Use -1 for little endian

Author: vstinner

Doc/c-api/long.rst

@@ -580,15 +580,15 @@ Import/Export API
 
       Word endian:
 
-      - 1 for most significant byte first (big endian)
-      - 0 for least significant first (little endian)
+      - ``1`` for most significant byte first (big endian)
+      - ``-1`` for least significant first (little endian)
 
    .. c:member:: int8_t array_endian;
 
       Array endian:
 
-      - 1 for most significant byte first (big endian)
-      - 0 for least significant first (little endian)
+      - ``1`` for most significant byte first (big endian)
+      - ``-1`` for least significant first (little endian)
 
 
 .. c:function:: PyObject* PyUnstable_Long_Import(int negative, size_t ndigits, Py_digit *digits)

Include/cpython/longintrepr.h

@@ -152,12 +152,12 @@ typedef struct PyUnstable_LongLayout {
 
     // Word endian:
     // - 1 for most significant byte first (big endian)
-    // - 0 for least significant first (little endian)
+    // - -1 for least significant first (little endian)
     int8_t word_endian;
 
     // Array endian:
     // - 1 for most significant byte first (big endian)
-    // - 0 for least significant first (little endian)
+    // - -1 for least significant first (little endian)
     int8_t array_endian;
 } PyUnstable_LongLayout;
 

Lib/test/test_capi/test_long.py

@@ -749,10 +749,10 @@ def test_long_layout(self):
         int_info = sys.int_info
         layout = _testcapi.get_pylong_layout()
         expected = {
-            'array_endian': 0,
+            'array_endian': -1,
             'bits_per_digit': int_info.bits_per_digit,
             'digit_size': int_info.sizeof_digit,
-            'word_endian': 1 if sys.byteorder == 'little' else 0,
+            'word_endian': -1 if sys.byteorder == 'little' else 1,
         }
         self.assertEqual(layout, expected)
 

Objects/longobject.c

@@ -6688,8 +6688,8 @@ PyUnstable_Long_CompactValue(const PyLongObject* op) {
 
 const PyUnstable_LongLayout PyUnstable_Long_LAYOUT = {
     .bits_per_digit = PyLong_SHIFT,
-    .word_endian = PY_LITTLE_ENDIAN,
-    .array_endian = 0,  // least significant first
+    .word_endian = PY_LITTLE_ENDIAN ? -1 : 1,
+    .array_endian = -1,  // least significant first
     .digit_size = sizeof(digit),
 };