[PATCH 1/4] 24-bit types: typedef and functions for accessing 3-bytearrays as integers

From: Chris Leech
Date: Wed Sep 10 2008 - 22:15:10 EST

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Both iSCSI and Fibre Channel make use of 24-bit big-endian values in
frame headers. This patch defines __be24 and __le24 typedefs for a
structure wrapped around a 3-byte array, and functions to convert back and
forth to a 32-bit integer.

The undefs in iscsi_proto.h are because of the different calling
convention for the existing hton24 macro in the iSCSI code. iSCSI will
be converted in a subsequent patch.

The undefs in fs/jfs/endian24.h allow JFS to continue using it's own le24
conversion macros. JFS is converted to use these types and functions in a
subsequent patch.

Change from last posting:

Moved the 24-bit inline functions to their own header instead of having
duplicate definitions in linux/byteorder.h and linux/byteorder/generic.h

Signed-off-by: Chris Leech <christopher.leech@xxxxxxxxx>
---

fs/jfs/endian24.h | 5 ++++
include/linux/byteorder.h | 9 ++++++++
include/linux/byteorder/generic.h | 10 ++++++++
include/linux/endian24.h | 44 +++++++++++++++++++++++++++++++++++++
include/linux/types.h | 2 ++
include/scsi/iscsi_proto.h | 2 ++
6 files changed, 72 insertions(+), 0 deletions(-)
create mode 100644 include/linux/endian24.h

diff --git a/fs/jfs/endian24.h b/fs/jfs/endian24.h
index fa92f7f..45b6397 100644
--- a/fs/jfs/endian24.h
+++ b/fs/jfs/endian24.h
@@ -33,6 +33,9 @@
((__x & (__u32)0x00ff0000UL) >> 16) )); \
})

+#undef __cpu_to_le24
+#undef __le24_to_cpu
+
#if (defined(__KERNEL__) && defined(__LITTLE_ENDIAN)) || (defined(__BYTE_ORDER) && (__BYTE_ORDER == __LITTLE_ENDIAN))
#define __cpu_to_le24(x) ((__u32)(x))
#define __le24_to_cpu(x) ((__u32)(x))
@@ -42,6 +45,8 @@
#endif

#ifdef __KERNEL__
+ #undef cpu_to_le24
+ #undef le24_to_cpu
#define cpu_to_le24 __cpu_to_le24
#define le24_to_cpu __le24_to_cpu
#endif
diff --git a/include/linux/byteorder.h b/include/linux/byteorder.h
index 29f002d..2334e3f 100644
--- a/include/linux/byteorder.h
+++ b/include/linux/byteorder.h
@@ -3,6 +3,7 @@

#include <linux/types.h>
#include <linux/swab.h>
+#include <linux/endian24.h>

#if defined(__LITTLE_ENDIAN) && defined(__BIG_ENDIAN)
# error Fix asm/byteorder.h to define one endianness
@@ -280,15 +281,19 @@ static inline __be64 __cpu_to_be64p(const __u64 *p)
#ifdef __KERNEL__

# define le16_to_cpu __le16_to_cpu
+# define le24_to_cpu __le24_to_cpu
# define le32_to_cpu __le32_to_cpu
# define le64_to_cpu __le64_to_cpu
# define be16_to_cpu __be16_to_cpu
+# define be24_to_cpu __be24_to_cpu
# define be32_to_cpu __be32_to_cpu
# define be64_to_cpu __be64_to_cpu
# define cpu_to_le16 __cpu_to_le16
+# define cpu_to_le24 __cpu_to_le24
# define cpu_to_le32 __cpu_to_le32
# define cpu_to_le64 __cpu_to_le64
# define cpu_to_be16 __cpu_to_be16
+# define cpu_to_be24 __cpu_to_be24
# define cpu_to_be32 __cpu_to_be32
# define cpu_to_be64 __cpu_to_be64

@@ -332,11 +337,15 @@ static inline __be64 __cpu_to_be64p(const __u64 *p)
# define ___htons(x) __cpu_to_be16(x)
# define ___ntohl(x) __be32_to_cpu(x)
# define ___ntohs(x) __be16_to_cpu(x)
+# define ___hton24(x) __cpu_to_be24(x)
+# define ___ntoh24(x) __be24_to_cpu(x)

# define htonl(x) ___htonl(x)
# define ntohl(x) ___ntohl(x)
# define htons(x) ___htons(x)
# define ntohs(x) ___ntohs(x)
+# define hton24(x) ___hton24(x)
+# define ntoh24(x) ___ntoh24(x)

static inline void le16_add_cpu(__le16 *var, u16 val)
{
diff --git a/include/linux/byteorder/generic.h b/include/linux/byteorder/generic.h
index 0846e6b..87cbec2 100644
--- a/include/linux/byteorder/generic.h
+++ b/include/linux/byteorder/generic.h
@@ -1,6 +1,8 @@
#ifndef _LINUX_BYTEORDER_GENERIC_H
#define _LINUX_BYTEORDER_GENERIC_H

