py/objint: Support "big" byte-order in int.to_bytes().

py/objint.c

@@ -432,15 +432,11 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(int_from_bytes_fun_obj, 3, 4, int_fro
 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 @@ STATIC mp_obj_t int_to_bytes(size_t n_args, const mp_obj_t *args) {
 
     #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);

tests/basics/int_bytes.py

@@ -8,3 +8,9 @@ print(int.from_bytes(b"\x00\x01\0\0\0\0\0\0", "little"))
 # check that extra zero bytes don't change the internal int value
 print(int.from_bytes(bytes(20), "little") == 0)
 print(int.from_bytes(b"\x01" + bytes(20), "little") == 1)
+
+# big-endian conversion
+print((10).to_bytes(1, "big"))
+print((100).to_bytes(10, "big"))
+print(int.from_bytes(b"\0\0\0\0\0\0\0\0\0\x01", "big"))
+print(int.from_bytes(b"\x01\0", "big"))

tests/basics/int_bytes_intbig.py

 print((2**64).to_bytes(9, "little"))
+print((2**64).to_bytes(9, "big"))
 
 b = bytes(range(20))
 
@@ -7,6 +8,7 @@ ib = int.from_bytes(b, "big")
 print(il)
 print(ib)
 print(il.to_bytes(20, "little"))
+print(ib.to_bytes(20, "big"))
 
 # check that extra zero bytes don't change the internal int value
 print(int.from_bytes(b + bytes(10), "little") == int.from_bytes(b, "little"))

tests/basics/int_bytes_notimpl.py

-try:
-    print((10).to_bytes(1, "big"))
-except Exception as e:
-    print(type(e))

tests/basics/int_bytes_notimpl.py.exp

-<class 'NotImplementedError'>