Constant RT_VAL_GET_NUMBER 

pub const RT_VAL_GET_NUMBER: u32 = 10;

Read the f64 payload from a NUMBER value; val_get_number(ptr: i32) -> f64 We return the raw bits as (i32, i32) or just store to a scratch global. Actually WASM does support f64 on the value stack, so we can return f64. But our function type table only has i32 returns. We’ll add a special type.