py/objint: Support "big" byte-order in int.to_bytes().
diff --git a/py/objint.c b/py/objint.c
index bda9c46..4801baa 100644
--- a/py/objint.c
+++ b/py/objint.c
@@ -432,15 +432,11 @@
 STATIC MP_DEFINE_CONST_CLASSMETHOD_OBJ(int_from_bytes_obj, MP_ROM_PTR(&int_from_bytes_fun_obj));
 
 STATIC mp_obj_t int_to_bytes(size_t n_args, const mp_obj_t *args) {
-    // TODO: Support byteorder param
     // TODO: Support signed param (assumes signed=False)
     (void)n_args;
 
-    if (args[2] != MP_OBJ_NEW_QSTR(MP_QSTR_little)) {
-        mp_not_implemented("");
-    }
-
     mp_uint_t len = MP_OBJ_SMALL_INT_VALUE(args[1]);
+    bool big_endian = args[2] != MP_OBJ_NEW_QSTR(MP_QSTR_little);
 
     vstr_t vstr;
     vstr_init_len(&vstr, len);
@@ -449,12 +445,13 @@
 
     #if MICROPY_LONGINT_IMPL != MICROPY_LONGINT_IMPL_NONE
     if (!MP_OBJ_IS_SMALL_INT(args[0])) {
-        mp_obj_int_to_bytes_impl(args[0], false, len, data);
+        mp_obj_int_to_bytes_impl(args[0], big_endian, len, data);
     } else
     #endif
     {
         mp_int_t val = MP_OBJ_SMALL_INT_VALUE(args[0]);
-        mp_binary_set_int(MIN((size_t)len, sizeof(val)), false, data, val);
+        size_t l = MIN((size_t)len, sizeof(val));
+        mp_binary_set_int(l, big_endian, data + (big_endian ? (len - l) : 0), val);
     }
 
     return mp_obj_new_str_from_vstr(&mp_type_bytes, &vstr);