source: trunk/packages/vizservers/nanovis/CircularQueue.h @ 2877

Last change on this file since 2877 was 2877, checked in by ldelgass, 8 years ago

Some minor refactoring, also add some more fine grained config.h defines
(e.g. replace NV40 define with feature defines). Add tests for some required
OpenGL extensions (should always check for extensions or base version before
calling entry points from the extension). Also, clamp diffuse and specular
values on input and warn when they are out of range.

  • Property svn:eol-style set to native
File size: 4.7 KB
Line 
1/* -*- mode: c++; c-basic-offset: 4; indent-tabs-mode: nil -*- */
2/* CircularFifo.h
3* Not any company's property but Public-Domain
4* Do with source-code as you will. No requirement to keep this
5* header if need to use it/change it/ or do whatever with it
6*
7* Note that there is No guarantee that this code will work
8* and I take no responsibility for this code and any problems you
9* might get if using it. The code is highly platform dependent!
10*
11* Code & platform dependent issues with it was originally
12* published at http://www.kjellkod.cc/threadsafecircularqueue
13* 2009-11-02
14* @author Kjell Hedström, hedstrom@kjellkod.cc */
15
16#ifndef CIRCULARFIFO_H_
17#define CIRCULARFIFO_H_
18
19/** Circular Fifo (a.k.a. Circular Buffer)
20* Thread safe for one reader, and one writer */
21template<typename Element, unsigned int Size>
22class CircularFifo {
23public:
24   enum {Capacity = Size+1};
25
26   CircularFifo() : tail(0), head(0){}
27   virtual ~CircularFifo() {}
28
29   bool push(Element& item_);
30   bool pop(Element& item_);
31   bool isEmpty() const;
32   bool isFull() const;
33   
34   // INSOO
35   bool push();
36   int tailIndex();
37   bool pop();
38   bool top(Element&);
39   
40public:
41   volatile unsigned int tail; // input index
42   Element array[Capacity];
43   volatile unsigned int head; // output index
44
45   unsigned int increment(unsigned int idx_) const;
46};
47
48
49
50
51/** Producer only: Adds item to the circular queue.
52* If queue is full at 'push' operation no update/overwrite
53* will happen, it is up to the caller to handle this case
54*
55* \param item_ copy by reference the input item
56* \return whether operation was successful or not */
57template<typename Element, unsigned int Size>
58bool CircularFifo<Element, Size>::push(Element& item_)
59{
60   int nextTail = increment(tail);
61   if(((unsigned int) nextTail) != head)
62   {
63      array[tail] = item_;
64      tail = nextTail;
65      return true;
66   }
67
68   // queue was full
69   return false;
70}
71
72template<typename Element, unsigned int Size>
73bool CircularFifo<Element, Size>::top(Element& data)
74{
75   if(head == tail)
76      return false;  // empty queue
77
78   data = array[head];
79   head = increment(head);
80   return true;
81}
82
83
84/** Consumer only: Removes and returns item from the queue
85* If queue is empty at 'pop' operation no retrieve will happen
86* It is up to the caller to handle this case
87*
88* \param item_ return by reference the wanted item
89* \return whether operation was successful or not */
90template<typename Element, unsigned int Size>
91bool CircularFifo<Element, Size>::pop(Element& item_)
92{
93   if(head == tail)
94      return false;  // empty queue
95
96   item_ = array[head];
97   head = increment(head);
98   return true;
99}
100
101/** Consumer only: Removes and returns item from the queue
102* If queue is empty at 'pop' operation no retrieve will happen
103* It is up to the caller to handle this case
104*
105* \return whether operation was successful or not */
106template<typename Element, unsigned int Size>
107bool CircularFifo<Element, Size>::pop()
108{
109   if(head == tail)
110      return false;  // empty queue
111   head = increment(head);
112   return true;
113}
114
115/** Useful for testinng and Consumer check of status
116  * Remember that the 'empty' status can change quickly
117  * as the Procuder adds more items.
118  *
119  * \return true if circular buffer is empty */
120template<typename Element, unsigned int Size>
121bool CircularFifo<Element, Size>::isEmpty() const
122{
123   return (head == tail);
124}
125
126/** Useful for testing and Producer check of status
127  * Remember that the 'full' status can change quickly
128  * as the Consumer catches up.
129  *
130  * \return true if circular buffer is full.  */
131template<typename Element, unsigned int Size>
132bool CircularFifo<Element, Size>::isFull() const
133{
134   int tailCheck = (tail+1) % Capacity;
135   return (((unsigned int) tailCheck) == head);
136}
137
138/** Increment helper function for index of the circular queue
139* index is inremented or wrapped
140*
141*  \param idx_ the index to the incremented/wrapped
142*  \return new value for the index */
143template<typename Element, unsigned int Size>
144unsigned int CircularFifo<Element, Size>::increment(unsigned int idx_) const
145{
146   // increment or wrap
147   // =================
148   //    index++;
149   //    if(index == array.lenght) -> index = 0;
150   //
151   //or as written below:   
152   //    index = (index+1) % array.length
153   idx_ = (idx_+1) % Capacity;
154   return idx_;
155}
156
157template<typename Element, unsigned int Size>
158int CircularFifo<Element, Size>::tailIndex()
159{
160   int nextTail = increment(tail);
161   if(((unsigned int)nextTail) != head)
162   {
163      return tail;
164   }
165
166   return -1;
167}
168
169
170template<typename Element, unsigned int Size>
171bool CircularFifo<Element, Size>::push()
172{
173   int nextTail = increment(tail);
174   if(((unsigned int)nextTail) != head)
175   {
176      tail = nextTail;
177      return true;
178   }
179
180   return false;
181}
182
183#endif /* CIRCULARFIFO_H_ */
Note: See TracBrowser for help on using the repository browser.