queue.h

lua脚本语言调用allegro游戏程序库的接口-跨平台

//-----------------------------------------------------------------------------------------
//---------- made by Peter Jamr髗 2001 ----------------------------------------------------
//-----------------------------------------------------------------------------------------
//This file implements improved Queue class which will be used by MyServSockets class
//and GRPC server and client


//this is probably optimal block size
#define QUEUE_BLOCK_SIZE 8192

//#define QUEUE_BLOCK_SIZE 50

//for test and debugging 
//#define QUEUE_BLOCK_SIZE 10000000 

//For debugging purposes
//#define QUEUE_BLOCK_SIZE 3

//-------------------------------------------------------------------------------------------
// This class is used internally by Queue class. Please don't use it
// This is queue block. It behaves like queue, but it's size is limited.
// It can point to another block,and we can have a list of blocks.
// Queue is a list of blocks
class qblock {

//this points to first byte of data in this block
    int BeginPointer;
//this points to last byte of data in this block
    int EndPointer;

char buffer[QUEUE_BLOCK_SIZE];

public:

qblock();
~qblock();

//this variable points to previous block or NULL if it is end of the queue
qblock* prev;

int IsFirstBlock();
//int IsLastBlock();

//it returns true if block is full
int IsFull();

//this function reads up to RequestedLength bytes to block. Function returns number of bytes succesfully read.
int Read(void* output,int RequestedLength);

//this function peeks data and it doesn't remove it from block
int PeekData(void* output,int RequestedLength);

//this function returns number of bytes stored in this block
int GetLength();

//this function writes RequestedLength bytes to block.Function returns number of bytes succesfully written.
int Write(void* input,int RequestedLength);
};

//-------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------
//-------------------------------------------------------------------------------------------
#ifndef __QUEUE__
#define __QUEUE__

class Queue {
    private:
    qblock* FirstBlock;
    qblock* LastBlock;

//these are internal function to expand and shrink the queue, and user programmen
//should not use them.
    int Expand();
    int RemoveLastBlock();

    public:

//it creates new, empty queue
    Queue();

//it destroys queue and all blocks which it contains
    ~Queue();

//this function reads up to RequestedLength bytes to buffer. Function returns number of bytes succesfully read.
    int Read(void* output,int RequestedLength);

//This function behaves like read, except that it does not remove data from the queue
    int PeekData(void* output,int RequestedLength);

//this function returns number of bytes stored in this queue
    int GetLength();

//this function writes up to RequestedLength bytes to queue.Function returns number of bytes succesfully written.
//function will return value less than RequestedLength only in case when there are be memory allocation problems.
    int Write(void* input,int RequestedLength);
    };

#endif