请问在 调用FIFO时出现了下错误，是什么原因?  在synthesize 通过了，在Implement design 出错.
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ERROR:NgdBuild:604 - logical block 'jb/u2' with type 'fifojb' could not be   resolved. A pin name misspelling can cause this, a missing edif or ngc file,   case mismatch between the block name and the edif or ngc file name, or the   misspelling of a type name. Symbol 'fifojb' is not supported in target   'spartan3e'. 此帖出自小平头技术问答