A HAL for component-based embedded operating systems

Many standards for operating system interfaces or on-chip bus interfaces have been developed. Component-based EOS projects are seeking approaches to adapt component based software development technologies to embedded systems. An important issue is to develop hardware independent software that meets differing requirements pertinent to embedded applications. The hardware abstraction layer (HAL) presented here is to serve this purpose. In JBEOS, a component based EOS developed at Peking Univ. The following aspects are stressed: abstraction of basic data types, including their in-memory representation and operations; encapsulation of H/W dependent features into clear interfaces for kernel and user applications; H/W peculiarities should be encapsulated but not masked, i.e., HAL should provide mechanisms to access H/W directly when desired; minimized ROM and RAM footprints; supports for EOS above with no bias to any specific design and/or implementation; minimum efforts required when porting to a new platform.