swapop.c revision 7c2fbfb345896881c631598ee3852ce9ce33fb07
/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1985-2008 AT&T Intellectual Property *
* and is licensed under the *
* Common Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.opensource.org/licenses/cpl1.0.txt *
* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Glenn Fowler <gsf@research.att.com> *
* David Korn <dgk@research.att.com> *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
/*
* Glenn Fowler
* AT&T Research
*
* internal representation conversion support
*/
#include <ast.h>
#include <swap.h>
/*
* return the swap operation for external to internal conversion
* if size<0 then (-size) used and (-size==4)&&(op==3) => op=7
* this is a workaround for 4 byte magic predicting 8 byte swap
*/
int
swapop(const void* internal, const void* external, int size)
{
register int op;
register int z;
char tmp[sizeof(intmax_t)];
if ((z = size) < 0)
z = -z;
if (z <= 1)
return 0;
if (z <= sizeof(intmax_t))
for (op = 0; op < z; op++)
if (!memcmp(internal, swapmem(op, external, tmp, z), z))
{
if (size < 0 && z == 4 && op == 3)
op = 7;
return op;
}
return -1;
}