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Updated ALU and Control

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This commit is contained in:
jc4419 2020-12-07 15:49:44 +04:00
parent a2bcf3ed1b
commit 9198c4f51b
2 changed files with 250 additions and 349 deletions
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93
rtl/mips_cpu_alu.v
View file

@ -1,6 +1,6 @@
module mips_cpu_alu(
input signed logic[31:0] A, //Bus A - Input from the Readdata1 output from the reg file which corresponds to rs.
input signed logic[31:0] B, //Bus B - Input from the Readdata2 output from the reg file which corresponds to rt.
input logic[31:0] A, //Bus A - Input from the Readdata1 output from the reg file which corresponds to rs.
input logic[31:0] B, //Bus B - Input from the Readdata2 output from the reg file which corresponds to rt. Or from the 16-bit immediate sign extended to 32-bit value taken from Instr[15-0].
input logic [4:0] ALUOp, // 5-bit output from Control that tells the alu what operation to do from a list of 20 distinct alu operations(see below).
input logic [4:0] shamt, //5-bit input used to specify shift amount for shift operations. Taken directly from the R-type instruction (Non-Variable) or from
@ -11,9 +11,9 @@ module mips_cpu_alu(
/*
Alu Operations:
-Manipulation Operations: The perform an operation on a value(s).
- Addition
- Subtraction
-Manipulation Operations: They perform an operation on a value(s) and have an output to ALURes.
- Addition (unsigned)
- Subtraction (unsigned)
- Multiplication
- Division
- Bitwise AND
@ -25,14 +25,18 @@ Alu Operations:
- Shift Right Logical Variable
- Shift Right Arithmetic
- Shift Right Arithmetic Variable
-Condtional Check Operations: They check conditions.
- Equality (=)
- Less Than (<)
- Less Than or Equal To (<=)
- Greater Than (>)
- Greater Than or Equal to (>=)
- Negative Equality(=/=)
-Implementation Operation:
- Set On Less Than (signed)
- Set On Less Than Unsigned
- Multiplication (unsigned)
- Division (unsigned)
-Condtional Check Operations: They check conditions and have an output to ALUCond
- Equality (=) (signed)
- Less Than (<) (signed)
- Less Than or Equal To (<=) (signed)
- Greater Than (>) (signed)
- Greater Than or Equal to (>=) (signed)
- Negative Equality(=/=) (signed)
-Implementation Operation: A design choice used for implmentation.
- Pass-through (Used to implement MTHI and MTLO, as these instructions do not need the ALU but the alu is in the pathway to the regfile, so the register value simply passes through.)
*/
@ -41,8 +45,8 @@ Alu Operations:
ADD = 5'd0,
SUB = 5'd1,
MUL = 5'd2,
DIV = 5'd3,
MUL = 5'd2,//signed multiply
DIV = 5'd3,//signed divide
AND = 5'd4,
OR = 5'd5,
XOR = 5'd6,
@ -58,11 +62,16 @@ Alu Operations:
GRT = 5'd16,
GEQ = 5'd17,
NEQ = 5'd18,
PAS = 5'd19
PAS = 5'd19,
SLT = 5'd20,//signed compare
SLTU = 5'd21,//unsigned compare
MULU = 5'd22,//unsigned divide
DIVU = 5'd23//unsigned multiply
} Ops;
Ops ALUOps; //Note confusing naming to avoid potential duplicate variable naming errors, as a result of enum implemetnation quirks.
Ops ALUOps; //Note confusing naming to avoid potential duplicate variable naming errors, as a result of enum implemetnation.
