Energy reduction in queues and stacks by adaptive bitwidth compression

A new micro-architectural technique to reduce energy dissipated by queues and stacks is proposed. Similarly to related research which targets the transition activity in bit-lines, the technique is based on bitwidth compression. However unlike them, it utilizes the fixed accessing order embodied in queues and stacks to exploit input data correlation. The technique dynamically adjusts the required bitwidth to the number of bits which changed in comparison to the last access. It is neither restricted to specific bit-patterns such as zero-byte or precharging value and works efficiently on read and write without large area, timing or power overhead. Simulations show that using this technique, we can save the energy of instruction queue by up to 30% and the energy of video data queue by 20%