Function add

crates/virtual-machine/tests/vm_pipeline.rs:51–53

add rd, rs1, rs2 -> opcode=0x33, funct3=0, funct7=0

(rd: u32, rs1: u32, rs2: u32)

// add rd, rs1, rs2  -> opcode=0x33, funct3=0, funct7=0
fn add(rd: u32, rs1: u32, rs2: u32) -> u32 {
    (rs2 << 20) | (rs1 << 15) | (rd << 7) | 0x33
}

// sw rs2, imm(rs1) -> opcode=0x23, funct3=2
fn sw(rs1: u32, rs2: u32, imm: i32) -> u32 {