Function emit_float_soc_tb 

pub fn emit_float_soc_tb() -> String

A self-checking testbench for float_soc: drive each float pair (bit-patterns), run to done, and $display(\"result_hex cycles\"). float_soc_lock runs it under iverilog (with fpu.v) and checks each result’s f64 bits ≡ the model/Rust and each cycle count > 1.