out;
}

class ivect;
class ipol //Integer version of pol
{
	public:
	inline ivect tovect(); //Returns conversion to an ivect

	int ang;
	long rad;
};

class ivect //Integer version of vect
{
	public:
	inline ipol topol(); //Returns conversion to an ipol

	long xx;
	long yy;
};

inline ivect ipol::tovect()
{
	ivect out; //Return value
	double cang; //Converted angle

	cang=(((double)ang-90)*M_PI)/180;
	out.xx=(long)(rad*cos(cang));
	out.yy=(long)(rad*sin(cang));
	return out;
}

inline ipol ivect::topol()
{
	ipol out; //Return value

	out.rad=(long)sqrt(xx*xx+yy*yy);
	if(xx!=0)
	{
		out.ang=(int)((double)atan(yy/xx)*(180/M_PI));
		if(yy>0)
		{
			if(xx>0)
				out.ang=90+out.ang;
			else
				out.ang=270+out.ang;
		}
		else
		{
			if(xx>0)
				out.ang=90+out.ang;
			else
				out.ang=360-(90-out.ang);
		}
	}
	else
	{
		if(yy>0)
			out.ang=180;
		else
			out.ang=0;
	}
	return out;
}

struct cord //A co-ordinate in the game
{
	double x;
	double y; //X and Y components
};

struct icord //Integer version of cord
{
	long x;
	long y;
};


struct box //A universe bounding box
{
	long x1,y1; //Top-left corner
	long x2,y2; //Top-right corner
};

class calc //Mathematics module
{
        public:
		static void init(); //Initialise some calculation data
        static long rnd(long max); //Return random integer from 0 to max-1
        static void getspeed(long spd,char* put); //Convert given game velocity to a string
        inline static long dattolong(unsigned char* in) //Converts a four byte buffer portably into a long
		{
			Uint32 tmp; //Temporary value holder
			unsigned char* tmpp=(unsigned char*)&tmp; //Accessor for tmp
			long out; //Value to output

			tmpp[0]=in[0];
			tmpp[1]=in[1];
			tmpp[2]=in[2];
			tmpp[3]=in[3];
			#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			tmp=SDL_Swap32(tmp);
			#endif	
			out=tmp-2147483647;

			return out;
		}
        inline static void longtodat(long in,unsigned char* out) //Puts a long portably into a four byte buffer
		{
			Uint32 tmp; //Temporary value holder
			unsigned char* tmpp=(unsigned char*)&tmp; //Accessor for tmp

			tmp=in+2147483647;
			#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			tmp=SDL_Swap32(tmp);
			#endif	
			out[0]=tmpp[0];
			out[1]=tmpp[1];
			out[2]=tmpp[2];
			out[3]=tmpp[3];
			return;
		}
        inline static int dattoint(unsigned char* in) //Converts a two byte buffer portably into a short
		{
			Uint16 tmp; //Temporary value holder
			unsigned char* tmpp=(unsigned char*)&tmp; //Accessor for tmp
			int out; //Value to output

			tmpp[0]=in[0];
			tmpp[1]=in[1];
			#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			tmp=SDL_Swap16(tmp);
			#endif	
			out=tmp-32768;

			return out;
		}
        inline static void inttodat(short in,unsigned char* out) //Puts a long portably into a four byte buffer
		{
			Uint16 tmp; //Temporary value holder
			unsigned char* tmpp=(unsigned char*)&tmp; //Accessor for tmp

			tmp=in+32768;
			#if SDL_BYTEORDER == SDL_LIL_ENDIAN
			tmp=SDL_Swap16(tmp);
			#endif	
			out[0]=tmpp[0];
			out[1]=tmpp[1];
			return;
		}
        static bool dateq(unsigned char* d1,unsigned char* d2,int n); //Test two data streams for equality, up to n bytes
		static void obscure(char* str); //Munges the string so it is no longer human readable; the munging is consisten, like a very weak crypt

        private:
        static long wrp[10]; //Warp speed table
        static char spds[33]; //Speed string (saves having to malloc, but it ain't threadsafe!)
};