.syntax unified
    .thumb_func

    .extern  flash_loader
    .global   _start

    # Calls a function with up to 6 arguments R0-R5
    # R0 - R3 are the first four function arguments, 5th and 6th arguments are on the stack in reverse order
_start:

    PUSH        { R4, R5 }
    BL          flash_loader
    BKPT