Fixed large number encoding on 32bit architectures

I was accidentally truncating numbers when casting to long on
machines that don't have longs that are 8 bytes.

Fixes #5

c_src/encoder.c

@@ -330,13 +330,20 @@ enc_string(Encoder* e, ERL_NIF_TERM val)
 }
 
 static inline int
-enc_long(Encoder* e, long val)
+enc_long(Encoder* e, ErlNifSInt64 val)
 {
     if(!enc_ensure(e, 32)) {
         return 0;
     }
 
+#if (defined(__WIN32__) || defined(_WIN32) || defined(_WIN32_))
     snprintf(&(e->p[e->i]), 32, "%ld", val);
+#elif SIZEOF_LONG == 8
+    snprintf(&(e->p[e->i]), 32, "%ld", val);
+#else
+    snprintf(&(e->p[e->i]), 32, "%lld", val);
+#endif
+
     e->i += strlen(&(e->p[e->i]));
     e->count++;
 
@@ -421,8 +428,8 @@ encode(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
     ERL_NIF_TERM item;
     const ERL_NIF_TERM* tuple;
     int arity;
+    ErlNifSInt64 lval;
     double dval;
-    long lval;
 
     if(argc != 2) {
         return enif_make_badarg(env);

test/003-numbers.t

@@ -6,7 +6,7 @@ main([]) ->
     code:add_pathz("ebin"),
     code:add_pathz("test"),
     
-    etap:plan(57),
+    etap:plan(59),
     util:test_good(good()),
     util:test_errors(errors()),
     etap:end_tests().
@@ -19,6 +19,7 @@ good() ->
         {<<"12">>, 12},
         {<<"-3">>, -3},
         {<<"1234567890123456789012345">>, 1234567890123456789012345},
+        {<<"1310050760199">>, 1310050760199},
         {
             <<"1234567890123456789012345.0">>,
             1.23456789012345678e24,