Add heaviside and boxcar mask IPs

Author: colluca

Bender.yml

@@ -39,6 +39,7 @@ sources:
       - src/exp_backoff.sv
       - src/fifo_v3.sv
       - src/gray_to_binary.sv
+      - src/heaviside.sv
       - src/isochronous_4phase_handshake.sv
       - src/isochronous_spill_register.sv
       - src/lfsr.sv
@@ -71,6 +72,7 @@ sources:
       - src/read.sv
       # Level 1
       - src/addr_decode_dync.sv
+      - src/boxcar.sv
       - src/cdc_2phase.sv
       - src/cdc_4phase.sv
       - src/clk_int_div_static.sv

src/boxcar.sv

@@ -0,0 +1,30 @@
+// Copyright 2025 ETH Zurich and University of Bologna.
+// Solderpad Hardware License, Version 0.51, see LICENSE for details.
+// SPDX-License-Identifier: SHL-0.51
+//
+// Author: Luca Colagrande <colluca@iis.ee.ethz.ch>
+
+// This module can be used to generate any mask that can be obtained
+// by a boxcar function (https://en.wikipedia.org/wiki/Boxcar_function).
+// Specifically, it generates a mask with all and only the bits in
+// the (lsb_i, msb_i] interval asserted.
+module boxcar #(
+    parameter int unsigned Width = 32,
+    /// Derived parameter *Do not override*
+    localparam int unsigned IdxWidth = cf_math_pkg::idx_width(Width),
+    localparam type idx_t = logic [IdxWidth-1:0],
+    localparam type mask_t = logic [Width-1:0]
+) (
+    input idx_t lsb_i,
+    input idx_t msb_i,
+    output mask_t mask_o
+);
+
+    mask_t low_mask, high_mask_n;
+
+    heaviside #(.Width(Width)) i_lo (.x_i(lsb_i), .mask_o(low_mask));
+    heaviside #(.Width(Width)) i_hi (.x_i(msb_i), .mask_o(high_mask_n));
+
+    assign mask_o = ~low_mask & high_mask_n;
+
+endmodule

src/heaviside.sv

@@ -0,0 +1,24 @@
+// Copyright 2025 ETH Zurich and University of Bologna.
+// Solderpad Hardware License, Version 0.51, see LICENSE for details.
+// SPDX-License-Identifier: SHL-0.51
+//
+// Author: Luca Colagrande <colluca@iis.ee.ethz.ch>
+
+// This module can be used to generate any mask that can be obtained by the
+// Heaviside function (https://en.wikipedia.org/wiki/Heaviside_step_function).
+// Specifically, it generates a mask with all and only the bits in
+// the [0, x_i] interval asserted.
+module heaviside #(
+    parameter int unsigned Width = 32,
+    /// Derived parameter *Do not override*
+    localparam int unsigned IdxWidth = cf_math_pkg::idx_width(Width),
+    localparam type idx_t = logic [IdxWidth-1:0],
+    localparam type mask_t = logic [Width-1:0]
+) (
+    input idx_t x_i,
+    output mask_t mask_o
+);
+
+    assign mask_o = (1 << (x_i + 1)) - 1;
+
+endmodule