CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog and this project adheres to Semantic Versioning.

1.39.0 - 2025-11-20

Added

• boxcar: Add boxcar function to compose bit masks
• heaviside: Add Heaviside function to compose bit masks
• ring_buffer: Add ring buffer with sequential write and random reads
• trip_counter: Add counter with 'trip' output when reaching threshold value

Changed

• cb_filter, id_queue, lzc, rr_arb_tree: Speed up Verilator simulation
• cdc_fifo_gray*, isochronous_spill_register: Change flip-flops without to flip-flops with reset
• isochronous_spill_register: Remove unnecessary data stability assertions
• addr_decode*: Change assumed integer index to arbitrary type (default remains integer)

Fixed

• id_queue: Fix struct access
• cdc_fifo_gray*: Fix Spyglass linting edge case
• lzc: Fix assertion for degenerate case WIDTH == 0
• Fix Verilator compilation by adding guard statements

1.38.0 - 2025-02-28

Changed

• Assertions no longer disabled for Verilator. Define ASSERTS_OFF to disable.
• Define ASSERTS_OVERRIDE_ON to override any defines that turn assertions off otherwise.
• id_queue: Parametrize number of compare ports.
• assertions.svh: Add optional argument to assertion macros to display custom error message.
• stream_to_mem: Disable assertions during reset.
• addr_decode_dync, cdc_fifo_gray_clearable, multiaddr_decode, spill_register_flushable: Promote $warning to $error.
• rr_arb_tree, stream_omega_net, stream_xbar: Remove default assertion disable.

Fixed

• delta_counter: Fix inverted reset.
• stream_join_dynamic: Handshake only selected streams.
• Various tool compatibility improvements.

1.37.0 - 2024-07-18

Added

• credit_counter: Add up/down counter for credit.

Fixed

• mem_to_banks_detailed: Ensure no spurious response after full dead write.

1.36.0 - 2024-07-08

Fixed

• registers: Fix else statement in FFARNC macro.
• stream_arbiter_flushable: Do not lock priority arbiter.

1.35.0 - 2024-04-22

Changed

• id_queue: Add parameter to cut a critical path.

1.34.0 - 2024-04-09

Changed

• stream_xbar: Add payload assertion stability mask.

1.33.1 - 2024-03-16

Fixed

• stream_omega_net: Fix assertion.
• Revert gitlab-ci trigger condition to pull_request.

1.33.0 - 2024-03-07

Added

• Add passthrough_stream_fifo: Stream FIFO which does not cut the timing path, this allows it to do a simultaneous push and pop when full.
• Registers: Add FFARNC macro: Flip-Flop with asynchronous active-low reset and synchronous clear.

Changed

• Enable assertions in verilator.
• Change pragma translate_off statements to ```ifndef SYNTHESIS`` according to IEEE 1364.1-2005 spec 6.3.2.
• plru_tree: Add assertion that output is onehot.
• Update CI trigger condition.

Fixed

• onehot_to_bin: Fix width mismatch in assignment.
• plru_tree: Improve tool compatibility.
• stream_xbar: Fix masked assertion.

1.32.0 - 2023-09-26

Added

• Add stream_join_dynamic: stream_join with a dynamically configurable subset selection.
• Add multiaddr_decode: Address map decoder using NAPOT regions and allowing for multiple address inputs.
• Add addr_decode_dync: addr_decode with support for dynamic online configuration.

Changed

• mem_to_banks: Change default value for NumBanks from 0 to 1 to avoid division by zero.

1.31.1 - 2023-08-09

Fixed

• mem_to_banks: Keep defaut values for localparams

1.31.0 - 2023-08-08

Added

• Add mem_to_banks_detailed: mem_to_banks with detailed response signals

Fixed

• unread: Add dummy signal assignment when targeting Vivado to avoid blackbox inference

1.30.0 - 2023-06-09

Added

• Add lossy_valid_to_stream: A converter between valid-only protocols and ready-valid where the latest transaction overwrites the most recently queue one.
• Add clk_int_div_static: A wrapper for clk_int_div for static clock division.

Changed

• popcount: Refactor and support all input widths.
• clk_int_div: Support clock output during reset.
• stream_delay: Support larger counts.

Fixed

• clk_int_div: Fix possible deadlock and avoid hold issues.

1.29.0 - 2023-04-14

Added

• Add shift_reg_gated: Shift register with ICG for arbitrary types.

Changed

• CI: Run testbenches in test/ on internal gitlab mirror.
• fifo_tb: Add test for DEPTH not power of two.

