Max 5 API Reference

urner.c

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/**
    @file
    urner - a max object shell
    jeremy bernstein - jeremy@bootsquad.com 

    @ingroup    examples    
*/

// The standard random() function is not standard on Windows.
// We need to do this to setup the rand_s() function.
#ifdef WIN_VERSION
#define _CRT_RAND_S
#endif

#include "ext.h"                            // standard Max include, always required
#include "ext_obex.h"                       // required for new style Max object


////////////////////////// object struct
typedef struct _urner 
{
    t_object                    ob;         // the object itself (must be first)
    char                        *table; // lookup table for urn values
    long                        count; // number of values already picked
    
    void                        *bangout; // bang when urn is empty
    void                        *out; // random num
} t_urner;

///////////////////////// function prototypes
//// standard set
void *urner_new(t_symbol *s, long argc, t_atom *argv);
void urner_free(t_urner *x);
void urner_assist(t_urner *x, void *b, long m, long a, char *s);
//// additional methods
void urner_bang(t_urner *x); // incoming bang message
void urner_reset(t_urner *x); // incoming reset message

//////////////////////// global class pointer variable
void *urner_class;


int main(void)
{   
    t_class *c;
    
    c = class_new("urner", (method)urner_new, (method)urner_free, (long)sizeof(t_urner), 0L, A_GIMME, 0);

    class_addmethod(c, (method)urner_bang,      "bang",     0);
    class_addmethod(c, (method)urner_reset,     "reset",    0);
    class_addmethod(c, (method)urner_assist,    "assist",   A_CANT, 0);  

    class_register(CLASS_BOX, c);
    urner_class = c;

    post("I am the urner object");
    return 0;
}

void urner_assist(t_urner *x, void *b, long m, long a, char *s)
{
    if (m == ASSIST_INLET) { //inlet
        sprintf(s, "I am inlet %ld", a);
    } 
    else {  // outlet
        sprintf(s, "I am outlet %ld", a);           
    }
}

void urner_reset(t_urner *x)
{
    long i;
    long size = sysmem_ptrsize(x->table);
    
    for (i = 0; i < size; i++) {
        x->table[i] = 0; // zero table
    }
    x->count = 0;
}

void urner_bang(t_urner *x)
{
    long rand;
    long size = sysmem_ptrsize(x->table); // RETURNS SIZE OF POINTER IN BYTES

#ifdef WIN_VERSION
    rand_s(&rand);
#else
    rand = random();
#endif

    rand = rand % size;

    if (x->count == size) {
        outlet_bang(x->bangout); // SEND A BANG WHEN WE'VE HIT MAXIMUM
        return;
    }
    
    if (x->table[rand] != 0) { // NUMBER HAS ALREADY BEEN CHOSEN
        do {
#ifdef WIN_VERSION
            rand_s(&rand);
#else
            rand = random();
#endif
            rand = rand % size;
        } while (x->table[rand] != 0);
    } 
    
    // WE GOT A NUMBER
    x->table[rand] = 1; // MARK THIS VALUE AS USED
    x->count++; // INCREMENT OUR COUNT
    outlet_int(x->out, rand);
}


void urner_free(t_urner *x)
{
    sysmem_freeptr(x->table); // FREE ALLOCED MEMORY
}

void *urner_new(t_symbol *s, long argc, t_atom *argv)
{
    t_urner *x = NULL;
    long size;
    
    if (argc < 1) return NULL;
    
    size = atom_getlong(argv); // SIZE OF OUR URN
    if (size < 1) return NULL; // CHECK FOR INVALID DATA
    
    if (x = (t_urner *)object_alloc(urner_class)) {
        x->table = (char *)sysmem_newptrclear(size); // size BYTES for the alloced pointer
        urner_reset(x); // initializes x->count
        
        x->bangout = outlet_new(x, NULL); // rightmost outlet first
        x->out = outlet_new(x, NULL); // then to the left
    }
    return (x);
}

Copyright © 2008, Cycling '74