NMODL and MOD2C pass different weight indices during initialisation

[olupton]

In the nrn_init_... method generated by NMODL for, for example, Gfluct3.mod there is a call

net_send_buffering(ml->_net_send_buffer, 0, inst->tqitem[2*pnodecount+id], -1, inst->point_process[1*pnodecount+id], nt->_t+0.0, 1.0);

where the 4th argument is -1, but in the MOD2C equivalent 0 is passed. This does not appear to have any effect on whether the tests pass, but it would be good to understand if this difference is a bug or not.

[alkino]

I think here we should get attention form @nrnhines

[pramodk]

@alkino : this is NMODL bug. We need to compare with MOD2C implementation and find out why/how NMODL doing it differently.

[pramodk]

Looking into MOD2C for _net_send_buffering function:

static void _net_send_buffering(NetSendBuffer_t* _nsb, int _sendtype, int _i_vdata, int _weight_index, int _ipnt, double _t, double _flag)

the 4th parameter is weight_index. If I look into how the _net_send_buffering() is printed in mod2c at this :

_net_send_buffering(_ml->_net_send_buffer, 0, _tqitem, 0, _ppvar[1*_STRIDE], t +  0.0 , %s );\n"

and this point

void acc_net_add(Item * qname, Item * qpar1, Item * qexpr, Item * qpar2,
        const char * xarg1,
            const char * xarg2) {
        Item * q;
        if (artificial_cell) {
            return;
        }
        sprintf(buf, "\
                n _net_send_buffering(_ml -> _net_send_buffer, % s\ ", xarg1);

.....
                      }else if (strcmp(SYM(qname)->name, "net_send") == 0) {
			if (blocktype == NETRECEIVE) {
			    acc_net_add(qname, qpar1, qexpr, qpar2, "0, _tqitem, _weight_index, _ppvar[1*_STRIDE],", "");
			    Insertstr(qpar1 -> next, "_tqitem, _weight_index, _pnt,");
			} else if (blocktype == INITIAL1) {
			    net_send_buffer_in_initial = 1;
			    acc_net_add(qname, qpar1, qexpr, qpar2, "0, _tqitem, 0,  _ppvar[1*_STRIDE],", "");
			    Insertstr(qpar1 -> next, "_tqitem, -1, (Point_process*) _nt->_vdata[_ppvar[1*_STRIDE]],");
			} else {
			    diag("net_send allowed only in INITIAL and NET_RECEIVE blocks", (char * ) 0);
			}
	             } else if (strcmp(SYM(qname) -> name, "net_event") == 0) {
			    net_event_seen_ = 1;
			    if (blocktype == NETRECEIVE) {
			        acc_net_add(qname, qpar1, qexpr, qpar2, "1, -1, -1,  _ppvar[1*_STRIDE],", ", 0.");
			        Insertstr(qpar1 -> next, "_pnt,");
			    } else {
			        diag("net_event", " only allowed in NET_RECEIVE block");
			    }
		      } else if (strcmp(SYM(qname) -> name, "net_move") == 0) {
			    if (artificial_cell) {
			        replacstr(qname, "artcell_net_move");
			    }
			    if (blocktype == NETRECEIVE) {
			        acc_net_add(qname, qpar1, qexpr, qpar2, "2, _tqitem, -1, _ppvar[1*_STRIDE],", ", 0.");
			        Insertstr(qpar1 -> next, "_tqitem, _pnt,");
			    } else {
			        diag("net_move", " only allowed in NET_RECEIVE block");
			    }
			}

The summary from above is:

• If we have net_send event then
  • weight_index is used for NET_RECEIVE block
  • 0 is used for INITIAL block
  • all others are error because net_send allowed only in INITIAL and NET_RECEIVE blocks
• If we have net_event event then
  • -1 is used for NET_RECEIVE block
  • all others are error because net_event only allowed in NET_RECEIVE block
• If we have net_move event then
  • -1 is used for NET_RECEIVE block
  • all others are error because net_move only allowed in NET_RECEIVE block