//
// Programmer:    Craig Stuart Sapp <craig@ccrma.stanford.edu>
// Creation Date: Wed Jan 29 04:20:01 PST 2003
// Last Modified: Tue Feb  4 05:47:19 PST 2003
// Filename:      mydiff.c
// Web Address:   http://peabody.sapp.org/class/dmp2/lab/mydiff/mydiff.c
// Derived from:  Fujinaga's Max/MSP Externals Tutorial, v2.41, p. 7-8
// Syntax:        C; Max4/MSP2 External Object; CodeWarrior 6.0
// OS:	          Mac OS 9; PPC
//
// Description:   Subtracts the second input integer from the
//     		  first input integer.
//

#include "ext.h"

typedef struct {
   t_object maxData;      // Max/MSP data, MUST come first in struct

   long     leftval;      // first input value
   long     rightval;     // second input value

   void*    output;       // output bang function pointer
} MyObject;

void* objectdata = NULL;

// function declarations:
void*  createObject (long value);
void   InputLeft    (MyObject* mo, long value);
void   InputRight   (MyObject* mo, long value);
void   Bang         (MyObject* mo);


//////////////////////////////
//
// main -- called once when the object is created in a patcher window.
//

void main(void) {
   setup((t_messlist**)&objectdata, (method)createObject, NULL, 
      sizeof(MyObject), NULL, A_DEFLONG, A_NOTHING);

   addbang((method)Bang);
   addint ((method)InputLeft);
   addint ((method)InputRight, 1);
}



//////////////////////////////
//
// createObject -- create the data storage for the mydiff object and
//     and setup input 1.
//

void* createObject(long value) {
   MyObject *mo;
   mo = (MyObject*)newobject(objectdata);

   mo->leftval  = 0;
   mo->rightval = value; 
   mo->output   = intout(mo);

   intin(mo, 1);
   return mo;
}



//////////////////////////////
//
// InputLeft -- behavior of the object when a new number comes
//    in on inlet 0.
//

void InputLeft(MyObject* mo, long value) {
   mo->leftval = value;
   Bang(mo);
}



//////////////////////////////
//
// InputRight -- behavior of the object when a new number comes
//    in on inlet 1.
//

void InputRight(MyObject* mo, long value) {
   mo->rightval = value;
}



//////////////////////////////
//
// Bang -- behaviour of the object when a "bang" message is received.
//

void Bang(MyObject* mo) {
   outlet_int(mo->output, mo->leftval - mo->rightval);
}