bus

What it is ¶

bus(label, kind) yields one row per bus construct a reader detected in the source but has not yet expanded into member nets (WS1-034 Phase 1). label is the source’s bus name (a KiCad bus-alias name, an xschem DATA[7:0] label, an EDIF array port name), empty for an anonymous bus wire. kind is the source construct token that was seen (bus, bus_entry, bus_alias, geda_bus, edif_array, xschem_bus_label), so a query can filter to one construct.

This is a detect-and-flag relation, not a defect report. The reader saw a bus and recorded it so that silence would not read as “no bus here”. A row means the construct is not fully modeled yet, not that the design is wrong.

bus is distinct from net.bus_like(net). That relation reports a solved net whose electrical role is shared-distribution, such as a ground plane, a global rail, or rail-scale fan-out. bus is about a source-file token the reader has not expanded; net.bus_like is about a net that already exists and passed a fan-out/role predicate.

For hardware engineers ¶

A bus is schematic shorthand for a group of related signals drawn as one thick line (DATA[7:0], ADDR[15:0]) with the members broken out at bus entries. The reader recognised the bus notation but has not yet split it into the individual member nets it stands for. You query bus during a review to see which bus constructs a design uses and which reader saw them, so you know where the connectivity model is still coarse. A row is a coverage note, not an error, since the members may be correct on the sheet and simply not expanded in the read yet.

For software engineers ¶

The parser emits this syntactic marker when it recognises a construct but does not fully lower it into the connectivity graph. Think of it as a TODO. The front end records one when it encounters syntax it can tokenize but not yet desugar, so the omission is visible instead of silent. It is a projection over Model.UnmodeledBuses(), so rows are 1:1 with detected bus constructs. An empty result means the read found no bus notation (or a later phase has modeled every one), not that the design has no shared-distribution nets. For those, query net.bus_like.

Go projector ¶

busFacts in stdlib/relations/facts.go iterates Model.UnmodeledBuses() and emits one bus(label, kind) row per entry, with the construct’s provenance as the citation. Model.UnmodeledBuses() returns the ir.BusNotModeled list the reader emits on InputDiagnostics. One row per detected bus construct; empty for a design whose read detected no bus notation. Every reader that recognizes bus notation (KiCad, EDIF, xschem, gEDA) populates the same channel, so the relation is format-neutral.

Datalog ¶

List every detected bus and its construct kind:

bus(?label, ?kind) => ?label

Filter to one source construct (here, gEDA buses):

bus(?label, "geda_bus") => ?label

Schematic ¶