Ripple is a VLSI placement tool developed by the research team supervised by Prof. Evangeline F.Y. Young in The Chinese University of Hong Kong (CUHK).
Circuits with increasing numbers of cells of multi-row height have brought challenges to traditional placers on efficiency and effectiveness. Besides providing an overlap-free solution close to the global placement (GP) solution, constraints on power and ground (P/G) alignments, fence region, and routability (e.g., edge spacing, pin short/inaccessible) should be considered. To tackle the challenges, we design and implement several efficient and effective data structures and algorithms under a holistic framework:

• a legalization method for mixed-cell-height circuits by a window-based cell insertion technique,
• an iterative network-flow-based maximum displacement optimizations,
• a dual-network-flow-based fixed-row-and-order optimization,
• ...

More details are in the following papers:

• Xu He, Tao Huang, Linfu Xiao, Haitong Tian, Guxin Cui, Evangeline F.Y. Young, "Ripple: An Effective Routability-Driven Placer by Iterative Cell Movement", IEEE/ACM International Conference on Computer-Aided Design (ICCAD), San Jose, CA, USA, Nov. 7 - Nov. 10, 2011.
• Xu He, Tao Huang, Wing-Kai Chow, Jian Kuang, Ka-Chun Lam, Wenzan Cai, Evangeline F.Y. Young, "Ripple 2.0: High Quality Routability-Driven Placement via Global Router Integration", ACM/IEEE Design Automation Conference (DAC), Austin, TX, USA, May 29 - June 7, 2013.
• Wing-Kai Chow, Chak-Wa Pui, Evangeline F.Y. Young, "Legalization Algorithm for Multiple-Row Height Standard Cell Design", ACM/EDAC/IEEE Design Automation Conference (DAC), Austin, TX, USA, June 5 - June 9, 2016.
• Haocheng Li, Wing-Kai Chow, Gengjie Chen, Evangeline F.Y. Young, Bei Yu, "Routability-Driven and Fence-Aware Legalization for Mixed-Cell-Height Circuits", ACM/EDAC/IEEE Design Automation Conference (DAC), San Francisco, CA, USA, June 24 - June 29, 2018.
• Haocheng Li, Wing-Kai Chow, Gengjie Chen, Bei Yu, Evangeline F.Y. Young, "Pin-Accessible Legalization for Mixed-Cell-Height Circuits", IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems (TCAD), 2021.

Step 1: Download the source codes. For example,

$ git clone https://github.com/cuhk-eda/ripple

Step 2: Go to the project root and build by

$ cd ripple/src
$ make mode=release

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License Agreement for Ripple

Copyright (c) 2021, The Chinese University of Hong Kong All rights reserved.

CU-SD LICENSE (adapted from the original BSD license) Redistribution of the any code, with or without modification, are permitted provided that the conditions below are met.

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.

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THIS FREE SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR ANY CONTRIBUTOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, EFFECTS OF UNAUTHORIZED OR MALICIOUS NETWORK ACCESS; PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.