Fixed

• clk_int_div: Allow configuration while clock is disabled.
• mem_to_banks: Cut possible timing loop for HideStrb feature.
• Improved tool compatibility (Verilator, Questasim, Synopsys).

1.28.0 - 2022-12-15

Added

• Add clk_mux_glitch_free: A glitch-free clock multiplexer.

1.27.1 - 2022-12-06

Fixed

• fall_through_register: Remove superfluous $size() call for tool compatibility

1.27.0 - 2022-12-01

Added

• Add mem_to_banks: split memory access over multiple parallel banks. Moved from the AXI4+ATOP axi_to_mem module.
• Add read: dummy module that prevents a signal from being removed during synthesis

Changed

• stream_fifo_optimal_wrap: Remove asserts
• fall_through_register: Update fifo to fifo_v3

Fixed

• FuseSoC: Add assertions.svh

1.26.0 - 2022-08-26

Added

• Add stream_throttle: restricts the number of outstanding transfers in a stream.

Changed

• Allow out-of-bounds (i.e. '0) top end address in addr_map of addr_decode module for end of address space.
• Update CI.

1.25.0 - 2022-08-10

Added

• Add addr_decode_napot: variant of addr_decode which uses a base address and mask instead of a start and end address.
• Add stream_fifo_optimal_wrap: instantiates a more optimal spill_register instead of a stream_fifo for depth == 2.

Changed

• Make stream_register truly stream by replacing internal FIFO with FFs.
• Avoid using $bits() call in id_queue's parameters.
• Remove cb_filter and cb_filter_pkg from from Vivado IP packager project sources due to compatibility issues.
• Use tc_clk_mux as glitch-free muxes in rstgen_bypass to avoid combinational glitches.
• Avoid program blocks in testbenches for simulator compatibility.

Fixed

• Update src_files.yml and common_cells.core

1.24.1 - 2022-04-13

Fixed

• Fix typos in Bender.yml and src_files.yml

1.24.0 - 2022-03-31

Added

• Add edge_propagator_ack: Edge/pulse propagator with sender-synchronous receive-acknowledge output. edge_propagator is now implemented by instantiating edge_propagator_ack.
• Add 4phase_cdc: A 4 phase handshaking CDC that allows glitch-free resetting (used internally in the new clearable CDC IPs).
• Add one-sided clearable and/or async resettable flavors of 2phase CDC (cdc_2phase_clearable) and gray-counting FIFO CDCs (cdc_fifo_gray_clearable).
• Add reset CDC controller cdc_reset_ctrl that supports reset/synchronous clear sequencing across clock domain crossings (used internally in clearable CDC IPs).
• Add clk_int_div arbitrary integer clock divider with at-runtime configurable divider selection and glitch-free, 50%duty cycle output clock.
• Add an assertion to the lzc to verify parameters.

Fixed

• Correct reset polarity in assertions in isochronous_4phase_handshake and isochronous_spill_register
• Fix compatibility of sub_per_hash constructs with Verilator

Changed

• Add dont_touch and async_reg attribute to FFs in sync cell.
• Improved reset behavior documentation (in module header) of existing CDC IPs.
• Deprecated flawed clk_div module and add elaboration warning message that will be shown for existing designs (can be disabled with optional instantiation parameter).
• Add optional Seed parameter to stream_delay module
• Update tech_cells_generic to 0.2.9

1.23.0 - 2021-09-05

Added

• Add cc_onehot
• isochronous_4phase_handshake: Isochronous clock domain crossing cutting all paths using a 4-phase handshake.
• Changed isochronous_spill_register_tb to isochronous_crossing_tb also covering the isochronous_4phase_handshake module.
• Make reset value of sync module parameterizable.

Changed

• id_queue: Allow simultaneous input and output requests in FULL_BW mode

1.22.1 - 2021-06-14

Fixed

• Remove breaking change of spill_register

1.22.0 - 2021-06-09

Added

• Add spill_register_flushable

Changed

• registers.svh: Merge explicit and implicit register variants into `FF and `FFL macros
• rr_arb_tree: Allow flushing locked decision
• Improved verific compatibility

1.21.0 - 2021-01-28

Changed

• Remove timeprecision/timeunit arguments
• Update common_verification to 0.2.0
• Update tech_cells_generic to 0.2.3

1.20.1 - 2021-01-21

Changed

• id_queue: Replace default or reset value of signals that were assigned 'x with '0.
• id_queue: Use cf_math_pkg::idx_width() for computation of localparams.

Fixed

• Add XSIM define guard for statements incompatible with xsim.

