Graduate

Signed-off-by: Matt Strapp <matt@mattstrapp.net>

1 files changed, 101 insertions, 0 deletions

diff --git a/ee4363/mp1/mp12/mipspipe.v b/ee4363/mp1/mp12/mipspipe.v
new file mode 100644
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+++ b/ee4363/mp1/mp12/mipspipe.v
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+// Incomplete behavioral model of MIPS pipeline
+
+module mipspipe(clock);
+   // in_out
+   input clock;
+
+   // Instruction opcodes
+   parameter LW = 6'b100011, SW = 6'b101011, BEQ = 6'b000100, nop = 32'b00000_100000, ALUop = 6'b0; 
+   reg [31:0] PC, // Program counter
+		  Regs[0:31],  // Register file
+			  IMemory[0:1023], DMemory[0:1023], // Instruction and data memories
+              IFIDIR, IDEXA, IDEXB, IDEXIR, EXMEMIR, EXMEMB, // pipeline latches
+              EXMEMALUOut, MEMWBValue, MEMWBIR; // pipeline latches
+
+   wire [4:0] IDEXrs, IDEXrt, EXMEMrd, MEMWBrd, MEMWBrt; // fields of pipeline latches
+   wire [5:0] EXMEMop, MEMWBop, IDEXop; // opcodes
+   wire [31:0] Ain, Bin; // ALU inputs
+
+   // Define fields of pipeline latches
+   assign IDEXrs = IDEXIR[25:21]; // rs field
+   assign IDEXrt = IDEXIR[20:16]; // rt field
+   assign EXMEMrd = EXMEMIR[15:11]; // rd field
+   assign MEMWBrd = MEMWBIR[15:11]; // rd field
+   assign MEMWBrt = MEMWBIR[20:16]; // rt field -- for loads
+   assign EXMEMop = EXMEMIR[31:26]; // opcode
+   assign MEMWBop = MEMWBIR[31:26]; // opcode
+   assign IDEXop = IDEXIR[31:26]; // opcode
+
+   // Inputs to the ALU come directly from the ID/EX pipeline latches
+   assign Ain = IDEXA;
+   assign Bin = IDEXB;
+   reg [5:0] i; //used to initialize registers
+   reg [10:0] j,k; //used to initialize registers
+
+   initial begin
+      PC = 0;
+      IFIDIR = nop; 
+      IDEXIR = nop; 
+      EXMEMIR = nop; 
+      MEMWBIR = nop; // no-ops placed in pipeline latches
+      // test some instructions
+      for (i=0;i<=31;i=i+1) Regs[i] = i; // initialize registers
+      IMemory[0] = 32'h00412820; // ADD OPCODE: 000000 00010 00001 00101 00000 100000
+      IMemory[1] = nop;
+      IMemory[2] = nop;
+      IMemory[3] = nop;
+      IMemory[4] = 32'h8CA30004; // First LW:   100011 00101 00011 00000 00000 000100
+      IMemory[5] = 32'h8C420000; // Second LW:  100011 00010 00010 00000 00000 000000
+      IMemory[6] = nop;
+      IMemory[7] = nop;
+      IMemory[8] = 32'h00A31825; // OR OPCODE:  000000 00101 00011 00011 00000 100101
+      IMemory[9] = nop;
+      IMemory[10] =nop;
+      IMemory[11] = nop;
+      IMemory[12] = 32'hACA30000; // SW:         101011 00101 00011 00000 00000 000000
+      for (j=13;j<=1023;j=j+1) IMemory[j] = nop;
+      DMemory[0] = 32'h00000000;
+      DMemory[1] = 32'hffffffff;
+      for (k=2;k<=1023;k=k+1) DMemory[k] = 0;
+   end
+   
+   always @ (posedge clock) 
+   begin
+      // FETCH: Fetch instruction & update PC
+      IFIDIR <= IMemory[PC>>2];
+	  PC <= PC + 4;
+    
+      // DECODE: Read registers 
+      IDEXA <= Regs[IFIDIR[25:21]]; 
+      IDEXB <= Regs[IFIDIR[20:16]]; // get two registers
+      
+	  IDEXIR <= IFIDIR; // pass along IR
+      
+      // EX: Address calculation or ALU operation
+      if ((IDEXop==LW) |(IDEXop==SW)) // address calculation
+         EXMEMALUOut <= IDEXA +{{16{IDEXIR[15]}}, IDEXIR[15:0]};
+      else if (IDEXop==ALUop) begin // ALU operation
+         case (IDEXIR[5:0]) // R-type instruction
+           32: EXMEMALUOut <= Ain + Bin; // add operation
+           37: EXMEMALUOut <= Ain | Bin; //or
+           default: ; // other R-type operations [to be implemented]
+         endcase
+      end
+   
+      EXMEMIR <= IDEXIR; EXMEMB <= IDEXB; //pass along the IR & B
+   
+      // MEM 
+      if (EXMEMop==ALUop) MEMWBValue <= EXMEMALUOut; //pass along ALU result
+      else if (EXMEMop == LW) MEMWBValue <= DMemory[EXMEMALUOut>>2]; // load
+      else if (EXMEMop == SW) DMemory[EXMEMALUOut>>2] <=EXMEMB; // store
+   
+      MEMWBIR <= EXMEMIR; //pass along IR
+   
+      // WB 
+      if ((MEMWBop==ALUop) & (MEMWBrd != 0)) // update registers if ALU operation and destination not 0
+		Regs[MEMWBrd] <= MEMWBValue; // ALU operation
+      else if ((MEMWBop == LW)& (MEMWBrt != 0)) // Update registers if load and destination not 0
+		Regs[MEMWBrt] <= MEMWBValue;
+    end
+
+endmodule