Gate

A (logical) gate is an electronic component comprising multiple in- and outputs that implements one or more Boolean fucntion(s). It is connected to a number of nets via its pins and can thus be used in larger circuits to implement complex logic operations. Such a circuit on gate-level is usually referred to as a netlist.

Similar to all other netlist components in HAL, a gate comprises basic information such as an ID, a name, and a gate type that can be read and sometimes written using dedicated commands such as get_id, get_name, set_name, and get_type. A gate can be created by using create_gate on the netlist while specifying its gate type and name. Furthermore, a gate can return the module and the grouping is is assigned to using get_module and get_grouping.

gt = GateType("example_type")                 # create an empty gate type
g = netlist.create_gate(gt, "example_gate")   # create a new gate
id = g.get_id()                               # get the gate's ID
name = g.get_name()                           # get the gate's name
grouping = g.get_grouping()                   # get the gate's grouping

Additionally, a gate can be retrieved from the netlist by ID using get_gate_by_id and may be deleted using delete_gate. Deleting a gate may result in dangling wires.

g = netlist.get_gate_by_id(3)   # get the gate with ID 3 from the netlist
netlist.delete_gate(g)          # delete the gate

Each gate offers functions has multiple input and output pins that are potentially connected to a variety of nets. The user can retrieve the names of the in- and output pins by using get_input_pins or get_output_pins respectively. Furthermore, the net connected to such a pin can be retrieved using get_fan_in_net and get_fan_out_net. If required, even the whole endpoint of a pin is accessible via get_fan_in_endpoint and get_fan_out_endpoint. A list of all connected nets or endpoints is also available via get_fan_in_nets', 'get_fan_out_nets, get_fan_in_endpoints and get_fan_out_endpoints.

out_pins = g.get_output_pins()                 # get all output pins
out_net = g.get_fan_out_net(out_pins[0])       # get net connected to first output pin
out_ep = g.get_fan_out_endpoint(out_pins[0])   # get endpoint of first output pin
in_eps = g.get_fan_in_endpoints()              # get all endpoints at input pins

Easy access to the predecessors and successors of a gate is provided by the functions get_predecessors, get_unique_predecessors, get_successors, and get_unique_successors. The functions retrieving unique predecessors or successors return a list of gates while all remaining function return a list of endpoints of the predecessor or successor gate.

pred = g.get_predecessors()               # get all predecessor endpoints
unique_succ = g.get_unique_successors()   # get all unique successor gates