ELEC50010-IAC-CW/rtl/mips_cpu_control.v

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module mips_cpu_control(
input logic[31:0] Instr,
input logic ALUCond,
output logic[1:0] CtrlRegDst,
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output logic[1:0] CtrlPC,
output logic CtrlMemRead,
output logic[1:0] CtrlMemtoReg,
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output logic[4:0] CtrlALUOp,
output logic[4:0] Ctrlshamt,
output logic CtrlMemWrite,
output logic CtrlALUSrc,
output logic CtrlRegWrite
);
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typedef enum logic[5:0]{
SPECIAL = 6'd0,
REGIMM = 6'd1,
J = 6'd2,
JAL = 6'd3,
BEQ = 6'd4,
BNE = 6'd5,
BLEZ = 6'd6,
BGTZ = 6'd7,
ADDI = 6'd8,
ADDIU = 6'd9,
SLTI = 6'd10,
SLTIU = 6'd11,
ANDI = 6'd12,
ORI = 6'd13,
XORI = 6'd14,
LUI = 6'd15,
LB = 6'd32,
LH = 6'd33,
LWL = 6'd34,
LW = 6'd35,
LBU = 6'd36,
LHU = 6'd37,
LWR = 6'd38,
SB = 6'd40,
SH = 6'd41,
SW = 6'd43
} op_enum;
op_enum op;
assign op = Instr[31:26];
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typedef enum logic[5:0]{
SLL = 6'd0,
SRL = 6'd2,
SRA = 6'd3,
SLLV = 6'd4,
SRLV = 6'd6,
SRAV = 6'd7,
JR = 6'd8,
JALR = 6'd9,
MTHI = 6'd17,
MTLO = 6'd19,
MULT = 6'd24,
MULTU = 6'd25,
DIV = 6'd26,
DIVU = 6'd27,
ADDU = 6'd33,
SUBU = 6'd35,
AND = 6'd36,
OR = 6'd37,
XOR = 6'd38,
SLT = 6'd42,
SLTU = 6'd43
} funct_enum;
funct_enum funct;
assign funct = Instr[5:0];
typedef enum logic[4:0]{
BLTZ = 5'd0,
BGEZ = 5'd1,
BLTZAL = 5'd16,
BGEZAL = 5'd17
} rt_enum;
rt_enum rt;
assign rt = Instr[20:16];
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always @(*) begin
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//CtrlRegDst logic
if((op==ADDIU) || (op==ANDI) || (op==LB) || (op==LBU) || (op==LH) || (op==LHU) || (op==LUI) || (op==LW) || (op==LWL) || (op==LWR) || (op==ORI) || (op==SLTI) || (op==SLTIU) || (op==XORI))begin
CtrlRegDst = 2'd0; //Write address comes from rt
$display("CTRLREGDST: Rt");
end else if ((op==SPECIAL)&&((funct==ADDU) || (funct==AND) || (funct==JALR) || (funct==OR) || (funct==SLL) || (funct==SLLV) || (funct==SLT) || (funct==SLTU) || (funct==SRA) || (funct==SRAV) || (funct==SRL) || (funct==SRLV) || (funct==SUBU) || (funct==XOR)))begin
CtrlRegDst = 2'd1; //Write address comes from rd
$display("CTRLREGDST: Rd");
end else if (op == JAL)begin
CtrlRegDst = 2'd2; //const reg 31, for writing to the link register
$display("CTRLREGDST: Link");
end else begin CtrlRegDst = 1'bx; $display("xxxxxxxxxxxxxx");end//Not all instructions are encompassed so, added incase for debug purposes
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//CtrlPC logic
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if(ALUCond && ((op==BEQ) || (op==BGTZ) || (op==BLEZ) || (op==BNE) || ((op==REGIMM)&&((rt==BGEZ) || (rt==BGEZAL) || (rt==BLTZ) || (rt==BLTZAL)))))begin
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CtrlPC = 2'd1; // Branches - Jumps relative to PC
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end else if((op==J) || (op==JAL))begin
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CtrlPC = 2'd2; // Jumps within 256MB Region using 26-bit immediate in J type instruction
$display("Jump PC Ctrl");
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end else if((op==SPECIAL)&&(funct==JR) || (funct==JALR))begin
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CtrlPC = 2'd3; // Jumps using Register.
