Wire Rendering¶

This page documents how Click renders wires in the ladder grid and how the encoder maps CSV wire tokens to binary flag bytes.

Wire flag bytes¶

The low bytes of three uint32 LE cell fields describe wires:

Wire tokens are classified by (right, down) only — the segment flag is independent:

Contacts and coils normally set right=1 — they behave like horizontal wires with instruction data layered on top. Instruction occupancy and right-wire presence are separate in the native format: a drum placed on a newly inserted blank row can have right=0. A contact cell can additionally set down=1 (a branch rooted directly under the contact): since right is already 1, that's the T shape, and the CSV renders it as a T: prefix on the contact token (e.g. T:C1204), mapping to wire_down=True on Contact/CompareContact.

Row-start flag¶

The uint32 field at +0x15 is separate from the segment flag. CLICK's clipboard writer copies the ordinary SCR row's low flag bit into column A and writes zero in other columns. The old enable/contact name described only some uses of this field; it is not specific to contacts or NOP instructions.

The encoder constructs this field through ClickCell.row_start_flag and its contact convention. It does not preserve arbitrary native row flags, because the public Rung model does not retain them. The full editing semantics of the row bit remain open; the SCR mapping is established by the native writer.

Left-edge rendering¶

Click renders the T's down-wire at the left edge of the cell, not the center. This means two cells can connect to a single T's down-wire — one from each side of that edge:

1. Same-column (DOWN): A - directly below a T connects via the standard vertical edge.
2. Diagonal (UP/RIGHT): A - one column to the LEFT and one row BELOW connects UP one row and ONE COLUMN TO THE RIGHT to the T. The -'s right-wire meets the T's down-wire at the shared cell boundary.

Connected:                          Not connected:
R, -, T, T, -, -, out(Y1)          R, -, T, T, -, -, out(Y1)
 , -, -, -, -, -, out(Y2)           , -,  , -, -, -, out(Y2)
      ^                                   ^
      B has "-" = bridge                  B is blank = gap

In the not-connected case: row 1 column A connects UP/RIGHT to T@B (rule 2), row 1 column C connects UP to T@C (rule 1), and the blank at B is the gap that keeps the two branches independent.

Segment flag¶

The segment flag (+0x19) determines branch zone membership. Getting it wrong causes contacts and wires to visually shift down to their own row in Click's editor.

Boundary rules¶

The encoder uses the following capture-derived construction conventions. CLICK itself persists segment bits per entry and copies them during clipboard serialization; it does not recompute them using these formulas.

The encoder computes a per-row boundary column:

Row 0 is exempt — boundary=0, all non-blank cells get seg=1.

Row R (R > 0):

1. Start with boundary = 0
2. From row R-1 only: T at column C → boundary = max(boundary, C+2); | at column C → boundary = max(boundary, C+1)
3. From rows 0..R-1: Contact/CompareContact at column C → boundary = max(boundary, C+2)
4. Non-blank cells at col < boundary get seg=0; at col >= boundary get seg=1
5. Blank cells and | cells are always seg=0

AF column segment rules¶

Single-rung buffers:

The encoder sets all AF instruction segment flags to zero in multi-rung buffers. This is its generation convention, not a native rule that selecting multiple rungs changes stored segment bits.

The native time_drum_insert_rows fixture demonstrates both drum AF states within one multi-rung capture: (segment, right) = (1, 1) on the original wired row and (0, 0) on an inserted blank row. The original NOP's wired row retains segment 1 after moving down beneath the drum. The encoder's zero-segment drum convention therefore does not describe all native captures.

Note on native captures¶

Click's native segment flags track editor creation order — "insert row above" keeps the original row exempt rather than row 0. The encoder always treats row 0 as exempt, matching top-down construction. Native captures built via "insert row above" can therefore show a different exempt row. They are evidence of state the encoder does not preserve, and a later exempt row is not evidence that earlier rows should be discarded.

Instruction index¶

Click stores a per-cell instruction index at +0x0D, but the value reflects editor creation order, not a structural rule. Click accepts any ordering on paste. The encoder uses a deterministic scheme: condition-side instructions numbered in row-major column-major order, then AF-side instructions in row order.

Validation constraints¶

• T and | tokens are rejected on the last row (vertical-down has nowhere to go)
• T and | tokens are rejected on column A (leftmost condition column)
• At most one NOP per rung