On Fri, Jan 20, 2023 at 01:08:15AM +0100, KP Singh wrote:
> This helps in easily initializing blocks of code (e.g. static calls and
> keys).
>
> UNROLL(N, MACRO, __VA_ARGS__) calls MACRO N times with the first
> argument as the index of the iteration. This allows string pasting to
> create unique tokens for variable names, function calls etc.
>
> As an example:
>
> #include <linux/unroll.h>
>
> #define MACRO(N, a, b) \
> int add_##N(int a, int b) \
> { \
> return a + b + N; \
> }
>
> UNROLL(2, MACRO, x, y)
>
> expands to:
>
> int add_0(int x, int y)
> {
> return x + y + 0;
> }
>
> int add_1(int x, int y)
> {
> return x + y + 1;
> }
>
> Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
> ---
> include/linux/unroll.h | 35 +++++++++++++++++++++++++++++++++++
> 1 file changed, 35 insertions(+)
> create mode 100644 include/linux/unroll.h
>
> diff --git a/include/linux/unroll.h b/include/linux/unroll.h
> new file mode 100644
> index 000000000000..e19aef95b94b
> --- /dev/null
> +++ b/include/linux/unroll.h
> @@ -0,0 +1,35 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +
> +/*
> + * Copyright (C) 2020 Google LLC.
> + */
> +
> +#ifndef __UNROLL_H
> +#define __UNROLL_H
> +
> +#define __UNROLL_CONCAT(a, b) a ## _ ## b
#include <linux/kernel.h>
and just use CONCATENATE
> +#define UNROLL(N, MACRO, args...) __UNROLL_CONCAT(__UNROLL, N)(MACRO, args)
Which would be, and it just loses the _, which isn't important here:
#define UNROLL(N, MACRO, args...) CONCATENATE(__UNROLL, N)(MACRO, args)
> +#define __UNROLL_0(MACRO, args...)
> +#define __UNROLL_1(MACRO, args...) __UNROLL_0(MACRO, args) MACRO(0, args)
But yeah, I like it. It's an expression version of the __MAP() macro
used by the syscall wrappers for arguments.
--
Kees Cook
