linux-kernel - [PATCH 1/2] wordpart.h: Helpers for making u16/u32/u64 values

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Date: Wed, 14 Feb 2024 22:46:53 +0100
From: Michal Wajdeczko <michal.wajdeczko@...el.com>
To: linux-kernel@...r.kernel.org
Cc: Michal Wajdeczko <michal.wajdeczko@...el.com>,
	Kees Cook <keescook@...omium.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Jani Nikula <jani.nikula@...el.com>
Subject: [PATCH 1/2] wordpart.h: Helpers for making u16/u32/u64 values

It is quite common practice to make u16, u32 or u64 values from
smaller words.  Add simple helpers for that.

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@...el.com>
---
v2: new macro names due to conflict with crypto/aria.h
    explicit cast and truncation everywhere (Alexey)
    moved to wordpart.h (Andy)
---
Cc: Kees Cook <keescook@...omium.org>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Alexey Dobriyan <adobriyan@...il.com>
Cc: Jani Nikula <jani.nikula@...el.com>
---
 include/linux/wordpart.h | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/include/linux/wordpart.h b/include/linux/wordpart.h
index f6f8f83b15b0..8c75a5355112 100644
--- a/include/linux/wordpart.h
+++ b/include/linux/wordpart.h
@@ -31,6 +31,38 @@
  */
 #define lower_16_bits(n) ((u16)((n) & 0xffff))
 
+/**
+ * make_u16_from_u8 - make u16 value from two u8 values
+ * @hi: value representing upper 8 bits
+ * @lo: value representing lower 8 bits
+ */
+#define make_u16_from_u8(hi, lo) ((u16)((u16)(u8)(hi) << 8 | (u8)(lo)))
+
+/**
+ * make_u32_from_u16 - make u32 value from two u16 values
+ * @hi: value representing upper 16 bits
+ * @lo: value representing lower 16 bits
+ */
+#define make_u32_from_u16(hi, lo) ((u32)((u32)(u16)(hi) << 16 | (u16)(lo)))
+
+/**
+ * make_u32_from_u8 - make u32 value from u8 values
+ * @a: value representing bits 31-24
+ * @b: value representing bits 23-16
+ * @c: value representing bits 15-8
+ * @d: value representing bits 7-0
+ */
+#define make_u32_from_u8(a, b, c, d) \
+	make_u32_from_u16(make_u16_from_u8((a), (b)), \
+			  make_u16_from_u8((c), (d)))
+
+/**
+ * make_u64_from_u32 - make u64 value from two u32 values
+ * @hi: value representing upper 32 bits
+ * @lo: value representing lower 32 bits
+ */
+#define make_u64_from_u32(hi, lo) ((u64)((u64)(u32)(hi) << 32 | (u32)(lo)))
+
 /**
  * REPEAT_BYTE - repeat the value @x multiple times as an unsigned long value
  * @x: value to repeat
-- 
2.43.0