In the system on a chip, some cells should be placed along a predefined coordinate within a relatively small region. This constraint comes from the requirement that the data should be ready on the common bus at the same time. In this paper, the module placement problem is studied where some modules have the predefined coordinate alignment (PCA) constraint. The relations are given between constrained modules, from which a necessary condition is induced. A polynomial-time algorithm is developed that can guarantee a feasible placement is always obtainable. The algorithm is implemented and tested on ami33 and ami49. The experimental results show that it is effective.%在片上系统(SOC)的设计中,常常需要把某些单元摆放在某一预定坐标线附近相对较小的区域内.这一约束的来源是,在总线结构中,通过总线传递的数据,应当同步地出现在总线上,不能有较大的时延.对带有预定坐标线对齐(PCA)约束的模块布局问题进行研究,导出了约束模块之间的一系列关系,由此得到满足约束布局的必要条件.并且设计了多项式时间复杂度的算法,能够确保得到可行的模块布局.使用ami33和ami49对该算法进行了测试.实验结果证明,算法是有效的.
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