From 21ee4ab6888d74f2ab5cdae7a2c552ad4a1171b1 Mon Sep 17 00:00:00 2001
From: Poul-Henning Kamp <phk@FreeBSD.org>
Date: Thu, 3 Apr 2003 08:58:04 +0000
Subject: [PATCH] Add inline functions {be,le}{16,32,64}{enc,dec}() for
 encoding decoding into byte strings of unknown alignment.

---
 share/man/man9/byteorder.9 |  40 +++++++++++++-
 sys/sys/endian.h           | 108 +++++++++++++++++++++++++++++++++++++
 2 files changed, 147 insertions(+), 1 deletion(-)

diff --git a/share/man/man9/byteorder.9 b/share/man/man9/byteorder.9
index 90dac1661c4c..6ef719f1b55b 100644
--- a/share/man/man9/byteorder.9
+++ b/share/man/man9/byteorder.9
@@ -41,6 +41,9 @@
 .Nm le32toh ,
 .Nm le64toh
 .Nd convert values between big endian, little endian, and host byte order
+.Pp
+.Nm {be,le}{16,32,64}{enc,dec}
+.Nd encode and decode big or little endian values to and from byte strings
 .Sh SYNOPSIS
 .In sys/endian.h
 .Ft uint16_t
@@ -73,6 +76,30 @@
 .Fn le32toh "uint32_t little32"
 .Ft uint64_t
 .Fn le64toh "uint64_t little64"
+.Ft uint16_t
+.Fn be16dec "const void *"
+.Ft uint32_t
+.Fn be32dec "const void *"
+.Ft uint64_t
+.Fn be64dec "const void *"
+.Ft uint16_t
+.Fn le16dec "const void *"
+.Ft uint32_t
+.Fn le32dec "const void *"
+.Ft uint64_t
+.Fn le64dec "const void *"
+.Ft void
+.Fn be16enc "void *, uint16_t"
+.Ft void
+.Fn be32enc "void *, uint32_t"
+.Ft void
+.Fn be64enc "void *, uint64_t"
+.Ft void
+.Fn le16enc "void *, uint16_t"
+.Ft void
+.Fn le32enc "void *, uint32_t"
+.Ft void
+.Fn le64enc "void *, uint64_t"
 .Sh DESCRIPTION
 The
 .Fn bswap16 ,
@@ -118,11 +145,22 @@ and
 functions return a integer in the system's native
 byte order converted to little endian byte order.
 The return value will be the same as the argument on little endian systems.
+.Pp
+The
+.Fn {be,le}{16,32,64}{enc,dec}
+functions encode and decode integers to/from byte strings on any alignment
+in big/little endian format.
 .Sh SEE ALSO
 .Xr byteorder 3
 .Sh HISTORY
-These functions first appeared in
+The hto* and toh*  functions first appeared in
 .Fx 5.0 ,
 and were originally developed by the
 .Nx
 project.
+.Pp
+The
+.Fn {be,le}{16,32,64}{enc,dec}
+Functions first appeared in
+.Fx 5.1 .
+
diff --git a/sys/sys/endian.h b/sys/sys/endian.h
index 027b59d2d71d..0458ffddae4d 100644
--- a/sys/sys/endian.h
+++ b/sys/sys/endian.h
@@ -89,4 +89,112 @@ typedef	__uint64_t	uint64_t;
 #define	le64toh(x)	bswap64((x))
 #endif /* _BYTE_ORDER == _LITTLE_ENDIAN */
 
+/* Alignment-agnostic encode/decode bytestream to/from little/big endian. */
+
+static __inline uint16_t
+be16dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return ((p[0] << 8) | p[1]);
+}
+
+static __inline uint32_t
+be32dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return ((p[0] << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
+}
+
+static __inline uint64_t
+be64dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return (((uint64_t)be32dec(p) << 32) | be32dec(p + 4));
+}
+
+static __inline uint16_t
+le16dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return ((p[1] << 8) | p[0]);
+}
+
+static __inline uint32_t
+le32dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return ((p[3] << 24) | (p[2] << 16) | (p[1] << 8) | p[0]);
+}
+
+static __inline uint64_t
+le64dec(const void *pp)
+{
+	u_char const *p = pp;
+
+	return (((uint64_t)be32dec(p + 4) << 32) | be32dec(p));
+}
+
+static __inline void
+be16enc(void *pp, uint16_t u)
+{
+	u_char *p = pp;
+
+	p[0] = (u >> 8) & 0xff;
+	p[1] = u & 0xff;
+}
+
+static __inline void
+be32enc(void *pp, uint32_t u)
+{
+	u_char *p = pp;
+
+	p[0] = (u >> 24) & 0xff;
+	p[1] = (u >> 16) & 0xff;
+	p[2] = (u >> 8) & 0xff;
+	p[3] = u & 0xff;
+}
+
+static __inline void
+be64enc(void *pp, uint64_t u)
+{
+	u_char *p = pp;
+
+	be32enc(p, u >> 32);
+	be32enc(p + 4, u & 0xffffffff);
+}
+
+static __inline void
+le16enc(void *pp, uint16_t u)
+{
+	u_char *p = pp;
+
+	p[0] = u & 0xff;
+	p[1] = (u >> 8) & 0xff;
+}
+
+static __inline void
+le32enc(void *pp, uint32_t u)
+{
+	u_char *p = pp;
+
+	p[0] = u & 0xff;
+	p[1] = (u >> 8) & 0xff;
+	p[2] = (u >> 16) & 0xff;
+	p[3] = (u >> 24) & 0xff;
+}
+
+static __inline void
+le64enc(void *pp, uint64_t u)
+{
+	u_char *p = pp;
+
+	be32enc(p, u & 0xffffffff);
+	be32enc(p + 4, u >> 32);
+}
+
 #endif	/* _SYS_ENDIAN_H_ */