Function reg_set_value 

pub unsafe extern "C" fn reg_set_value(
    reg: reg_id_t,
    mc: *mut dr_mcontext_t,
    value: reg_t,
)

Sets the register \p reg in the passed in mcontext \p mc to \p value. \p mc->flags must include DR_MC_CONTROL and DR_MC_INTEGER. \note This function is limited to setting pointer-sized registers only (no sub-registers, and no non-general-purpose registers). See \p reg_set_value_ex for setting other register values.