#Constants
N = 32 #number of mask gates we are going to insert
TB = "ben_tb.v" #test bench file
CKT = "ben_scan.v" #circuit file
CPR = "critpaths.report"
CLKTOD = /^(?<dstart>DFF\_\d+\_Q\_reg)\/CLK\s\(SDFFX1\).*(?<dend>DFF\_\d+\_Q\_reg)\/D\s\(SDFFX1\)/ #for finding paths in critpaths.report
KEY = ["0"]*N
TRN = ["0"]*N


#read in the first file
ckt = File.read(CKT).split(/\n/) #read in circuit

#flatten the verilog so that it is easier to work with
a = "\n" #initialize, don't know why inject wasn't working
ckt.each do |b|
    if (a[-1] != "\n") #if last line wasn't complete
        a.concat(b.sub(/^\s*/,"")) #add this line with trailing whitespace removed
    else #if last line is already complete
        a.concat(b) #add this line just as it was before
    end
    (b =~ /\;$/) ? a.concat("\n") : nil #if command terminated, add newline
end

#we now have a as a flatter version of the input file.
a = a.split(/\n/)
#we need to add key and trn signature/inputs to the verilog file.
a = a.map{|l| (l =~ /^\s*module/) ? (l.sub(" );",(0...N).inject(""){|a,b| a.concat(", key#{b}, trn#{b}")}.concat(");"))) : l}
a = a.map{|l| (l =~ /^\s*input/) ? (l.sub(";",(0...N).inject(""){|a,b| a.concat(", key#{b}, trn#{b}")}.concat(";"))) : l}

#need to find the paths that we are going to insert the xor gates onto
paths = File.read('critpaths.report').split(/\n/).reverse.map{|e| (e.to_s =~ CLKTOD) ? $2 : nil}.select{|e| e != nil}.take(N) #takes lowest 32 paths matching regex
gates = paths.map{|e| a.select{|f| f =~ Regexp.new(Regexp.escape(e))}} #finds the gates terminating those paths
nets = gates.map{|e| (e.to_s =~ /\.D\((?<gate>.*?)\)/) ? $1 : nil} #finds the nets feeding into the gates terminating those paths

#create the masks
(0...N).each do |e|
    s = "  XOR3X1 MSK#{e.to_s} ( .IN1(key#{e.to_s}), .IN2(trn#{e.to_s}), .IN3(#{nets[e]}), .Q(xgt#{e.to_s}));"
    a.insert(-2,s)
    a.map!{|f| (f =~ Regexp.new(Regexp.escape(paths[e]))) ? (f=f.sub(nets[e],"xgt#{e.to_s}")) : f}
end

#write the file
a = a.inject(""){|a,l| a.concat(l.concat("\n"))} #compresses a back into a single string
File.open("scan_edit.v",'w+') {|f| f.write(a)}

#read in testbench, edit file.  a little hackier than above but should usually still work.
tbn = File.read(TB).split(/\n/)
ins = (0...N).reduce(""){|f,g| f.concat(",\n      .key#{g}(1'b#{KEY[g]}),\n      .trn#{g}(1'b#{TRN[g]})")}
tbn.map!{|e| (e =~ /\.test\_se\(test_se\)/) ? (e.insert(-6,ins)): e}
tbn = tbn.reduce(""){|a,l| a.concat(l.concat("\n"))}
File.open("tb_edit.v",'w+') {|f| f.write(tbn)}