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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.
*
* $URL$
* $Id$
*
* To ensure exclusive use of resources and exclusive control responsibilities.
*/
#include "common/util.h"
#include "tinsel/sched.h"
#include "tinsel/token.h"
namespace Tinsel {
//----------------- LOCAL GLOBAL DATA --------------------
struct Token {
PROCESS *proc;
};
static Token tokens[NUMTOKENS];
/**
* Release all tokens held by this process, and kill the process.
*/
static void TerminateProcess(PROCESS *tProc) {
// Release tokens held by the process
for (int i = 0; i < NUMTOKENS; i++) {
if (tokens[i].proc == tProc) {
tokens[i].proc = NULL;
}
}
// Kill the process
g_scheduler->killProcess(tProc);
}
/**
* Gain control of the CONTROL token if it is free.
*/
void GetControlToken() {
const int which = TOKEN_CONTROL;
if (tokens[which].proc == NULL) {
tokens[which].proc = g_scheduler->getCurrentProcess();
}
}
/**
* Release control of the CONTROL token.
*/
void FreeControlToken() {
// Allow anyone to free TOKEN_CONTROL
tokens[TOKEN_CONTROL].proc = NULL;
}
/**
* Gain control of a token. If the requested token is out of range, or
* is already held by the calling process, then the calling process
* will be killed off.
*
* Otherwise, the calling process will gain the token. If the token was
* held by another process, then the previous holder is killed off.
*/
void GetToken(int which) {
assert(TOKEN_LEAD <= which && which < NUMTOKENS);
if (tokens[which].proc != NULL) {
assert(tokens[which].proc != g_scheduler->getCurrentProcess());
TerminateProcess(tokens[which].proc);
}
tokens[which].proc = g_scheduler->getCurrentProcess();
}
/**
* Release control of a token. If the requested token is not owned by
* the calling process, then the calling process will be killed off.
*/
void FreeToken(int which) {
assert(TOKEN_LEAD <= which && which < NUMTOKENS);
assert(tokens[which].proc == g_scheduler->getCurrentProcess()); // we'd have been killed if some other proc had taken this token
tokens[which].proc = NULL;
}
/**
* If it's a valid token and it's free, returns true.
*/
bool TestToken(int which) {
if (which < 0 || which >= NUMTOKENS)
return false;
return (tokens[which].proc == NULL);
}
/**
* Call at the start of each scene.
*/
void FreeAllTokens() {
for (int i = 0; i < NUMTOKENS; i++) {
tokens[i].proc = NULL;
}
}
} // End of namespace Tinsel
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