From 61e76d2aaab98d4b0397e749e33c2e2c7abf82e4 Mon Sep 17 00:00:00 2001
From: Sergey B Kirpichev <skirpichev@gmail.com>
Date: Thu, 19 Dec 2024 06:54:51 +0300
Subject: [PATCH] use PyLong_GetNativeLayout() to query layout

---
 Modules/_decimal/_decimal.c | 42 +++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 20 deletions(-)

diff --git a/Modules/_decimal/_decimal.c b/Modules/_decimal/_decimal.c
index a13cfdd175f10a..f302cc77f9fff6 100644
--- a/Modules/_decimal/_decimal.c
+++ b/Modules/_decimal/_decimal.c
@@ -2335,18 +2335,19 @@ dec_from_long(decimal_state *state, PyTypeObject *type, PyObject *v,
         return NULL;
     }
     if (export_long.digits) {
+        const PyLongLayout *layout = PyLong_GetNativeLayout();
+        const uint32_t base = 1 << layout->bits_per_digit;
         const uint8_t sign = export_long.negative ? MPD_NEG : MPD_POS;
         const Py_ssize_t len = export_long.ndigits;
 
-#if PYLONG_BITS_IN_DIGIT == 30
-        mpd_qimport_u32(MPD(dec), export_long.digits, len, sign,
-                        PyLong_BASE, ctx, status);
-#elif PYLONG_BITS_IN_DIGIT == 15
-        mpd_qimport_u16(MPD(dec), export_long.digits, len, sign,
-                        PyLong_BASE, ctx, status);
-#else
-  #error "PYLONG_BITS_IN_DIGIT should be 15 or 30"
-#endif
+        if (base > UINT16_MAX) {
+            mpd_qimport_u32(MPD(dec), export_long.digits, len, sign,
+                            base, ctx, status);
+        }
+        else {
+            mpd_qimport_u16(MPD(dec), export_long.digits, len, sign,
+                            base, ctx, status);
+        }
         PyLong_FreeExport(&export_long);
     }
     else {
@@ -3684,7 +3685,9 @@ dec_as_long(PyObject *dec, PyObject *context, int round)
         return PyLong_FromInt64(val);
     }
 
-    size_t len = mpd_sizeinbase(x, PyLong_BASE);
+    const PyLongLayout *layout = PyLong_GetNativeLayout();
+    const uint32_t base = 1 << layout->bits_per_digit;
+    size_t len = mpd_sizeinbase(x, base);
     PyLongWriter *writer = PyLongWriter_Create(mpd_isnegative(x), len, &digits);
     if (writer == NULL) {
         mpd_del(x);
@@ -3692,16 +3695,15 @@ dec_as_long(PyObject *dec, PyObject *context, int round)
     }
 
     status = 0;
-    /* mpd_sizeinbase can overestimate size by 1 digit, set it to zero. */
-#if PYLONG_BITS_IN_DIGIT == 30
-    ((uint32_t *)digits)[len - 1] = 0;
-    n = mpd_qexport_u32((uint32_t **)&digits, len, PyLong_BASE, x, &status);
-#elif PYLONG_BITS_IN_DIGIT == 15
-    ((uint16_t *)digits)[len - 1] = 0;
-    n = mpd_qexport_u16((uint16_t **)&digits, len, PyLong_BASE, x, &status);
-#else
-    #error "PYLONG_BITS_IN_DIGIT should be 15 or 30"
-#endif
+    /* mpd_sizeinbase can overestimate size by 1 digit, set it first to zero. */
+    if (base > UINT16_MAX) {
+        ((uint32_t *)digits)[len - 1] = 0;
+        n = mpd_qexport_u32((uint32_t **)&digits, len, base, x, &status);
+    }
+    else {
+        ((uint16_t *)digits)[len - 1] = 0;
+        n = mpd_qexport_u16((uint16_t **)&digits, len, base, x, &status);
+    }
     assert(n == len || n == len - 1);
 
     if (n == SIZE_MAX) {