AAX_RandomGen.h

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/*================================================================================================*/
/*
 *  Copyright 2013-2015, 2023 Avid Technology, Inc.
 *  All rights reserved.
 *  
 *  CONFIDENTIAL: this document contains confidential information of Avid. Do
 *  not disclose to any third party. Use of the information contained in this
 *  document is subject to an Avid SDK license.
 */
 
/*================================================================================================*/
#pragma once
 
#ifndef AAX_RANDOMGEN_H
#define AAX_RANDOMGEN_H
 
// Standard headers
#include <stdlib.h>
#include <time.h>
#include <stdint.h>
 
#include "AAX_PlatformOptimizationConstants.h"
#include "AAX_Constants.h"
 
namespace AAX
{
 
const float cSeedDivisor = 1/127773.0f;
 
const int32_t cInitialSeedValue=0x00F54321;
 
/*===================================================================================================*/
inline int32_t GetInt32RPDF(int32_t* iSeed)
{
    // Requirement: iSeed param must be a static in the calling function.
    int64_t seed = *iSeed;
    int64_t k = static_cast<int64_t>(seed*cSeedDivisor);
    seed = 16807 * (seed - k * 127773LL) - 2836 * k + 7395;
    *iSeed = static_cast<int32_t>(seed);
    if (*iSeed < 0) 
        *iSeed += 2147483647;
    return (*iSeed - 1073741824) * 2;       // -2147483647..+2147483647
}
 
/*===================================================================================================*/
 
 
inline int32_t GetFastInt32RPDF(int32_t* iSeed)
{
   *iSeed = (*iSeed * 196314165) + 907633515;
   return *iSeed;
}
 
/*===================================================================================================*/
inline float GetRPDFWithAmplitudeOneHalf(int32_t* iSeed)        //An amplitude of 0.5 = 1 LSBs
{
    // Requirement: iSeed param must be a static in the calling function.
    return float(cNormalizeLongToAmplitudeOneHalf) * float(GetInt32RPDF(iSeed));
}
 
/*===================================================================================================*/
inline float GetRPDFWithAmplitudeOne(int32_t* iSeed)            //An amplitude of 1.0 = 2 LSBs
{
    // Requirement: iSeed param must be a static in the calling function.
    return float(cNormalizeLongToAmplitudeOne) * float(GetInt32RPDF(iSeed));
}
 
/*===================================================================================================*/
inline float GetFastRPDFWithAmplitudeOne(int32_t* iSeed)            //An amplitude of 1.0 = 2 LSBs
{
    // Requirement: iSeed param must be a static in the calling function.
    return float(cNormalizeLongToAmplitudeOne) * float(GetFastInt32RPDF(iSeed));
}
 
/*===================================================================================================*/
inline float GetTPDFWithAmplitudeOne(int32_t* iSeed)            //An amplitude of 1.0 = 2 LSBs
{
    // Generate a random number with a triangular pdf (tpdf) using two 
    // separate rectangular pdf noise sources.
 
    // We are using only one seed input for both rect pdf noise generators, 
    // but because they are of course executed sequentially independent noise 
    // will be produced.
 
    return float(cNormalizeLongToAmplitudeOne) * (float(GetFastInt32RPDF(iSeed) + float(GetFastInt32RPDF(iSeed))));
}
 
} // namespace AAX
 
#endif // AAX_RANDOMGEN_H