On Fri, Jan 03, 2025 at 12:39:38PM -0800, Andre Muezerie wrote:
> __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.
>
> Signed-off-by: Andre Muezerie <andre...@linux.microsoft.com>
> ---
> lib/eal/include/meson.build | 1 +
> lib/eal/include/rte_math.h | 46 +++++++++++++++++++++++++++++++++++++
> 2 files changed, 47 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..2f4581f81b
> --- /dev/null
> +++ b/lib/eal/include/rte_math.h
> @@ -0,0 +1,46 @@
> +/* 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
> +
> +/*
> + * Function that allows performing simple arithmetic operations together with
> + * checking whether the operation overflowed.
> + * Example of usage:
> + * uint8_t overflow;
> + * uint16_t a, b, result;
> + * a = 1;
> + * b = 2;
> + * overflow = rte_add_overflow(a, b, &result);
> + */
> +#ifdef RTE_TOOLCHAIN_MSVC
> +#define rte_add_overflow(a, b, res) _Generic((a), \
> + uint8_t : _addcarry_u8, \
> + uint16_t : _addcarry_u16, \
> + uint32_t : _addcarry_u32, \
> + uint64_t : _addcarry_u64)(0, a, b, res)
> +#else
> +#define rte_add_overflow(a, b, res) _Generic((a), \
> + uint8_t : __builtin_add_overflow, \
> + uint16_t : __builtin_add_overflow, \
> + uint32_t : __builtin_add_overflow, \
> + uint64_t : __builtin_add_overflow)(a, b, res)
> +#endif
For the gcc version, can you just simplify to the one-line below?
#define rte_add_overflow __builtin_add_overflow
/Bruce
