Optimise encoding algorithm

1 files changed, 37 insertions, 19 deletions

diff --git a/lib/stdlib/src/binary.erl b/lib/stdlib/src/binary.erl
index 73b619d192..f73621371e 100644
--- a/lib/stdlib/src/binary.erl
+++ b/lib/stdlib/src/binary.erl
@@ -365,30 +365,48 @@ get_opts_replace(_,_) ->
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
 %% Hex encoding functions
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+-define(HEX(X), (hex(X)):16).
 -spec encode_hex(Bin) -> Bin2 when
       Bin :: binary(),
-      Bin2 :: binary().
-encode_hex(Bin) when is_binary(Bin) ->
-    encode_hex(Bin, <<>>);
+      Bin2 :: <<_:_*16>>.
+encode_hex(Data) when byte_size(Data) band 7 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C),?HEX(D),?HEX(E),?HEX(F),?HEX(G),?HEX(H)>> || <<A,B,C,D,E,F,G,H>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 7 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C),?HEX(D),?HEX(E),?HEX(F),?HEX(G)>> || <<A,B,C,D,E,F,G>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 6 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C),?HEX(D),?HEX(E),?HEX(F)>> || <<A,B,C,D,E,F>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 5 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C),?HEX(D),?HEX(E)>> || <<A,B,C,D,E>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 4 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C),?HEX(D)>> || <<A,B,C,D>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 3 =:= 0 ->
+    << <<?HEX(A),?HEX(B),?HEX(C)>> || <<A,B,C>> <= Data >>;
+encode_hex(Data) when byte_size(Data) rem 2 =:= 0 ->
+    << <<?HEX(A),?HEX(B)>> || <<A,B>> <= Data >>;
+encode_hex(Data) when is_binary(Data) ->
+    << <<?HEX(N)>> || <<N>> <= Data >>;
 encode_hex(Bin) ->
     badarg_with_info([Bin]).
 
--spec encode_hex(Bin, Acc) -> Bin2 when
-      Bin :: binary(),
-      Acc :: binary(),
-      Bin2 :: Acc.
-encode_hex(<<>>, Acc) ->
-    Acc;
-encode_hex(<<A0:4, B0:4, Rest/binary>>, Acc) ->
-    A = encode_hex_digit(A0),
-    B = encode_hex_digit(B0),
-    encode_hex(Rest, <<Acc/binary, A, B>>).
-
--spec encode_hex_digit(0..15) -> byte().
-encode_hex_digit(Char) when Char =< 9 ->
-    Char + $0;
-encode_hex_digit(Char) when Char =< 15 ->
-    Char + $A - 10.
+hex(X) ->
+    element(
+      X+1, {16#3030, 16#3031, 16#3032, 16#3033, 16#3034, 16#3035, 16#3036, 16#3037, 16#3038, 16#3039, 16#3041, 16#3042, 16#3043, 16#3044, 16#3045, 16#3046,
+            16#3130, 16#3131, 16#3132, 16#3133, 16#3134, 16#3135, 16#3136, 16#3137, 16#3138, 16#3139, 16#3141, 16#3142, 16#3143, 16#3144, 16#3145, 16#3146,
+            16#3230, 16#3231, 16#3232, 16#3233, 16#3234, 16#3235, 16#3236, 16#3237, 16#3238, 16#3239, 16#3241, 16#3242, 16#3243, 16#3244, 16#3245, 16#3246,
+            16#3330, 16#3331, 16#3332, 16#3333, 16#3334, 16#3335, 16#3336, 16#3337, 16#3338, 16#3339, 16#3341, 16#3342, 16#3343, 16#3344, 16#3345, 16#3346,
+            16#3430, 16#3431, 16#3432, 16#3433, 16#3434, 16#3435, 16#3436, 16#3437, 16#3438, 16#3439, 16#3441, 16#3442, 16#3443, 16#3444, 16#3445, 16#3446,
+            16#3530, 16#3531, 16#3532, 16#3533, 16#3534, 16#3535, 16#3536, 16#3537, 16#3538, 16#3539, 16#3541, 16#3542, 16#3543, 16#3544, 16#3545, 16#3546,
+            16#3630, 16#3631, 16#3632, 16#3633, 16#3634, 16#3635, 16#3636, 16#3637, 16#3638, 16#3639, 16#3641, 16#3642, 16#3643, 16#3644, 16#3645, 16#3646,
+            16#3730, 16#3731, 16#3732, 16#3733, 16#3734, 16#3735, 16#3736, 16#3737, 16#3738, 16#3739, 16#3741, 16#3742, 16#3743, 16#3744, 16#3745, 16#3746,
+            16#3830, 16#3831, 16#3832, 16#3833, 16#3834, 16#3835, 16#3836, 16#3837, 16#3838, 16#3839, 16#3841, 16#3842, 16#3843, 16#3844, 16#3845, 16#3846,
+            16#3930, 16#3931, 16#3932, 16#3933, 16#3934, 16#3935, 16#3936, 16#3937, 16#3938, 16#3939, 16#3941, 16#3942, 16#3943, 16#3944, 16#3945, 16#3946,
+            16#4130, 16#4131, 16#4132, 16#4133, 16#4134, 16#4135, 16#4136, 16#4137, 16#4138, 16#4139, 16#4141, 16#4142, 16#4143, 16#4144, 16#4145, 16#4146,
+            16#4230, 16#4231, 16#4232, 16#4233, 16#4234, 16#4235, 16#4236, 16#4237, 16#4238, 16#4239, 16#4241, 16#4242, 16#4243, 16#4244, 16#4245, 16#4246,
+            16#4330, 16#4331, 16#4332, 16#4333, 16#4334, 16#4335, 16#4336, 16#4337, 16#4338, 16#4339, 16#4341, 16#4342, 16#4343, 16#4344, 16#4345, 16#4346,
+            16#4430, 16#4431, 16#4432, 16#4433, 16#4434, 16#4435, 16#4436, 16#4437, 16#4438, 16#4439, 16#4441, 16#4442, 16#4443, 16#4444, 16#4445, 16#4446,
+            16#4530, 16#4531, 16#4532, 16#4533, 16#4534, 16#4535, 16#4536, 16#4537, 16#4538, 16#4539, 16#4541, 16#4542, 16#4543, 16#4544, 16#4545, 16#4546,
+            16#4630, 16#4631, 16#4632, 16#4633, 16#4634, 16#4635, 16#4636, 16#4637, 16#4638, 16#4639, 16#4641, 16#4642, 16#4643, 16#4644, 16#4645, 16#4646}).
+
 
 -spec decode_hex(Bin) -> Bin2 when
       Bin :: binary(),