Implementation of swab()

[Alexandre Oliva <oliva at lsd dot ic dot unicamp dot br>]

I'm checking this in, approved by J. Johnston:

Index: newlib/ChangeLog
from  Alexandre Oliva  <oliva@lsd.ic.unicamp.br>
	
	* libc/string/Makefile.am (lib_a_SOURCES): Added swab.c.
	(CHEWOUT_FILES): Added swab.def.
	* libc/string/Makefile.in: Rebuilt.
	* libc/string/string.tex: Include swab.def.
	* libc/include/string.h (swab): Declare.
	* libc/string/swab.c: New file.
	
Index: newlib/libc/string/Makefile.am
===================================================================
RCS file: /cvs/cvsfiles/devo/newlib/libc/string/Makefile.am,v
retrieving revision 1.1
diff -u -r1.1 Makefile.am
--- newlib/libc/string/Makefile.am	1998/07/17 20:21:27	1.1
+++ newlib/libc/string/Makefile.am	2000/03/04 06:54:40
@@ -39,13 +39,14 @@
 	strupr.c \
 	strxfrm.c  \
 	strstr.c \
+	swab.c \
 	u_strerr.c
 
 CHEWOUT_FILES=\
 bcmp.def	memcpy.def	strcmp.def	strncat.def strstr.def \
 bcopy.def	memmove.def	strcoll.def	strncmp.def strtok.def \
 bzero.def	memset.def	strcpy.def	strncpy.def strxfrm.def \
-index.def	rindex.def	strcspn.def	strpbrk.def \
+index.def	rindex.def	strcspn.def	strpbrk.def swab.def \
 memchr.def	strcat.def	strerror.def	strrchr.def \
 memcmp.def	strchr.def	strlen.def	strspn.def \
 strcasecmp.def	strncasecmp.def strlwr.def	strupr.def
Index: newlib/libc/string/strings.tex
===================================================================
RCS file: /cvs/cvsfiles/devo/newlib/libc/string/strings.tex,v
retrieving revision 1.8
diff -u -r1.8 strings.tex
--- newlib/libc/string/strings.tex	1999/01/25 17:07:57	1.8
+++ newlib/libc/string/strings.tex	2000/03/04 06:54:40
@@ -37,6 +37,7 @@
 * strtok::      Get next token from a string
 * strupr::	Convert string to upper case
 * strxfrm::     Transform string
+* swab::        Swap adjacent bytes
 @end menu
 
 @page
@@ -131,3 +132,6 @@
 
 @page
 @include string/strxfrm.def
+
+@page
+@include string/swab.def
Index: newlib/libc/include/string.h
===================================================================
RCS file: /cvs/cvsfiles/devo/newlib/libc/include/string.h,v
retrieving revision 1.20
diff -u -r1.20 string.h
--- newlib/libc/include/string.h	2000/01/11 00:20:58	1.20
+++ newlib/libc/include/string.h	2000/03/04 06:54:40
@@ -69,6 +69,7 @@
 char    *_EXFUN(strsignal, (int __signo));
 int     _EXFUN(strtosigno, (const char *__name));
 #endif
+void	 _EXFUN(swab,(const void *, void *, ssize_t));
 
 /* These function names are used on Windows and perhaps other systems.  */
 #ifndef strcmpi
Index: newlib/libc/string/swab.c
===================================================================
RCS file: swab.c
diff -N swab.c
--- newlib/libc/string/swab.c	Tue May  5 13:32:27 1998
+++ newlib/libc/string/swab.c	Tue Mar  7 19:33:34 2000
@@ -0,0 +1,44 @@
+/*
+FUNCTION
+	<<swab>>---swap adjacent bytes
+
+ANSI_SYNOPSIS
+	#include <string.h>
+	void swab(const void *<[in]>, void *<[out]>, size_t <[n]>);
+
+TRAD_SYNOPSIS
+	void swab(<[in]>, <[out]>, <[n]>
+	void *<[in]>;
+	void *<[out]>;
+	size_t <[n]>;
+
+DESCRIPTION
+	This function copies <[n]> bytes from the memory region
+	pointed to by <[in]> to the memory region pointed to by
+	<[out]>, exchanging adjacent even and odd bytes.
+
+PORTABILITY
+<<swab>> requires no supporting OS subroutines.
+*/
+
+#include <string.h>
+
+void
+_DEFUN (swab, (b1, b2, length),
+	_CONST void *b1 _AND
+	void *b2 _AND
+	ssize_t length)
+{
+  const char *from = b1;
+  char *to = b2;
+  ssize_t ptr;
+  for (ptr = 1; ptr < length; ptr += 2)
+    {
+      char p = from[ptr];
+      char q = from[ptr-1];
+      to[ptr-1] = p;
+      to[ptr  ] = q;
+    }
+  if (ptr == length) /* I.e., if length is odd, */
+    to[ptr-1] = 0;   /* then pad with a NUL. */
+}
Index: newlib/libc/string/Makefile.in
===================================================================
RCS file: /cvs/cvsfiles/devo/newlib/libc/string/Makefile.in,v
retrieving revision 1.25
diff -u -r1.25 Makefile.in
--- newlib/libc/string/Makefile.in	2000/01/11 00:21:01	1.25
+++ newlib/libc/string/Makefile.in	2000/03/04 06:30:06
@@ -121,6 +121,7 @@
 	strupr.c \
 	strxfrm.c  \
 	strstr.c \
+	swab.c \
 	u_strerr.c
 
 
@@ -128,7 +129,7 @@
 bcmp.def	memcpy.def	strcmp.def	strncat.def strstr.def \
 bcopy.def	memmove.def	strcoll.def	strncmp.def strtok.def \
 bzero.def	memset.def	strcpy.def	strncpy.def strxfrm.def \
-index.def	rindex.def	strcspn.def	strpbrk.def \
+index.def	rindex.def	strcspn.def	strpbrk.def swab.def \
 memchr.def	strcat.def	strerror.def	strrchr.def \
 memcmp.def	strchr.def	strlen.def	strspn.def \
 strcasecmp.def	strncasecmp.def strlwr.def	strupr.def
@@ -155,7 +156,7 @@
 memcpy.o memmove.o memset.o rindex.o strcat.o strchr.o strcmp.o \
 strcasecmp.o strcoll.o strcpy.o strcspn.o strerror.o strlen.o strlwr.o \
 strncat.o strncmp.o strncasecmp.o strncpy.o strpbrk.o strrchr.o \
-strspn.o strtok.o strtok_r.o strupr.o strxfrm.o strstr.o u_strerr.o
+strspn.o strtok.o strtok_r.o strupr.o strxfrm.o strstr.o swab.o u_strerr.o
 CFLAGS = @CFLAGS@
 COMPILE = $(CC) $(DEFS) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(AM_CFLAGS) $(CFLAGS)
 CCLD = $(CC)

-- 
Alexandre Oliva     http://www.ic.unicamp.br/~oliva/     Enjoy Guaranį
Cygnus Solutions, a Red Hat company        aoliva@{redhat, cygnus}.com
Free Software Developer and Evangelist    CS PhD student at IC-Unicamp
oliva@{lsd.ic.unicamp.br, gnu.org}   Write to mailing lists, not to me