L s , ▁which ▁have ▁been ▁compared ▁to ▁the ▁equivalent ▁of ▁assembly ▁languages , ▁there ▁are ▁moves ▁to ▁raise ▁the ▁abstra ction ▁level ▁through ▁the ▁introduction ▁of ▁alternative ▁languages . ▁National ▁Inst ru ments ' ▁Lab V IE W ▁graph ical ▁programming ▁language ▁( s ometimes ▁referred ▁to ▁as ▁" G ") ▁has ▁an ▁F P GA ▁add - in ▁module ▁available ▁to ▁target ▁and ▁program ▁F P GA ▁hardware . ▁ ▁To ▁simplify ▁the ▁design ▁of ▁complex ▁systems ▁in ▁F PG As , ▁there ▁exist ▁libraries ▁of ▁pre defined ▁complex ▁functions ▁and ▁circ uits ▁that ▁have ▁been ▁tested ▁and ▁optimized ▁to ▁speed ▁up ▁the ▁design ▁process . ▁These ▁pre defined ▁circ uits ▁are ▁commonly ▁called ▁intellectual ▁property ▁( IP ) ▁cores , ▁and ▁are ▁available ▁from ▁F P GA ▁vend ors ▁and ▁third - party ▁IP ▁supp liers . ▁They ▁are ▁rarely ▁free , ▁and ▁typically ▁released ▁under ▁propriet ary ▁lic enses . ▁Other ▁pre defined ▁circ uits ▁are ▁available ▁from ▁developer ▁communities ▁such ▁as ▁Open C ores ▁( typ ically ▁released ▁under ▁free ▁and ▁open ▁source ▁lic enses ▁such ▁as ▁the ▁G PL , ▁B SD ▁or ▁similar ▁license ), ▁and ▁other ▁sources . S uch ▁designs ▁are ▁known ▁as ▁" open - source ▁hardware ." ▁ ▁In ▁a ▁typical ▁design ▁flow , ▁an ▁F P GA ▁application ▁developer ▁will ▁simulate ▁the ▁design ▁at ▁multiple ▁stages ▁throughout ▁the ▁design ▁process . ▁Initial ly ▁the ▁R TL ▁description ▁in ▁V H DL ▁or ▁Ver ilog ▁is ▁sim ulated ▁by ▁creating ▁test ▁ben