Moved and ranamed btb to btb.sv

Fixed btb to use the fixed port 2 sram.

pipelined/src/generic/mem/ram2p1r1wb.sv

@@ -74,12 +74,14 @@ module ram2p1r1wb #(parameter DEPTH = 10, WIDTH = 2) (
   flopenr #(WIDTH) wd2Reg(clk, reset, ren1, wd2, wd2q);
 
   // read port
-  assign rd1 = mem[ra1q];
+  //assign rd1 = mem[ra1q];
+  always_ff @(posedge clk)
+	if(ren1) rd1 <= mem[ra1];
   
   // write port
-  assign bwe = {WIDTH{wen2q}} & bwe2;
+  assign bwe = {WIDTH{wen2}} & bwe2;
   always_ff @(posedge clk)
-    mem[wa2q] <= wd2q & bwe | mem[wa2q] & ~bwe;
+    mem[wa2] <= wd2 & bwe | mem[wa2] & ~bwe;
  
 endmodule  
 

pipelined/src/generic/mem/ram2p1rwbefix.sv

@@ -59,13 +59,13 @@ module ram2p1r1wbefix #(parameter DEPTH=128, WIDTH=256) (
   
   // Write divided into part for bytes and part for extra msbs
   if(WIDTH >= 8) 
-    always_ff @(posedge clk) 
+    always @(posedge clk) 
       if (ce2 & we2) 
         for(i = 0; i < WIDTH/8; i++) 
           if(bwe2[i]) mem[wa2][i*8 +: 8] <= #1 wd2[i*8 +: 8];
   
   if (WIDTH%8 != 0) // handle msbs if width not a multiple of 8
-    always_ff @(posedge clk) 
+    always @(posedge clk) 
       if (ce2 & we2 & bwe2[WIDTH/8])
         mem[wa2][WIDTH-1:WIDTH-WIDTH%8] <= #1 wd2[WIDTH-1:WIDTH-WIDTH%8];
 

pipelined/src/ifu/brpred/btb.sv

@@ -0,0 +1,110 @@
+///////////////////////////////////////////
+// btb.sv
+//
+// Written: Ross Thomposn ross1728@gmail.com
+// Created: February 15, 2021
+// Modified: 24 January 2023 
+//
+// Purpose: Branch Target Buffer (BTB). The BTB predicts the target address of all control flow instructions.
+//          It also guesses the type of instrution; jalr(r), return, jump (jr), or branch.
+//
+// Documentation: RISC-V System on Chip Design Chapter 10 (Figure ***)
+// 
+// A component of the CORE-V-WALLY configurable RISC-V project.
+// 
+// Copyright (C) 2021-23 Harvey Mudd College & Oklahoma State University
+//
+// SPDX-License-Identifier: Apache-2.0 WITH SHL-2.1
+//
+// Licensed under the Solderpad Hardware License v 2.1 (the “License”); you may not use this file 
+// except in compliance with the License, or, at your option, the Apache License version 2.0. You 
+// may obtain a copy of the License at
+//
+// https://solderpad.org/licenses/SHL-2.1/
+//
+// Unless required by applicable law or agreed to in writing, any work distributed under the 
+// License is distributed on an “AS IS” BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, 
+// either express or implied. See the License for the specific language governing permissions 
+// and limitations under the License.
+////////////////////////////////////////////////////////////////////////////////////////////////
+
+`include "wally-config.vh"
+
+module btb
+  #(parameter int Depth = 10
+    )
+  (input  logic             clk,
+   input  logic             reset,
+   input  logic             StallF, StallE,
+   input  logic [`XLEN-1:0] PCNextF,
+   output logic [`XLEN-1:0] BTBPredPCF,
+   output logic [3:0]       InstrClass,
+   output logic             Valid,
+   // update
+   input  logic             UpdateEN,
+   input  logic [`XLEN-1:0] PCE,
+   input  logic [`XLEN-1:0] IEUAdrE,
+   input  logic [3:0]       InstrClassE,
+   input  logic             UpdateInvalid
+   );
+
+  localparam TotalDepth = 2 ** Depth;
+  logic [TotalDepth-1:0]    ValidBits;
+  logic [Depth-1:0]         PCNextFIndex, PCEIndex, PCNextFIndexQ, PCEIndexQ;
+  logic                     UpdateENQ;
+  logic [`XLEN-1:0] 		ResetPC;
+
+
+  // hashing function for indexing the PC
+  // We have Depth bits to index, but XLEN bits as the input.
+  // bit 0 is always 0, bit 1 is 0 if using 4 byte instructions, but is not always 0 if
+  // using compressed instructions.  XOR bit 1 with the MSB of index.
+  assign PCEIndex = {PCE[Depth+1] ^ PCE[1], PCE[Depth:2]};
+  assign ResetPC = `RESET_VECTOR;
+  assign PCNextFIndex = reset ? ResetPC[Depth+1:2] : {PCNextF[Depth+1] ^ PCNextF[1], PCNextF[Depth:2]};  
+  //assign PCNextFIndex = {PCNextF[Depth+1] ^ PCNextF[1], PCNextF[Depth:2]};  
+
+  flopenr #(Depth) PCEIndexReg(.clk(clk),
+        .reset(reset),
+        .en(~StallE),
+        .d(PCEIndex),
+        .q(PCEIndexQ));
+  
+  // The valid bit must be resetable.
+  always_ff @ (posedge clk) begin
+    if (reset) begin
+      ValidBits <= #1 {TotalDepth{1'b0}};
+    end else 
+    if (UpdateENQ) begin
+      ValidBits[PCEIndexQ] <= #1 ~ UpdateInvalid;
+    end
+  end
+  assign Valid = ValidBits[PCNextFIndexQ];
+
+
+  flopenr #(1) UpdateENReg(.clk(clk),
+     .reset(reset),
+     .en(~StallF),
+     .d(UpdateEN),
+     .q(UpdateENQ));
+
+
+  flopenr #(Depth) LookupPCIndexReg(.clk(clk),
+        .reset(reset),
+        .en(~StallF),
+        .d(PCNextFIndex),
+        .q(PCNextFIndexQ));
+
+
+
+  // the BTB contains the target address.
+  // Another optimization may be using a PC relative address.
+  // *** need to add forwarding.
+
+  // *** optimize for byte write enables
+
+  ram2p1r1wbefix #(2**Depth, `XLEN+4) memory(
+    .clk, .ce1(~StallF | reset), .ra1(PCNextFIndex), .rd1({InstrClass, BTBPredPCF}),
+     .ce2(~StallE), .wa2(PCEIndex), .wd2({InstrClassE, IEUAdrE}), .we2(UpdateEN), .bwe2('1));
+
+endmodule