+#include <linux/endian24.h>
+
/*
* linux/byteorder_generic.h
* Generic Byte-reordering support
@@ -86,12 +88,16 @@
#define le64_to_cpu __le64_to_cpu
#define cpu_to_le32 __cpu_to_le32
#define le32_to_cpu __le32_to_cpu
+#define cpu_to_le24 __cpu_to_le24
+#define le24_to_cpu __le24_to_cpu
#define cpu_to_le16 __cpu_to_le16
#define le16_to_cpu __le16_to_cpu
#define cpu_to_be64 __cpu_to_be64
#define be64_to_cpu __be64_to_cpu
#define cpu_to_be32 __cpu_to_be32
#define be32_to_cpu __be32_to_cpu
+#define cpu_to_be24 __cpu_to_be24
+#define be24_to_cpu __be24_to_cpu
#define cpu_to_be16 __cpu_to_be16
#define be16_to_cpu __be16_to_cpu
#define cpu_to_le64p __cpu_to_le64p
@@ -134,11 +140,15 @@
#define ___htons(x) __cpu_to_be16(x)
#define ___ntohl(x) __be32_to_cpu(x)
#define ___ntohs(x) __be16_to_cpu(x)
+#define ___hton24(x) __cpu_to_be24(x)
+#define ___ntoh24(x) __be24_to_cpu(x)

#define htonl(x) ___htonl(x)
#define ntohl(x) ___ntohl(x)
#define htons(x) ___htons(x)
#define ntohs(x) ___ntohs(x)
+#define hton24(x) ___hton24(x)
+#define ntoh24(x) ___ntoh24(x)

static inline void le16_add_cpu(__le16 *var, u16 val)
{
diff --git a/include/linux/endian24.h b/include/linux/endian24.h
new file mode 100644
index 0000000..beffa57
--- /dev/null
+++ b/include/linux/endian24.h
@@ -0,0 +1,44 @@
+#ifndef _LINUX_ENDIAN24_H
+#define _LINUX_ENDIAN24_H
+
+#if !defined(_LINUX_BYTEORDER_H) && !defined(_LINUX_BYTEORDER_GENERIC_H)
+#error "do not include linux/endian24.h directly, use asm/byteorder.h instead"
+#endif
+
+/**
+ * __le24_to_cpu - read a 3-byte array as a 24-bit little-endian integer
+ * @x: __le24, a structure wrapper around a 3-byte array
+ */
+static __always_inline __u32 __le24_to_cpu(const __le24 x)
+{
+ return (__u32) ((x.b[2] << 16) | (x.b[1] << 8) | (x.b[0]));
+}
+
+/**
+ * __cpu_to_le24 - store a value in a 3-byte array in little-endian format
+ * @x: __u32, there is no checking to ensure only the lower 24 bits are set
+ */
+static __always_inline __le24 __cpu_to_le24(const __u32 x)
+{
+ return (__le24) { { x & 0xff, (x >> 8) & 0xff, (x >> 16) & 0xff } };
+}
+
+/**
+ * __be24_to_cpu - read a 3-byte array as a 24-bit big-endian integer
+ * @x: __be24, a structure wrapper around a 3-byte array
+ */
+static __always_inline __u32 __be24_to_cpu(const __be24 x)
+{
+ return (__u32) ((x.b[0] << 16) | (x.b[1] << 8) | (x.b[2]));
+}
+
+/**
+ * __cpu_to_be24 - store a value in a 3-byte array in big-endian format
+ * @x: __u32, there is no checking to ensure only the lower 24 bits are set
+ */
+static __always_inline __be24 __cpu_to_be24(const __u32 x)
+{
+ return (__be24) { { (x >> 16) & 0xff, (x >> 8) & 0xff, x & 0xff } };
+}
+
+#endif /* _LINUX_ENDIAN24_H */
diff --git a/include/linux/types.h b/include/linux/types.h
index d4a9ce6..85fcff7 100644
--- a/include/linux/types.h
+++ b/include/linux/types.h
@@ -188,6 +188,8 @@ typedef __u64 __bitwise __be64;
typedef __u16 __bitwise __sum16;
typedef __u32 __bitwise __wsum;

+typedef struct { __u8 b[3]; } __be24, __le24;
+
#ifdef __KERNEL__
typedef unsigned __bitwise__ gfp_t;

diff --git a/include/scsi/iscsi_proto.h b/include/scsi/iscsi_proto.h
index f2a2c11..429c5ff 100644
--- a/include/scsi/iscsi_proto.h
+++ b/include/scsi/iscsi_proto.h
@@ -35,6 +35,8 @@
/*
* useful common(control and data pathes) macro
*/
+#undef ntoh24
+#undef hton24
#define ntoh24(p) (((p)[0] << 16) | ((p)[1] << 8) | ((p)[2]))
#define hton24(p, v) { \
p[0] = (((v) >> 16) & 0xFF); \

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Next message: Chris Leech: "[PATCH 2/4] 24-bit types: convert iSCSI to use the __be24 type andmacros"
Previous message: KAMEZAWA Hiroyuki: "Re: [Approach #2] [RFC][PATCH] Remove cgroup member from structpage"
Next in thread: Chris Leech: "[PATCH 2/4] 24-bit types: convert iSCSI to use the __be24 type andmacros"
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