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rocket-chip/vsrc/SimJTAG.v

80 lines
2.2 KiB
Verilog

// See LICENSE.SiFive for license details.
//VCS coverage exclude_file
import "DPI-C" function int jtag_tick
(
output bit jtag_TCK,
output bit jtag_TMS,
output bit jtag_TDI,
output bit jtag_TRSTn,
input bit jtag_TDO
);
module SimJTAG #(
parameter TICK_DELAY = 50
)(
input clock,
input reset,
input enable,
input init_done,
output jtag_TCK,
output jtag_TMS,
output jtag_TDI,
output jtag_TRSTn,
input jtag_TDO_data,
input jtag_TDO_driven,
output [31:0] exit
);
reg [31:0] tickCounterReg;
wire [31:0] tickCounterNxt;
assign tickCounterNxt = (tickCounterReg == 0) ? TICK_DELAY : (tickCounterReg - 1);
bit r_reset;
wire [31:0] random_bits = $random;
wire #0.1 __jtag_TDO = jtag_TDO_driven ?
jtag_TDO_data : random_bits[0];
bit __jtag_TCK;
bit __jtag_TMS;
bit __jtag_TDI;
bit __jtag_TRSTn;
int __exit;
assign #0.1 jtag_TCK = __jtag_TCK;
assign #0.1 jtag_TMS = __jtag_TMS;
assign #0.1 jtag_TDI = __jtag_TDI;
assign #0.1 jtag_TRSTn = __jtag_TRSTn;
assign #0.1 exit = __exit;
always @(posedge clock) begin
r_reset <= reset;
if (reset || r_reset) begin
__exit = 0;
tickCounterReg <= TICK_DELAY;
end else begin
if (enable && init_done) begin
tickCounterReg <= tickCounterNxt;
if (tickCounterReg == 0) begin
__exit = jtag_tick(
__jtag_TCK,
__jtag_TMS,
__jtag_TDI,
__jtag_TRSTn,
__jtag_TDO);
end
end // if (enable && init_done)
end // else: !if(reset || r_reset)
end // always @ (posedge clock)
endmodule