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* [PATCH v2] rust: add new macro for common bitmap operations
@ 2025-03-25 13:10 Filipe Xavier
  2025-03-25 13:34 ` Benno Lossin
                   ` (3 more replies)
  0 siblings, 4 replies; 8+ messages in thread
From: Filipe Xavier @ 2025-03-25 13:10 UTC (permalink / raw)
  To: Miguel Ojeda, Alex Gaynor, Boqun Feng, Gary Guo,
	Björn Roy Baron, Benno Lossin, Andreas Hindborg, Alice Ryhl,
	Trevor Gross, Danilo Krummrich
  Cc: daniel.almeida, rust-for-linux, felipe_life, linux-kernel,
	Filipe Xavier, Lyude Paul

We have seen a proliferation of mod_whatever::foo::Flags
being defined with essentially the same implementation
for BitAnd, BitOr, contains and etc.

This macro aims to bring a solution for this,
allowing to generate these methods for user-defined structs.
With some use cases in KMS and VideoCodecs.

Small use sample:
`
const READ: Permission = Permission(1 << 0);
const WRITE: Permission = Permission(1 << 1);

impl_flags!(Permissions, Permission, u32);

let read_write = Permissions::from(READ) | WRITE;
let read_only = read_write & READ;
`

Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/We.20really.20need.20a.20common.20.60Flags.60.20type
Signed-off-by: Filipe Xavier <felipeaggger@gmail.com>
Suggested-by: Daniel Almeida <daniel.almeida@collabora.com>
Suggested-by: Lyude Paul <lyude@redhat.com>
---
Changes in v2:
- rename: change macro and file name to impl_flags.
- negation sign: change char for negation to `!`. 
- transpose docs: add support to transpose user provided docs.
- visibility: add support to use user defined visibility.
- operations: add new operations for flag, 
to support use between bit and bitmap, eg: flag & flags.
- code style: small fixes to remove warnings.
- Link to v1: https://lore.kernel.org/r/20250304-feat-add-bitmask-macro-v1-1-1c2d2bcb476b@gmail.com
---
 rust/kernel/impl_flags.rs | 214 ++++++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs        |   1 +
 rust/kernel/prelude.rs    |   1 +
 3 files changed, 216 insertions(+)

