Skip to contentSkip to conversation

mac80211: remove unnecessary byteshifts in frame control testing

PATCH In review Harvey Harrison 2 participants 3 messages Apr 21, 2008 802.11 (including cfg80211/NL80211)

lore
Share & tools
lore

Harvey Harrison

author
#0 lore raw

PATCH 1/1 mac80211: remove unnecessary byteshifts in frame control testing

Byteshift the constants rather than the data.

Signed-off-by Harvey Harrison <[email protected]>
---
 include/linux/ieee80211.h |   32 +++++++++++++++++---------------
 1 files changed, 17 insertions(+), 15 deletions(-)
include/linux/ieee80211.h +17 -15
index f27d11a..1068965 100644
@@ -546,16 +546,17 @@ enum ieee80211_back_parties {
  */
 static inline u8 *ieee80211_get_SA(struct ieee80211_hdr *hdr)
 {
-	u8 *raw = (u8 *) hdr;
-	u8 tofrom = (*(raw+1)) & 3; /* get the TODS and FROMDS bits */
-
-	switch (tofrom) {
-		case 2:
-			return hdr->addr3;
-		case 3:
-			return hdr->addr4;
+	__le16 fc = hdr->frame_control;
+	fc &= __constant_cpu_to_le16(IEEE80211_FCTL_TODS|IEEE80211_FCTL_FROMDS);
+
+	switch (fc) {
+	case __constant_cpu_to_le16(IEEE80211_FCTL_FROMDS):
+		return hdr->addr3;
+	case __constant_cpu_to_le16(IEEE80211_FCTL_TODS|IEEE80211_FCTL_FROMDS):
+		return hdr->addr4;
+	default:
+		return hdr->addr2;
 	}
-	return hdr->addr2;
 }
 
 /**

@@ -571,12 +572,13 @@ static inline u8 *ieee80211_get_SA(struct ieee80211_hdr *hdr)
  */
 static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
 {
-	u8 *raw = (u8 *) hdr;
-	u8 to_ds = (*(raw+1)) & 1; /* get the TODS bit */
+	__le16 fc = hdr->frame_control;
+	fc &= __constant_cpu_to_le16(IEEE80211_FCTL_TODS);
 
-	if (to_ds)
+	if (fc)
 		return hdr->addr3;
-	return hdr->addr1;
+	else
+		return hdr->addr1;
 }
 
 /**

@@ -589,8 +591,8 @@ static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
  */
 static inline int ieee80211_get_morefrag(struct ieee80211_hdr *hdr)
 {
-	return (le16_to_cpu(hdr->frame_control) &
-		IEEE80211_FCTL_MOREFRAGS) != 0;
+	__le16 fc = hdr->frame_control;
+	return !!(fc & __constant_cpu_to_le16(IEEE80211_FCTL_MOREFRAGS));
 }
 
 #endif /* IEEE80211_H */
Signature · 1 line
1.5.5.144.g3e42
maintainer
#1 lore raw
Quoted 10 lines · Harvey Harrison

Byteshift the constants rather than the data.

include/linux/ieee80211.h +0 -0
index f27d11a..1068965 100644
@@ -546,16 +546,17 @@ enum ieee80211_back_parties {
  */
 static inline u8 *ieee80211_get_SA(struct ieee80211_hdr *hdr)
 {

include/linux/ieee80211.h enum ieee80211_back_parties { · line 550

Quoted 10 lines
include/linux/ieee80211.h +2 -8
-	u8 *raw = (u8 *) hdr;
-	u8 tofrom = (*(raw+1)) & 3; /* get the TODS and FROMDS bits */
-
-	switch (tofrom) {
-		case 2:
-			return hdr->addr3;
-		case 3:
-			return hdr->addr4;
+	__le16 fc = hdr->frame_control;
+	fc &= __constant_cpu_to_le16(IEEE80211_FCTL_TODS|IEEE80211_FCTL_FROMDS);

Can you use the non-underscore versions except where necessary (i.e. for "case ...")

johannes

author
#2 lore raw

Byteswap the constants rather than the frame_control member.

Signed-off-by Harvey Harrison <[email protected]>

---
Johannes, incorporated your suggestionsre non-underscored version where possible.

 include/linux/ieee80211.h |   32 +++++++++++++++++---------------
 1 files changed, 17 insertions(+), 15 deletions(-)
include/linux/ieee80211.h +17 -15
index f27d11a..b73749a 100644
@@ -546,16 +546,17 @@ enum ieee80211_back_parties {
  */
 static inline u8 *ieee80211_get_SA(struct ieee80211_hdr *hdr)
 {
-	u8 *raw = (u8 *) hdr;
-	u8 tofrom = (*(raw+1)) & 3; /* get the TODS and FROMDS bits */
-
-	switch (tofrom) {
-		case 2:
-			return hdr->addr3;
-		case 3:
-			return hdr->addr4;
+	__le16 fc = hdr->frame_control;
+	fc &= cpu_to_le16(IEEE80211_FCTL_TODS | IEEE80211_FCTL_FROMDS);
+
+	switch (fc) {
+	case __constant_cpu_to_le16(IEEE80211_FCTL_FROMDS):
+		return hdr->addr3;
+	case __constant_cpu_to_le16(IEEE80211_FCTL_TODS|IEEE80211_FCTL_FROMDS):
+		return hdr->addr4;
+	default:
+		return hdr->addr2;
 	}
-	return hdr->addr2;
 }
 
 /**

@@ -571,12 +572,13 @@ static inline u8 *ieee80211_get_SA(struct ieee80211_hdr *hdr)
  */
 static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
 {
-	u8 *raw = (u8 *) hdr;
-	u8 to_ds = (*(raw+1)) & 1; /* get the TODS bit */
+	__le16 fc = hdr->frame_control;
+	fc &= cpu_to_le16(IEEE80211_FCTL_TODS);
 
-	if (to_ds)
+	if (fc)
 		return hdr->addr3;
-	return hdr->addr1;
+	else
+		return hdr->addr1;
 }
 
 /**

@@ -589,8 +591,8 @@ static inline u8 *ieee80211_get_DA(struct ieee80211_hdr *hdr)
  */
 static inline int ieee80211_get_morefrag(struct ieee80211_hdr *hdr)
 {
-	return (le16_to_cpu(hdr->frame_control) &
-		IEEE80211_FCTL_MOREFRAGS) != 0;
+	__le16 fc = hdr->frame_control;
+	return !!(fc & cpu_to_le16(IEEE80211_FCTL_MOREFRAGS));
 }
 
 #endif /* IEEE80211_H */
Signature · 1 line
1.5.5.144.g3e42