module CtrlUnit(
input [31:0] instr,
input [31:0] rdata1, rdata2,
input [31:0] pc,ram_data,hi,lo,alu_r,cop_data,mul_out,
input [31:0] exc_addr,
input clk,
output mtc0,eret,teq_exc,
output reg [2:0] mdu,
output reg reg_wena,
output ram_wena,
output reg [3:0] cause,
output [4:0] rs,rt,rd,waddr,
output reg [31:0] wdata,reg_data,
output [31:0] ram_addr,
output reg [31:0] pc_in,
output reg [31:0] alu_a,alu_b,
output reg [3:0] alu_op
);
//******MIPS-55*********//
parameter //SPECIAL OP LIST 5-0
ADDU = 6'b100001,
SUBU = 6'b100011,
ADD = 6'b100000,
SUB = 6'b100010,
AND = 6'b100100,
OR = 6'b100101,
XOR = 6'b100110,
NOR = 6'b100111,
SLT = 6'b101010,
SLTU = 6'b101011,
SRL = 6'b000010,
SRA = 6'b000011,
SLL = 6'b000000,
SLLV = 6'b000100,
SRLV = 6'b000110,
SRAV = 6'b000111,
JR = 6'b001000,
JALR = 6'b001001,
MULT = 6'b011000,
MULTU = 6'b011001,
DIV = 6'b011010,
DIVU = 6'b011011,
MFHI = 6'b010000,
MFLO = 6'b010010,
MTHI = 6'b010001,
MTLO = 6'b010011,
BREAK = 6'b001101,
SYSCALL = 6'b001100,
TEQ = 6'b110100,
//SPECIAL 2 func
CLZ = 6'b100000,
MUL = 6'b000010,
//REGIMM OP LIST 20-16
BLTZ = 5'b00000,
BGEZ = 5'b00001,
//COP0 OP LIST
ERET = 6'b011000, //5-0&&25TH=1
MFC0 = 5'b00000, //20-16
MTC0 = 5'b00100,
//OPCODE FIELD 31-26
ADDI = 6'b001000,
ADDIU = 6'b001001,
ANDI = 6'b001100,
ORI = 6'b001101,
XORI = 6'b001110,
LW = 6'b100011,
SW = 6'b101011,
BEQ = 6'b000100,
BNE = 6'b000101,
BLEZ = 6'b000110,
BGTZ = 6'b000111,
SLTI = 6'b001010,
SLTIU = 6'b001011,
LUI = 6'b001111,
J = 6'b000010,
JAL = 6'b000011,
LB = 6'b100000,// Load Byte Function=6'h24
LBU = 6'b100100,// 1Load Byte Unsigned
LH = 6'b100001,// Load high
LHU = 6'b100101,// Load High Unsigned
SB = 6'b101000,// Send Byte
SH = 6'b101001,// Send High
SPECIAL = 6'b000000,
SPECIAL2= 6'b011100,
REGIMM = 6'b000001,
COP0 = 6'b010000;
//ALU OPCODE
parameter _ADDU = 4'b0000; //r=a+b unsigned
parameter _ADD = 4'b0010; //r=a+b signed
parameter _SUBU = 4'b0001; //r=a-b unsigned
parameter _SUB = 4'b0011; //r=a-b signed
parameter _AND = 4'b0100; //r=a&b
parameter _OR = 4'b0101; //r=a|b
parameter _XOR = 4'b0110; //r=a^b
parameter _NOR = 4'b0111; //r=~(a|b)
parameter _LUI = 4'b1000; //r={b[15:0],16'b0}
parameter _SLT = 4'b1011; //r=(a-b<0)?1:0 signed
parameter _SLTU = 4'b1010; //r=(a-b<0)?1:0 unsigned
parameter _SRA = 4'b1100; //r=b>>>a
parameter _SLL = 4'b1110; //r=b<<a
parameter _SRL = 4'b1101; //r=b>>a
parameter _SYSCALL= 4'b1000,
_BREAK = 4'b1001,
_TEQ = 4'b1101;
wire [5:0] op = instr[31:26];
assign rs = instr[25:21];
assign rt = instr[20:16];
assign rd = instr[15:11];
wire [5:0] func = instr[5:0];
wire [4:0] shamt = instr[10:6];
wire [15:0] imm = instr[15:0];
wire [25:0] addr = instr[25:0];
parameter SIGN = 1'b1;
parameter UNSIGN = 1'b0;
wire imm_sign = (op==ANDI||op==ORI||op==XORI)?UNSIGN:SIGN;
