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%%% -*- erlang-indent-level: 2 -*-
%%%-------------------------------------------------------------------
%%% File : bs_bincomp.erl
%%% Author : Per Gustafsson <[email protected]>
%%% Purpose : Test bit comprehensions
%%% Created : 13 Sep 2006
%%%-------------------------------------------------------------------
-module(bs_bincomp).
-export([test/0]).
test() ->
ok = byte_aligned(),
ok = bit_aligned(),
ok = extended_byte_aligned(),
ok = extended_bit_aligned(),
ok = mixed(),
ok.
byte_aligned() ->
<<"abcdefg">> = << <<(X+32)>> || <<X>> <= <<"ABCDEFG">> >>,
<<1:32/little,2:32/little,3:32/little,4:32/little>> =
<< <<X:32/little>> || <<X:32>> <= <<1:32,2:32,3:32,4:32>> >>,
<<1:32/little,2:32/little,3:32/little,4:32/little>> =
<< <<X:32/little>> || <<X:16>> <= <<1:16,2:16,3:16,4:16>> >>,
ok.
bit_aligned() ->
<<$a:7,$b:7,$c:7,$d:7,$e:7,$f:7,$g:7>> =
<< <<(X+32):7>> || <<X>> <= <<"ABCDEFG">> >>,
<<"ABCDEFG">> =
<< <<(X-32)>> || <<X:7>> <= <<$a:7,$b:7,$c:7,$d:7,$e:7,$f:7,$g:7>> >>,
<<1:31/little,2:31/little,3:31/little,4:31/little>> =
<< <<X:31/little>> || <<X:31>> <= <<1:31,2:31,3:31,4:31>> >>,
<<1:31/little,2:31/little,3:31/little,4:31/little>> =
<< <<X:31/little>> || <<X:15>> <= <<1:15,2:15,3:15,4:15>> >>,
ok.
extended_byte_aligned() ->
<<"abcdefg">> = << <<(X+32)>> || X <- "ABCDEFG" >>,
"abcdefg" = [(X+32) || <<X>> <= <<"ABCDEFG">>],
<<1:32/little,2:32/little,3:32/little,4:32/little>> =
<< <<X:32/little>> || X <- [1,2,3,4] >>,
[256,512,768,1024] =
[X || <<X:16/little>> <= <<1:16,2:16,3:16,4:16>>],
ok.
extended_bit_aligned() ->
<<$a:7,$b:7,$c:7,$d:7,$e:7,$f:7,$g:7>> =
<< <<(X+32):7>> || X <- "ABCDEFG" >>,
"ABCDEFG" = [(X-32) || <<X:7>> <= <<$a:7,$b:7,$c:7,$d:7,$e:7,$f:7,$g:7>>],
<<1:31/little,2:31/little,3:31/little,4:31/little>> =
<< <<X:31/little>> || X <- [1,2,3,4] >>,
[256,512,768,1024] =
[X || <<X:15/little>> <= <<1:15,2:15,3:15,4:15>>],
ok.
mixed() ->
<<2,3,3,4,4,5,5,6>> =
<< <<(X+Y)>> || <<X>> <= <<1,2,3,4>>, <<Y>> <= <<1,2>> >>,
<<2,3,3,4,4,5,5,6>> =
<< <<(X+Y)>> || <<X>> <= <<1,2,3,4>>, Y <- [1,2] >>,
<<2,3,3,4,4,5,5,6>> =
<< <<(X+Y)>> || X <- [1,2,3,4], Y <- [1,2] >>,
[2,3,3,4,4,5,5,6] =
[(X+Y) || <<X>> <= <<1,2,3,4>>, <<Y>> <= <<1,2>>],
[2,3,3,4,4,5,5,6] =
[(X+Y) || <<X>> <= <<1,2,3,4>>, Y <- [1,2]],
<<2:3,3:3,3:3,4:3,4:3,5:3,5:3,6:3>> =
<< <<(X+Y):3>> || <<X:3>> <= <<1:3,2:3,3:3,4:3>>, <<Y:3>> <= <<1:3,2:3>> >>,
<<2:3,3:3,3:3,4:3,4:3,5:3,5:3,6:3>> =
<< <<(X+Y):3>> || <<X:3>> <= <<1:3,2:3,3:3,4:3>>, Y <- [1,2] >>,
<<2:3,3:3,3:3,4:3,4:3,5:3,5:3,6:3>> =
<< <<(X+Y):3>> || X <- [1,2,3,4], Y <- [1,2] >>,
[2,3,3,4,4,5,5,6] =
[(X+Y) || <<X:3>> <= <<1:3,2:3,3:3,4:3>>, <<Y:3>> <= <<1:3,2:3>>],
[2,3,3,4,4,5,5,6] =
[(X+Y) || <<X:3>> <= <<1:3,2:3,3:3,4:3>>, Y <- [1,2]],
ok.
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