//
// Copyright:     Copyright 2003 Craig Stuart Sapp
// Programmer:    Craig Stuart Sapp <craig@ccrma.stanford.edu>
// Creation Date: Tue Mar 11 10:16:26 PST 2003
// Last Modified: Tue Mar 11 10:16:28 PST 2003
// Filename:      osc.c
// Web Address:   http://peabody.sapp.org/class/dmp2/lab/osc/osc.c
// Syntax:        C; Max4/MSP2 External Object; CodeWarrior 6.0
// OS:            Mac OS 9; PPC
//
// Description:   A non-wavetable sinewave oscillator generating object.
//

#include "ext.h"
#include "z_dsp.h"
#include <cmath>              /* included for use of cos() function */

#ifndef TWOPI
   #define TWOPI 6.28318530718
#endif

typedef struct {
   t_pxobject msp_data;       // must always be the first field; used by MSP
   float      currentphase;   // the current phase of the oscillator
   float      phaseincrement; // related to the frequency input
} MyObject;

void* object_data;            // pointer to data for object (created in setup());

// function declarations:
void   main             (void);
void*  create_object    (void);
void   MessageDSP       (MyObject* mo, t_signal** signal, short* count);
void   InputFrequency   (MyObject* mo, float value);
void   InputPhase       (MyObject* mo, float value);
t_int* Perform          (t_int *parameters);
float  randfloat        (void);


//////////////////////////////////////////////////////////////////////////
//
// Initialization functions:
//


void main(void) {
   setup((t_messlist**)&object_data, (method)create_object, (method)dsp_free,
         (short)sizeof(MyObject), NULL, A_NOTHING);             
   addfloat((method)InputFrequency);     // input 1
   addftx((method)InputPhase, 1);        // input 2
   addmess((method)MessageDSP,   "dsp",   A_CANT, A_NOTHING);
   dsp_initclass();
}


 
//////////////////////////////
//
// create_object -- object initializing function.  
//

void* create_object(void) {
   MyObject *mo = (MyObject*)newobject(object_data);
   dsp_setup((t_pxobject*)mo, 1);           // create one signal input (ignored)
   outlet_new((t_pxobject*)mo, "signal");   // output 1
   floatin(mo, 1);                          // input 2
   InputPhase(mo, 0.0);
   InputFrequency(mo, 440.0);
   return mo;
}


//////////////////////////////////////////////////////////////////////////
//
// Behavior functions:
//


//////////////////////////////
//
// MessageDSP -- What to do when a "dsp" message arrives into the object.
//

void MessageDSP(MyObject* mo, t_signal** signal, short* count) {
   #pragma unused(mo)
   #pragma unused(count)
   dsp_add(Perform, 5, 5, mo, signal[0]->s_vec, signal[1]->s_vec, signal[0]->s_n);
}



//////////////////////////////
//
// InputFrequency -- handle input of the frequency in Hertz.
//   the Max/MSP function sys_getsr() returns the sampling rate.
//

void InputFrequency(MyObject *mo, float value) {
   static float factor = TWOPI / sys_getsr();
   mo->phaseincrement = value * factor;
}



//////////////////////////////
//
// InputPhase -- set the exact phase of the oscillator.
//    the phase is in radians, where 0 and 2 pi are the same phase position.
//

void InputPhase(MyObject *mo, float value) {
   mo->currentphase = value;
}



//////////////////////////////
//
// Perform -- do the calculations for one sample group.
//

t_int* Perform(t_int *parameters) {
   long      pcount = (long)     (parameters[1]);
   MyObject *mo     = (MyObject*)(parameters[2]);
   t_float  *input  = (t_float*) (parameters[3]);
   t_float  *output = (t_float*) (parameters[4]);
   long      count  = (int)      (parameters[5]);
   long      i;
   
   // the input is ignored, but Max/MSP crashes when it is not created.
   for (i=0; i<count; i++) {
      output[i] = cos(mo->currentphase);
      mo->currentphase += mo->phaseincrement;
   }

   // prevent round-off error from occuring with floats.
   if (mo->currentphase > TWOPI) {
      mo->currentphase -= TWOPI;
   }

   return parameters+pcount+1;   
}