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//-----------------------------------------------------
// This is FSM demo program using function
// Design Name : fsm_using_function
// File Name : fsm_using_function.v
//-----------------------------------------------------
module fsm_using_function (
clock , // clock
reset , // Active high, syn reset
req_0 , // Request 0
req_1 , // Request 1
gnt_0 , // Grant 0
gnt_1
);
//-------------Input Ports-----------------------------
input clock,reset,req_0,req_1;
//-------------Output Ports----------------------------
output gnt_0,gnt_1;
//-------------Input ports Data Type-------------------
wire clock,reset,req_0,req_1;
//-------------Output Ports Data Type------------------
reg gnt_0,gnt_1;
//-------------Internal Constants--------------------------
parameter SIZE = 3 ;
parameter IDLE = 3'b001,GNT0 = 3'b010,GNT1 = 3'b100 ;
//-------------Internal Variables---------------------------
reg [SIZE-1:0] state ;// Seq part of the FSM
wire [SIZE-1:0] next_state ;// combo part of FSM
//----------Code startes Here------------------------
assign next_state = fsm_function(state, req_0, req_1);
//----------Function for Combo Logic-----------------
function [SIZE-1:0] fsm_function;
input [SIZE-1:0] state ;
input req_0 ;
input req_1 ;
case(state)
IDLE : if (req_0 == 1'b1) begin
fsm_function = GNT0;
end else if (req_1 == 1'b1) begin
fsm_function= GNT1;
end else begin
fsm_function = IDLE;
end
GNT0 : if (req_0 == 1'b1) begin
fsm_function = GNT0;
end else begin
fsm_function = IDLE;
end
GNT1 : if (req_1 == 1'b1) begin
fsm_function = GNT1;
end else begin
fsm_function = IDLE;
end
default : fsm_function = IDLE;
endcase
endfunction
//----------Seq Logic-----------------------------
always @ (posedge clock)
begin : FSM_SEQ
if (reset == 1'b1) begin
state <= #1 IDLE;
end else begin
state <= #1 next_state;
end
end
//----------Output Logic-----------------------------
always @ (posedge clock)
begin : OUTPUT_LOGIC
if (reset == 1'b1) begin
gnt_0 <= #1 1'b0;
gnt_1 <= #1 1'b0;
end
else begin
case(state)
IDLE : begin
gnt_0 <= #1 1'b0;
gnt_1 <= #1 1'b0;
end
GNT0 : begin
gnt_0 <= #1 1'b1;
gnt_1 <= #1 1'b0;
end
GNT1 : begin
gnt_0 <= #1 1'b0;
gnt_1 <= #1 1'b1;
end
default : begin
gnt_0 <= #1 1'b0;
gnt_1 <= #1 1'b0;
end
endcase
end
end // End Of Block OUTPUT_LOGIC
endmodule // End of Module arbiter
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