sparrowMath.h

 /* This file is part of sparrow3d.
  * Sparrow3d is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation, either version 2 of the License, or
  * (at your option) any later version.
  * 
  * Sparrow3d is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  * 
  * You should have received a copy of the GNU General Public License
  * along with Foobar.  If not, see <http://www.gnu.org/licenses/>
  * 
  * For feedback and questions about my Files and Projects please mail me,
  * Alexander Matthes (Ziz) , zizsdl_at_googlemail.com */

/* File: sparrowMath
 * 
 * This file is for fast functions for fixed point numbers like
 * trigonometric functions, square root, etc. */
#ifndef _SPARROW_MATH_H
#define _SPARROW_MATH_H

#include "sparrowDefines.h"
#include <SDL.h>

/* Function: spInitMath
 * 
 * Initializes the fixed point look up tables for sin, cos, etc. Is called by
 * <spInitCore>.*/
PREFIX void spInitMath( void );

/* Function: spSin
 * 
 * Calculates the sinus of a fixed point value
 * 
 * Parameters:
 * value - fixed point radian value
 * 
 * Returns:
 * Sint32 - fixed point result
 * 
 * See Also:
 * <spCos>, <spTan>*/
PREFIX Sint32 spSin( Sint32 value );

/* Function: spCos
 * 
 * Calculates the cosinus of a fixed point value
 * 
 * Parameters:
 * value - fixed point radian value
 * 
 * Returns:
 * Sint32 - fixed point result
 * 
 * See Also:
 * <spSin>, <spTan>*/
PREFIX Sint32 spCos( Sint32 value );

/* Function: spTan
 * 
 * Calculates the tangent of a fixed point value
 * 
 * Parameters:
 * value - fixed point radian value
 * 
 * Returns:
 * Sint32 - fixed point result
 * 
 * See Also:
 * <spSin>, <spCos>*/
PREFIX Sint32 spTan( Sint32 value );

/* Function: spAsin
 * 
 * Calculates the arcus sinus of a fixed point value
 * 
 * Parameters:
 * value - fixed point radian value
 * 
 * Returns:
 * Sint32 - fixed point result. If the value out of the range (not between
 * -<SP_ONE> and <SP_ONE>) zero is returned. If you want some error handling, do
 * it yourself.
 * 
 * See Also:
 * <spAcos>*/
PREFIX Sint32 spAsin(Sint32 value);

/* Function: spAcos
 * 
 * Calculates the arcus cosinus of a fixed point value
 * 
 * Parameters:
 * value - fixed point radian value
 * 
 * Returns:
 * Sint32 - fixed point result. If the value out of the range (not between
 * -<SP_ONE> and <SP_ONE>) zero is returned. If you want some error handling, do
 * it yourself.
 * 
 * See Also:
 * <spAsin>*/
PREFIX Sint32 spAcos(Sint32 value);

/* Function: spSqrt
 * 
 * Fast square root for fixed point numbers
 * 
 * Parameters:
 * n - the fixed point value to be square rooted
 * 
 * Returns:
 * Sint32 - square root of n*/
PREFIX Sint32 spSqrt ( Sint32 n );

/* Function: spUnsave_Small_Sqrt
 * 
 * This functions returns the square root of a number between 0 and
 * 1 << <SP_SQRT_ACCURACY>. If you give a number outside this range
 * IT WILL CRASH! So use spSqrt if you are unsure. The light calculation uses
 * this function for fast rendering.
 * 
 * Parameters:
 * n - as said a fixed point value between 0 and 1 << <SP_SQRT_ACCURACY>
 * 
 * Returns:
 * Sint32 - the square root of n. Always keep in mind, that the normal fixed
 * point numbers with shift of <SP_ACCURACY> may not be compatible to this fixed
 * point numbers with shift of <SP_SQRT_ACCURACY>!*/
PREFIX Sint32 spUnsave_Small_Sqrt(Sint32 n);

/* Function: spMin
 * 
 * Returns the smallest of 2 numbers. To get the smallest of three and more
 * numbers, use a tree like function call like: spMin(spMin(a,b),c) or
 * spMin(spMin(a,b),spMin(c,d)).
 * 
 * Parameters:
 * a,b - numbers to compare
 * 
 * Returns:
 * Sint32 - the smaller number. If the numbers are even, it returns the bigger
 * on.
 * 
 * See Also:
 * <spMax>*/
PREFIX Sint32 spMin( Sint32 a, Sint32 b );

/* Function: spMax
 * 
 * Returns the biggest of 2 numbers. To get the biggest of three and more
 * numbers, use a tree like function call like: spMax(spMax(a,b),c) or
 * spMax(spMax(a,b),spMax(c,d)).
 * 
 * Parameters:
 * a,b - numbers to compare
 * 
 * Returns:
 * Sint32 - the bigger number. If the numbers are even, it returns the smaller
 * on.
 * 
 * See Also:
 * <spMin>*/
PREFIX Sint32 spMax( Sint32 a, Sint32 b );

/* Function: spAtof
 * 
 * Converts a string to a Sint32 fixed point number like atof. Be careful, it
 * is slow, especially on devices without FPU. But perfect for loading stuff.
 * 
 * Parameters:
 * buffer - string to convert
 * 
 * Returns:
 * Sint32 - the fixed point value stored in buffer. That means, if buffer is
 * "12.3" the fixed point conversion of 12.3 will be saved, which is 806092 and
 * not 12. ;)*/
PREFIX Sint32 spAtof( char* buffer );

/* Function: spSetRand
 * 
 * Does in fact the same as srand() of the glibc or other implementations. It
 * sets the start value of the random function. However this implementation is
 * deterministic the same on every target, doesn't matter whether Windows, Linux
 * or a Toaster.
 * 
 * Parameters:
 * seed - seed of the Randomness. Default is 0.
 * 
 * See Also:
 * <spRand>*/
PREFIX void spSetRand( Sint32 seed );

/* Function: spRand
 * 
 * Returns a pseudo random number. Don't use it for cryptographic stuff. ;)
 * 
 * Returns:
 * Sint32 - "random" number between 0 and 2^30-1
 * 
 * See Also:
 * <spSetRand>*/
PREFIX Sint32 spRand( void );

/* Function: spAtoFloat
 * 
 * Same as atof, but atof doesn't work correctly on the gp2x for some
 * reason... 
 * 
 * Parameters:
 * buffer - string to convert
 * 
 * Returns:
 * double - the string as double*/
PREFIX double spAtoFloat( char* buffer );

#endif