Jal: RISC-V JAL opcode decode and encode

Tools/Python/Jal/Jal.py

@@ -0,0 +1,63 @@
+import argparse
+
+def generate_jal_opcode(pc, target_address, rd=1):
+    # Calculate the offset (immediate value) as the difference between target address and current PC
+    offset = target_address - pc
+
+    # Check if the offset is within the valid range (-2^20 to 2^20-1)
+    if offset < -(1 << 20) or offset >= (1 << 20):
+        raise ValueError("Offset out of range for JAL instruction")
+
+    # Decompose the offset into fields
+    imm_20 = (offset >> 20) & 0x1
+    imm_10_1 = (offset >> 1) & 0x3FF
+    imm_11 = (offset >> 11) & 0x1
+    imm_19_12 = (offset >> 12) & 0xFF
+
+    # Combine the fields to generate the opcode
+    opcode = (imm_20 << 31) | (imm_19_12 << 12) | (imm_11 << 20) | (imm_10_1 << 21) | (rd << 7) | 0x6F
+
+    return opcode
+
+def parse_jal_opcode(opcode):
+    # Extract each field
+    imm_20 = (opcode >> 31) & 0x1
+    imm_10_1 = (opcode >> 21) & 0x3FF
+    imm_11 = (opcode >> 20) & 0x1
+    imm_19_12 = (opcode >> 12) & 0xFF
+
+    # Combine into a 21-bit immediate value
+    imm = (imm_20 << 20) | (imm_19_12 << 12) | (imm_11 << 11) | (imm_10_1 << 1)
+    print(f"Opcode Immediate hex value: {imm:x}")
+
+    # Sign extension
+    if imm_20 == 1:
+        imm -= (1 << 21)
+
+    return imm
+
+def main():
+    # Create argument parser
+    parser = argparse.ArgumentParser(description="RISC-V JAL opcode generator and parser.")
+    group = parser.add_mutually_exclusive_group(required=True)
+    group.add_argument("-e", "--encode", action="store_true", help="Generate a RISC-V JAL opcode.")
+    group.add_argument("-d", "--decode", action="store_true", help="Parse a RISC-V JAL opcode.")
+    parser.add_argument("pc_or_opcode", type=lambda x: int(x, 16), help="The current PC value or the JAL opcode in hexadecimal format.")
+    parser.add_argument("target_address", type=lambda x: int(x, 16), nargs='?', help="The target address in hexadecimal format (required for encoding).")
+
+    # Parse command line arguments
+    args = parser.parse_args()
+
+    if args.encode:
+        if args.target_address is None:
+            parser.error("The target address is required for encoding.")
+        # Generate JAL opcode
+        opcode = generate_jal_opcode(args.pc_or_opcode, args.target_address)
+        print(f"Generated JAL opcode: 0x{opcode:08X}")
+    elif args.decode:
+        # Parse immediate value
+        imm_value = parse_jal_opcode(args.pc_or_opcode)
+        print(f"Immediate value: {imm_value}")
+
+if __name__ == "__main__":
+    main()