[PATCH 2/5] lib/eal: add portable version of __builtin_add_overflow

[Andre Muezerie <andremue@linux.microsoft.com>]

__builtin_add_overflow is gcc specific. There's a need for a portable
version that can also be used with other compilers.

This patch introduces __rte_add_overflow_u8, __rte_add_overflow_u16
and __rte_add_overflow_u32.

Signed-off-by: Andre Muezerie <andremue@linux.microsoft.com>
---
 lib/eal/include/meson.build |  1 +
 lib/eal/include/rte_math.h  | 42 +++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)
 create mode 100644 lib/eal/include/rte_math.h

diff --git a/lib/eal/include/meson.build b/lib/eal/include/meson.build
index d903577caa..041a4105b5 100644
--- a/lib/eal/include/meson.build
+++ b/lib/eal/include/meson.build
@@ -31,6 +31,7 @@ headers += files(
         'rte_lcore_var.h',
         'rte_lock_annotations.h',
         'rte_malloc.h',
+        'rte_math.h',
         'rte_mcslock.h',
         'rte_memory.h',
         'rte_memzone.h',
diff --git a/lib/eal/include/rte_math.h b/lib/eal/include/rte_math.h
new file mode 100644
index 0000000000..df2f3d4d34
--- /dev/null
+++ b/lib/eal/include/rte_math.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2025 Microsoft Corporation
+ */
+
+#ifndef _RTE_MATH_H_
+#define _RTE_MATH_H_
+
+/**
+ * @file
+ *
+ * Math function definitions for DPDK.
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*
+ * Functions that allow performing simple arithmetic operations together with
+ * checking whether the operations overflowed.
+ * Example of usage:
+ *     uint8_t overflow;
+ *     uint16_t a, b, result;
+ *     a = 1;
+ *     b = 2;
+ *     overflow = __rte_add_overflow_u16(a, b, &result);
+ */
+#ifdef RTE_TOOLCHAIN_MSVC
+#define __rte_add_overflow_u8(a, b, res) _addcarry_u8(0, a, b, res)
+#define __rte_add_overflow_u16(a, b, res) _addcarry_u16(0, a, b, res)
+#define __rte_add_overflow_u32(a, b, res) _addcarry_u32(0, a, b, res)
+#else
+#define __rte_add_overflow_u8(a, b, res) __builtin_add_overflow(a, b, res)
+#define __rte_add_overflow_u16(a, b, res) __builtin_add_overflow(a, b, res)
+#define __rte_add_overflow_u32(a, b, res) __builtin_add_overflow(a, b, res)
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
-- 
2.47.0.vfs.0.3