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Finish chapter 7 code.

This commit is contained in:
Kyle Isom 2019-04-25 19:18:39 -07:00
parent dbbdcadb51
commit 26dcb6035a
1 changed files with 8 additions and 9 deletions
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17
pe/chapter7.erl
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@ -13,14 +13,14 @@ breverse(Bin) ->
%% Need to packetize %% Need to packetize
term_to_packet(Term) -> term_to_packet(Term) ->
BinaryTerm = erlang:term_to_binary(Term), BinaryTerm = term_to_binary(Term),
Length = erlang:byte_size(BinaryTerm), Length = byte_size(BinaryTerm),
<<Length:32, BinaryTerm:Length/bytes>>. <<Length:32, BinaryTerm:Length/bytes>>.
%% 3. Write the inverse function packet_to_term(Packet) -> Term that %% 3. Write the inverse function packet_to_term(Packet) -> Term that
%% is the inverse of the previous function. %% is the inverse of the previous function.
packet_to_term(<<Length:32, BinaryTerm:Length/bytes>>) -> packet_to_term(<<Length:32, BinaryTerm:Length/bytes>>) ->
erlang:binary_to_term(BinaryTerm). binary_to_term(BinaryTerm).
packet_test(Term) -> packet_test(Term) ->
Term = packet_to_term(term_to_packet(Term)). Term = packet_to_term(term_to_packet(Term)).
@ -34,7 +34,8 @@ test() ->
packet_test(Squared), packet_test(Squared),
packet_test(32), packet_test(32),
packet_test(<<"Goodbye, Joe.">>), packet_test(<<"Goodbye, Joe.">>),
<<0:7, 1:1>> = reverse_byte(<<1:1, 0:7>>). <<0:7, 1:1>> = reverse_byte(<<1:1, 0:7>>),
<<246, 54, 54, 166, 22>> = reverse_bits(<<"hello">>).
%% 5. Write a function to reverse the bits in a binary. %% 5. Write a function to reverse the bits in a binary.
reverse_byte(<<A:1, B:1, C:1, D:1, E:1, F:1, G:1, H:1>>) -> reverse_byte(<<A:1, B:1, C:1, D:1, E:1, F:1, G:1, H:1>>) ->
@ -43,10 +44,8 @@ reverse_byte(<<>>) -> <<>>.
reverse_bitlist([]) -> []; reverse_bitlist([]) -> [];
reverse_bitlist([H|T]) -> reverse_bitlist([H|T]) ->
[reverse_byte(H) || reverse_bitlist(T)]. [reverse_byte(<<H>>) | reverse_bitlist(T)].
reverse_bits(Binary) -> reverse_bits(Binary) ->
erlang:list_to_binary(reverse_bitlist(erlang:binary_to_list(Binary))). ReversedBits = reverse_bitlist(binary_to_list(Binary)),
erlang:list_to_binary(lists:reverse(ReversedBits)).