#include "m_pd.h"
#include <stdio.h> 
#include <sys/shm.h> 
#include <sys/stat.h> 

typedef struct shmem
{
  t_object x_obj;
  int segment_id;
  t_float *share_memory; 
  int segment_size; 
} t_shmem;

inline t_float min(t_float x1,t_float x2)
{
	if (x1 <= x2) {
		return x1;
	} else {
		return x2;
	}
}

void shmem_set(t_shmem *x, t_symbol *unused, int argc, t_atom *argv)
{

    t_garray *a;
    int npoints;
	int array_offset;
    t_word *vec;
    int i, index_max, shmem_offset;

	if (argc <= 1) {
		pd_error(x, "shmem usage : memset offset data (data can be a float, a list, or a table name)");
		return;
	}
	if (argv[0].a_type != A_FLOAT) {
		pd_error(x, "shmem usage : memset offset data (data can be a float, a list, or a table name)");
		return;
	}

	shmem_offset = atom_getfloatarg(0,argc,argv);
	if (shmem_offset < 0) shmem_offset=0;

	if (argv[1].a_type == A_SYMBOL) { // argument is an arrayname
		t_symbol *s = atom_getsymbolarg(1,argc,argv);
		if (!(a = (t_garray *)pd_findbyclass(s, garray_class)))
			pd_error(x, "%s: no such array", s->s_name);
		else if (!garray_getfloatwords(a, &npoints, &vec))
			pd_error(x, "%s: bad template for tabread", s->s_name);
		else {
			if (argc == 2) { // memset index_mem arrayname
				index_max = min(x->segment_size-shmem_offset,npoints);
				// post("i=%d", index_max);
				for (i=0; i<index_max; i++)
					x->share_memory[i+shmem_offset] = vec[i].w_float;
				}
			else if (argc == 3) { // memset index_mem arrayname array_offset
				array_offset = atom_getfloatarg(2,argc,argv);
				index_max = min(x->segment_size-shmem_offset,npoints-array_offset);
				//post("i=%d", x->segment_size-shmem_offset);
				//post("i=%d", npoints);
				//post("i=%d", index_max);
				for (i=0; i<index_max; i++)
					x->share_memory[i+shmem_offset] = vec[i+array_offset].w_float;
			}
		}
	}
	else if (argv[1].a_type == A_FLOAT) { // argument is a float
		index_max = x->segment_size - shmem_offset;
		if (index_max > argc-1) index_max = argc-1;
		for (i=0; i<index_max ; i++)
			x->share_memory[i+shmem_offset]=atom_getfloatarg(i+1, argc, argv);
	}
}

void shmem_dump(t_shmem *x, t_symbol *unused, int argc, t_atom *argv)
{
    int i, vecsize, index_max, shmem_offset;
    t_garray *a;
    t_word *vec;

	if (argc == 0) {
		pd_error(x, "shmem usage : memdump offset dest (dest can be nothing (outlet), or a table name)");
		return;
	}
	if (argv[0].a_type != A_FLOAT) {
		pd_error(x, "shmem usage : memdump offset dest (dest can be nothing (outlet), or a table name)");
		return;
	}
   	shmem_offset = atom_getfloatarg(0,argc,argv);
   	if (shmem_offset < 0) shmem_offset = 0;
   	if (shmem_offset > x->segment_size-1) i = x->segment_size-1;
    // post("i=%d", offset);

	if (argc == 1)
	   	outlet_float(x->x_obj.ob_outlet, x->share_memory[shmem_offset]);
	else if (argv[1].a_type == A_SYMBOL) { // argument is an arrayname
		t_symbol *s = atom_getsymbolarg(1,argc,argv);
	    if (!(a = (t_garray *)pd_findbyclass(s, garray_class)))
	        pd_error(x, "%s: no such array", s->s_name);
	    else {
	        if (!garray_getfloatwords(a, &vecsize, &vec))
	            pd_error(x, "%s: bad template for tabwrite", s->s_name);
	        else {
	            index_max = x->segment_size-shmem_offset;
	            if (index_max > vecsize)
	                index_max = vecsize;
	            // post("i=%d", index_max);
	            for (i=0; i<index_max; i++)
	                vec[i].w_float = x->share_memory[i+shmem_offset];
	        }
	        garray_redraw(a);
	    }	
	}
}

t_class *shmem_class;

void *shmem_new( t_floatarg id,  t_floatarg size)
{  
    struct shmid_ds shmbuffer; 
    // post ("id, size: %f, %f", id, size); 
    t_shmem *x = (t_shmem *)pd_new(shmem_class);

    x->segment_size = (int)size;
    x->segment_id  =  shmget  ((int)id,  sizeof(t_float)*x->segment_size, 
        IPC_CREAT | S_IRUSR | S_IWUSR | S_IROTH | S_IWOTH); 
    if(x->segment_id>0) {
        x->share_memory = (t_float*) shmat (x->segment_id, 0, 0); 
        // post("shmem memory attached at address %p\n", x->share_memory); 

        shmctl (x->segment_id, IPC_STAT, &shmbuffer); 
        // post ("segment size: %d\n", shmbuffer.shm_segsz); 

	    if ((int)shmbuffer.shm_segsz < (int)sizeof(t_float)*x->segment_size) {
	        // there was a problem, set object meme size to 0
	        error("could not allocate shmem memory Id : %d, size %d", (int)id,  x->segment_size );
	        x->segment_size = 0;
   		}
	}
	else {
		error("could not allocate shmem memory Id : %d, size %d", (int)id,  x->segment_size );
        x->segment_size = 0;
	}

    outlet_new(&x->x_obj, 0);
    return (void *)x;
}

void shmem_free(t_shmem *x)
{
	shmdt (x->share_memory);
	shmctl (x->segment_id, IPC_RMID, 0); 
}

void shmem_clear(t_shmem *x)
{
	int i;
	for (i=0; i<x->segment_size; i++)
		x->share_memory[i] = 0;
}

void shmem_setup(void)
{
    shmem_class = class_new(gensym("shmem"), (t_newmethod)shmem_new, (t_method)shmem_free,
        sizeof(t_shmem), 0, A_DEFFLOAT, A_DEFFLOAT, 0);
    class_addmethod(shmem_class, (t_method)shmem_set, gensym("memset"), A_GIMME, 0);
    class_addmethod(shmem_class, (t_method)shmem_dump, gensym("memdump"), A_GIMME, 0);
    class_addmethod(shmem_class, (t_method)shmem_clear, gensym("memclear"), 0);
}