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SubjectRe: [PATCH] bitops: Provide generic sign_extend function (moving it out from wireless code)
On Fri, Aug 27, 2010 at 03:16:51AM -0700, Andreas Herrmann wrote:
> From: Andreas Herrmann <andreas.herrmann3@amd.com>
>
> Provide a common function to sign extend a value.
>
> Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
> ---
> drivers/net/wireless/ath/ath5k/phy.c | 6 ------
> drivers/net/wireless/ath/ath9k/hw.h | 6 ------
> drivers/net/wireless/iwlwifi/iwl-4965.c | 16 ----------------
> include/linux/bitops.h | 11 +++++++++++
> 4 files changed, 11 insertions(+), 28 deletions(-)
>
> Recently I needed to sign extend some register values for further
> computation. I also stumbled over two functions in wireless code
> which do the same (in different ways).
>
> Thus I wonder whether a generic function should be provided for this.
>
> Below patch (against tip/master) provides the iwl-4965-variant of that
> function in bitops.h I am not sure whether that's the right place to
> add this function. What do you think? Or is it a dumb idea anyway?

Think its reasonable. Adding linux-wireless.

Luis
>
>
> Thanks,
> Andreas
>
> diff --git a/drivers/net/wireless/ath/ath5k/phy.c b/drivers/net/wireless/ath/ath5k/phy.c
> index 6284c38..9e6f551 100644
> --- a/drivers/net/wireless/ath/ath5k/phy.c
> +++ b/drivers/net/wireless/ath/ath5k/phy.c
> @@ -1101,12 +1101,6 @@ int ath5k_hw_channel(struct ath5k_hw *ah, struct ieee80211_channel *channel)
> PHY calibration
> \*****************/
>
> -static int sign_extend(int val, const int nbits)
> -{
> - int order = BIT(nbits-1);
> - return (val ^ order) - order;
> -}
> -
> static s32 ath5k_hw_read_measured_noise_floor(struct ath5k_hw *ah)
> {
> s32 val;
> diff --git a/drivers/net/wireless/ath/ath9k/hw.h b/drivers/net/wireless/ath/ath9k/hw.h
> index 399f7c1..5dad02f 100644
> --- a/drivers/net/wireless/ath/ath9k/hw.h
> +++ b/drivers/net/wireless/ath/ath9k/hw.h
> @@ -858,12 +858,6 @@ static inline struct ath_hw_ops *ath9k_hw_ops(struct ath_hw *ah)
> return &ah->ops;
> }
>
> -static inline int sign_extend(int val, const int nbits)
> -{
> - int order = BIT(nbits-1);
> - return (val ^ order) - order;
> -}
> -
> /* Initialization, Detach, Reset */
> const char *ath9k_hw_probe(u16 vendorid, u16 devid);
> void ath9k_hw_deinit(struct ath_hw *ah);
> diff --git a/drivers/net/wireless/iwlwifi/iwl-4965.c b/drivers/net/wireless/iwlwifi/iwl-4965.c
> index d92b729..9a53dee 100644
> --- a/drivers/net/wireless/iwlwifi/iwl-4965.c
> +++ b/drivers/net/wireless/iwlwifi/iwl-4965.c
> @@ -1551,22 +1551,6 @@ static void iwl4965_txq_update_byte_cnt_tbl(struct iwl_priv *priv,
> }
>
> /**
> - * sign_extend - Sign extend a value using specified bit as sign-bit
> - *
> - * Example: sign_extend(9, 3) would return -7 as bit3 of 1001b is 1
> - * and bit0..2 is 001b which when sign extended to 1111111111111001b is -7.
> - *
> - * @param oper value to sign extend
> - * @param index 0 based bit index (0<=index<32) to sign bit
> - */
> -static s32 sign_extend(u32 oper, int index)
> -{
> - u8 shift = 31 - index;
> -
> - return (s32)(oper << shift) >> shift;
> -}
> -
> -/**
> * iwl4965_hw_get_temperature - return the calibrated temperature (in Kelvin)
> * @statistics: Provides the temperature reading from the uCode
> *
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index fc68053..618f69e 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -109,6 +109,17 @@ static inline __u8 ror8(__u8 word, unsigned int shift)
> return (word >> shift) | (word << (8 - shift));
> }
>
> +/**
> + * sign_extend - Sign extend a value using specified bit as sign-bit
> + * @value: value to sign extend
> + * @index: 0 based bit index (0<=index<32) to sign bit
> + */
> +static inline __s32 sign_extend(__u32 value, int index)
> +{
> + __u8 shift = 31 - index;
> + return (__s32)(value << shift) >> shift;
> +}
> +
> static inline unsigned fls_long(unsigned long l)
> {
> if (sizeof(l) == 4)
> --
> 1.6.4.4
>


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