diff mbox series

[4/4] parisc: checksum: Optimize from32to16

Message ID 20240221-parisc_use_generic_checksum-v1-4-ad34d895fd1b@rivosinc.com
State New
Headers
Series parisc: checksum: Use generic implementations and optimize checksum |

Commit Message

Charlie Jenkins Feb. 22, 2024, 2:37 a.m. UTC 
  Replace the shifting and masking of x with a rotation. This generates
better assembly.

Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
---
 arch/parisc/lib/checksum.c | 7 ++-----
 1 file changed, 2 insertions(+), 5 deletions(-)
diff mbox series

Patch

diff --git a/arch/parisc/lib/checksum.c b/arch/parisc/lib/checksum.c
index eaa660491e24..1ae8cc730d13 100644
--- a/arch/parisc/lib/checksum.c
+++ b/arch/parisc/lib/checksum.c
@@ -27,11 +27,8 @@ 
 
 static inline unsigned short from32to16(unsigned int x)
 {
-	/* 32 bits --> 16 bits + carry */
-	x = (x & 0xffff) + (x >> 16);
-	/* 16 bits + carry --> 16 bits including carry */
-	x = (x & 0xffff) + (x >> 16);
-	return (unsigned short)x;
+	x += ror32(x, 16);
+	return (unsigned short)(x >> 16);
 }
 
 unsigned int do_csum(const unsigned char *buff, int len)