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[WIP] Fixing Subtraction CIN Bug #3261

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[WIP] Fixing Subtraction CIN Bug #3261

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7c82726
Fixed output port size to be defined output port y size instead of in…
loglav03 Jun 19, 2025
4f87a31
Merge branch 'master' into Sub_Cin_Bug_Fix
loglav03 Jul 22, 2025
b61db0f
Attempting fixes for sub_cin_bug
loglav03 Jul 25, 2025
8db8825
Connected GND and VCC to inputs of last adder in chain
loglav03 Aug 1, 2025
6f2f206
Merge branch 'master' into Sub_Cin_Bug_Fix
loglav03 Aug 20, 2025
8ea75c8
Attempting to fix tail slice output connections
loglav03 Aug 21, 2025
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98 changes: 73 additions & 25 deletions parmys/parmys-plugin/core/subtractor.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -501,7 +501,7 @@ void split_adder_for_sub(nnode_t *nodeo, int a, int b, int sizea, int sizeb, int

if ((flag == 0 || count > 1) && !configuration.adder_cin_global) {
// connect the a[0] of first adder node to ground, and b[0] of first adder node to vcc
connect_nodes(netlist->gnd_node, 0, node[0], 0);
connect_nodes(netlist->vcc_node, 0, node[0], 0);
connect_nodes(netlist->vcc_node, 0, node[0], sizea);
// hang the first sumout
node[0]->output_pins[1] = allocate_npin();
Expand All @@ -516,14 +516,25 @@ void split_adder_for_sub(nnode_t *nodeo, int a, int b, int sizea, int sizeb, int

// for normal subtraction: if any input pins beside intial cin is NULL, it should connect to unconn
// for unary subtraction: the first number should has the number of a input pins connected to gnd. The others are as same as normal subtraction
int tail = count -1;
for (int i = 0; i < count; i++) {
num = node[i]->num_input_pins;
for (int j = 0; j < num - 1; j++) {
if (node[i]->input_pins[j] == NULL) {
if (nodeo->num_input_port_sizes != 3 && i * sizea + j < a)
connect_nodes(netlist->gnd_node, 0, node[i], j);
else
connect_nodes(netlist->pad_node, 0, node[i], j);
else{
if (i == count - 1){
if (j == 0){
connect_nodes(netlist->gnd_node, 0, node[i], j);
}
else if (j == 1)
connect_nodes(netlist->vcc_node, 0, node[i], j);
}
else{
connect_nodes(netlist->pad_node, 0, node[i], j);
}
}
}
}
}
Expand Down Expand Up @@ -554,23 +565,36 @@ void split_adder_for_sub(nnode_t *nodeo, int a, int b, int sizea, int sizeb, int
}
}

//if(nodeo->output_pins[nodeo->num_output_pins - 1] == allocate_npin()) {
// npin_t* p = allocate_npin();
// add_output_pin_to_node(nodeo, p, nodeo->num_output_pins - 1);
// nodeo->output_pins[nodeo->num_output_pins - 1] = p;
//}
// int W = nodeo->num_output_pins - 1;
// int sums_mapped = 0;
if (count > 1 || configuration.adder_cin_global) {
// remap the output pins of each adder to nodeo
for (int i = offset; i < count; i++) {
for (int i = offset; i < count - 1; i++) {
for (int j = 0; j < node[i]->num_output_pins - 1; j++) {
if ((i * sizea + j - offset) < nodeo->num_output_pins)
if ((i * sizea + j - offset) < nodeo->num_output_pins-1){
remap_pin_to_new_node(nodeo->output_pins[i * sizea + j - offset], node[i], j + 1);
}
else {
node[i]->output_pins[j + 1] = allocate_npin();
// Pad outputs with a unique and descriptive name to avoid collisions.
node[i]->output_pins[j + 1]->name = append_string("", "%s~dummy_output~%d~%d", node[i]->name, i, j + 2);
}
}
}
remap_pin_to_new_node(nodeo->output_pins[nodeo->num_output_pins - 1], node[count - 1], 0);
}
node[count - 1]->output_pins[0] = allocate_npin();
//node[count - 1]->output_pins[1] = allocate_npin();
//printf("Net of tail node: %s\n", node[5]->output_pins[1]->net);
//std::cout << "TESTING " << node[5]->output_pins[1]->net->fanout_pins << "\n";
//std::cout << "TESTING " << node[3]->output_pins[1]->net->fanout_pins << "\n";
//remap_pin_to_new_node(nodeo->output_pins[nodeo->num_output_pins - 1], node[count - 1], 0);
// Pad outputs with a unique and descriptive name to avoid collisions.
node[count - 1]->output_pins[0]->name = append_string("", "%s~dummy_output~%d~%d", node[(count - 1)]->name, (count - 1), 0);
//node[count - 1]->output_pins[0]->name = append_string("", "%s~dummy_output~%d~%d", node[(count - 1)]->name, (count - 1), 0);
// connect_nodes(node[count - 1], (node[(count - 1)]->num_output_pins - 1), netlist->gnd_node, 0);
// }