wire [31:0] shamt_ext = {27'b0,shamt};
wire [31:0] imm_ext = imm_sign?{{(16){imm[15]}},imm}:{16'b0,imm};
reg [31:0] load_data,clz_data;
assign waddr = (op==SPECIAL||op==SPECIAL2)? rd: (op==JAL) ?5'b11111:rt;
always@(*)begin
case(op)
SB: reg_data = {24'b0,rdata2[7:0]};
SH: reg_data = {16'b0,rdata2[15:0]};
SW: reg_data = rdata2;
default:reg_data = rdata2;
endcase
case(op)
LB: load_data = {{24{ram_data[7]}},ram_data[7:0]};
LBU: load_data = {24'b0,ram_data[7:0]};
LH: load_data = {{16{ram_data[15]}},ram_data[15:0]};
LHU: load_data = {16'b0,ram_data[15:0]};
LW: load_data = ram_data;
default:load_data = ram_data;
endcase
if(op==SPECIAL)
case(func)
SYSCALL:cause = _SYSCALL;
BREAK: cause = _BREAK;
TEQ: cause = _TEQ;
default:cause = 5'b0;
endcase
else cause = 5'b0;
/*
1 mult
2 multu
3 div
4 divu
5 mthi
6 mtlo
7 mul
*/
if(op==SPECIAL)
case(func)
MULT: mdu = 3'h1;
MULTU: mdu = 3'h2;
DIV: mdu = 3'h3;
DIVU: mdu = 3'h4;
MTHI: mdu = 3'h5;
MTLO: mdu = 3'h6;
default:mdu = 3'h0;
endcase
else mdu = 3'h0;
end
wire [31:0] npc = pc+4;
wire [31:0] pc_branch = npc + {{(14){imm[15]}},imm,2'b00};
wire [31:0] pc_jmp = {npc[31:28],addr,2'b00};
assign ram_addr = rdata1 + imm_ext;
assign eret = op==COP0 && func==ERET;
wire mfc0 = op==COP0 && rs==MFC0;
assign mtc0 = op==COP0 && rs==MTC0;
assign teq_exc = rdata1==rdata2;
parameter ENA = 1'b1;
parameter DIS = 1'b0;
wire mem_load = op==LB || op==LH || op==LBU || op==LHU || op==LW;
assign ram_wena = op==SW || op==SH || op==SB;
integer i;
always@(*)begin
case(op)
SPECIAL: case(func)
MULTU,
DIV,
DIVU,
JR,
MTHI,
MTLO,
BREAK,
SYSCALL:reg_wena = DIS;
default:reg_wena = ENA;
endcase
COP0: reg_wena = rs==MFC0?ENA:DIS;
SPECIAL2,
LB,
LBU,
LH,
LHU,
ADDI,
ADDIU,
ANDI,
ORI,
XORI,
LW,
SLTI,
SLTIU,
LUI,
JAL: reg_wena = ENA;
default: reg_wena = DIS;
endcase
case(op)
SPECIAL:case(func)
JALR: wdata = npc;
MFHI: wdata = hi;
MFLO: wdata = lo;
default:wdata = alu_r;
endcase
SPECIAL2:begin
if(func==CLZ) casez(rdata1)
32'b1???????????????????????????????: wdata = 32'h0;
32'b01??????????????????????????????: wdata = 32'h1;
32'b001?????????????????????????????: wdata = 32'h2;
32'b0001????????????????????????????: wdata = 32'h3;
32'b00001???????????????????????????: wdata = 32'h4;
32'b000001??????????????????????????: wdata = 32'h5;
32'b0000001?????????????????????????: wdata = 32'h6;
32'b00000001????????????????????????: wdata = 32'h7;
32'b000000001???????????????????????: wdata = 32'h8;
32'b0000000001??????????????????????: wdata = 32'h9;
32'b00000000001?????????????????????: wdata = 32'ha;
32'b000000000001????????????????????: wdata = 32'hb;
32'b0000000000001???????????????????: wdata = 32'hc;
32'b00000000000001??????????????????: wdata = 32'hd;
32'b000000000000001?????????????????: wdata = 32'he;
32'b0000000000000001????????????????: wdata = 32'hf;