assign ALUOps = ALUOp
@ -72,19 +81,19 @@ assign ALUOps = ALUOp
case(ALUOps)
ADD: begin
ALURes = A + B;
ALURes = $signed(A) + $signed(B);
end
SUB: begin
ALURes = A - B;
ALURes = $signed(A) - $signed(B) ;
end
MUL: begin
ALURes = A * B;
ALURes = $signed(A) * $signed(B);
end
DIV: begin
ALURes = A / B;
ALURes = $signed(A) / $signed(B);
end
AND: begin
@ -124,7 +133,7 @@ assign ALUOps = ALUOp
end
EQ: begin
if A == B begin
if ($signed(A) == $signed(B)) begin
ALUCond = 1;
end
else begin
@ -134,7 +143,7 @@ assign ALUOps = ALUOp
end
LES: begin
if A < B begin
if ($signed(A) < $signed(B)) begin
ALUCond = 1;
end
else begin
@ -144,17 +153,7 @@ assign ALUOps = ALUOp
end
LEQ: begin
if A <= B begin
ALUCond = 1;
end
else begin
ALUCond = 0;
end
end
LEQ: begin
if A <= B begin
if ($signed(A) <= $signed(B)) begin
ALUCond = 1;
end
else begin
@ -164,7 +163,7 @@ assign ALUOps = ALUOp
end
GRT: begin
if A > B begin
if ($signed(A) > $signed(B)) begin
ALUCond = 1;
end
else begin
@ -174,7 +173,7 @@ assign ALUOps = ALUOp
end
GEQ: begin
if A >= B begin
if ($signed(A) >= $signed(B)) begin
ALUCond = 1;
end
else begin
@ -184,7 +183,7 @@ assign ALUOps = ALUOp
end
NEQ: begin
if A != B begin
if ($signed(A) != $signed(B)) begin
ALUCond = 1;
end
else begin
@ -197,6 +196,26 @@ assign ALUOps = ALUOp
ALURes = A;
end
SLT: begin
if ($signed(A) < $signed(B)) begin
ALURes = 1;
end
end
SLTU: begin
if (A < B) begin
ALURes = 1;
end
end
MULU: begin
ALURes = A * B;
end
DIVU: begin
ALURes = A / B;
end
endcase
end
endmodule

506
rtl/mips_cpu_control.v
View file

@ -1,319 +1,201 @@
/*
Instr
*0: XOR SUBU SRLV SRL SRAV SRA SLTU SLT SLLV
SLL OR MULTU MULT MTLO MTHI JR JALR DIVU
DIV AND ADDU
1: BLTZAL BLTZ BGEZAL BGEZ
2: J
3: JAL
4: BEQ
5: BNE
6: BLEZ
7: BGTZ
*9: ADDIU
10: SLTI
11: SLTIU
12: ANDI
13: ORI
14: XORI
15: LUI
32: LB
33: LH
34: LWL
*35: LW
36: LBU
37: LHU
38: LWR
40: SB
41: SH
*43: SW
*/
module mips_cpu_control(
/*
Regdst:
00:Instr[20-16]
01:Instr[15-11]
10:2'd31
*/
input logic[31:0] Instr,
input logic ALUCond,
output logic CtrlRegDst,
output logic[1:0] CtrlPC,
output logic CtrlMemRead,
output logic CtrlMemtoReg,
output logic[4:0] CtrlALUOp,
output logic[4:0] Ctrlshamt,
output logic CtrlMemWrite,
output logic CtrlALUSrc,
output logic CtrlRegWrite
/*
Memtoreg:
00: Alu output
01: Memory output
10: PC+4 output
*/
);
//Commented signals represents dont care(x)
/* logic[5:0] op;
logic[5:0] funct;
logic[4:0] rt; */
module mips_cpu_control{
input logic[5:0] Instr,
input logic[5:0] rt,
output logic[1:0] Regdst,
output logic Branch,
output logic Memread,
output logic[1:0] Memtoreg,
output logic Memwrite,
output logic Alusrc,
output logic Regwrite,
output logic Jump,
);
/* assign op = Instr[31:26];
assign funct = Instr[5:0];
assign rt = Instr[20:16]; */
always_comb begin
case(Instr)
6'd0: begin
Regdst=2'b01;
Branch=0;
Memread=0;
Memwrite=0;
Memtoreg=2'b00;
Alusrc=0;
Regwrite=1;
Jump=0;
end
6'd1: begin
Regdst=2'b10;
Branch=1;
Memread=0;
Memwrite=0;
if(rt[5]==1)begin
Memtoreg=2'b10;
Regwrite=1;
end
Alusrc=0;
Jump=0;
end
6'd2: begin
//Regdst=2'b;
Branch=0;
Memread=0;
//Memtoreg=;
Memwrite=0;
//Alusrc=;
Regwrite=0;
Jump=1;
end
6'd3: begin
Regdst=2'b10;
Branch=0;
Memread=0;
Memtoreg=2'b10;
Memwrite=0;
//Alusrc=;
Regwrite=1;
Jump=1;
end
6'd4: begin
//Regdst=2'b;
Branch=1;
Memread=0;
//Memtoreg=;
Memwrite=0;
Alusrc=0;
Regwrite=0;
Jump=0;
end
6'd5: begin
//Regdst=2'b;
Branch=1;
