3 files changed, 45 insertions, 18 deletions
diff --git a/rtl/config_pkg.sv b/rtl/config_pkg.sv
new file mode 100644
index 0000000..0120b14
--- /dev/null
+++ b/rtl/config_pkg.sv
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: CERN-OHL-P-2.0 */
+
+package config_pkg;
+
+  /* Word width as defined in the RISC-V spec. */
+  localparam int unsigned XLEN = 32;
+
+  /* We use a byte-sliced datapath, inspired by the
+   * classic bit-sliced architecture of old CPUs. */
+  localparam int unsigned SLICE_WIDTH      = 8;
+
+  /* The RV32E ISA defines 16 general-purpose registers.
+   * We have two read ports to allow for pipelined reads. */
+  localparam int unsigned REG_ADDR_WIDTH     = 4;
+  localparam int unsigned REG_NUM_READ_PORTS = 2;
+
+endpackage : config_pkg
diff --git a/rtl/montreal_pkg.sv b/rtl/montreal_pkg.sv
new file mode 100644
index 0000000..b3a13a0
--- /dev/null
+++ b/rtl/montreal_pkg.sv
@@ -0,0 +1,8 @@
+/* SPDX-License-Identifier: CERN-OHL-P-2.0 */
+
+package montreal_pkg;
+
+  typedef logic unsigned [config_pkg::XLEN-1:0]        word_t;
+  typedef logic unsigned [config_pkg::SLICE_WIDTH-1:0] slice_t;
+
+endpackage : montreal_pkg
diff --git a/rtl/regfile.sv b/rtl/regfile.sv
index 1758c1a..e18301a 100644
--- a/rtl/regfile.sv
+++ b/rtl/regfile.sv
@@ -8,40 +8,42 @@
  * Register file
  *
  * This module contains the register file for the RISC-V core. Each word is
- * partitioned into chunks (default 8 bits). A global chunk selector determines
- * which chunk of each word is accessed for both read and write operations.
+ * partitioned into slices (default 8 bits). A global slice selector determines
+ * which slice of each word is accessed for both read and write operations.
  *
  * The register file has one synchronous write port and a configurable number of
  * read ports (default 2). Register 0 is fixed to 0 for all reads.
  */
 
-module regfile #(
-  parameter int unsigned WORD_WIDTH = 32,
-  parameter int unsigned ADDR_WIDTH = 4,
-  parameter int unsigned CHUNK_WIDTH = 8,
-  parameter int unsigned NUM_READ_PORTS = 2,
+module regfile
+  import montreal_pkg::*;
+#(
+  parameter int unsigned XLEN           = config_pkg::XLEN,
+  parameter int unsigned SLICE_WIDTH    = config_pkg::SLICE_WIDTH,
+  parameter int unsigned ADDR_WIDTH     = config_pkg::REG_ADDR_WIDTH,
+  parameter int unsigned NUM_READ_PORTS = config_pkg::REG_NUM_READ_PORTS,
 
-  localparam int unsigned NUM_WORDS  = 2 ** ADDR_WIDTH,
-  localparam int unsigned NUM_CHUNKS = WORD_WIDTH / CHUNK_WIDTH
+  localparam int unsigned NUM_WORDS        = 2 ** ADDR_WIDTH,
+  localparam int unsigned SLICE_ADDR_WIDTH = $clog2(XLEN / SLICE_WIDTH)
 ) (
   input logic clk_i,
   input logic rst_ni,
-  input logic [$clog2(NUM_CHUNKS)-1:0] chunk_sel_i,
+  input logic [SLICE_ADDR_WIDTH-1:0] slice_sel_i,
 
-  input  logic [NUM_READ_PORTS-1:0][ ADDR_WIDTH-1:0] raddr_i,
-  output logic [NUM_READ_PORTS-1:0][CHUNK_WIDTH-1:0] rdata_o,
+  input  logic [NUM_READ_PORTS-1:0][ADDR_WIDTH-1:0]  raddr_i,
+  output logic [NUM_READ_PORTS-1:0][SLICE_WIDTH-1:0] rdata_o,
 
   input logic wen_i,
-  input logic [ADDR_WIDTH-1:0] waddr_i,
-  input logic [CHUNK_WIDTH-1:0] wdata_i
+  input logic [ADDR_WIDTH-1:0]  waddr_i,
+  input logic [SLICE_WIDTH-1:0] wdata_i
 );
 
-  logic [NUM_WORDS-1:0][WORD_WIDTH-1:0] register;
+  logic [NUM_WORDS-1:0][XLEN-1:0] register;
 
   always_comb begin
     for (int i = 0; i < NUM_READ_PORTS; i++) begin : gen_read_block
-      rdata_o[i] = (raddr_i[i] == 0)
-          ? '0 : register[raddr_i[i]][chunk_sel_i*CHUNK_WIDTH +: CHUNK_WIDTH];
+      rdata_o[i] = (raddr_i[i] == '0)
+          ? '0 : register[raddr_i[i]][slice_sel_i*SLICE_WIDTH +: SLICE_WIDTH];
     end : gen_read_block
   end
 
@@ -50,7 +52,7 @@ module regfile #(
       register <= '0;
     end else if (wen_i && (waddr_i != '0)) begin
       /* verilog_lint: waive dff-name-style */
-      register[waddr_i][chunk_sel_i*CHUNK_WIDTH +: CHUNK_WIDTH] <= wdata_i;
+      register[waddr_i][slice_sel_i*SLICE_WIDTH +: SLICE_WIDTH] <= wdata_i;
     end
   end