diff --git a/rust/kernel/impl_flags.rs b/rust/kernel/impl_flags.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e7cf00e14bdcd2acea47b8c158a984ac0206568b
--- /dev/null
+++ b/rust/kernel/impl_flags.rs
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! impl_flags utilities for working with flags.
+
+/// Declares a impl_flags type with its corresponding flag type.
+///
+/// This macro generates:
+/// - Implementations of common bitmask operations ([`BitOr`], [`BitAnd`], etc.).
+/// - Utility methods such as `.contains()` to check flags.
+///
+/// # Examples
+///
+/// Defining and using impl_flags:
+///
+/// ```
+/// impl_flags!(
+///     /// Represents multiple permissions.
+///     pub Permissions,
+///     /// Represents a single permission.
+///     pub Permission,
+///     u32
+/// );
+///
+/// // Define some individual permissions.
+/// const READ: Permission = Permission(1 << 0);
+/// const WRITE: Permission = Permission(1 << 1);
+/// const EXECUTE: Permission = Permission(1 << 2);
+///
+/// // Combine multiple permissions using operation OR (`|`).
+/// let read_write = Permissions::from(READ) | WRITE;
+///
+/// assert!(read_write.contains(READ));
+/// assert!(read_write.contains(WRITE));
+/// assert!(!read_write.contains(EXECUTE));
+///
+/// // Removing a permission with operation AND (`&`).
+/// let read_only = read_write & READ;
+/// assert!(read_only.contains(READ));
+/// assert!(!read_only.contains(WRITE));
+///
+/// // Toggling permissions with XOR (`^`).
+/// let toggled = read_only ^ Permissions::from(READ);
+/// assert!(!toggled.contains(READ));
+///
+/// // Inverting permissions with negation (`!`).
+/// let negated = !read_only;
+/// assert!(negated.contains(WRITE));
+/// ```
+#[macro_export]
+macro_rules! impl_flags {
+    (
+        $(#[$outer_flags:meta])* $vis_flags:vis $flags:ident,
+        $(#[$outer_flag:meta])* $vis_flag:vis $flag:ident,
+        $ty:ty
+    ) => {
+        $(#[$outer_flags])*
+        #[repr(transparent)]
+        #[derive(Copy, Clone, Default, PartialEq, Eq)]
+        $vis_flags struct $flags($ty);
+
+        $(#[$outer_flag])*
+        #[derive(Copy, Clone, PartialEq, Eq)]
+        $vis_flag struct $flag($ty);
+
+        impl From<$flag> for $flags {
+            #[inline]
+            fn from(value: $flag) -> Self {
+                Self(value.0)
+            }
+        }
+
+        impl From<$flags> for $ty {
+            #[inline]
+            fn from(value: $flags) -> Self {
+                value.0
+            }
+        }
+
+        impl core::ops::BitOr for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn bitor(self, rhs: Self) -> Self::Output {
+                Self(self.0 | rhs.0)
+            }
+        }
+
+        impl core::ops::BitOrAssign for $flags {
+            #[inline]
+            fn bitor_assign(&mut self, rhs: Self) {
+                *self = *self | rhs;
+            }
+        }
+
+        impl core::ops::BitAnd for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn bitand(self, rhs: Self) -> Self::Output {
+                Self(self.0 & rhs.0)
+            }
+        }
+
+        impl core::ops::BitAndAssign for $flags {
+            #[inline]
+            fn bitand_assign(&mut self, rhs: Self) {
+                *self = *self & rhs;
+            }
+        }
+
+        impl core::ops::BitOr<$flag> for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn bitor(self, rhs: $flag) -> Self::Output {
+                self | Self::from(rhs)
+            }
+        }
+
+        impl core::ops::BitOrAssign<$flag> for $flags {
+            #[inline]
+            fn bitor_assign(&mut self, rhs: $flag) {
+                *self = *self | rhs;
+            }
+        }
+
+        impl core::ops::BitAnd<$flag> for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn bitand(self, rhs: $flag) -> Self::Output {
+                self & Self::from(rhs)
+            }
+        }
+
+        impl core::ops::BitAndAssign<$flag> for $flags {
+            #[inline]
+            fn bitand_assign(&mut self, rhs: $flag) {
+                *self = *self & rhs;
+            }
+        }
+
+        impl core::ops::BitXor for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn bitxor(self, rhs: Self) -> Self::Output {
+                Self(self.0 ^ rhs.0)
+            }
+        }
+
+        impl core::ops::BitXorAssign for $flags {
+            #[inline]
+            fn bitxor_assign(&mut self, rhs: Self) {
+                *self = *self ^ rhs;
+            }
+        }
+
+        impl core::ops::Not for $flags {
+            type Output = Self;
+
+            #[inline]
+            fn not(self) -> Self::Output {
+                Self(!self.0)
+            }
+        }
+
+        impl core::ops::BitOr for $flag {
+            type Output = $flags;
+            #[inline]
+            fn bitor(self, rhs: Self) -> Self::Output {
+                $flags(self.0 | rhs.0)
+            }
+        }
+
+        impl core::ops::BitAnd for $flag {
+            type Output = $flags;
+            #[inline]
+            fn bitand(self, rhs: Self) -> Self::Output {
+                $flags(self.0 & rhs.0)
+            }
+        }
+
+        impl core::ops::BitXor for $flag {
+            type Output = $flags;
+            #[inline]
+            fn bitxor(self, rhs: Self) -> Self::Output {
+                $flags(self.0 ^ rhs.0)
+            }
+        }
+
+        impl core::ops::Not for $flag {
+            type Output = $flags;
+            #[inline]
+            fn not(self) -> Self::Output {
+                $flags(!self.0)
+            }
+        }
+
+        impl $flags {
+            /// Returns an empty instance of `type` where no flags are set.
+            #[inline]
+            pub const fn empty() -> Self {
+                Self(0)
+            }
+
+            /// Checks if a specific flag is set.
+            #[inline]
+            pub fn contains(self, flag: $flag) -> bool {
+                (self.0 & flag.0) == flag.0
+            }
+        }
+    };
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index 496ed32b0911a9fdbce5d26738b9cf7ef910b269..7653485a456ae5aa51becbf04153ea54a7067d9e 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -49,6 +49,7 @@
 #[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
 pub mod firmware;
 pub mod fs;
+pub mod impl_flags;
 pub mod init;
 pub mod io;
 pub mod ioctl;
diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs
index dde2e0649790ca24e6c347b29465ea0a1c3e503b..0f691dd2df71d821265fae01555ba50e6a76f372 100644
--- a/rust/kernel/prelude.rs
+++ b/rust/kernel/prelude.rs
@@ -25,6 +25,7 @@
 #[doc(no_inline)]
 pub use super::dbg;
 pub use super::fmt;
+pub use super::impl_flags;
 pub use super::{dev_alert, dev_crit, dev_dbg, dev_emerg, dev_err, dev_info, dev_notice, dev_warn};
 pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr_notice, pr_warn};
 

---
base-commit: beeb78d46249cab8b2b8359a2ce8fa5376b5ad2d
change-id: 20250304-feat-add-bitmask-macro-6424b1c317e2

Best regards,
-- 
Filipe Xavier <felipeaggger@gmail.com>


^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2025-03-31 22:50 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-03-25 13:10 [PATCH v2] rust: add new macro for common bitmap operations Filipe Xavier
2025-03-25 13:34 ` Benno Lossin
2025-03-25 14:17   ` Miguel Ojeda
2025-03-25 13:54 ` Daniel Almeida
2025-03-27  5:05 ` kernel test robot
2025-03-31 22:29 ` Lyude Paul
2025-03-31 22:35   ` Daniel Almeida
2025-03-31 22:50     ` Lyude Paul

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