Memread=0;
//Memtoreg=;
Memwrite=0;
Alusrc=0;
Regwrite=0
Jump=0;
end
6'd6: begin
//Regdst=2'b;
Branch=1;
Memread=0;
//Memtoreg=;
Memwrite=0;
Alusrc=0;
Regwrite=0;
Jump=0;
end
6'd7: begin
//Regdst=2'b;
Branch=1;
Memread=0;
//Memtoreg=;
Memwrite=0;
Alusrc=0;
Regwrite=0;
Jump=0;
end
6'd9: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd10: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd11: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd12: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd13: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd14: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2'b00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd15: begin
Regdst=2'b00;
Branch=0;
Memread=0;
Memtoreg=2b'00;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd32: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd33: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd34: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd35: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd36: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd37: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd38: begin
Regdst=2'b00;
Branch=0;
Memread=1;
Memtoreg=2'b01;
Memwrite=0;
Alusrc=1;
Regwrite=1;
Jump=0;
end
6'd40: begin
//Regdst=2'b;
Branch=0;
Memread=0;
//Memtoreg=;
Memwrite=1;
Alusrc=1;
Regwrite=0;
Jump=0;
end
6'd41: begin
//Regdst=2'b;
Branch=0;
Memread=0;
//Memtoreg=;
Memwrite=1;
Alusrc=1;
Regwrite=0;
Jump=0;
end
6'd43: begin
//Regdst=2'b;
Branch=0;
Memread=0;
//Memtoreg=;
Memwrite=1;
Alusrc=1;
Regwrite=0;
Jump=0;
end
endcase
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];
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];
always_comb begin
//CtrlRegDst logic
if(op == (ADDIU | ANDI | LB | LBU | LH | LHU | LUI | LW | LWL | LWR | ORI | SLTI | SLTIU | XORI))begin
CtrlRegDst = 0; //Write address comes from rt
end else if (op == (SPECIAL & (funct == (ADDU | AND | JALR | OR | SLL | SLLV | SLT | SLTU | SRA | SRAV | SRL | SRLV | SUBU | XOR))))begin
CtrlRegDst = 1; //Write address comes from rd
end else begin CtrlRegDst = 1'bx; end//Not all instructions are encompassed so, added incase for debug purposes
//CtrlPC logic
if(op == (BEQ | BGTZ | BLEZ | BNE | (REGIMM & (rt == (BGEZ | BGEZAL | BLTZ | BLTZAL)))))begin
CtrlPC = 2'd1; // Branches - Jumps relative to PC
end else if(op == (J | JAL))begin
CtrlPC = 2'd2; // Jumps within 256MB Region using 26-bit immediate in J type instruction
end else if(op == (JR | JALR))begin
CtrlPC = 2'd3; // Jumps using Register.
end else begin CtrlPC = 2'd0;end // No jumps, just increment to next word
//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.
if(op == (LB | LBU | LH | LHU | LW | LWL | LWR))begin
CtrlMemRead = 1;//Memory is read enabled
CtrlMemtoReg = 1;//write data port of memory is fed from data memory
end else if (op == (ADDIU | ANDI | ORI | SLTI | SLTIU | XORI | (SPECIAL & (funct == (ADDU | AND | DIV | DIVU | MTHI | MTLO | MULT | MULTU | OR | SLL | SLLV | SLT | SLTU | SRA | SRAV | SRL | SRLV | SUBU | XOR)))))begin
CtrlMemRead = 0;//Memory is read disabled
CtrlMemtoReg = 0;//write data port of memory if fed from ALURes
end else begin CtrlMemRead = 1'bx;end//Not all instructions are encompassed so, added incase for debug purposes
//CtrlALUOp Logic
if(op == (ADDIU | (SPECIAL & (funct == ADDU))))begin
CtrlALUOp = 5'd0; //ADD from ALUOps
