Function u_imm

crates/virtual-machine/src/cpu/decoder.rs:902–904

U-type immediate: upper 20 bits placed at [31:12], lower 12 bits zero. We sign-extend from the 32-bit word so that large addresses work correctly.

(word: u32)

}

// B-type immediate: [31]<<12 | [7]<<11 | [30:25]<<5 | [11:8]<<1, sign-extended to 13 bits.
fn b_imm(word: u32) -> i64 {
    let bit12 = field(word, 31, 31) << 12;
    let bit11 = field(word, 7, 7) << 11;
    let bits10_5 = field(word, 30, 25) << 5;
    let bits4_1 = field(word, 11, 8) << 1;