1 files changed, 33 insertions, 0 deletions
diff --git a/src/hex.erl b/src/hex.erl
new file mode 100644
index 0000000..8529f95
--- /dev/null
+++ b/src/hex.erl
@@ -0,0 +1,33 @@
+-module(hex).
+-export([bin_to_hexstr/1,hexstr_to_bin/1]).
+
+hex(N) when N < 10 ->
+    $0+N;
+hex(N) when N >= 10, N < 16 ->
+    $a+(N-10).
+
+int(C) when $0 =< C, C =< $9 ->
+    C - $0;
+int(C) when $A =< C, C =< $F ->
+    C - $A + 10;
+int(C) when $a =< C, C =< $f ->
+    C - $a + 10.
+    
+to_hex(N) when N < 256 ->
+    [hex(N div 16), hex(N rem 16)].
+ 
+list_to_hexstr([]) -> 
+    [];
+list_to_hexstr([H|T]) ->
+    to_hex(H) ++ list_to_hexstr(T).
+
+bin_to_hexstr(Bin) ->
+    list_to_hexstr(binary_to_list(Bin)).
+
+hexstr_to_bin(S) ->
+    list_to_binary(hexstr_to_list(S)).
+
+hexstr_to_list([X,Y|T]) ->
+    [int(X)*16 + int(Y) | hexstr_to_list(T)];
+hexstr_to_list([]) ->
+    [].