sinewaves.c

这是在TMS320C5416上实现的吉他发声程序

/*****************************************************************************/
/*                                                                           */
/* FILENAME                                                                  */
/* 	 sinewaves.c                                                             */
/*                                                                           */
/* DESCRIPTION                                                               */
/*   Sinewave generation for the TMS320C5416 DSK.                            */
/*                                                                           */
/*   Generates two sinewaves of adjustable frequency using sine() function   */
/*   in dsplib.lib                                                           */
/*                                                                           */
/*   The frequency of range of the sine wave is 10 Hz to 8000 Hz.            */
/*                                                                           */
/* REVISION                                                                  */
/*   Revision: 1.00	                                                         */
/*   Author  : Richard Sikora                                                */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/* HISTORY                                                                   */
/*   Revision 1.00                                                           */
/*   9th December 2002. Created by Richard Sikora.                           */
/*                                                                           */
/*****************************************************************************/

#include <stdio.h>    /* Required for functions printf() and puts()          */

#include "tms320.h"
#include "dsplib.h"

/*****************************************************************************/
/* generate_sinewave_1()                                                     */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/* Generate a sinewave.                                                      */
/*                                                                           */
/*                                                                           */
/* PARAMETER 1: The frequency of the sinewave between 10 Hz and 16000 Hz.    */ 
/* PARAMETER 2: The maximum amplitude of the sinewave between 1 to 32767.    */
/*                                                                           */
/*****************************************************************************/

signed int generate_sinewave_1( signed short int frequency, 
                                signed short int amplitude)
{
 short int sinusoid;
 signed long result;
 static short int count = 0;
 
 /* Multiply frequency by scaling factor of 32767 / 24000 */
 
 result = (long)( frequency * 22368 ) >> 14 ;
 
 if ( result > 32767)
   {
     result = 32767; /* Maximum value for highest frequency */
   }
 else if ( 0 == result)  
   {
     result = 1;     /* Minimum value for lowest fequency */
   }
 else if ( result < -32767)
   {
     result = -32767;
   }  
 
 count += (signed int) result; 
 
 /* Obtain sine of input */

 sine ( &count, &sinusoid, 1);

 if ( amplitude > 32767 )
   {
     amplitude = 32767; /* Range limit amplitude */
   } 

 /* Scale sine wave to have maximum value set by amplitude */

 result =  (long)( sinusoid * amplitude ) >> 15;
 
 return ( (signed int ) result );
}

/*****************************************************************************/
/* generate_sinewave_2()                                                     */
/*---------------------------------------------------------------------------*/
/*                                                                           */
/* Generate a second sinewave.                                               */
/*                                                                           */
/*                                                                           */
/* PARAMETER 1: The frequency of the sinewave between 10 Hz and 16000 Hz.    */ 
/* PARAMETER 2: The maximum amplitude of the sinewave between 1 to 32767.    */
/*                                                                           */
/*****************************************************************************/

signed int generate_sinewave_2( signed short int frequency, 
                                signed short int amplitude)
{
 short int sinusoid;
 signed long result;
 static short int count = 0;
 
 /* Multiply frequency by scaling factor of ratio 32767 / 48000 */
 
 result = (long)( frequency * 22368 ) >> 14 ;
 
 if ( result > 32767)
   {
     result = 32767; /* Maximum value for highest frequency */
   }
 else if ( 0 == result)  
   {
     result = 1;     /* Minimum value for lowest fequency */
   }
 else if ( result < -32767)
   {
     result = -32767;
   }  
 
 count += (signed int) result; 
 
 /* Obtain sine of input */

 sine ( &count, &sinusoid, 1);

 if ( amplitude > 32767 )
   {
     amplitude = 32767; /* Range limit amplitude */
   } 

 /* Scale sine wave to have maximum value set by amplitude */

 result =  (long)( sinusoid * amplitude ) >> 15;
 
 return ( (signed int ) result );
}



/******************************************************************************/
/* End of sinewaves.c                                                         */
/******************************************************************************/