1.20.0 - 2020-11-04

Added

• assertions: Assertion include header with macros (from lowrisc)

Changed

• sram.sv: Deprecated as it has been moved to tech_cells_generic

Fixed

• stream_register: Fix DATA_WIDTH of instantiated FIFO.
• stream_xbar: Add missing argument in assertion error string.
• Lint style fixes
• stream_omega: Fix parse issue with verible.
• src_files.yml: Fix compile order and missing modules.

1.19.0 - 2020-05-25

Added

• stream_to_mem: Allows to use memories with flow control (req/gnt) for requests but without flow control for output data to be used in streams.
• isochronous_spill_register: Isochronous clock domain crossing cutting all paths.
• rr_arb_tree_tb: Systemverilog testbench for rr_arb_tree, which checks for fair throughput.
• cf_math_pkg::idx_width: Constant function for defining the binary representation width of an index signal.

Changed

• addr_decode: Use cf_math_pkg::idx_width for computing the index width, inline documentation.
• lzc: Use cf_math_pkg::idx_width for computing the index width, inline documentation.
• Bender: Change levels of modules affected by depending on cf_math_pkg::idx_width().
• stream_xbar: Fully connected stream bassed interconnect with variable number of inputs and outputs.
• stream_xbar: Fully connected stream-bassed interconnect with a variable number of inputs and outputs.
• stream_omega_net: Stream-based network implementing an omega topology. Variable number of inputs, outputs and radix. Topology is isomorphic to a butterfly network.

Fixed

• Improve tool compatibility.
• rr_arb_tree: Properly degenerate rr_i and idx_o signals.
• rr_arb_tree: Add parameter FairArb to distribute throughput of input requests evenly when not all inputs have requests active.
• stream_demux: Properly degenerate inp_sel_i signal.

1.18.0 - 2020-04-15

Added

• stream_fork_dynamic: Wrapper around stream_fork for partial forking.
• stream_join: Join multiple Ready/Valid handshakes to one common handshake.
• SECDED (Single Error Correction, Double Error Detection) encoder and decoder
• SECDED Verilator-based testbench
• Travis build for SECDED module

1.17.0 - 2020-04-09

Added

• stream_fifo: Ready/Valid handshake wrapper around fifo_v3

1.16.4 - 2020-03-02

Fixed

• id_queue: Fix generation of head_tail_q registers

1.16.3 - 2020-02-11

Fixed

• Handle degenerated addr_decode with NoIndices == 1, change default parameters to 32'd0

1.16.2 - 2020-02-04

Fixed

• Fix author section in Bender.yml

1.16.1 - 2020-02-03

Fixed

• rr_arb_tree: Add guard SVA statement for Verilator
• Added missing sources in Bender.yml and src_files.yml

1.16.0 - 2020-01-13

Fixed

• Handle degenerated onehot_to_bin with ONEHOT_WIDTH == 1
• Handle degenerated id_queue with CAPACITY == 1 or HT_CAPACITY == 1
• Fix cdc_fifo_gray to be a safe clock domain crossing (CDC)

1.15.0 - 2019-12-09

Added

• Added address map decoder module

Fixed

• Handle degenerated lzc with WIDTH == 1

1.14.0 - 2019-10-08

Added

• Added spubstitution-permutation hash function module
• Added couning-bloom-filter module
• spill_register: Added Bypass parameter
• counter: Added sticky overflow
• Added counter with variable delta
• Added counter that tracks its maximum value

Changed

• Added formal testbench for fifo and fall_through_regsiter

1.13.1 - 2019-06-01

Changed

• Fix path in src_files.yml for stream_arbiter and stream_arbiter_flushable

1.13.0 - 2019-05-29

Added

• Added exponential backoff window module
• Added parametric Galois LFSR module with optional whitening feature
• Added cf_math_pkg: Constant Function implementations of mathematical functions for HDL elaboration

Changed

• Parametric payload data type for rr_arb_tree

Deprecated

• The following arbiter implementations are deprecated and superseded by rr_arb_tree:
• Priority arbiter prioarbiter
• Round-robin arbiter rrarbiter

Fixed

1.12.0 - 2019-04-09

Added

• Add priority arbiter
• Add Pseudo Least Recently Used tree
• Add round robin arbiter mux tree

Changed

• Add selectable arbiter implementation for stream_arbiter and stream_arbiter_flushable. One can choose between priority (prio) and round-robin arbitration (rr).
• Add $onehot0 assertion in one-hot to bin
• Rework rrarbiter unit (uses rr_arb_tree implementation underneath)

1.11.0 - 2019-03-20

Added

• Add stream fork
• Add fall-through register
• Add stream filter
• Add ID queue

Changed

• sync_wedge use existing synchronizer. This defines a single place where a tech-specific synchronizer can be defined.

