1. An apparatus to execute a function in a first environment from a second: environment, the apparatus comprising: a bridge module configured to store parameters and a proxy function pointer for a proxy function in a bridge structure for a second context executing in the second environment, the proxy function configured to execute in the first environment, and to store a bridge pointer for the bridge structure in a bridge pointer register of a first context structure that stores a first context state for a first context configured to execute in the first environment; a swap context module configured to swap to the first context; an execute module configured to retrieve the proxy function pointer from the bridge structure using the bridge pointer if the bridge pointer register is not null, execute the proxy function, and store the results of the proxy function in the bridge structure; and the swap context module further configured to swap to the second context.