/*H*****************************************************************************
*
* $Archive::                                                                   $
* $Revision::                                                                  $
* $Date::                                                                      $
* $Author::                                                                    $
*
* DESCRIPTION:  
*	This program contains the various functions for a sine wave
*	a square wave, a saw tooth, and a triangle wave.  It also contains a 
*	scaling function where zero is the minimum and a reverse function
*	
*
* GLOBALS
*
* PUBLIC FUNCTIONS:
*                              
* PRIVATE FUNCTIONS:
*
* USAGE/LIMITATIONS:
*
* NOTES:
*   
* By: Patrick Cresap  
*
*H***************************************************************************/
#define waveforms_c

/*---- compilation control switches ----------------------------------------*/

/*****************************************************************************
* INCLUDE FILES
*****************************************************************************/
/*---- system and platform files -------------------------------------------*/
#include <math.h>
/*---- program files -------------------------------------------------------*/

/*****************************************************************************
* EXTERNAL REFERENCE    
*****************************************************************************/
/*---- data declarations ---------------------------------------------------*/
#define SIN_TABLE_SIZE  256    
extern unsigned short SineTable[SIN_TABLE_SIZE];

/*---- function prototypes -------------------------------------------------*/

/*****************************************************************************
* PUBLIC DECLARATIONS 
*****************************************************************************/

/*---- data declarations ---------------------------------------------------*/
#define SIN_WAVE_POS   0x0000
#define SIN_WAVE_NEG   0x0001

unsigned short sin_wave_count = 0;
unsigned short sin_section    = SIN_WAVE_POS;

/*---- InitSinTable --------------------------------------------------------*/
#define SIN_TABLE_SIZE  256    
#define PI             ( ( double )3.1415927  )
#define SINE_MAX_SCALE_FACTOR   0x7FFE
double sined = 0;
unsigned short SineTable[SIN_TABLE_SIZE];   

#define MAX_VOLTAGE 0x7FFE
#define MIN_VOLTAGE 0x8000                  

unsigned short square_wave_period = 100;
unsigned short square_wave_count  = 0;

#define TRIANGLE_INCREASING_SLOPE           0x0001
#define TRIANGLE_DECREASING_SLOPE           0x0002    
unsigned short triangle_dir  =  TRIANGLE_INCREASING_SLOPE;

#define ZERO_VOLTAGE_NEG        0xFFFE
#define ZERO_VOLTAGE_POS        0x0000

/*****************************************************************************
* PRIVATE DECLARATIONS  
*****************************************************************************/
/*---- context -------------------------------------------------------------*/

/*---- data declarations ---------------------------------------------------*/

/*---- function prototypes -------------------------------------------------*/

/*---- macros --------------------------------------------------------------*/

/*****************************************************************************
* PUBLIC FUNCTION DEFINITIONS
*****************************************************************************/


/*F***************************************************************************
* NAME: unsigned short saw_wave ( unsigned short data )
*
* DESCRIPTION:  
*	creates a saw wave.  
*
* NOTES:
*
*F***************************************************************************/ 

unsigned short saw_wave ( unsigned short data )
{   
	/*-- this value determines the slope of the wave ----------------------*/
	int saw_wave_inc = 0x80;
	
	data += saw_wave_inc;	
	
	return data;
}            


/*F***************************************************************************
* NAME: unsigned short square_wave ( unsigned short data )
*
* DESCRIPTION:  
*	creates a square wave
*
* NOTES:
*
*F***************************************************************************/                                                                            

unsigned short square_wave ( unsigned short data )
{
	square_wave_count++;
	if ( square_wave_count == square_wave_period )
	{
		if ( data == MIN_VOLTAGE )
		{
			data = MAX_VOLTAGE;
		}
		else
		{                    
			data= MIN_VOLTAGE;
		}
		square_wave_count = 0;
	}         
	return data;
}                  

/*F***************************************************************************
* NAME: unsigned short triangle_wave ( unsigned short data )
*
* DESCRIPTION:  
*	creates a triangle wave  
*
* NOTES:
*
*F***************************************************************************/ 
unsigned short triangle_wave ( unsigned short data )
{
	/*-- the slope of the wave ---------------------------------------------*/
	unsigned short triangle_wave_inc = 0x80;
	unsigned short temp;
	
