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Subject[PATCH] bitops: Provide generic sign_extend function (moving it out from wireless code)
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?


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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