Placement information is useful in producing efficient circuit layout, especially for hardware libraries or for run-time reconfigurable designs. Relative placement information enables control of circuit layout at a higher level of abstraction than placement information in the form of explicit coordinates. We present a functional specification of a procedure for compiling programs with relative placement information in Pebble, a simple language based on Structural VHDL, into programs with explicit placement coordinate information. This procedure includes source-level transformation for compiling into descriptions that support conditional compilation based on symbolic placement constraints, a feature essential for parametrised library elements. Partial evaluation is used to optimise a description using relative placement to improve its size and speed. We illustrate our approach using a DES encryption design, which results in a 60% reduction in area and a 6% improvement in speed.
['Steve McKeever', 'Wayne Luk', 'Arran Derbyshire']
Compiling Hardware Descriptions with Relative Placement Information for Parametrised Libraries