32'b00000000000000001???????????????: wdata = 32'h10;
32'b000000000000000001??????????????: wdata = 32'h11;
32'b0000000000000000001?????????????: wdata = 32'h12;
32'b00000000000000000001????????????: wdata = 32'h13;
32'b000000000000000000001???????????: wdata = 32'h14;
32'b0000000000000000000001??????????: wdata = 32'h15;
32'b00000000000000000000001?????????: wdata = 32'h16;
32'b000000000000000000000001????????: wdata = 32'h17;
32'b0000000000000000000000001???????: wdata = 32'h18;
32'b00000000000000000000000001??????: wdata = 32'h19;
32'b000000000000000000000000001?????: wdata = 32'h1a;
32'b0000000000000000000000000001????: wdata = 32'h1b;
32'b00000000000000000000000000001???: wdata = 32'h1c;
32'b000000000000000000000000000001??: wdata = 32'h1d;
32'b0000000000000000000000000000001?: wdata = 32'h1e;
32'b00000000000000000000000000000001: wdata = 32'h1f;
32'b00000000000000000000000000000000: wdata = 32'h20;
endcase
else if(func==MUL) wdata = mul_out;
else wdata = alu_r;
end
JAL: wdata = npc;
LW,LB,LH,LBU,LHU: wdata = load_data;
COP0: if(rs==MFC0) wdata = cop_data;
else wdata = alu_r;
default: wdata = alu_r;
endcase
//Below is OK
case(op)
SPECIAL: case(func)
SLL,
SRL,
SRA:begin
alu_a = shamt_ext;
alu_b = rdata2;
end
default:begin
alu_a = rdata1;
alu_b = rdata2;
end
endcase
ADDI,
ADDIU,
ANDI,
ORI,
XORI,
SLTI,
SLTIU,
LUI:begin
alu_a = rdata1;
alu_b = imm_ext;
end
default:begin
alu_a = rdata1;
alu_b = rdata2;
end
endcase
//PC Source
case(op)
SPECIAL: case(func)
SYSCALL,
TEQ,
BREAK: pc_in = exc_addr;
JALR,
JR: pc_in = rdata1;
default:pc_in = npc;
endcase
COP0: case(func)
ERET: pc_in = exc_addr;
default:pc_in = npc;
endcase
REGIMM: case(rt)
BLTZ:if(rdata1[31])
pc_in = pc_branch;
else
pc_in = npc;
BGEZ:if(!rdata1[31])
pc_in = pc_branch;
else
pc_in = npc;
default:pc_in = npc;
endcase
J,
JAL: pc_in = pc_jmp;
BEQ:if(rdata1==rdata2)
pc_in = pc_branch;
else pc_in = npc;
BNE:if(rdata1!=rdata2)
pc_in = pc_branch;
else pc_in = npc;
BLEZ:if(rdata1[31] || rdata1==32'b0)
pc_in = pc_branch;
else pc_in = npc;
BGTZ:if(!rdata1[31] && rdata1!=32'b0)
pc_in = pc_branch;
else pc_in = npc;
default: pc_in = npc;
endcase
case(op)
SPECIAL:case(func)
ADDU: alu_op = _ADDU;
SUBU: alu_op = _SUBU;
ADD: alu_op = _ADD;
SUB: alu_op = _SUB;
AND: alu_op = _AND;
OR: alu_op = _OR;
XOR: alu_op = _XOR;
NOR: alu_op = _NOR;
SLT: alu_op = _SLT;
SRL: alu_op = _SRL;
SLL: alu_op = _SLL;
SRA: alu_op = _SRA;
SLTU: alu_op = _SLTU;
SRLV: alu_op = _SRL;
SLLV: alu_op = _SLL;
SRAV: alu_op = _SRA;
default: alu_op = _ADDU;
endcase
ORI: alu_op = _OR;
XORI: alu_op = _XOR;
BEQ: alu_op = _SUBU;
BNE: alu_op = _SUBU;
ANDI: alu_op = _AND;
ADDIU: alu_op = _ADDU;
ADDI: alu_op = _ADD;
SLTI: alu_op = _SLT;
SLTIU: alu_op = _SLTU;
LUI: alu_op = _LUI;
default: alu_op = _ADDU;
endcase
end
endmodule