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List:       lm-sensors
Subject:    Re: [lm-sensors] [PATCH 1/2] hwmon: (jc42) Use sign_extend32 for sign extension
From:       Jean Delvare <jdelvare () suse ! de>
Date:       2015-01-23 9:06:26
Message-ID: 20150123100626.0efad5c6 () endymion ! delvare
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Hi Guenter,

On Sun, 18 Jan 2015 17:36:47 -0800, Guenter Roeck wrote:
> Despite the name, sign_extend32 works just fine for 16 bit variables,
> so it is safe to use.
> 
> Cc: Martin Kepplinger <martink@posteo.de>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
>  drivers/hwmon/jc42.c | 6 +-----
>  1 file changed, 1 insertion(+), 5 deletions(-)
> 
> diff --git a/drivers/hwmon/jc42.c b/drivers/hwmon/jc42.c
> index 388f8bc..262d808 100644
> --- a/drivers/hwmon/jc42.c
> +++ b/drivers/hwmon/jc42.c
> @@ -213,11 +213,7 @@ static u16 jc42_temp_to_reg(int temp, bool extended)
>  
>  static int jc42_temp_from_reg(s16 reg)
>  {
> -	reg &= 0x1fff;
> -
> -	/* sign extend register */
> -	if (reg & 0x1000)
> -		reg |= 0xf000;
> +	reg = sign_extend32(reg, 12);
>  
>  	/* convert from 0.0625 to 0.001 resolution */
>  	return reg * 125 / 2;

Good idea, tested OK.

Reviewed-by: Jean Delvare <jdelvare@suse.de>

-- 
Jean Delvare
SUSE L3 Support

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