Description

Java applet for the optimization and synthesis of prefix graphs and the generation of parallel-prefix adders.
It allows the size optimization of prefix graphs under arbitrary depth constraints, which can be different for each column (i.e. bit position). The algorithm is described in the reference below.

Documentation

• VHDL Library of Arithmetic Units
• R. Zimmermann, ``Non-Heuristic Optimization and Synthesis of Parallel-Prefix Adders'', in Proc. Int. Workshop on Logic and Architecture Synthesis (IWLAS'96), Grenoble, France, Dec. 1996, pp. 123-132.

[abstract, postscript]

Usage

• Usage is rather straightforward, just play around with it.
• Single local prefix transformations:
• depth-decreasing transformation: click `mouse-left' on a black node
• area-decreasing transformation: click `shift-mouse-left 'on a black node
• Depth constraints for individual columns:
• top constraint: hold `mouse-left' and move from left to right over vertical line
• bottom constraint: hold `mouse-left' and move from right to left over vertical line
• Parameters:
• Max o/l: maximum number of black nodes per level (i.e. row)
• Max o/b: maximum number of black nodes per bit position (i.e. column)
• Writing VHDL code for adder circuit:
• only works in `appletviewer,' not in Java-enabled browsers (security)
• see instructions for enabling `appletviewer' to write files

Download

• Files for use in `appletviewer'

Applet