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/********************************************************************************
* *
* Q u e u e O f P o i n t e r s *
* *
*********************************************************************************
* Copyright (C) 2006,2022 by Jeroen van der Zijp. All Rights Reserved. *
*********************************************************************************
* This library is free software; you can redistribute it and/or modify *
* it under the terms of the GNU Lesser General Public License as published by *
* the Free Software Foundation; either version 3 of the License, or *
* (at your option) any later version. *
* *
* This library 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 Lesser General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public License *
* along with this program. If not, see <http://www.gnu.org/licenses/> *
********************************************************************************/
#include "xincs.h"
#include "fxdefs.h"
#include "fxmath.h"
#include "FXElement.h"
#include "FXPtrList.h"
#include "FXPtrQueue.h"
/*
Notes:
- Fixed-sized, circular buffer of pointers to stuff.
- A building block for all sorts of useful things.
- The head and tail pointer can assume arbitrary values,
with constraint that 0 <= head-tail <= N.
- Access slots by taking modulo of head or tail pointers.
- Thus all N (not N-1) slots can be filled.
*/
using namespace FX;
/*******************************************************************************/
namespace FX {
// Create initially empty queue
FXPtrQueue::FXPtrQueue():head(0),tail(0){
}
// Create queue with initial size
FXPtrQueue::FXPtrQueue(FXival sz):list((FXptr)nullptr,sz),head(0),tail(0){
}
// Change size of queue; return true if success
FXbool FXPtrQueue::setSize(FXival sz){
if(list.no(sz)){
head=0;
tail=0;
return true;
}
return false;
}
// Return used slots
FXival FXPtrQueue::getUsed() const {
return head-tail;
}
// Return free slots
FXival FXPtrQueue::getFree() const {
return getSize()+tail-head;
}
// Check if queue is full
FXbool FXPtrQueue::isFull() const {
return (head-tail)>=getSize();
}
// Check if queue is empty
FXbool FXPtrQueue::isEmpty() const {
return (head-tail)<=0;
}
// Peek for item
FXbool FXPtrQueue::peek(FXptr& ptr){
if(__likely((head-tail)>0)){
ptr=list[tail%getSize()];
return true;
}
return false;
}
// Add item to queue, return true if success
FXbool FXPtrQueue::push(FXptr ptr){
if(__likely((head-tail)<getSize())){
list[head%getSize()]=ptr;
head++;
return true;
}
return false;
}
// Remove item from queue, return true if success
FXbool FXPtrQueue::pop(FXptr& ptr){
if(__likely((head-tail)>0)){
ptr=list[tail%getSize()];
tail++;
return true;
}
return false;
}
// Pop onject from queue
FXbool FXPtrQueue::pop(){
if(__likely((head-tail)>0)){
tail++;
return true;
}
return false;
}
// Destroy job queue
FXPtrQueue::~FXPtrQueue(){
}
}
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