71 lines
2.2 KiB
Systemverilog
71 lines
2.2 KiB
Systemverilog
// Copyright © 2019-2023
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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`include "VX_platform.vh"
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`TRACING_OFF
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module VX_cyclic_arbiter #(
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parameter NUM_REQS = 1,
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parameter LOCK_ENABLE = 0,
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parameter LOG_NUM_REQS = `LOG2UP(NUM_REQS)
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) (
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input wire clk,
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input wire reset,
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input wire [NUM_REQS-1:0] requests,
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output wire [LOG_NUM_REQS-1:0] grant_index,
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output wire [NUM_REQS-1:0] grant_onehot,
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output wire grant_valid,
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input wire grant_unlock
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);
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if (NUM_REQS == 1) begin
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`UNUSED_VAR (clk)
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`UNUSED_VAR (reset)
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assign grant_index = '0;
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assign grant_onehot = requests;
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assign grant_valid = requests[0];
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end else begin
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localparam IS_POW2 = (1 << LOG_NUM_REQS) == NUM_REQS;
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reg [LOG_NUM_REQS-1:0] grant_index_r;
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always @(posedge clk) begin
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if (reset) begin
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grant_index_r <= '0;
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end else begin
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if (!IS_POW2 && grant_index_r == LOG_NUM_REQS'(NUM_REQS-1)) begin
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grant_index_r <= '0;
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end else if (!LOCK_ENABLE || ~grant_valid || grant_unlock) begin
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grant_index_r <= grant_index_r + LOG_NUM_REQS'(1);
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end
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end
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end
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reg [NUM_REQS-1:0] grant_onehot_r;
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always @(*) begin
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grant_onehot_r = '0;
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grant_onehot_r[grant_index_r] = 1'b1;
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end
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assign grant_index = grant_index_r;
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assign grant_onehot = grant_onehot_r;
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assign grant_valid = requests[grant_index_r];
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end
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endmodule
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`TRACING_ON
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