end else if (op == (ANDI | (SPECIAL & (funct == AND))))begin
CtrlALUOp = 5'd4;//AND from ALUOps
end else if (op == BEQ) begin
CtrlALUOp = 5'd13;//EQ from ALUOps
end else if (op == (REGIMM & (rt == (BGEZ | BGEZAL))))begin
CtrlALUOp = 5'd17;//GEQ from ALUOps
end else if (op == BGTZ)begin
CtrlALUOp = 5'd16;//GRT from ALUOps
end else if (op == BLEZ)begin
CtrlALUOp = 5'd15;//LEQ from ALUOps
end else if (op == (REGIMM & (rt == (BLTZ | BLTZAL))))begin
CtrlALUOp = 5'd14;//LES from ALUOps
end else if (OP == BNE)begin
CtrlALUOp = 5'd18;//NEQ from ALUOps
end else if (op == (SPECIAL & (funct == DIV)))begin
CtrlALUOp = 5'd3;//DIV from ALUOps
end else if (op == (SPECIAL & (funct == DIVU)))begin
CtrlALUOp = 5'd23;//DIVU from ALUOps
end else if (op == (LB | LBU | LH | LHU | LW | LWL | LWR | SB | SBH | SW))begin
CtrlALUOp = 5'd0;//ADD from ALUOps
end else if (op == LUI)begin
CtrlALUOp = 5'd7;//SLL from ALUOps
end else if (op == (SPECIAL & (funct == MTHI | MTLO)))begin
CtrlALUOp = 5'd19;//PAS from ALUOps
end else if (op == (SPECIAL & (funct == MULT)))begin
CtrlALUOp = 5'd2;//MUL from ALUOps
end else if (op == (SPECIAL & (funct == MULTU)))begin
CtrlALUOp = 5'd22;//MULU from ALUOps
end else if (op == (ORI | (SPECIAL & (funct == OR))))begin
CtrlALUOp = 5'd5;//OR from ALUOps
end else if (op == (SPECIAL & (funct == SLL)))begin
CtrlALUOp = 5'd7;//SLL from ALUOps
end else if (op == (SPECIAL & (funct == SLLV)))begin
CtrlALUOp = 5'd8;//SLLV from ALUOps
end else if (op == (SPECIAL & (funct == SRA)))begin
CtrlALUOp = 5'd11;//SRA from ALUOps
end else if (op == (SPECIAL & (funct == SRAV)))begin
CtrlALUOp = 5'd12;//SRAV from ALUOps
end else if (op == (SPECIAL & (funct == SRL)))begin
CtrlALUOp = 5'd9;//SRL from ALUOps
end else if (op == (SPECIAL & (funct == SRLV)))begin
CtrlALUOp = 5'd10;//SRLV from ALUOps
end else if (op == (SLTI | (SPECIAL & (funct == SLT))))begin
CtrlALUOp = 5'd20;//SLT from ALUOps
end else if (op == (SLTIU | (SPECIAL & (funct == SLTU))))begin
CtrlALUOp = 5'd21;//SLTU from ALUOps
end else if (op == (SPECIAL & (funct == SUBU)))begin
CtrlALUOp = 5'd1;//SUB from ALUOps
end else if (op == (XORI | (SPECIAL & (funct == XOR))))begin
CtrlALUOp = 5'd6;//XOR from ALUOps
end else begin
CtrlALUOp = 5'bxxxxx;
end
//Ctrlshamt logic
if(op == (SPECIAL & (funct == (SRA | SRL | SLL))))begin
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
if(op == (SB | SH | SW)begin
CtrlMemWrite = 1;//Memory is write enabled
end else begin CtrlMemWrite = 0;end//default is 0 to ensure no accidental overwriting.
//CtrlALUSrc logic
if(op == (ADDIU | ANDI | LUI | ORI | SLTI | SLTIU | XORI | LB | LBU | LH | LHU | LW | LWL | LWR | SB | SH | SW)begin
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 | BGTZ | BLEZ | BNE | (REGIMM & (rt == (BGEZ | BGEZAL | BLTZ | BLTZAL)) (SPECIAL & (funct == (ADDU | AND | DIV | DIVU | MULT | MULTU | OR | SLLV | SLT | SLTU | SRAV | SRLV | SUBU | XOR)))))begin
CtrlALUSrc = 0;///ALU Bus B is fed from rt.
end else begin CtrlALUSrc = 1'bx;end
//CtrlRegWrite logic
if(op == (ADDIU | ANDI | LB | LBU | LH | LHU | LUI | LW | LWL | LWR | ORI | SLTI | SLTIU | XORI | (SPECIAL & (funct == (ADDU | AND | DIV | DIVU | MULT | MULTU | JALR | OR | SLL | SLLV | SLT | SLTU | SRA | SRAV | SRL | SRLV | SUBU | XOR)))))begin
CtrlRegWrite = 1;//The Registers are Write Enabled
end else begin CtrlRegWrite = 0;end // The Registers are Write Disabled
end
endmodule