[PATCH 16/17] Input: joystick - Replace open-coded parity calculation with parity64()

Kuan-Wei Chiu
2025-02-23T16:45:52Z

Refactor parity calculations to use the standard parity64() helper.
This change eliminates redundant implementations and improves code
efficiency.

Co-developed-by: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Yu-Chun Lin <eleanor15x@gmail.com>
Signed-off-by: Kuan-Wei Chiu <visitorckw@gmail.com>
---
drivers/input/joystick/sidewinder.c | 24 +++++-------------------
1 file changed, 5 insertions(+), 19 deletions(-)

diff --git a/drivers/input/joystick/sidewinder.c b/drivers/input/joystick/sidewinder.c
index 3a5873e5fcb3..9fe980096f70 100644
--- a/drivers/input/joystick/sidewinder.c
+++ b/drivers/input/joystick/sidewinder.c
@@ -7,6 +7,7 @@
* Microsoft SideWinder joystick family driver for Linux
*/

+#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -240,21 +241,6 @@ static void sw_init_digital(struct gameport *gameport)
local_irq_restore(flags);
}

-/*
- * sw_parity() computes parity of __u64
- */
-
-static int sw_parity(__u64 t)
-{
- int x = t ^ (t >> 32);
-
- x ^= x >> 16;
- x ^= x >> 8;
- x ^= x >> 4;
- x ^= x >> 2;
- x ^= x >> 1;
- return x & 1;
-}

/*
* sw_ccheck() checks synchronization bits and computes checksum of nibbles.
@@ -316,7 +302,7 @@ static int sw_parse(unsigned char *buf, struct sw *sw)

for (i = 0; i < sw->number; i ++) {

- if (sw_parity(GB(i*15,15)))
+ if (parity64(GB(i*15,15)))
return -1;

input_report_abs(sw->dev[i], ABS_X, GB(i*15+3,1) - GB(i*15+2,1));
@@ -333,7 +319,7 @@ static int sw_parse(unsigned char *buf, struct sw *sw)
case SW_ID_PP:
case SW_ID_FFP:

- if (!sw_parity(GB(0,48)) || (hat = GB(42,4)) > 8)
+ if (!parity64(GB(0,48)) || (hat = GB(42,4)) > 8)
return -1;

dev = sw->dev[0];
@@ -354,7 +340,7 @@ static int sw_parse(unsigned char *buf, struct sw *sw)

case SW_ID_FSP:

- if (!sw_parity(GB(0,43)) || (hat = GB(28,4)) > 8)
+ if (!parity64(GB(0,43)) || (hat = GB(28,4)) > 8)
return -1;

dev = sw->dev[0];
@@ -379,7 +365,7 @@ static int sw_parse(unsigned char *buf, struct sw *sw)

case SW_ID_FFW:

- if (!sw_parity(GB(0,33)))
+ if (!parity64(GB(0,33)))
return -1;

dev = sw->dev[0];
--
2.34.1