gen_switchmatrix

Switch matrix generation module for FABulous FPGA tiles.

This module generates RTL code for configurable switch matrices within FPGA tiles. Switch matrices handle the routing of signals between tile ports, BEL inputs/outputs, and jump wires. The module supports various configuration modes and multiplexer styles.

Key features:

  • CSV and list file parsing for switch matrix configurations

  • Support for custom and generic multiplexer implementations

  • Configuration bit calculation and management

  • Debug signal generation for switch matrix analysis

  • Multiple configuration modes (FlipFlop chain, Frame-based)

Functions

genTileSwitchMatrix(writer, tile, ...[, ...])

Generate the RTL code for the tile switch matrix.

Module Contents

genTileSwitchMatrix(writer, tile, switch_matrix_debug_signal, csv_output_dir=None, config_bit_mode=ConfigBitMode.FRAME_BASED, multiplexer_style=MultiplexerStyle.CUSTOM, default_pip_delay=80, preserve_list_order=False) → None[source]

Generate the RTL code for the tile switch matrix.

The switch matrix generated will be based on the matrixDir attribute of the tile. If the given file format is .csv, it will be parsed as a switch matrix .csv file. If the given file format is .list, the tool will convert the .list file into a switch matrix with specific ordering first before progressing. If the given file format is Verilog or VHDL, then the function will not generate anything.

Parameters:

  • writer (CodeGenerator) – The code generator instance for RTL output

  • tile (Tile) – The tile object containing BELs and port information

  • switch_matrix_debug_signal (bool) – Whether to generate debug signals for the switch matrix.

  • csv_output_dir (Path | None) – Optional directory to write the generated CSV file when converting from .list format. If None, the CSV is written to the same directory as the source .list file. This parameter is ignored when the input is already a .csv file.

  • config_bit_mode (ConfigBitMode) – The configuration-bit mode for the tile (frame-based or flip-flop chain).

  • multiplexer_style (MultiplexerStyle) – The multiplexer style used to implement switch-matrix muxes.

  • default_pip_delay (int) – Per-mux delay (ps) emitted on assign statements in the switch matrix.

  • preserve_list_order (bool) – When True, list2CSV writes a per-row 1-based index encoding the connection’s position in the .list file so the mux input order can be recovered downstream. Defaults to False (legacy behaviour).

Raises:

  • InvalidFileType – If matrixDir does not contain a valid file format.

  • ValueError – If any port in the switch matrix is not connected to anything.