This work presents some contributions to hardware and software computer arithmetic. Computer arithmetic is the domain of computer science dedicated to the study of number systems, algorithms for basic arithmetic computations, quality validation of arithmetic computations, efficiency analysis of arithmetic computations and computer aided tools for designing arithmetic operators. Our works have links with digital integrated circuit design, computer architecture and software development of computation libraries and tools. Our main application domains are: embedded systems, cryptography and digital security, digital signal and image processing and digital control. The dissertation summarizes research works performed, alone or during collaborati...