//$display("Ctrl PC Jump Register");
end else begin CtrlPC = 2'd0; /*/$display("Ctrl PC No Jump/Branch");*/end // No jumps or branches, just increment to next word
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//CtrlMemRead and CtrlMemtoReg logic -- Interesting quirk that they have the same logic. Makes sense bc you'd only want to select the read data out when the memory itself is read enabled.
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if((op==LB) || (op==LBU) || (op==LH) || (op==LHU) || (op==LW) || (op==LWL) || (op==LWR))begin
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CtrlMemRead = 1;//Memory is read enabled
CtrlMemtoReg = 2'd1;//write data port of memory is fed from data memory
$display("Memory read enabled");
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end else if ((op==ADDIU) || (op==ANDI) || (op==ORI) || (op==SLTI) || (op==SLTIU) || (op==XORI) || ((op==SPECIAL)&&((funct==ADDU) || (funct==AND) || (funct==DIV) || (funct==DIVU) || (funct==MTHI) || (funct==MTLO) || (funct==MULT) || (funct==MULTU) || (funct==OR) || (funct==SLL) || (funct==SLLV) || (funct==SLT) || (funct==SLTU) || (funct==SRA) || (funct==SRAV) || (funct==SRL) || (funct==SRLV) || (funct==SUBU) || (funct==XOR))))begin
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CtrlMemRead = 0;//Memory is read disabled
CtrlMemtoReg = 2'd0;//write data port of memory is fed from ALURes
$display("Memory read disabled");
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end else if ((op==JAL) || ((op==SPECIAL)&&(funct == JALR)))begin
CtrlMemtoReg = 2'd2;//write data port of memory is fed from PC + 8
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end else begin CtrlMemRead = 1'bx;end//Not all instructions are encompassed so, added incase for debug purposes
//CtrlALUOp Logic
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if((op==ADDIU) || ((op==SPECIAL)&&(funct==ADDU)))begin
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CtrlALUOp = 5'd0; //ADD from ALUOps
$display("ALU OP = 0 (ADDU/ADDIU)");
end else if((op==ANDI) || ((op==SPECIAL)&&(funct==AND)))begin
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CtrlALUOp = 5'd4;//AND from ALUOps
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end else if(op==BEQ) begin
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CtrlALUOp = 5'd13;//EQ from ALUOps
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end else if((op==REGIMM)&&((rt==BGEZ) || (rt==BGEZAL)))begin
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CtrlALUOp = 5'd17;//GEQ from ALUOps
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end else if(op==BGTZ)begin
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CtrlALUOp = 5'd16;//GRT from ALUOps
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end else if(op==BLEZ)begin
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CtrlALUOp = 5'd15;//LEQ from ALUOps
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end else if((op==REGIMM)&&((rt==BLTZ) || (rt==BLTZAL)))begin
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CtrlALUOp = 5'd14;//LES from ALUOps
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end else if(op==BNE)begin
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CtrlALUOp = 5'd18;//NEQ from ALUOps
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end else if((op==SPECIAL)&&(funct==DIV))begin
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CtrlALUOp = 5'd3;//DIV from ALUOps
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end else if((op==SPECIAL)&&(funct==DIVU))begin
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CtrlALUOp = 5'd23;//DIVU from ALUOps
end else if((op==LB) || (op==LBU) || (op==LH) || (op==LHU) || (op==LW) || (op==LWL) || (op==LWR) || (op==SB) || (op==SH) || (op==SW))begin
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CtrlALUOp = 5'd0;//ADD from ALUOps
$display("LB IN CONTROL");
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end else if(op==LUI)begin
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CtrlALUOp = 5'd7;//SLL from ALUOps
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end else if((op==SPECIAL)&&((funct==MTHI) || (funct==MTLO)))begin
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CtrlALUOp = 5'd19;//PAS from ALUOps
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end else if((op==SPECIAL)&&(funct==MULT))begin
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CtrlALUOp = 5'd2;//MUL from ALUOps
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end else if((op==SPECIAL)&&(funct==MULTU))begin
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CtrlALUOp = 5'd22;//MULU from ALUOps
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end else if((op==ORI) || ((op==SPECIAL)&&(funct==OR)))begin
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CtrlALUOp = 5'd5;//OR from ALUOps
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end else if((op==SPECIAL)&&(funct==SLL))begin
