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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
/*
* This code is based on original Soltys source code
* Copyright (c) 1994-1995 Janus B. Wisniewski and L.K. Avalon
*/
#include "cge/btfile.h"
#include "common/system.h"
#include "common/str.h"
#include <string.h>
namespace CGE {
#ifndef BT_SIZE
#define BT_SIZE K(1)
#endif
#ifndef BT_KEYLEN
#define BT_KEYLEN 13
#endif
BTFILE::BTFILE(const char *name, IOMODE mode, CRYPT *crpt)
: IOHAND(name, mode, crpt) {
for (int i = 0; i < BT_LEVELS; i++) {
Buff[i].Page = new BT_PAGE;
Buff[i].PgNo = BT_NONE;
Buff[i].Indx = -1;
Buff[i].Updt = false;
if (Buff[i].Page == NULL)
error("No core");
}
}
BTFILE::~BTFILE(void) {
for (int i = 0; i < BT_LEVELS; i++) {
PutPage(i);
delete Buff[i].Page;
}
}
void BTFILE::PutPage(int lev, bool hard) {
if (hard || Buff[lev].Updt) {
Seek(Buff[lev].PgNo * sizeof(BT_PAGE));
Write((uint8 *) Buff[lev].Page, sizeof(BT_PAGE));
Buff[lev].Updt = false;
}
}
BT_PAGE *BTFILE::GetPage(int lev, uint16 pgn) {
if (Buff[lev].PgNo != pgn) {
int32 pos = pgn * sizeof(BT_PAGE);
PutPage(lev);
Buff[lev].PgNo = pgn;
if (Size() > pos) {
Seek((uint32) pgn * sizeof(BT_PAGE));
Read((uint8 *) Buff[lev].Page, sizeof(BT_PAGE));
Buff[lev].Updt = false;
} else {
Buff[lev].Page->Hea.Count = 0;
Buff[lev].Page->Hea.Down = BT_NONE;
memset(Buff[lev].Page->Data, '\0', sizeof(Buff[lev].Page->Data));
Buff[lev].Updt = true;
}
Buff[lev].Indx = -1;
}
return Buff[lev].Page;
}
BT_KEYPACK *BTFILE::Find(const char *key) {
int lev = 0;
uint16 nxt = BT_ROOT;
while (! Error) {
BT_PAGE *pg = GetPage(lev, nxt);
// search
if (pg->Hea.Down != BT_NONE) {
int i;
for (i = 0; i < pg->Hea.Count; i++) {
// Does this work, or does it have to compare the entire buffer?
if (scumm_strnicmp((const char *) key, (const char*)pg->Inn[i].Key, BT_KEYLEN) < 0)
break;
}
nxt = (i) ? pg->Inn[i - 1].Down : pg->Hea.Down;
Buff[lev].Indx = i - 1;
++ lev;
} else {
int i;
for (i = 0; i < pg->Hea.Count - 1; i++) {
if (scumm_stricmp((const char *)key, (const char *)pg->Lea[i].Key) <= 0)
break;
}
Buff[lev].Indx = i;
return &pg->Lea[i];
}
}
return NULL;
}
int keycomp(const void *k1, const void *k2) {
return scumm_strnicmp((const char *) k1, (const char*) k2, BT_KEYLEN);
}
void BTFILE::Make(BT_KEYPACK *keypack, uint16 count) {
#if BT_LEVELS != 2
#error This tiny BTREE implementation works with exactly 2 levels!
#endif
_fqsort(keypack, count, sizeof(*keypack), keycomp);
uint16 n = 0;
BT_PAGE *Root = GetPage(0, n++),
*Leaf = GetPage(1, n);
Root->Hea.Down = n;
PutPage(0, true);
while (count--) {
if (Leaf->Hea.Count >= ArrayCount(Leaf->Lea)) {
PutPage(1, true); // save filled page
Leaf = GetPage(1, ++n); // take empty page
memcpy(Root->Inn[Root->Hea.Count].Key, keypack->Key, BT_KEYLEN);
Root->Inn[Root->Hea.Count++].Down = n;
Buff[0].Updt = true;
}
Leaf->Lea[Leaf->Hea.Count++] = *(keypack++);
Buff[1].Updt = true;
}
}
} // End of namespace CGE
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