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%%% -*- erlang-indent-level: 2 -*-
%%%-------------------------------------------------------------------
%%% File : bs_remove3.erl
%%% Author : Per Gustafsson <[email protected]>
%%% Purpose :
%%%
%%% Created : 13 Apr 2004 by Per Gustafsson
%%%-------------------------------------------------------------------
-module(bs_remove3).
-export([test/0]).
-define(A, <<56,0,120,0,0,31,255,255,102,42,12,0,3,3,16,5,24,3,240,0,0,32,0,196,
2,128,4,0,255,255,254,33,68,96,0,8,8,213,40,192,31,196,0,4,0,0>>).
-define(B, <<28,32,0,96,0,8,0,7,255,255,212,33,98,12,0,0,1,0,48,72,66,3,0,7,240,
64,0,0,8,0,0,224,0,10,128,0,64,0,63,255,254,133,10,80,96,0,0,8,1,6,
18,4,24,0,63,128,0,0,4,64,0,0>>).
test() ->
Bin1 = <<30,16,0,90,0,1,0,0,255,255,255,255,81,67,101,7,0,
0,0,96,6,12,146,18,14,0,15,252,16,0,0,17,0,0>>,
Bin = <<Bin1/binary, Bin1/binary>>,
?A = loop(Bin, 10, fun run_list/1),
?A = loop(Bin, 10, fun run_bin/1),
?B = loop(Bin, 10, fun r31/1),
ok.
loop(Arg, 0, F) ->
F(Arg);
loop(Arg, N, F) ->
F(Arg),
loop(Arg, N-1, F).
run_list(Bin) ->
List = run1(Bin),
list_to_binary(List).
run1(<<A1:2,_:1,A2:2,_:1,A3:2,_:1,A4:2,_:1,
A5:2,_:1,A6:2,_:1,A7:2,_:1,A8:2,_:1,Rest/binary>>) ->
[<<A1:2,A2:2,A3:2,A4:2,A5:2,A6:2,A7:2,A8:2>>, run2(Rest)];
run1(<<A1:2,_:1,A2:2,_:1,A3:2,_:1,A4:2,_:1,A5:2,_:1,A6:1>>) ->
[<<A1:2,A2:2,A3:2,A4:2,A5:2,A6:1,0:5>>];
run1(<<A1:2,_:1,A2:2,_:1,A3:2>>) ->
[<<A1:2,A2:2,A3:2,0:2>>];
run1(<<>>) ->
[].
run_bin(Bin) ->
run2(Bin).
run2(<<A1:2,_:1,A2:2,_:1,A3:2,_:1,A4:2,_:1,
A5:2,_:1,A6:2,_:1,A7:2,_:1,A8:2,_:1,Rest/binary>>) ->
Bin = run2(Rest),
<<A1:2,A2:2,A3:2,A4:2,A5:2,A6:2,A7:2,A8:2,Bin/binary>>;
run2(<<A1:2,_:1,A2:2,_:1,A3:2,_:1,A4:2,_:1,A5:2,_:1,A6:1>>) ->
<<A1:2,A2:2,A3:2,A4:2,A5:2,A6:1,0:5>>;
run2(<<A1:2,_:1,A2:2,_:1,A3:2>>) ->
<<A1:2,A2:2,A3:2,0:2>>;
run2(<<>>) ->
<<>>.
r31(Bin) ->
List = remove3rd1(0, 0, Bin, [-1]),
build(List, Bin, 0, <<>>).
build([N1, N2|Rest], Bin, N, Present) ->
X = N1+1, Y = N2-X,
S = rest(N2),
<<_:X,A:Y,_:S,_/binary>> = Bin,
S1 = rest(N+Y),
NewPresent = <<Present:N/binary-unit:1, A:Y, 0:S1>>,
build([N2|Rest], Bin, N+Y, NewPresent);
build([_], _Bin, _N, Present) ->
Present.
rest(X) ->
case 8 - (X rem 8) of
8 -> 0;
H -> H
end.
remove3rd1(N, 2, Bin, List) ->
S = rest(N+1),
case Bin of
<<_:N, 1:1, _:S,_/binary>> ->
remove3rd1(N+1, 0, Bin, [N|List]);
<<_:N, 0:1, _:S,_/binary>> ->
remove3rd1(N+1, 2, Bin, List);
_ ->
Size = byte_size(Bin) * 8,
lists:reverse([Size|List])
end;
remove3rd1(N, I, Bin, List) ->
S = rest(N+1),
case Bin of
<<_:N, 1:1, _:S,_/binary>> ->
remove3rd1(N+1, I+1, Bin, List);
<<_:N, 0:1, _:S,_/binary>> ->
remove3rd1(N+1, I, Bin, List);
_ ->
Size = byte_size(Bin) * 8,
lists:reverse([Size|List])
end.
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