Fixed

• Fix FIFO push and pop signals in stream_register to observe interface prerequisites.
• In fifo_v3, fix data output when pushing into empty fall-through FIFO. Previously, the data output of an empty fall-through FIFO with data at its input (and push_i=1) depended on pop_i: When pop_i=0, old, invalid data were visible at the output (even though empty_o=0, indicating that the data output is valid). Only when pop_i=1, the data from the input fell through. One consequence of this bug was that data_o of the fall_through_register could change while valid_o=1, violating the basic stream specification.

1.10.0 - 2018-12-18

Added

• Add fifo_v3 with generic fill count
• Add 16 bit LFSR
• Add stream delayer
• Add stream arbiter
• Add register macros for RTL
• Add shift register

Changed

• Make number of registers of rstgen_bypass a parameter.

Fixed

• Fix valid_i and grant_i guarantees in generic_fifo for backward compatibility.
• LZC: Synthesis of streaming operators in ternary operators
• Add missing entry for popcount to Bender.yml.
• Add default values for parameters to improve compatibility with Synopsys DC and Vivado.

1.9.0 - 2018-11-02

Added

• Add popcount circuit popcount

1.8.0 - 2018-10-15

Added

• Add lock feature to the rrarbiter. This prevents the arbiter to change the decision when we have pending requests that remain unaknowledged for several cycles.
• Add deglitching circuit
• Add generic clock divider
• Add edge detecter as alias to sync_wedge (name is more expressive)
• Add generic counter
• Add moving deglitcher

1.7.6 - 2018-09-27

Added

• Add reset synchronizer with explicit reset bypass in testmode

1.7.5 - 2018-09-06

Fixed

• Fix incompatibility with verilator
• Fix dependency to open-source repo

1.7.4 - 2018-09-06

• Fix assertions in fifo_v2 (write on full / read on empty did not trigger properly)

1.7.3 - 2018-08-27

Fixed

• Use proper fifo_v2 in generic_fifo module.

1.7.2 - 2018-08-27

Added

• Almost full/empty flags to FIFO, as fifo_v2.

Changed

• FIFO moved to fifo_v1 and instantiates fifo_v2.

1.7.1 - 2018-08-27

Fixed

• Revert breaking changes to fifo.

1.7.0 - 2018-08-24

Added

• Add stream register (stream_register).
• Add stream multiplexer and demultiplexer (stream_mux, stream_demux).
• Add round robin arbiter (rrarbiter).
• Add leading zero counter (lzc).

Changed

• Deprecate find_first_one in favor of lzc.

1.6.0 - 2018-04-03

Added

• Add binary to Gray code converter.
• Add Gray code to binary converter.
• Add Gray code testbench.
• Add CDC FIFO based on Gray counters. This is a faster alternative to the 2-phase FIFO which also works if a domain's clock has stopped.

Changed

• Rename cdc_fifo to cdc_fifo_2phase.
• Adjust CDC FIFO testbench to cover both implementations.

1.5.4 - 2018-03-31

Changed

• Replace explicit clock gate in fifo with implicit one.

1.5.3 - 2018-03-16

Changed

• Remove duplicate deprecated modules.

1.5.2 - 2018-03-16

Changed

• Remove deprecated rstgen and fix interface.

1.5.1 - 2018-03-16

Changed

• Remove deprecated onehot_to_bin.

1.5.0 - 2018-03-14

Added

• Add behavioural SRAM model

1.4.0 - 2018-03-14

Added

• Clock domain crossing FIFO

Changed

• Re-name new sync modules to resolve namespace collisions

1.3.0 - 2018-03-12

Added

• 2-phase clock domain crossing
• Add old common cells as deprecated legacy modules

1.2.3 - 2018-03-09

Added

• Backwards compatibility wrapper for generic_LFSR_8bit

1.2.2 - 2018-03-09

Added

• Backwards compatibility wrapper for generic_fifo

1.2.1 - 2018-03-09

Fixed

• Fix an issue in the spill register which causes transactions to be lost

1.2.0 - 2018-03-09

Added

• Add spill register

1.1.0 - 2018-03-06

Added

• Find first zero

1.0.0 - 2018-03-02

Added

• Re-implementation of the generic FIFO supporting all kinds of use-cases
• Testbench for FIFO

Changed

• Re-formatting and artistic code clean-up

0.1.0 - 2018-02-23

Added

• Fork of PULP common cells repository