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-rw-r--r--rtl/regfile.sv54
1 files changed, 54 insertions, 0 deletions
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+/* SPDX-License-Identifier: CERN-OHL-P-2.0 */
+
+/*
+ * Copyright 2026 UBC ASIC contributors (Montreal project).
+ *
+ * Author: Warrick Lo <wlo@warricklo.net>
+ *
+ * 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.
+ *
+ * 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,
+
+ localparam int unsigned NUM_WORDS = 2 ** ADDR_WIDTH,
+ localparam int unsigned NUM_CHUNKS = WORD_WIDTH / CHUNK_WIDTH
+) (
+ input logic clk_i,
+ input logic [$clog2(NUM_CHUNKS)-1:0] chunk_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 wen_i,
+ input logic [ADDR_WIDTH-1:0] waddr_i,
+ input logic [CHUNK_WIDTH-1:0] wdata_i
+);
+
+ logic [NUM_WORDS-1:0][WORD_WIDTH-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];
+ end : gen_read_block
+ end
+
+ always_ff @(posedge clk_i) begin
+ 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;
+ end
+ end
+
+endmodule : regfile