?? barrel.v
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// Barrel Shifter with 32 bit input & 32 bit output `timescale 1ns/100psmodule Barrel_Shifter(BS_Enable,BS_Input_Bus,BS_Shift_Type,BS_Shift_Amt,BS_Cin,BS_Shift_Output,BS_Cout);input[31:0] BS_Input_Bus;input[4:0] BS_Shift_Amt;input[1:0] BS_Shift_Type;input BS_Enable;input BS_Cin;output BS_Cout;output[31:0] BS_Shift_Output;wire[31:0] BS_Input_Bus;wire[4:0] BS_Shift_Amt;wire[1:0] BS_Shift_Type;wire BS_Enable;wire BS_Cin;reg BS_Cout;reg[31:0] BS_Shift_Output;integer i; always @(BS_Enable or BS_Input_Bus or BS_Shift_Type or BS_Shift_Amt or BS_Cin) begin if (BS_Enable==1'b0) begin BS_Shift_Output[31:0]=BS_Input_Bus[31:0]; BS_Cout=BS_Cin; end else if (BS_Enable==1'b1) //If shift needed begin case(BS_Shift_Type[1:0]) //Case for Shift type 2'b00:begin //LSL - Logical Shift Left if (BS_Shift_Amt[4:0]==5'b00000) begin //LSL#0 -special case BS_Shift_Output[31:0]=BS_Input_Bus[31:0]; BS_Cout=BS_Cin; end else //Shift of nonzero bits begin for (i=0;i<=31;i=i + 1) //for each bit of output check the condition and assign a value begin if (BS_Shift_Amt[4:0] > i) //Condition BS_Shift_Output[i]=1'b0; else BS_Shift_Output[i]=BS_Input_Bus[i-BS_Shift_Amt[4:0]]; end BS_Cout=BS_Input_Bus[31-BS_Shift_Amt[4:0]+1]; end end 2'b01:begin //LSR - Logic Shift Right if (BS_Shift_Amt[4:0]==5'b00000) //LSR#0 -used to encode LSR#32 begin BS_Shift_Output[31:0]=32'b00000000000000000000000000000000; BS_Cout=BS_Input_Bus[31]; end else //Shift of nonzero bits begin for (i=0;i<=31;i=i+1) //for each bit of output check the condition and assign a value begin if (i > 31-BS_Shift_Amt[4:0]) //Condition BS_Shift_Output[i]=1'b0; else BS_Shift_Output[i]=BS_Input_Bus[i+BS_Shift_Amt[4:0]]; end BS_Cout=BS_Input_Bus[BS_Shift_Amt[4:0]-1]; end end 2'b10:begin //ASR - Arithmetic Shift Right if (BS_Shift_Amt[4:0]==5'b00000) //ASR#0 -used to encode ASR#32 begin for (i=0;i<=31;i=i+1) BS_Shift_Output[i]=BS_Input_Bus[31]; BS_Cout=BS_Input_Bus[31]; end else //Shift of nonzero bits begin for (i=0;i<=31;i=i+1) //for each bit of output check the condition and assign a value begin if (i > 31-BS_Shift_Amt[4:0]) //Condition BS_Shift_Output[i]=BS_Input_Bus[31]; else BS_Shift_Output[i]=BS_Input_Bus[i+BS_Shift_Amt[4:0]]; end BS_Cout=BS_Input_Bus[BS_Shift_Amt[4:0]-1]; end end 2'b11:begin //ROR - Rotate Right if (BS_Shift_Amt[4:0]==5'b00000) //Shift of Zero(RRX) - Special case begin for (i=0;i<=31;i=i+1) if (i < 31) BS_Shift_Output[i]=BS_Input_Bus[i+1]; else if (i==31) BS_Shift_Output[i]=BS_Cin; BS_Cout=BS_Input_Bus[0]; end else //Shift of nonzero bits begin for (i=0;i<=31;i=i+1) //for each bit of output check the condition and assign a value begin if (i > 31-BS_Shift_Amt[4:0]) //Condition BS_Shift_Output[i]=BS_Input_Bus[i-31+BS_Shift_Amt[4:0]-1]; else BS_Shift_Output[i]=BS_Input_Bus[i+BS_Shift_Amt[4:0]]; end BS_Cout = BS_Input_Bus[BS_Shift_Amt[4:0]-1]; end end default:begin end endcase // case(BS_Shift_Type[1:0]) end // if (BS_Enable==1'b1) end //always endmodule //module ?? 快捷鍵說明
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