Initial commit
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pjht
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3
README.md
Normal file
3
README.md
Normal file
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# nand-to-tetris
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This is an emulator and Jack compiler for the Nand to Tetris VM.
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314
emulator.rb
Executable file
314
emulator.rb
Executable file
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$debug=true
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$pfdebug=true
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$fdebug=false
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$mname="the initialization code"
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$arg=[]
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$local=[]
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$static=[]
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$pointer=[nil,nil]
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$temp=[nil,nil,nil,nil,nil,nil,nil,nil]
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$heap=[]
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$stack=[]
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$labels={}
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$gstack=[]
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$funcs={}
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def runvmcommand(cmd,lno)
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def putsd(arg)
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if $debug
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puts arg
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end
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end
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def putspfd(arg)
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if $pfdebug or $debug
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puts arg
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end
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end
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def putsdf(arg)
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if $fdebug
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puts arg
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end
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end
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def raised(etype,arg=nil)
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if arg==nil
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raise etype
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else
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raise etype,arg
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end
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end
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def checklistbounds(lname,list,index,lno=nil)
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if index > list.length-1
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if lno
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raised "Line #{lno}: Index #{index} is out of bounds for #{lname}"
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else
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raised "Index #{index} is out of bounds for #{lname}"
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end
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exit
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end
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end
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oldstack=$stack
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funcdef=false
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pflowc=false
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cmd=cmd.split(" ")
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op=cmd.shift
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putsd "#{op} "+cmd.join(" ") unless op == "function" or op==nil or op=="#"
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case op
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when "add"
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$stack.push($stack.pop+$stack.pop)
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when "sub"
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second=$stack.pop
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first=$stack.pop
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$stack.push(first-second)
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when "neg"
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$stack.push(-$stack.pop)
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when "push"
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cmd[1]=cmd[1].to_i
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case cmd[0]
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when "argument"
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checklistbounds("arg",$arg,cmd[1],lno)
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$stack.push($arg[cmd[1]])
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when "local"
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checklistbounds("local",$local,cmd[1],lno)
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$stack.push($local[cmd[1]])
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when "static"
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$stack.push($static[cmd[1]])
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when "constant"
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$stack.push(cmd[1])
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when "this"
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$stack.push($heap[$pointer[0]+cmd[1]])
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when "that"
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$stack.push($heap[$pointer[1]+cmd[1]])
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when "temp"
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checklistbounds("temp",$temp,cmd[1],lno)
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$stack.push($temp[cmd[1]])
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when "pointer"
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checklistbounds("pointer",$pointer,cmd[1],lno)
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$stack.push($pointer[cmd[1]])
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end
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when "pop"
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cmd[1]=cmd[1].to_i
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case cmd[0]
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when "local"
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checklistbounds("local",$local,cmd[1],lno)
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$local[cmd[1]]=$stack.pop
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putsd "New local:#{$local}"
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when "static"
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$static[cmd[1]]=$stack.pop
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putsd "New static:#{$static}"
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when "this"
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$heap[$pointer[0]+cmd[1]]=$stack.pop
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putsd "New heap:#{$heap}"
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when "that"
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$heap[$pointer[1]+cmd[1]]=$stack.pop
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putsd "New heap:#{$heap}"
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when "pointer"
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checklistbounds("pointer",$pointer,cmd[1],lno)
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$pointer[cmd[1]]=$stack.pop
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putsd "New pointer:#{$pointer}"
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when "temp"
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checklistbounds("temp",$temp,cmd[1],lno)
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$temp[cmd[1]]=$stack.pop
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putsd "New temp:#{$temp}"
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end
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when "label"
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$labels[cmd[0]]=lno+1
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putsd "New labels:#{$labels}"
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when "goto"
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pflowc=true
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nlno=$labels[cmd[0]]
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when "if-goto"
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pflowc=true
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if $stack.pop == 0
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nlno=$labels[cmd[1]]
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end
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when "call"
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if $funcs[cmd[0]]==nil
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puts "Line #{lno}: Function #{cmd[0]} is undefined"
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exit
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end
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pflowc=true
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args=[]
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i=cmd[1].to_i-1
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if i == -1
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i=0
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else
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while i >= 0
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args[i]=$stack.pop
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i-=1
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end
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end
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hash={"local"=>$local,"arg"=>$arg,"pointer"=>$pointer,"stack"=>$stack,"ret"=>lno+1,"mname"=>$mname}
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$gstack.push(hash)
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$arg=args
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$local=Array.new($funcs[cmd[0]][1])
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nlno=$funcs[cmd[0]][0]
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$mname=cmd[0]
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puts "Transferring control from #{hash["mname"]} to #{$mname}"