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CtrlALUOp = 5'd7;//SLL from ALUOps
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$display("ALU Op = 7 (SLL)");
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end else if((op==SPECIAL)&&(funct==SLLV))begin
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CtrlALUOp = 5'd8;//SLLV from ALUOps
$display("ALU Op = 9 (SLLV)");
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end else if((op==SPECIAL)&&(funct==SRA))begin
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CtrlALUOp = 5'd11;//SRA from ALUOps
$display("ALU Op = 11 (SRA)");
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end else if((op==SPECIAL)&&(funct==SRAV))begin
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CtrlALUOp = 5'd12;//SRAV from ALUOps
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end else if((op==SPECIAL)&&(funct==SRL))begin
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$display("ALU Op = 7 (SRL)");
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CtrlALUOp = 5'd9;//SRL from ALUOps
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end else if((op==SPECIAL)&&(funct==SRLV))begin
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CtrlALUOp = 5'd10;//SRLV from ALUOps
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end else if((op==SLTI) || ((op==SPECIAL)&&(funct==SLT)))begin
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CtrlALUOp = 5'd20;//SLT from ALUOps
$display("ALU Op = 20 (SLT/SLTI)");
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end else if((op==SLTIU) || ((op==SPECIAL)&&(funct==SLTU)))begin
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CtrlALUOp = 5'd21;//SLTU from ALUOps
$display("ALU Op = 21 (SLTU/SLTIU)");
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end else if((op==SPECIAL)&&(funct==SUBU))begin
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CtrlALUOp = 5'd1;//SUB from ALUOps
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end else if((op==XORI) || ((op==SPECIAL)&&(funct==XOR)))begin
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CtrlALUOp = 5'd6;//XOR from ALUOps
$display("ALU Op = 6 (XOR)");
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end else begin
CtrlALUOp = 5'bxxxxx;
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end
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//Ctrlshamt logic
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if((op==SPECIAL)&&((funct==SRA) || (funct==SRL) || (funct==SLL)))begin
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Ctrlshamt = Instr[10:6];// Shift amount piped in from the instruction
end else if(op == LUI)begin
Ctrlshamt = 5'd16;//Used specifically to implement LUI as the instruction itslef does not include shamt
end else begin Ctrlshamt = 5'bxxxxx;end
//CtrlMemWrite logic
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if((op==SB) || (op==SH) || (op==SW))begin
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CtrlMemWrite = 1;//Memory is write enabled
end else begin CtrlMemWrite = 0;end//default is 0 to ensure no accidental overwriting.
//CtrlALUSrc logic
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if((op==ADDIU) || (op==ANDI) || (op==LUI) || (op==ORI) || (op==SLTI) || (op==SLTIU) || (op==XORI) || (op==LB) || (op==LBU) || (op==LH) || (op==LHU) || (op==LW) || (op==LWL) || (op==LWR) || (op==SB) || (op==SH) || (op==SW))begin
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CtrlALUSrc = 1;//ALU Bus B is fed from the 16-bit immediate sign extended to 32-bit value taken from Instr[15-0]
end else if((op==BEQ) || (op==BGTZ) || (op==BLEZ) || (op==BNE) || ((op==SPECIAL)&&((funct==ADDU) || (funct==AND) || (funct==DIV) || (funct==DIVU) || (funct==MULT) || (funct==MULTU) || (funct==OR) || (funct==SLL) || (funct==SLLV) || (funct==SLT) || (funct==SLTU) || (funct==SRA) || (funct==SRAV) || (funct==SRL) || (funct==SRLV) || (funct==SUBU) || (funct==XOR))) || ((op==REGIMM)&&((rt==BGEZ) || (rt==BGEZAL) || (rt==BLTZ) || (rt==BLTZAL))))begin
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CtrlALUSrc = 0;///ALU Bus B is fed from rt.
end else begin CtrlALUSrc = 1'bx;end
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//CtrlRegWrite logic
if((op==ADDIU) || (op==ANDI) || (op==LB) || (op==LBU) || (op==LH) || (op==LHU) || (op==LUI) || (op==LW) || (op==LWL) || (op==LWR) || (op==ORI) || (op==SLTI) || (op==XORI) || ((op==SPECIAL)&&((funct==ADDU) || (funct==AND) || (funct==DIV) || (funct==DIVU) || (funct==MULT) || (funct==MULTU) || (funct==OR) || (funct==SLL) || (funct==SLLV) || (funct==SLT) || (funct==SLTU) || (funct==SRA) || (funct==SRAV) || (funct==SRL) || (funct==SRLV) || (funct==SUBU) || (funct==XOR)))) begin
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CtrlRegWrite = 1;//The Registers are Write Enabled
end else begin CtrlRegWrite = 0;end // The Registers are Write Disabled
end
endmodule