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authorRossTheRoss <mstrapp@protonmail.com>2020-12-18 19:13:58 -0600
committerRossTheRoss <mstrapp@protonmail.com>2020-12-18 19:13:58 -0600
commit8412c80bf488ad5c5b796bf4ea639b6f5f3957bf (patch)
tree8e5875fad13dc2537cf0c5a843f306b3a59957c7 /ee4363/mp2
parentaaaaaaaaaaaaa (diff)
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Diffstat (limited to '')
-rw-r--r--ee4363/mp2/mipspipe_mp2.v81
1 files changed, 55 insertions, 26 deletions
diff --git a/ee4363/mp2/mipspipe_mp2.v b/ee4363/mp2/mipspipe_mp2.v
index 2e8b98b..303522a 100644
--- a/ee4363/mp2/mipspipe_mp2.v
+++ b/ee4363/mp2/mipspipe_mp2.v
@@ -10,12 +10,12 @@ module mipspipe_mp2 (clock);
IFIDIR, IDEXA, IDEXB, IDEXIR, EXMEMIR, EXMEMB, // pipeline latches
EXMEMALUOut, MEMWBValue, MEMWBIR;
- wire [4:0] IDEXrs, IDEXrt, EXMEMrd, MEMWBrd, MEMWBrt; // hold register fields
- wire [5:0] EXMEMop, MEMWBop, IDEXop; // hold opcodes
+ wire [4:0] IDEXrs, IDEXrt, EXMEMrd, MEMWBrd, MEMWBrt, IFIDrt, IFIDrs; // hold register fields
+ wire [5:0] EXMEMop, MEMWBop, IDEXop, IFIDop; // hold opcodes
wire [31:0] Ain, Bin; // ALU inputs
// declare the bypass signals
- wire bypassAfromMEM, bypassAfromALUinWB, bypassBfromMEM, bypassBfromALUinWB, bypassAfromLWinWB, bypassBfromLWinWB;
+ wire bypassAfromMEM, bypassAfromALUinWB, bypassBfromMEM, bypassBfromALUinWB, bypassAfromLWinWB, bypassBfromLWinWB, bypassIDEXAfromWB, bypassIDEXBfromWB, STALL;
// Define fields of pipeline latches
assign IDEXrs = IDEXIR[25:21]; // rs field
@@ -26,6 +26,9 @@ module mipspipe_mp2 (clock);
assign EXMEMop = EXMEMIR[31:26]; // opcode
assign MEMWBop = MEMWBIR[31:26]; // opcode
assign IDEXop = IDEXIR[31:26]; // opcode
+ assign IFIDrs = IFIDIR[25:21];
+ assign IFIDrt = IFIDIR[20:16];
+ assign IFIDop = IFIDIR[31:26];
// The bypass to input A from the MEM stage for an ALU operation
@@ -40,18 +43,30 @@ module mipspipe_mp2 (clock);
assign bypassAfromLWinWB = (IDEXrs == MEMWBIR[20:16]) & (IDEXrs!=0) & (MEMWBop==LW);
// The bypass to input B from the WB stage for an LW operation
assign bypassBfromLWinWB = 0;
-
+ //Stall in case of WB
+ assign bypassIDEXAfromWB = ((MEMWBIR != nop) & (IFIDIR != nop) & (IFIDrs == MEMWBrt) & (MEMWBop == LW)) |
+ ((MEMWBop == ALUop) & (MEMWBrd == IFIDrs));
+ assign bypassIDEXBfromWB = ((MEMWBIR != nop) & (IFIDIR != nop) & (IFIDrt == MEMWBrt) & (MEMWBop == LW)) |
+ ((MEMWBop == ALUop) & (MEMWBrd == IFIDrt));
// The A input to the ALU is bypassed from MEM if there is a bypass there,
// Otherwise from WB if there is a bypass there, and otherwise comes from the IDEX register
assign Ain = bypassAfromMEM? EXMEMALUOut : (bypassAfromALUinWB | bypassAfromLWinWB)? MEMWBValue : IDEXA;
// The B input to the ALU is bypassed from MEM if there is a bypass there,
// Otherwise from WB if there is a bypass there, and otherwise comes from the IDEX register
- assign Bin = IDEXB;
+ // Ripped off of above just replacing "A" with "B"
+ assign Bin = bypassBfromMEM? EXMEMALUOut : (bypassBfromALUinWB | bypassBfromLWinWB)? MEMWBValue : IDEXB;
reg [5:0] i; // used to initialize latches
reg [10:0] j,k; // used to initialize memories
+
+ // Make the Big Stall
+ assign STALL = (IDEXop == LW) &&
+ //All of this is anded with the above (Lisp would be proud)
+ (((IFIDop == LW) && (IFIDrs == IDEXrt)) |
+ ((IFIDop == ALUop) && ((IFIDrs == IDEXrt) | (IFIDrt == IDEXrt))) |
+ ((IFIDop == SW) && ((IFIDrs == IDEXrt) | (IFIDrt == IDEXrt))));
initial begin
PC = 0;
@@ -62,16 +77,16 @@ module mipspipe_mp2 (clock);
for (i = 0;i<=31;i = i+1) Regs[i] = i; // initialize latches
- IMemory[0] = 32'h00412820;
- IMemory[1] = 32'h8ca30004;
- IMemory[2] = 32'haca70005;
- IMemory[3] = 32'h00602020;
- IMemory[4] = 32'h01093020;
- IMemory[5] = 32'hac06000c;
- IMemory[6] = 32'h00c05020;
- IMemory[7] = 32'h8c0b0010;
- IMemory[8] = 32'h00000020;
- IMemory[9] = 32'h002b6020;
+ IMemory[0] = 32'h00412820; // ADD $5, $2, $1
+ IMemory[1] = 32'h8ca30004; // LW $3, 4($5)
+ IMemory[2] = 32'haca70005; // SW $7, 5($5)
+ IMemory[3] = 32'h00602020; // ADD $4, $3, $0
+ IMemory[4] = 32'h01093020; // ADD $6, $8, $9
+ IMemory[5] = 32'hac06000c; // SW $6, $12($0)
+ IMemory[6] = 32'h00c05020; // ADD $10, $6, $0
+ IMemory[7] = 32'h8c0b0010; // LW $11, 32($0)
+ IMemory[8] = 32'h00000020; // ADD $0, $0, $0
+ IMemory[9] = 32'h002b6020; // ADD $12, $1, $11
for (j=10; j<=1023; j=j+1) IMemory[j] = nop;
DMemory[0] = 32'h00000000;
@@ -82,17 +97,31 @@ module mipspipe_mp2 (clock);
for (k=5; 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]];
- IDEXIR <= IFIDIR;
+ always @ (posedge clock) begin
+ if (~STALL) begin
+ // FETCH: Fetch instruction & update PC
+ IFIDIR <= IMemory[PC>>2];
+ PC <= PC + 4;
+
+ // DECODE: Read registers
+ if (~bypassIDEXAfromWB) begin
+ IDEXA <= Regs[IFIDIR[25:21]];
+ end
+ else begin
+ IDEXA <= MEMWBValue;
+ end
+
+ if (~bypassIDEXBfromWB) begin
+ IDEXB <= Regs[IFIDIR[20:16]];
+ end
+ else begin
+ IDEXB <= MEMWBValue;
+ end
+ IDEXIR <= IFIDIR;
+ end
+ else begin //IF (STALL)
+ IDEXIR <= nop;
+ end
// EX: Address calculation or ALU operation
if ((IDEXop==LW) |(IDEXop==SW)) // address calculation & copy B