Expand Down Expand Up @@ -628,27 +652,51 @@ void iterate_adders_for_sub(netlist_t *netlist)

if (num >= min_threshold_adder) {
// how many subtractors base on a can split
if ((a + 1) % sizea == 0)
counta = (a + offset) / sizea;
else
counta = (a + 1) / sizea + 1;
// how many subtractors base on b can split
if ((b + 1) % sizeb == 0)
countb = (b + offset) / sizeb;
else
countb = (b + 1) / sizeb + 1;
// how many subtractors need to be split
if (counta >= countb)
count = counta;
if (num >= min_threshold_adder && num >= min_add) {
// if the first cin in a chain is fed by a global input (offset = 0) the adder width is the
// input width + 1 (to pass the last cout -> sumout) divided by size of the adder input ports
// otherwise (offset = 1) a dummy adder is added to the chain to feed the first cin with gnd
// how many adders a can split
counta = (a + 1) / sizea + offset;
// how many adders b can split
countb = (b + 1) / sizeb + offset;
// how many adders need to be split
if (counta >= countb)
count = counta;
else
count = countb;
subchaintotal++;
split_adder_for_sub(node, a, b, sizea, sizeb, 1, 1, count, netlist);
}
// Store the node into processed_adder_list if the threshold is bigger than num
else
count = countb;
subchaintotal++;

split_adder_for_sub(node, a, b, sizea, sizeb, 1, 1, count, netlist);
processed_adder_list = insert_in_vptr_list(processed_adder_list, node);
}
// Store the node into processed_adder_list if the threshold is bigger than num
else
processed_adder_list = insert_in_vptr_list(processed_adder_list, node);
processed_adder_list = insert_in_vptr_list(processed_adder_list, node);
// if (num >= min_threshold_adder) {
// // how many subtractors base on a can split
// if ((a + 1) % sizea == 0)
// counta = (a + offset) / sizea;
// else
// counta = (a + 1) / sizea + 1;
// // how many subtractors base on b can split
// if ((b + 1) % sizeb == 0)
// countb = (b + offset) / sizeb;
// else
// countb = (b + 1) / sizeb + 1;
// // how many subtractors need to be split
// if (counta >= countb)
// count = counta;
// else
// count = countb;
// subchaintotal++;

// split_adder_for_sub(node, a, b, sizea, sizeb, 1, 1, count, netlist);
// }
// // Store the node into processed_adder_list if the threshold is bigger than num
// else
// processed_adder_list = insert_in_vptr_list(processed_adder_list, node);
}
}

Expand Down
4 changes: 2 additions & 2 deletions parmys/parmys-plugin/netlist/netlist_utils.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -1392,7 +1392,7 @@ void equalize_ports_size(nnode_t *&node, uintptr_t traverse_mark_number, netlist
return;

/* new port size */
int new_out_size = port_a_size;
int new_out_size = port_y_size;

/* creating the new node */
nnode_t *new_node = (port_b_size == -1) ? make_1port_gate(node->type, port_a_size, new_out_size, node, traverse_mark_number)
Expand Down Expand Up @@ -1469,4 +1469,4 @@ void delete_npin(npin_t *pin)
}
// CLEAN UP
free_npin(pin);
}
}
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