	
	if ( data <= MAX_VOLTAGE )
	{
	    switch ( triangle_dir )
	    {
	    	case TRIANGLE_INCREASING_SLOPE:
	    		temp = data + triangle_wave_inc; 
				if (temp > MAX_VOLTAGE) /* at peak */
				{                 
				    data = MAX_VOLTAGE;
				    triangle_dir = TRIANGLE_DECREASING_SLOPE;
				}  
				else 
				{
				    data = temp;
	   		    }
	   		    break;
	   		case TRIANGLE_DECREASING_SLOPE:
	   			if ( data < triangle_wave_inc  )
				{   
				    data = ZERO_VOLTAGE_NEG;
					triangle_dir = TRIANGLE_DECREASING_SLOPE;
				}
				else
				{  
				    data -= triangle_wave_inc;
				}
				break;	
			default:
				break;
		}
	}
	else /* data > MIN_VOLTAGE */
	{
		switch ( triangle_dir )
		{
			case TRIANGLE_INCREASING_SLOPE:
				temp = data + triangle_wave_inc;
				if ( (ZERO_VOLTAGE_NEG - data) < triangle_wave_inc )
				{                           
					data = ZERO_VOLTAGE_POS;    
					triangle_dir = TRIANGLE_INCREASING_SLOPE;
				}
				else
				{
					data += triangle_wave_inc;
				}
				break;
			case TRIANGLE_DECREASING_SLOPE:               
	    		temp = data - triangle_wave_inc;
				if ( temp < MIN_VOLTAGE ) /* at trough */
				{
					triangle_dir = TRIANGLE_INCREASING_SLOPE;
					data = MIN_VOLTAGE;
				}
				else
				{
					data = temp;
				}
				break;
			default:
				break;
		}
	}
	return ( data );
}

/*F***************************************************************************
* NAME: void Init_Sin_Table ( void )
*
* DESCRIPTION:
*	Uses a predefined table of the positive half of a sine wave to create
*	a sin wave
*	
* NOTES:
*	
*F***************************************************************************/                                      

void Init_Sin_Table ( void )
{         
	unsigned short x =0;
	double increment= 0;
	double radian = 0;
	double ScaleSine = 0;
	
	for (x=0; x <= (SIN_TABLE_SIZE - 1); x++)
	{
		SineTable[x]=0;
	}	
	
	increment = PI / SIN_TABLE_SIZE; 
	
	for (x=0; x <= (SIN_TABLE_SIZE - 1); x++)
	{              
		ScaleSine = sin(radian);
		SineTable[x] = ( unsigned short ) ( ScaleSine * SINE_MAX_SCALE_FACTOR);
		radian += increment;
	}                                  
}

/*F***************************************************************************
* NAME: unsigned short sin_wave ( )
*
* DESCRIPTION:
*	Uses a predefined table of the positive half of a sine wave to create
*	a sin wave
*	
* NOTES:
*	
*F***************************************************************************/                                      

unsigned short sin_wave ( )
{           
	unsigned short data;
	sin_wave_count++;               
	/* after going through half of the sine wave (or through the entire sine
	*  table), it switches over and does the other half of the sine wave.
	*/
	if (sin_wave_count == SIN_TABLE_SIZE)
	{
		sin_wave_count = 0;
		data = SineTable[SIN_TABLE_SIZE-1];
		if (sin_section == SIN_WAVE_NEG)
		{
			sin_section = SIN_WAVE_POS;
		}
		else 
		{
			sin_section = SIN_WAVE_NEG;
		}
	}        
	/*-- produces the bottom or negative half of the sine wave -------------*/
	else if (sin_section == SIN_WAVE_NEG)
	{
		data = SineTable[sin_wave_count];
		data = 0xFFFE - data;
	}                          
	/*-- produces the top or positive half of the sine wave -------------*/
	else 
	{
		data = SineTable[sin_wave_count];
	}                                    
	          	
	data &= 0xFFFE;
	
	return data;

}

/*F***************************************************************************
* NAME: unsigned short reverse_zero_min_scale ( unsigned short data )
*
* DESCRIPTION:  
*	if the user wishes to use 0 as the minimum and 0xFFFE as the maximum, this
*	reverses the conversion from zer0_min_scale so that the user's values and
*	the codec values are seperated.
*
* NOTES:
*	reverses zero_min_scale
*F***************************************************************************/                                      
                                             
unsigned short reverse_zero_min_scale ( unsigned short data )
{
	if ( data >= 0x8000 )
	{
		data = data + 0x8000;
	}                        
	else
	{
		data = data - 0x8000;
	}
	return data;
}                            

/*F***************************************************************************
* NAME: unsigned short zero_min_scale ( unsigned short data )
*
* DESCRIPTION:  
*	if the user wishes to use 0 as the minimum and 0xFFFE as the maximum, this
*	will convert the value to the proper codec values
*
* NOTES:
*	to reverse it, use reverse_zero_min_scale
*F***************************************************************************/                                      

unsigned short zero_min_scale ( unsigned short data )
{
	if ( data >= 0x8000 )
	{
		data = data - 0x8000;
	}                        
	else            
	{
		data = data + 0x8000;
	}                        
	return data;
}