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Port Checking

PortCheck is an IntFlag bitmask for comparing two ports. The check_connection() function compares position, orientation, width, layer, cross-section, and port type — returning a bitmask that callers test against their required flags.

PortCheck flags

Flag Meaning
opposite Ports face opposite directions (180°)
same Ports face the same direction
width Port widths match
layer Ports are on the same layer
cross_section Cross-sections are identical (implies layer + width)
port_type Port types match (e.g. both "optical")
position Positions match (within tolerance)

Composite flags

Flag Composition
all_opposite opposite \| width \| port_type \| layer
all_overlap width \| port_type \| layer 
from kfnetlist import PortCheck

print("Individual flags:")
for flag in [
    PortCheck.opposite,
    PortCheck.same,
    PortCheck.width,
    PortCheck.layer,
    PortCheck.cross_section,
    PortCheck.port_type,
    PortCheck.position,
]:
    print(f"  {flag.name:>15s} = {flag.value}")

print("\nComposite flags:")
print(f"  all_opposite = {PortCheck.all_opposite.value} = {PortCheck.all_opposite}")
print(f"  all_overlap  = {PortCheck.all_overlap.value} = {PortCheck.all_overlap}")

Individual flags:
         opposite = 1
             same = 2
            width = 4
            layer = 8
    cross_section = 16
        port_type = 32
         position = 64

Composite flags:
  all_opposite = 45 = 45
  all_overlap  = 44 = 44

Using the bitmask

check_connection() returns an int bitmask. Test it with bitwise AND:

result = check_connection(port_a, port_b)
if (result & PortCheck.all_opposite) == PortCheck.all_opposite:
    # ports are a valid opposite-facing connection
    ...

Integer vs complex transforms

check_connection() uses integer transforms (kdb.Trans) when both ports expose trans, giving exact comparison. When either port uses a complex transform (kdb.DCplxTrans), it falls back to floating-point comparison with configurable tolerances.

Parameter Default Purpose
tolerance 0.1 Position tolerance in dbu units
angle_tolerance 0.01 Angle tolerance in degrees
snapped False Force integer-transform comparison

Bitmask algebra

Since PortCheck is an IntFlag, standard bitwise operations work:

# Build a custom required check
required = PortCheck.position | PortCheck.opposite | PortCheck.layer
print(f"Required: {required}")
print(f"Value: {required.value}")

# Test if a result satisfies requirements
simulated_result = (
    PortCheck.position | PortCheck.opposite | PortCheck.layer | PortCheck.width
)
passes = (simulated_result & required) == required
print(f"Passes: {passes}")

Required: 73
Value: 73
Passes: True

See Also

Topic Where
Optical net extraction Optical Nets
Extraction pipeline Extraction Overview