amf_peakhold.c

ADI SHARC DSP 音频算法标准模块库

// Copyright(c) 2003 Analog Devices, Inc. All Rights Reserved. ADI Confidential.

// File    : $Id: //depot/development/visualaudio/modules/2.5.0/SHARC/Source/AMF_PeakHold.c#3 $ 
// Part of : VisualAudio V2.5.0 
// Updated : $Date: 2006/10/12 $ by $Author: Fernando $

#include "AMF_PeakHold.h"
#include "math.h"


void AMF_PeakHold_Render(AMF_PeakHold * restrict instance,AMF_Signal * restrict * buffers,int tickSize);

SEG_MOD_FAST_CODE  void AMF_PeakHold_Render(AMF_PeakHold * restrict instance,AMF_Signal * restrict * buffers,int tickSize) {
    int i;

    AMF_Signal *in = buffers[0];

    // parameters
    float attackCoef = instance->attackCoef;
    float decayCoef = instance->decayCoef;

    // states
    float *state = &instance->state[0];
    
    // local variables    
    float maxInput, envCoef;
    
    // find maximum input value in tick
    maxInput = 0;
    for(i=0;i<tickSize;i++)
        maxInput = fmaxf(maxInput, in[i]);
    
       // determine if envelope detector is in attack or release    
    if(state[0] < maxInput) 
        envCoef = attackCoef;
    else 
        envCoef = decayCoef;

    // move value of state into part of array that can be
    // modified by inspector
    state[1] = fmaxf(state[0],state[1]);

    // one pole filter for envelope detector, 
    // where filter coef is determined above 
    state[0] = envCoef*maxInput + (1.0-envCoef)*state[0];
}

SEG_MOD_SLOW_CONST const AMF_ModuleClass AMFClassPeakHold = {
    
    /* Flags */
    0,
     
    /* Render function */
    (AMF_RenderFunction)AMF_PeakHold_Render,  // render function 
    
    /* Default bypass */
    (void *)0,
    
    /* Input descriptor - one input. */
    1, 0,

    /* Output descriptor - no ouputs, and control rate if there was one. */
    0, AMF_ControlPin(1)
};