Graph generation with fixed degree

gistfile1.mathematica

insufficient[degs_, edgelist_, donelist_] := Catch[Module[
   {j, k, n = Length[degs], diff},
   For[j = 1; j <= n, j++,
    If[degs[[j]] == 0, Continue[]];
    diff = degs[[j]] - Length[Union[donelist, edgelist[[j]]]];
    If[diff <= 0, Throw[True]];
    ];
   False
   ]]

decode[val_, degs_] := 
 Module[{j = 0, k = 0}, While[val > k && j < Length[degs], j++;
   k += degs[[j]];];
  j]

decode[val_, degs_, skip_] := 
 Module[{j = 0, k = 0}, While[val > k && j < Length[degs], j++;
   If[! MemberQ[skip, j], k += degs[[j]]];];
  j]

randomDegreeGraph[degrees : {_Integer ..}, tries_: Infinity] := 
 Catch[Module[
   {edgelist, degs, n = Length[degrees], nedges, npairs, j, v1, v2, 
    subtot, try = 0, donelist = {}, prob}, 
   If[(tries =!= Infinity && (! IntegerQ[tries] || tries < 0)), 
    Throw[$Failed]];
       If[! EvenQ[Total[degrees]], Throw[$Failed]];
   While[try < tries, try++;
    npairs = n*(n - 1)/2;
    nedges = Total[degrees]/2;
    edgelist = Table[{j}, {j, n}];
    degs = degrees;
    While[npairs >= nedges > 0,
     j = RandomInteger[{1, 2*nedges}];
     v1 = decode[j, degs];
     subtot = 2*nedges - Total[degs[[edgelist[[v1]]]]];
     If[subtot <= 0, Break[]];
     j = RandomInteger[{1, subtot}];
     v2 = decode[j, degs, edgelist[[v1]]];
     nedges--;
     npairs--;
     edgelist[[v1]] = Append[edgelist[[v1]], v2];
     edgelist[[v2]] = Append[edgelist[[v2]], v1];
     degs[[v1]] = degs[[v1]] - 1;
     degs[[v2]] = degs[[v2]] - 1;
     If[(degs[[v1]] == 0 || degs[[v2]] == 0) && 
       insufficient[degs, edgelist, donelist], Break[]];
     If[degs[[v1]] == 0, donelist = Append[donelist, v1];
      npairs = npairs - (n - Length[Union[donelist, edgelist[[v1]]]])];
     If[degs[[v2]] == 0, donelist = Append[donelist, v2];
      npairs = 
       npairs - (n - Length[Union[donelist, edgelist[[v2]]]])];];
    If[nedges == 0, Throw[Map[Sort, edgelist[[All, 2 ;; -1]]]]];];
   Throw[$Failed["too many iterations"]];]]