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putsd "New arg:#{$arg}"
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putsd "New local:#{$local}"
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putsd "Stack is now cleared"
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when "function"
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funcdef=true
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$funcs[cmd[0]]=[lno+1,cmd[1].to_i]
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putsdf "New funcs:#{$funcs}"
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when "return"
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pflowc=true
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hash=$gstack.pop
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putspfd "Transferring control from #{$mname} to method #{hash["mname"]}"
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ostack=$stack
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$stack=hash["stack"]
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rval=ostack.pop
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unless rval == nil
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$stack.push(rval)
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end
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$local=hash["local"]
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$arg=hash["arg"]
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$pointer=hash["pointer"]
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nlno=hash["ret"]
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$mname=hash["mname"]
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putsd "New arg:#{$arg}"
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putsd "New local:#{$local}"
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putsd "New pointer:#{$pointer}"
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when "halt"
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return lno,funcdef,true
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end
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unless pflowc
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nlno=lno+1
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end
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putsd "New stack:#{$stack}" unless op=="function" or op=="call" or (oldstack==[] and $stack==[])
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undef checklistbounds
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undef raised
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undef putsd
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undef putspfd
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undef putsdf
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return nlno,funcdef,false
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end
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def runprog(prog)
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prog=prog.split("\n")
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i=1
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temp={}
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prog.each do |line|
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temp[i]=line
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i+=1
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end
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prog=temp
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lno=1
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while lno <= prog.length
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lno,funcdef,halt=runvmcommand(prog[lno],lno)
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break if halt
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if funcdef
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i=lno
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while i <= prog.length
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if prog[i]=="return"
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lno=i+1
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break
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end
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i+=1
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end
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end
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end
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puts "Program halted. Heap:#{$heap} "
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if $stack[0]
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puts "Return value:#{$stack[0]}"
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end
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end
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prog=<<-END
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# Memory class
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function Memory.alloc 0
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push static 0
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pop temp 0
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push static 0
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push argument 0
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add
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pop static 0
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push temp 0
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return
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# Array class
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function x[y]=z 0
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push argument 0
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push argument 1
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add
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pop pointer 0
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push argument 2
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pop this 0
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return
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function x[y] 0
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push argument 0
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push argument 1
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add
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pop pointer 0
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push this 0
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return
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# Test class
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function Test.new 0
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# this=Memory.alloc(2)
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push constant 1
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call Memory.alloc 1
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pop pointer 0
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# this.var=0
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push constant 0
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pop this 0
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# this.var2=0
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push constant 0
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pop this 1
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# push return value
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push pointer 0
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return
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function Test.var= 0
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push argument 0
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pop pointer 0
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push argument 1
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pop this 0
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return
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function Test.var 0
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push argument 0
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pop pointer 0
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push this 0
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return
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function Test.var2= 0
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push argument 0
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pop pointer 0
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push argument 1
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pop this 1
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return
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function Test.var2 0
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push argument 0
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pop pointer 0
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push this 1
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return
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# Main class
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function Main.main 1
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# Set t=Test.new
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call Test.new 0
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pop local 0
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# t.var=10
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push local 0
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push constant 10
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call Test.var= 2
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# t.var2=11
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push local 0
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push constant 11
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call Test.var2= 2
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return
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# Sys class
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function Sys.init 0
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call Main.main
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return
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# Init code
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push constant 0
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pop static 0
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call Sys.init 0
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halt
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END
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boundtest=<<-END
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pop pointer 2
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END
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runprog(prog)
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