full_case 与 parallel_case 是如何引入bug的 从上面的例子中,我们知道,full_case 会让Vivado综合时只考虑列出的case语句,parallel_case 会让Vivado综合时消除掉优先级。但是,对于仿真工具来说,比如 questsim,full_case 与 parallel_case 都只是一段注释,不会改变代码的逻辑。 那么full_case 与 parallel_case 引入...
仿真和综合对 full_case 与 parallel_case 的处理方式不同。仿真只把它们当成注释,不做任何处理,而综合会做相应的优化。因此仿真结果看起来很正常,但是综合后逻辑可能已经变了 为了避免 full_case 和 parallel_case 的问题,systemverilog添加了两个新的 case 语句。priority case 和 unique case。本篇文章便来看一...
Warning (10935): Verilog HDL Casex/Casezwarning at Verilog1.v(16): casex/casez item expression overlaps with a previouscasex/casez item expression Warning (10209): Verilog HDL CaseStatement warning at Verilog1.v(13): honored parallel_case synthesis attribute- differences between design synthesis an...
(还有一个verilog标准里的是加attribute_instance,(*full_case,parallel_case*)) 总是想写点东西,区分一下synopsysparallel_case和full_case的使用方法,今天就写一点吧。 在写RTL的时候,常常会用到CASE语句,但是case语句实际综合后,产生的逻辑变化比较多,parallel_case和full_case主要就是用来控制综合器把case语句综...
"full_caseparallel_case",theEvilTwinsofVerilogSynthesisCliffordE.CummingsSunburstDesign,Inc.ABSTRACTTwoofthemostoverusedandabuseddirectiv..
内容提示: "full_case parallel_case", the Evil Twins of VerilogSynthesisClifford E. CummingsSunburst Design, Inc.ABSTRACTTwo of the most over used and abused directives included in Verilog models are the directives"//synopsys full_case parallel_case". The popular myth that exists surrounding "...
1,如果你的条件是互斥的,那么就用case语句,这样综合的面积和时序都会更优一些。 2,如果你的条件不是互斥的,而是有优先级结构的,那么就用if elseif else。。。吧。 3,如果不是互斥而用了case,并且不加 //synopsys parallel_case,那么综合后的电路会有优先级的结构,可能不是最优的结构(相比if else而言) ...
SNUG2005 Israel Rev 1.0 1 SystemVerilog's priority & unique - A Solution to Verilog's "full_case" & "parallel_case" Evil Twins! 1.0 The legend of full_case parallel_case Prior to 1999, I found that engineers routinely added full_case parallel_case to all RTL case statements. Indeed, ...
1.0 Introduction The "full_case parallel_case" commands are two of the most abused synthesis directives employed by Verilog synthesis design engineers. The reasons cited most often to the author for using "full_case parallel_case" are: ? ? ? "full_case parallel_case" makes my designs ...
内容提示: "full_case parallel_case", the Evil Twins of VerilogSynthesisClifford E. CummingsSunburst Design, Inc.ABSTRACTTwo of the most over used and abused directives included in Verilog models are the directives"//synopsys full_case parallel_case". The popular myth that exists surrounding "...