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/*
* $NCDXorg: @(#)lbxdelta.c,v 1.2 1994/01/22 02:23:40 dct Exp $
* $Xorg: lbxdelta.c,v 1.5 2000/08/17 19:46:40 cpqbld Exp $
* $XdotOrg: xc/lib/lbxutil/delta/lbxdelta.c,v 1.7 2005/07/30 21:07:25 alanc Exp $
*
* Copyright 1993 Network Computing Devices
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that
* copyright notice and this permission notice appear in supporting
* documentation, and that the name of NCD. not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. NCD. makes no representations about the
* suitability of this software for any purpose. It is provided "as is"
* without express or implied warranty.
*
* NCD. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL NCD.
* BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Author: Dale Tonogai, Network Computing Devices
*/
/* $XFree86: xc/lib/lbxutil/delta/lbxdelta.c,v 1.7 2001/07/25 15:04:57 dawes Exp $ */
#include <X11/X.h>
#include <X11/Xproto.h>
#define _XLBX_SERVER_
#include <X11/extensions/lbxstr.h>
#include <X11/extensions/lbxdeltastr.h>
#include <stddef.h>
#include <string.h>
#ifdef LBXREQSTATS
#include "../lbx_zlib/reqstats.h"
extern int LbxWhoAmI;
extern struct ReqStats CoreRequestStats[128];
extern struct ReqStats LbxRequestStats[LbxNumberReqs];
#define LBX_CODE 136 /* XXX - this should not be hardcoded - on todo list */
#endif
/* Copied from xc/programs/Xserver/include/xorg/os.h */
#ifndef _HAVE_XALLOC_DECLS
#define _HAVE_XALLOC_DECLS
#include <X11/Xdefs.h>
extern pointer Xalloc(unsigned long /*amount*/);
extern pointer Xcalloc(unsigned long /*amount*/);
extern pointer Xrealloc(pointer /*ptr*/, unsigned long /*amount*/);
extern void Xfree(pointer /*ptr*/);
#endif
/*
* Allocate data structures needed for doing Delta compaction
*/
int
LBXInitDeltaCache(LBXDeltasPtr pcache,
int nDeltas,
int maxDeltasize)
{
int i;
unsigned char *mem;
if ((pcache->nDeltas = nDeltas)) {
pcache->maxDeltasize = maxDeltasize;
if ((pcache->deltas = (LBXDeltaElemPtr)
Xalloc(pcache->nDeltas * sizeof(LBXDeltaElemRec) +
pcache->nDeltas * pcache->maxDeltasize)) == NULL) {
return -1;
}
mem = (unsigned char *) (pcache->deltas + pcache->nDeltas);
for (i = 0; i < pcache->nDeltas; i++) {
pcache->deltas[i].buf = mem;
mem += pcache->maxDeltasize;
}
}
else
pcache->maxDeltasize = 0;
pcache->nextDelta = 0;
pcache->activeDeltas = 0;
return 0;
}
/*
* Free data structures used for doing Delta compaction
*/
void
LBXFreeDeltaCache(LBXDeltasPtr pcache)
{
if (pcache->nDeltas && pcache->deltas)
Xfree(pcache->deltas);
}
static int
BytesDiff(unsigned char *ptr1, unsigned char *ptr2,
int n,
int maxn)
{
int result = 0;
while (n--)
if (*(ptr1++) != *(ptr2++))
if (++result >= maxn)
break;
return (result);
}
/*
* Find the message in the outgoing delta cache with the least number of
* differing bytes and return the number of differences. If all
* messages have greater than maxdiff differences, return -1.
*/
int
LBXDeltaMinDiffs(LBXDeltasPtr pcache,
unsigned char *inmsg,
int inmsglen,
int maxdiff,
int *pindex)
{
int i, j, k = 0, l = maxdiff + 1;
int m;
LBXDeltaElemPtr dm;
for (m = pcache->nextDelta-1, dm = &pcache->deltas[m], i = 0;
i < pcache->activeDeltas;
i++, m--, dm--
) {
if (m < 0) {
m = pcache->nDeltas - 1;
dm = &pcache->deltas[m];
}
if (dm->length == inmsglen) {
j = BytesDiff(inmsg, dm->buf, inmsglen, l);
if (j < l) {
k = m;
l = j;
}
}
}
if (l > maxdiff)
return -1;
else {
*pindex = k;
return l;
}
}
/*
* Delta compact a given message
*/
void
LBXEncodeDelta(LBXDeltasPtr pcache,
unsigned char *inmsg,
int ndiff,
int index,
unsigned char *buf)
{
int i, off, diff;
xLbxDiffItem *deltas = (xLbxDiffItem *)buf;
for (off = i = 0; i < ndiff; off++) {
if ((diff = inmsg[off] - pcache->deltas[index].buf[off])) {
deltas[i].offset = off;
deltas[i++].diff = diff;
}
}
}
/*
* Uncompact a message
*/
int
LBXDecodeDelta(LBXDeltasPtr pcache,
xLbxDiffItem *deltas,
int ndiff,
int index,
unsigned char **buf)
{
int i;
int newindex = pcache->nextDelta;
int len = pcache->deltas[index].length;
unsigned char *p = pcache->deltas[newindex].buf;
#ifdef LBXREQSTATS
xReq *req;
#endif
pcache->nextDelta = (pcache->nextDelta + 1) % pcache->nDeltas;
if (index != newindex) {
memcpy(p, pcache->deltas[index].buf, len);
pcache->deltas[newindex].length = len;
}
for (i = 0; i < ndiff; i++)
p[deltas[i].offset] += deltas[i].diff;
*buf = p;
#ifdef LBXREQSTATS
req = (xReq *) p;
if (LbxWhoAmI == 1) /* server */
{
struct ReqStats *reqStat = NULL;
if (req->reqType == LBX_CODE)
reqStat = &LbxRequestStats[req->data];
else if (req->reqType < 128)
reqStat = &CoreRequestStats[req->reqType];
if (reqStat)
{
reqStat->delta_count++;
reqStat->pre_delta_bytes += (req->length << 2);
reqStat->post_delta_bytes +=
(((sz_xLbxDeltaReq + sz_xLbxDiffItem * ndiff + 3) >> 2) << 2);
}
}
#endif
return len;
}
/*
* Add a message to the outgoing delta cache
*/
void
LBXAddDeltaOut(LBXDeltasPtr pcache,
unsigned char *inmsg,
int inmsglen)
{
memcpy(pcache->deltas[pcache->nextDelta].buf, inmsg, inmsglen);
pcache->deltas[pcache->nextDelta].length = inmsglen;
pcache->nextDelta = (pcache->nextDelta + 1) % pcache->nDeltas;
if (pcache->activeDeltas < pcache->nDeltas)
pcache->activeDeltas++;
}
/*
* Add a message to the incoming delta cache
*/
void
LBXAddDeltaIn(LBXDeltasPtr pcache,
unsigned char *inmsg,
int inmsglen)
{
memcpy(pcache->deltas[pcache->nextDelta].buf, inmsg, inmsglen);
pcache->deltas[pcache->nextDelta].length = inmsglen;
pcache->nextDelta = (pcache->nextDelta + 1) % pcache->nDeltas;
}
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