# HG changeset patch
# User Erik Quanstrom <quanstro@quanstro.net>
# Date 1329519746 0
# Node ID 1938bae8cbbc02a2c6c5fa253f695b32fadc8201
# Parent  00051c3d3125358716d3de95381f18231ce15cbf
getbe, getle, putbe, putle: marshal any-sized intergers

generic functions to marshal big or little endian integers,
based on presotto's code from nsec(2).

R=nixiedev, john, nemo
CC=nix-dev
http://codereview.appspot.com/5677045

Committer: John Floren <john@jfloren.net>

diff -r 00051c3d3125 -r 1938bae8cbbc sys/include/libc.h
--- a/sys/include/libc.h	Fri Feb 17 22:51:48 2012 +0000
+++ b/sys/include/libc.h	Fri Feb 17 23:02:26 2012 +0000
@@ -333,6 +333,14 @@
 extern	void	cycles(uvlong*);	/* 64-bit value of the cycle counter if there is one, 0 if there isn't */
 
 /*
+ * endian conversion
+ */
+extern	uvlong	getbe(uchar*, int);
+extern	void	putbe(uchar*, uvlong, int);
+extern	uvlong	getle(uchar*, int);
+extern	void	putle(uchar*, uvlong, int);
+
+/*
  * one-of-a-kind
  */
 enum
diff -r 00051c3d3125 -r 1938bae8cbbc sys/man/2/getbe
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/man/2/getbe	Fri Feb 17 23:02:26 2012 +0000
@@ -0,0 +1,44 @@
+.TH GETBE 2
+getbe, setbe, getle, setle \- integer marshalling
+.SH SYNOPSIS
+.ta +\w'\fLuvlong 'u
+.PP
+.nf
+.B
+uvlong	getbe(uchar *buf, int nbytes)
+.PP
+.nf
+.B
+void	putbe(uchar *buf, uvlong v, int nbytes)
+.PP
+.nf
+.B
+uvlong	getle(uchar *buf, int nbytes)
+.PP
+.nf
+.B
+void	putle(uchar *buf, uvlong v, int nbytes)
+.SH DESCRIPTION
+These functions marshal a 1- to 8-byte integer to
+or from little- or big-endian formats.  The size
+of the integer is specified in bytes, and is not restricted
+to a power of two.
+.SH SOURCE
+.B /sys/src/libc/port/getbe.c
+.SH "SEE ALSO"
+.IR fcall (2),
+.IR ip (2)
+.SH BUGS
+.IR GBIT *
+and 
+.IR PBIT *
+(from
+.IR fcall (2))
+provide similar functionality for little-endian integers.
+The
+.IR nhget *
+and
+.IR nhput *
+functions from
+.IR ip (2)
+provide similar functionality  for big-endian integers.
diff -r 00051c3d3125 -r 1938bae8cbbc sys/src/libc/port/getbe.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/sys/src/libc/port/getbe.c	Fri Feb 17 23:02:26 2012 +0000
@@ -0,0 +1,54 @@
+#include <u.h>
+#include <libc.h>
+
+static uvlong border = 0x0001020304050607ull;
+static uvlong lorder = 0x0706050403020100ull;
+
+uvlong
+getle(uchar *t, int w)
+{
+	uint i;
+	uvlong r;
+
+	r = 0;
+	for(i = w; i != 0; )
+		r = r<<8 | t[--i];
+	return r;
+}
+
+void
+putle(uchar *t, uvlong r, int w)
+{
+	uchar *o, *f;
+	uint i;
+
+	f = (uchar*)&r;
+	o = (uchar*)&lorder;
+	for(i = 0; i < w; i++)
+		t[o[i]] = f[i];
+}
+
+uvlong
+getbe(uchar *t, int w)
+{
+	uint i;
+	uvlong r;
+
+	r = 0;
+	for(i = 0; i < w; i++)
+		r = r<<8 | t[i];
+	return r;
+}
+
+void
+putbe(uchar *t, uvlong r, int w)
+{
+	uchar *o, *f;
+	uint i;
+
+	f = (uchar*)&r;
+	o = (uchar*)&border + (sizeof border-w);
+	for(i = 0; i < w; i++)
+		t[i] = f[o[i]];
+}
+
diff -r 00051c3d3125 -r 1938bae8cbbc sys/src/libc/port/mkfile
--- a/sys/src/libc/port/mkfile	Fri Feb 17 22:51:48 2012 +0000
+++ b/sys/src/libc/port/mkfile	Fri Feb 17 23:02:26 2012 +0000
@@ -28,6 +28,7 @@
 	fmod.c\
 	frand.c\
 	frexp.c\
+	getbe.c\
 	getcallerpc.c\
 	getfields.c\
 	getuser.c\