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[/] [s80186/] [trunk/] [rtl/] [Flags.sv] - Rev 2
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// Copyright Jamie Iles, 2017
//
// This file is part of s80x86.
//
// s80x86 is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// s80x86 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with s80x86. If not, see <http://www.gnu.org/licenses/>.
module Flags(input logic clk,
input logic reset,
// verilator lint_off UNUSED
input logic [15:0] flags_in,
// verilator lint_on UNUSED
input logic [8:0] update_flags,
output logic [15:0] flags_out);
reg C, P, A, Z, S, T, I, D, O;
assign flags_out = {4'b1111, O, D, I, T, S, Z, 1'b0, A, 1'b0, P, 1'b1, C};
always_ff @(posedge clk or posedge reset) begin
if (reset) begin
C <= 1'b0;
P <= 1'b0;
A <= 1'b0;
Z <= 1'b0;
S <= 1'b0;
T <= 1'b0;
I <= 1'b0;
D <= 1'b0;
O <= 1'b0;
end else begin
C <= update_flags[UpdateFlags_CF] ? flags_in[CF_IDX] : C;
P <= update_flags[UpdateFlags_PF] ? flags_in[PF_IDX] : P;
A <= update_flags[UpdateFlags_AF] ? flags_in[AF_IDX] : A;
Z <= update_flags[UpdateFlags_ZF] ? flags_in[ZF_IDX] : Z;
S <= update_flags[UpdateFlags_SF] ? flags_in[SF_IDX] : S;
T <= update_flags[UpdateFlags_TF] ? flags_in[TF_IDX] : T;
I <= update_flags[UpdateFlags_IF] ? flags_in[IF_IDX] : I;
D <= update_flags[UpdateFlags_DF] ? flags_in[DF_IDX] : D;
O <= update_flags[UpdateFlags_OF] ? flags_in[OF_IDX] : O;
end
end
endmodule