Key Techniques Of Trustworthiness Improvement On Hybird Arithmetic Addition Of Floating-point Fused Multiply-add Unit

System trustworthiness is novel concept based on properties such as correct-ness, reliability, safety, maintainability and so on. Traditionally, trustworthiness isdefined as the system's behaviors and its results are always consistent with the user'sexpectations. When there are some interferences from operation errors, environmentchanges and outside attacks, the trustworthy system is required to supply servicessuccessfully and continuously.Industry and Academic begin to acknowledge that trustworthiness is a intrinsicproperty of the system, which is not a simple union of attributes such as security,reliability and so on. It is well-known that traditional quality attributes are de-fined from various perspectives, which are not orthogonal. It does not make senseto understand trustworthiness as a holistic property of the system, encompassingall of the traditional quality attributes. Right now, researchers are trying to ex-plain the concept of trustworthiness from various perspectives and develop relatedtrustworthiness improving techniques.Based on the trust models from the sociology, psychology and the existingsystem trustworthiness models from the computer science, this paper presents ageneral trust model and a novel system trustworthiness model. The characteristicsof trustworthiness and its main research contexts are concluded in the proposedsystem trustworthiness model, which also explains the trustworthiness improvementtechnologies.By the proposed system trustworthiness model, this paper focuses on the keytechniques of trustworthiness improvement on hybird arithmetic addition of ?oating-point fused multiply-add unit, including analysis and proof of the hardware func-tionality correctness, estimation and optimization of the non-functional propertiessuch as power consumption, as well as high-level hardware modeling and modeltransformation. The end-around-carry adder in IBM POWER6 microprocessor istaken as the case study in this paper.For the correctness of arithmetic addition algorithms, the semi-group basedformal analysis and proof methodology is proposed in this paper. Firstly, the cor- rectness of basic addition algorithms such as ripple carry adder, carry look-aheadadder and parallel prefix adders are proved. Then, a general architecture for the de-sign of hybrid prefix/carry-select adder is proposed. A detailed proof of this generalarchitecture is described. By the above addition algorithms, a general architecturefor the design of hybrid prefix/end-around-carry adder is developed. The details ofits correctness proof are also described. This ensures the algorithm level correctnessof the real design of end-around-carry adder followed the general architecture. Theend-around-carry adder in IBM POWER6 microprocessor is a special case of theproposed hybrid prefix/end-around-carry adder general architecture, which meansits correctness can be verified easily.For the adder's non-functional properties ( such as power consumption ), thispaper presents an AOP-based hardware design space exploration methodology, whichdoes the analysis and estimation for the hardware system's functionality and non-functional properties at the early stage of the design circle. This methodology ishelpful to search the optimized design under a number of constraints. The IBM'send-around-carry adder is taken as a case study to show the e?ectiveness of theproposed methodology.Furthermore, this paper also presents a MDA-based and service-oriented high-level hardware modeling and design method. By using the high-level modelingtechnology and model transformation, the e?ciency of system development and thesystem's trustworthiness can be both improved. The IBM's end-around-carry adderis also taken as a case study to show the e?ectiveness of the proposed methodology.At last, the paper discusses the UML-based method to model the notions of AOPfor hardware design at the high level of abstraction.