branch unit and test

2 files changed, 65 insertions, 0 deletions

diff --git a/rv64cpu/rtl/core/branch_unit.sv b/rv64cpu/rtl/core/branch_unit.sv
new file mode 100644
index 0000000..c9662ce
--- /dev/null
+++ b/rv64cpu/rtl/core/branch_unit.sv
@@ -0,0 +1,52 @@
+//     Richard CPU
+//     Copyright (C) 2026  Richard Qin
+
+//     This program is free software: you can redistribute it and/or modify
+//     it under the terms of the GNU General Public License as published by
+//     the Free Software Foundation, either version 3 of the License, or
+//     (at your option) any later version.
+
+//     This program is distributed in the hope that it will be useful,
+//     but WITHOUT ANY WARRANTY; without even the implied warranty of
+//     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//     GNU General Public License for more details.
+
+//     You should have received a copy of the GNU General Public License
+//     along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+// File path: rtl/core/branch_unit.sv
+// Description: Branch Unit, responsible for determining whether conditional jump instructions are effective
+
+module branch_unit 
+    import rv64_pkg::*;
+(
+    input   logic              is_branch,      // Indicates whether the current instruction is a branch instruction
+    input   logic [2:0]        branch_op,      // Specific branch types func3
+    input   logic [XLEN-1:0]   operand_a,      // operand 1
+    input   logic [XLEN-1:0]   operand_b,      // operand 2
+    output  logic              branch_taken    // Branch taken signal
+);
+
+    always_comb begin
+        branch_taken = 1'b0;
+        
+        if (is_branch) begin
+            case (branch_op)
+                // 3'b000: BEQ (Branch if Equal)
+                BRANCH_EQ: branch_taken = (operand_a == operand_b);
+                // 3'b001: BNE (Branch if Not Equal)
+                BRANCH_NE: branch_taken = (operand_a != operand_b);
+                // 3'b100: BLT (Branch if Less Than, Signed)
+                BRANCH_LT: branch_taken = ($signed(operand_a) < $signed(operand_b));
+                // 3'b101: BGE (Branch if Greater Than or Equal, Signed)
+                BRANCH_GE: branch_taken = ($signed(operand_a) >= $signed(operand_b));
+                // 3'b110: BLTU (Branch if Less Than, Unsigned)
+                BRANCH_LTU: branch_taken = (operand_a < operand_b);
+                // 3'b111: BGEU (Branch if Greater Than or Equal, Unsigned)
+                BRANCH_GEU: branch_taken = (operand_a >= operand_b);
+                default: branch_taken = 1'b0;
+            endcase
+        end
+    end
+
+endmodule
diff --git a/rv64cpu/rtl/core/include/rv64_pkg.sv b/rv64cpu/rtl/core/include/rv64_pkg.sv
index 984a93b..372cc1b 100644
--- a/rv64cpu/rtl/core/include/rv64_pkg.sv
+++ b/rv64cpu/rtl/core/include/rv64_pkg.sv
@@ -92,4 +92,17 @@ package rv64_pkg;
         ALU_AND  = 4'b0111   // And
     } alu_op_t;
 
+
+    // Branch Operation Encoding
+    // Derived from funct3 of B-type instructions
+    typedef enum logic [2:0] {
+        BRANCH_EQ  = 3'b000,  // BEQ:  Branch if Equal
+        BRANCH_NE  = 3'b001,  // BNE:  Branch if Not Equal
+        BRANCH_LT  = 3'b100,  // BLT:  Branch if Less Than (signed)
+        BRANCH_GE  = 3'b101,  // BGE:  Branch if Greater Than or Equal (signed)
+        BRANCH_LTU = 3'b110,  // BLTU: Branch if Less Than (unsigned)
+        BRANCH_GEU = 3'b111   // BGEU: Branch if Greater Than or Equal (unsigned)
+    } branch_op_t;
+
 endpackage
+