bpo-41324 Add a minimal decimal capsule API (#21519)
diff --git a/Include/pydecimal.h b/Include/pydecimal.h
new file mode 100644
index 0000000..9b6440e
--- /dev/null
+++ b/Include/pydecimal.h
@@ -0,0 +1,180 @@
+/*
+ * Copyright (c) 2020 Stefan Krah. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+
+#ifndef CPYTHON_DECIMAL_H_
+#define CPYTHON_DECIMAL_H_
+
+
+#include <Python.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/****************************************************************************/
+/* Libmpdec API */
+/****************************************************************************/
+
+#ifndef LIBMPDEC_MPDECIMAL_H_
+struct mpd_t; /* ABI-stable in the libmpdec-2.x series */
+
+/* status cases for getting a triple */
+enum mpd_triple_class {
+ MPD_TRIPLE_NORMAL,
+ MPD_TRIPLE_INF,
+ MPD_TRIPLE_QNAN,
+ MPD_TRIPLE_SNAN,
+ MPD_TRIPLE_ERROR,
+};
+
+typedef struct {
+ enum mpd_triple_class tag;
+ uint8_t sign;
+ uint64_t hi;
+ uint64_t lo;
+ int64_t exp;
+} mpd_uint128_triple_t;
+#endif
+
+
+/****************************************************************************/
+/* Capsule API */
+/****************************************************************************/
+
+/* Simple API */
+#define PyDec_TypeCheck_INDEX 0
+#define PyDec_TypeCheck_RETURN int
+#define PyDec_TypeCheck_ARGS (const PyObject *)
+
+#define PyDec_IsSpecial_INDEX 1
+#define PyDec_IsSpecial_RETURN int
+#define PyDec_IsSpecial_ARGS (const PyObject *)
+
+#define PyDec_IsNaN_INDEX 2
+#define PyDec_IsNaN_RETURN int
+#define PyDec_IsNaN_ARGS (const PyObject *)
+
+#define PyDec_IsInfinite_INDEX 3
+#define PyDec_IsInfinite_RETURN int
+#define PyDec_IsInfinite_ARGS (const PyObject *)
+
+#define PyDec_GetDigits_INDEX 4
+#define PyDec_GetDigits_RETURN int64_t
+#define PyDec_GetDigits_ARGS (const PyObject *)
+
+#define PyDec_AsUint128Triple_INDEX 5
+#define PyDec_AsUint128Triple_RETURN mpd_uint128_triple_t
+#define PyDec_AsUint128Triple_ARGS (const PyObject *)
+
+#define PyDec_FromUint128Triple_INDEX 6
+#define PyDec_FromUint128Triple_RETURN PyObject *
+#define PyDec_FromUint128Triple_ARGS (const mpd_uint128_triple_t *triple)
+
+/* Advanced API */
+#define PyDec_Alloc_INDEX 7
+#define PyDec_Alloc_RETURN PyObject *
+#define PyDec_Alloc_ARGS (void)
+
+#define PyDec_Get_INDEX 8
+#define PyDec_Get_RETURN mpd_t *
+#define PyDec_Get_ARGS (PyObject *)
+
+#define PyDec_GetConst_INDEX 9
+#define PyDec_GetConst_RETURN const mpd_t *
+#define PyDec_GetConst_ARGS (const PyObject *)
+
+#define CPYTHON_DECIMAL_MAX_API 10
+
+
+#ifdef CPYTHON_DECIMAL_MODULE
+/* Simple API */
+static PyDec_TypeCheck_RETURN PyDec_TypeCheck PyDec_TypeCheck_ARGS;
+static PyDec_IsSpecial_RETURN PyDec_IsSpecial PyDec_IsSpecial_ARGS;
+static PyDec_IsNaN_RETURN PyDec_IsNaN PyDec_IsNaN_ARGS;
+static PyDec_IsInfinite_RETURN PyDec_IsInfinite PyDec_IsInfinite_ARGS;
+static PyDec_GetDigits_RETURN PyDec_GetDigits PyDec_GetDigits_ARGS;
+static PyDec_AsUint128Triple_RETURN PyDec_AsUint128Triple PyDec_AsUint128Triple_ARGS;
+static PyDec_FromUint128Triple_RETURN PyDec_FromUint128Triple PyDec_FromUint128Triple_ARGS;
+
+/* Advanced API */
+static PyDec_Alloc_RETURN PyDec_Alloc PyDec_Alloc_ARGS;
+static PyDec_Get_RETURN PyDec_Get PyDec_Get_ARGS;
+static PyDec_GetConst_RETURN PyDec_GetConst PyDec_GetConst_ARGS;
+#else
+static void **_decimal_api;
+
+/* Simple API */
+#define PyDec_TypeCheck \
+ (*(PyDec_TypeCheck_RETURN (*)PyDec_TypeCheck_ARGS) _decimal_api[PyDec_TypeCheck_INDEX])
+
+#define PyDec_IsSpecial \
+ (*(PyDec_IsSpecial_RETURN (*)PyDec_IsSpecial_ARGS) _decimal_api[PyDec_IsSpecial_INDEX])
+
+#define PyDec_IsNaN \
+ (*(PyDec_IsNaN_RETURN (*)PyDec_IsNaN_ARGS) _decimal_api[PyDec_IsNaN_INDEX])
+
+#define PyDec_IsInfinite \
+ (*(PyDec_IsInfinite_RETURN (*)PyDec_IsInfinite_ARGS) _decimal_api[PyDec_IsInfinite_INDEX])
+
+#define PyDec_GetDigits \
+ (*(PyDec_GetDigits_RETURN (*)PyDec_GetDigits_ARGS) _decimal_api[PyDec_GetDigits_INDEX])
+
+#define PyDec_AsUint128Triple \
+ (*(PyDec_AsUint128Triple_RETURN (*)PyDec_AsUint128Triple_ARGS) _decimal_api[PyDec_AsUint128Triple_INDEX])
+
+#define PyDec_FromUint128Triple \
+ (*(PyDec_FromUint128Triple_RETURN (*)PyDec_FromUint128Triple_ARGS) _decimal_api[PyDec_FromUint128Triple_INDEX])
+
+/* Advanced API */
+#define PyDec_Alloc \
+ (*(PyDec_Alloc_RETURN (*)PyDec_Alloc_ARGS) _decimal_api[PyDec_Alloc_INDEX])
+
+#define PyDec_Get \
+ (*(PyDec_Get_RETURN (*)PyDec_Get_ARGS) _decimal_api[PyDec_Get_INDEX])
+
+#define PyDec_GetConst \
+ (*(PyDec_GetConst_RETURN (*)PyDec_GetConst_ARGS) _decimal_api[PyDec_GetConst_INDEX])
+
+
+static int
+import_decimal(void)
+{
+ _decimal_api = (void **)PyCapsule_Import("_decimal._API", 0);
+ if (_decimal_api == NULL) {
+ return -1;
+ }
+
+ return 0;
+}
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* CPYTHON_DECIMAL_H_ */