noise.cpp

来自「Mobile STK for Symbian OS V0.1」· C++ 代码 · 共 77 行

/***************************************************/
/*! \class Noise
    \brief STK noise generator.

    Generic random number generation using the
    C rand() function.  The quality of the rand()
    function varies from one OS to another.

    by Perry R. Cook and Gary P. Scavone, 1995 - 2005.
*/
/***************************************************/

#include "Noise.h"
#if !defined(SYMBIAN)
#include <stdlib.h>
#include <time.h>
#else
#include "symbmath.h"
#include "debug.h"
#undef DEBUG
#endif

Noise :: Noise() : Generator()
{
  // Seed the random number generator with system time.
  this->setSeed( 0 );
  lastOutput_ = (StkFloat) 0.0;
  dcnt = 0;
}

Noise :: Noise( unsigned int seed ) : Generator()
{
  // Seed the random number generator
  this->setSeed( seed );
  lastOutput_ = (StkFloat) 0.0;
  dcnt = 0;
}

Noise :: ~Noise()
{
}

void Noise :: setSeed( unsigned int seed )
{
  if ( seed == 0 )
#if !defined(SYMBIAN)
    srand( (unsigned int) time(NULL) );
#else
  {
	  unsigned int seed = (unsigned int) User::TickCount();
	  srand( seed );
  }
#endif
  else
    srand( seed );
}

StkFloat Noise :: computeSample()
{
	TUint32 trnd;

	trnd = rand();
	trnd = trnd & 0x7fffffff;

  lastOutput_= (StkFloat) (2.0 * trnd / (RAND_MAX + 1.0) );
  lastOutput_ -= 1.0;
#ifdef DEBUG
    if(dcnt < 5)
	{
  	CStaticDebug::WriteIntN((TInt)(lastOutput_*1000));
	dcnt ++;
	}
#endif
  return lastOutput_;
}