FINAL FINAL

FINAL/RISCCore.v

@@ -120,7 +120,9 @@ module RISCCore (
   wire isJALR = (opcode == 7'b1100111) && (funct3 == 3'b000);
 
   //Mem address calculation
-  wire [31:0] mem_addr = (is_mem_op) ? alu_result : 32'b0;
+  /*wire [31:0] mem_addr = (is_mem_op) ? alu_result : 32'b0;
+  Using direct */
+  wire [31:0] mem_addr = rs1_val + (isSType ? Simm : Iimm);
 
   //Mem address logic
   //For simplicity we only implement all loads as word loads (lw)
@@ -153,40 +155,52 @@ module RISCCore (
   end
 
 //Store operations
-always @(*) begin 
+always @(posedge clk) begin 
   if (!rst && is_store && (word_addr < 32) && (mem_addr[1:0] == 2'b00)) begin 
+
     case (funct3)
-      3'b000: begin //SB: store byte 0 
-        dmem[word_addr][7:0] = rs2_val[7:0];
-      end 
-      3'b001: begin //SH: store halfword
-        dmem[word_addr][15:0] = rs2_val[15:0];
-      end 
-      3'b010: begin //SW: store word 
-        dmem[word_addr] = rs2_val;
-      end 
+      3'b000: dmem[word_addr] <= {dmem[word_addr][31:8], rs2_val[7:0]};   // SB
+      3'b001: dmem[word_addr] <= {dmem[word_addr][31:16], rs2_val[15:0]}; // SH
+      3'b010: dmem[word_addr] <= rs2_val;                                 // SW
     endcase
+    // The $display can be simplified now as well
     $display("MEM Write: word_addr=%h, data=%h", word_addr, rs2_val);
   end
 end
   // ALU operations
 
   //sltu and slt
-  wire [31:0] sltu_rslt = {31'b0, (rs1_val < rs2_val)};
-  wire [31:0] signed_slt = (rs1_val[31] && !rs2_val[31]) ? 1'b1 :
-                           (!rs1_val[31] && rs2_val[31]) ? 1'b0 :
-                           (rs1_val < rs2_val);
-  wire [31:0] slt_rslt = {31'b0, signed_slt};
-  wire [31:0] slti_rslt = ((rs1_val[31] == Iimm[31]) ? sltu_rslt : {31'b0, rs1_val[31]});
+  // For signed operations, cast the inputs to 'signed'.
+  // Verilog will then use 2's complement arithmetic automatically.
+  wire signed [31:0] signed_rs1_val = rs1_val;
+  wire signed [31:0] signed_Iimm    = Iimm;
 
-  wire [63:0] SErs1_val = {{32{rs1_val[31]}}, (rs1_val < rs2_val)};
+  // SLTU: Set if Less Than (Unsigned)
+  // Compares rs1_val and rs2_val as unsigned integers.
+  wire [31:0] sltu_rslt = (rs1_val < rs2_val) ? 32'd1 : 32'd0;
 
-  wire [63:0] sra_rslt = {SErs1_val >> rs2_val[4:0]};
-  wire [63:0] srai_rslt = {SErs1_val >> Iimm[4:0]};
-  wire [31:0] sltiu_rslt = {31'b0, (rs1_val < Iimm)};
+  // SLT: Set if Less Than (Signed)
+  // Compares rs1_val and rs2_val as signed integers.
+  wire [31:0] slt_rslt = (signed_rs1_val < $signed(rs2_val)) ? 32'd1 : 32'd0;
+
+  // SLTIU: Set if Less Than Immediate (Unsigned)
+  // Compares rs1_val (unsigned) with the sign-extended immediate (unsigned).
+  wire [31:0] sltiu_rslt = (rs1_val < Iimm) ? 32'd1 : 32'd0;
+
+  // SLTI: Set if Less Than Immediate (Signed)
+  // Compares rs1_val and the immediate as signed integers.
+  wire [31:0] slti_rslt = (signed_rs1_val < signed_Iimm) ? 32'd1 : 32'd0;
+
+  // SRA: Shift Right Arithmetic
+  // Shifts signed_rs1_val right by the amount in rs2_val[4:0].
+  // The '>>>' operator performs an arithmetic shift, preserving the sign bit.
+  wire [31:0] sra_rslt = signed_rs1_val >>> rs2_val[4:0];
+
+  // SRAI: Shift Right Arithmetic Immediate
+  // Shifts signed_rs1_val right by the immediate amount in Iimm[4:0].
+  wire [31:0] srai_rslt = signed_rs1_val >>> Iimm[4:0];
  
-  wire [31:0] alu_result = (is_mem_op) ? (rs1_val + Iimm) : // Mem address computation
-                           (isADDI) ? (rs1_val + Iimm) :
+  wire [31:0] alu_result = (isADDI) ? (rs1_val + Iimm) :
                            (isADD) ? (rs1_val + rs2_val) : 
                            (isSLT) ? slt_rslt :
                            (isSLTU) ? sltu_rslt :
@@ -203,11 +217,11 @@ end
                            (isSLL) ? (rs1_val << rs2_val[4:0]) :
                            (isSRL) ? (rs1_val >> rs2_val[4:0]) :
                            (isSLTIU) ? (sltiu_rslt) :
-                           (isLUI) ? ({Iimm[31:12], 12'b0}) :
-                           (isAUIPC) ? (pc + Iimm) :
+                           (isLUI) ? Uimm :
+                           (isAUIPC) ? (pc + Uimm) :
                            (isJAL || isJALR) ? (pc + 32'd4) :
-                           (isSRA) ? (sra_rslt[31:0]) :
-                           (isSRAI) ? (srai_rslt[31:0]) :
+                           (isSRA) ? sra_rslt :
+                           (isSRAI) ? srai_rslt :
                            32'b0;
 
 
@@ -226,10 +240,11 @@ end
   // Next PC calculation - FIXED: using wire for continuous assignment
   wire [31:0] branch_target = pc + Bimm;
   wire [31:0] next_pc_base = pc + 32'h4;
-  wire [31:0] jalr_tgt_pc = rs1_val + Iimm;
+  wire [31:0] jalr_tgt_pc = (rs1_val + Iimm) & 32'hFFFFFFFE;
+  wire [31:0] jal_target = pc + Jimm;
   
   assign next_pc = branch_taken ? branch_target :
-                   isJAL ? branch_target :
+                   isJAL ? jal_target :
                    isJALR ? jalr_tgt_pc :
                    next_pc_base;