//-----------------------------------------------------------------------------
// name: ksvoice.cpp
// desc: sample class for Karplus Strong
//
// Music 256a, Fall 2009, Stanford University
//     http://ccrma.stanford.edu/courses/256a-fall-2009/
//-----------------------------------------------------------------------------
#include "ksvoice.h"
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;


KSVoice::KSVoice()
{
    // initialize members
    m_delay = NULL;
    m_delayMax = 200000;
    m_delayLen = 800;
    m_factor = .99;
    m_prev = 0.0;
    m_writer = 0;
    m_reader = 0;
    m_pluck = 0;
}


bool KSVoice::init( long delayLen )
{
    // check
    if( delayLen > m_delayMax )
    {
        cerr << "BAD! requested delay length exceeds hard coded max" << endl;
        return false;
    }
    
    // set delayLen
    m_delayLen = delayLen;
    // dynamically allocate delay line
    m_delay = new SAMPLE[m_delayMax];
    // zero out
    memset( m_delay, 0, m_delayMax*sizeof(SAMPLE) );
    // set indices
    m_reader = m_writer - m_delayLen;
    // wrap
    if( m_reader < 0 ) m_reader += m_delayMax;
    
    return true;
}


void KSVoice::pluck()
{
    m_pluck = m_delayLen;
}


void KSVoice::synthesize( SAMPLE * buffy, long numFrames )
{
    // sanity check
    assert( m_delay != NULL );
    
    for( long i = 0; i < numFrames; i++ )
    {
        // write into the buffer
        if( m_pluck > 0 )
        {
            m_delay[m_writer] = ((SAMPLE)rand() / RAND_MAX)*2 - 1;
            m_pluck--;
        }
        else m_delay[m_writer] = 0.0;
        
        // feedback, attenuation, and moving average
        m_delay[m_writer] += m_factor * (.5 * m_delay[m_reader] + .5 * m_prev);
        
        // remember the previous output
        m_prev = m_delay[m_reader];
        // read out of the buffer
        buffy[i] = m_delay[m_reader];
        
        // increment
        m_writer++; m_reader++;        
        // wrap
        m_writer %= m_delayMax;
        m_reader %= m_delayMax;
    }
}