42 lines
493 B
Coq
42 lines
493 B
Coq
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module jyh_4490_3_counter(out,clk,clr,load,in,en,upd);
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input[3:0] in;
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input en,clk,clr,load,upd;
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output reg [3:0] out;
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always@(posedge clk,negedge clr)
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begin
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//异步清零
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if(!clr)
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out<=0;
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else if(en)
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begin
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//同步置数
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if(load)
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out<=in;
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//正反计数
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else if(upd)
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begin
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if(out>=4'd9)
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out=4'd0;
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else
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out <= out+1;
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end
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else
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begin
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if(out<=4'd0)
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out=4'd9;
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else
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out <= out-1;
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end
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end
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else
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out<=0;
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end
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endmodule
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