diff mbox series

[v5,06/23] xen/asm-generic: introduce generic ffz()

Message ID a5b5c23122ee55cad72dad74b47cb7a539ebbc01.1708962629.git.oleksii.kurochko@gmail.com (mailing list archive)
State Superseded
Headers show
Series Enable build of full Xen for RISC-V | expand

Commit Message

Oleksii Kurochko Feb. 26, 2024, 5:38 p.m. UTC 
The generic ffz() can be useful for architectures
that don't have corresponding arch-specific instruction.

Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
 Changes in V5:
   - new patch
---
 xen/include/asm-generic/bitops/ffz.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 xen/include/asm-generic/bitops/ffz.h
diff mbox series

Patch

diff --git a/xen/include/asm-generic/bitops/ffz.h b/xen/include/asm-generic/bitops/ffz.h
new file mode 100644
index 0000000000..5932fe6695
--- /dev/null
+++ b/xen/include/asm-generic/bitops/ffz.h
@@ -0,0 +1,18 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_BITOPS_FFZ_H_
+#define _ASM_GENERIC_BITOPS_FFZ_H_
+
+/*
+ * ffz - find first zero in word.
+ * @word: The word to search
+ *
+ * Undefined if no zero exists, so code should check against ~0UL first.
+ *
+ * ffz() is defined as __ffs() and not as ffs() as it is defined in such
+ * a way in Linux kernel (6.4.0 ) from where this header was taken, so this
+ * header is supposed to be aligned with Linux kernel version.
+ * Also, most architectures are defined in the same way in Xen.
+ */
+#define ffz(x)  __ffs(~(x))
+
+#endif /* _ASM_GENERIC_BITOPS_FFZ_H_ */