All of lore.kernel.org
 help / color / mirror / Atom feed
* [PATCH] bitops: Provide generic sign_extend function (moving it out from wireless code)
@ 2010-08-27 10:16 Andreas Herrmann
  2010-08-27 10:27 ` Andi Kleen
                   ` (3 more replies)
  0 siblings, 4 replies; 5+ messages in thread
From: Andreas Herrmann @ 2010-08-27 10:16 UTC (permalink / raw)
  To: H. Peter Anvin, Ingo Molnar, Peter Zijlstra, Andrew Morton
  Cc: linux-kernel, Borislav Petkov, Zhu Yi, Luis R. Rodriguez

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


^ permalink raw reply related	[flat|nested] 5+ messages in thread
end of thread, other threads:[~2010-08-30 18:34 UTC | newest]

Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-08-27 10:16 [PATCH] bitops: Provide generic sign_extend function (moving it out from wireless code) Andreas Herrmann
2010-08-27 10:27 ` Andi Kleen
2010-08-27 19:28 ` Luis R. Rodriguez
2010-08-27 22:09 ` Bob Copeland
2010-08-30 19:04 ` [PATCH v2] bitops: Provide generic sign_extend32 function Andreas Herrmann

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.