Re: [PATCH 2/2] [2/2] extcon: optimising the check_mutually_exclusive function

Re: [PATCH 2/2] [2/2] extcon: optimising the check_mutually_exclusive function

[MyungJoo Ham]

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> From: anish kumar <anish198519851985@gmail.com>
> 
> Rather than re-inventing the wheel we can use the hamming function
> to calculate the number of bits set to check for violation of
> exclusivity.
> 
> Signed-off-by: anish kumar <anish198519851985@gmail.com>

Ah.. we've got such a convinient one. Thanks.

Singed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>


> ---
>  drivers/extcon/extcon-class.c |   14 +++++---------
>  1 files changed, 5 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c
> index e09a6c3..06df95a 100644
> --- a/drivers/extcon/extcon-class.c
> +++ b/drivers/extcon/extcon-class.c
> @@ -89,17 +89,13 @@ static int check_mutually_exclusive(struct extcon_dev *edev, u32 new_state)
>  		return 0;
>  
>  	for (i = 0; edev->mutually_exclusive[i]; i++) {
> -		int count = 0, j;
> +		int weight;
>  		u32 correspondants = new_state & edev->mutually_exclusive[i];
> -		u32 exp = 1;
> -
> -		for (j = 0; j < 32; j++) {
> -			if (exp & correspondants)
> -				count++;
> -			if (count > 1)
> -				return i + 1;
> -			exp <<= 1;
> -		}
> +
> +		/* calculate the total number of bits set */
> +		weight = hweight32(correspondants);
> +		if (weight > 1)
> +			return i + 1;
>  	}
>  
>  	return 0;
> -- 
> 1.7.1
> 
> 
> 
> 
>        
>   
>          
> 
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[PATCH 2/2] [2/2] extcon: optimising the check_mutually_exclusive function

[anish kumar]

From: anish kumar <anish198519851985@gmail.com>

Rather than re-inventing the wheel we can use the hamming function
to calculate the number of bits set to check for violation of
exclusivity.

Signed-off-by: anish kumar <anish198519851985@gmail.com>
---
 drivers/extcon/extcon-class.c |   14 +++++---------
 1 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c
index e09a6c3..06df95a 100644
--- a/drivers/extcon/extcon-class.c
+++ b/drivers/extcon/extcon-class.c
@@ -89,17 +89,13 @@ static int check_mutually_exclusive(struct extcon_dev *edev, u32 new_state)
 		return 0;
 
 	for (i = 0; edev->mutually_exclusive[i]; i++) {
-		int count = 0, j;
+		int weight;
 		u32 correspondants = new_state & edev->mutually_exclusive[i];
-		u32 exp = 1;
-
-		for (j = 0; j < 32; j++) {
-			if (exp & correspondants)
-				count++;
-			if (count > 1)
-				return i + 1;
-			exp <<= 1;
-		}
+
+		/* calculate the total number of bits set */
+		weight = hweight32(correspondants);
+		if (weight > 1)
+			return i + 1;
 	}
 
 	return 0;
-- 
1.7.1