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authorMikael Pettersson <[email protected]>2017-09-25 22:11:28 +0200
committerMikael Pettersson <[email protected]>2017-09-25 22:11:28 +0200
commitd14f1512b01261c1cfdff2effe587118d9ddc012 (patch)
tree2a2faf9e2251dcfe1f216f62614aa16dc759f93b /lib
parentec2b785a09959b7c0a85ac8e9ad9b36e7b2166a3 (diff)
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base64:decode(Binary) optimized reimplementation
Diffstat (limited to 'lib')
-rw-r--r--lib/stdlib/src/base64.erl70
1 files changed, 35 insertions, 35 deletions
diff --git a/lib/stdlib/src/base64.erl b/lib/stdlib/src/base64.erl
index 6e96f7d1f7..c8cf6fdffe 100644
--- a/lib/stdlib/src/base64.erl
+++ b/lib/stdlib/src/base64.erl
@@ -113,7 +113,7 @@ encode_binary(Bin) ->
Data :: ascii_binary().
decode(Bin) when is_binary(Bin) ->
- decode_binary(<<>>, Bin);
+ decode_binary(Bin, <<>>);
decode(List) when is_list(List) ->
decode_list(List, <<>>).
@@ -186,31 +186,41 @@ mime_decode_to_string(List) when is_list(List) ->
bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,
bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad,bad}).
-decode_binary(Result0, <<C:8,T0/bits>>) ->
- case element(C, ?DECODE_MAP) of
- bad ->
- erlang:error({badarg,C});
- ws ->
- decode_binary(Result0, T0);
- eq ->
- case strip_ws(T0) of
- <<$=:8,T/binary>> ->
- <<>> = strip_ws(T),
- Split = byte_size(Result0) - 1,
- <<Result:Split/bytes,_:4>> = Result0,
- Result;
- T ->
- <<>> = strip_ws(T),
- Split = byte_size(Result0) - 1,
- <<Result:Split/bytes,_:2>> = Result0,
- Result
- end;
- Bits ->
- decode_binary(<<Result0/bits,Bits:6>>, T0)
+decode_binary(<<C1:8, Cs/bits>>, A) ->
+ case element(C1, ?DECODE_MAP) of
+ ws -> decode_binary(Cs, A);
+ B1 -> decode_binary(Cs, A, B1)
end;
-decode_binary(Result, <<>>) ->
- true = is_binary(Result),
- Result.
+decode_binary(<<>>, A) ->
+ A.
+
+decode_binary(<<C2:8, Cs/bits>>, A, B1) ->
+ case element(C2, ?DECODE_MAP) of
+ ws -> decode_binary(Cs, A, B1);
+ B2 -> decode_binary(Cs, A, B1, B2)
+ end.
+
+decode_binary(<<C3:8, Cs/bits>>, A, B1, B2) ->
+ case element(C3, ?DECODE_MAP) of
+ ws -> decode_binary(Cs, A, B1, B2);
+ B3 -> decode_binary(Cs, A, B1, B2, B3)
+ end.
+
+decode_binary(<<C4:8, Cs/bits>>, A, B1, B2, B3) ->
+ case element(C4, ?DECODE_MAP) of
+ ws -> decode_binary(Cs, A, B1, B2, B3);
+ eq when B3 =:= eq -> only_ws_binary(Cs, <<A/binary,B1:6,(B2 bsr 4):2>>);
+ eq -> only_ws_binary(Cs, <<A/binary,B1:6,B2:6,(B3 bsr 2):4>>);
+ B4 -> decode_binary(Cs, <<A/binary,B1:6,B2:6,B3:6,B4:6>>)
+ end.
+
+only_ws_binary(<<>>, A) ->
+ A;
+only_ws_binary(<<C:8, Cs/bits>>, A) ->
+ case element(C, ?DECODE_MAP) of
+ ws -> only_ws_binary(Cs, A);
+ _ -> erlang:error(function_clause)
+ end.
%% Skipping pad character if not at end of string. Also liberal about
%% excess padding and skipping of other illegal (non-base64 alphabet)
@@ -328,16 +338,6 @@ strip_spaces([$\r|Cs], A) -> strip_spaces(Cs, A);
strip_spaces([$\n|Cs], A) -> strip_spaces(Cs, A);
strip_spaces([C|Cs], A) -> strip_spaces(Cs, [C | A]).
-strip_ws(<<$\t,T/binary>>) ->
- strip_ws(T);
-strip_ws(<<$\n,T/binary>>) ->
- strip_ws(T);
-strip_ws(<<$\r,T/binary>>) ->
- strip_ws(T);
-strip_ws(<<$\s,T/binary>>) ->
- strip_ws(T);
-strip_ws(T) -> T.
-
%% Skipping pad character if not at end of string. Also liberal about
%% excess padding and skipping of other illegal (non-base64 alphabet)
%% characters. See section 3.3 of RFC4648