stream_util.h

//
// Created by hijiang on 2019/8/4.
//

#ifndef GB28181_HIKVISION_JAIN_SIP_STREAMUTIL_H
#define GB28181_HIKVISION_JAIN_SIP_STREAMUTIL_H

#include <string>
#include <stdlib.h>
#include <string.h>

#include "../base/log.h"
/**
* bytes utility, used to:
* convert basic types to bytes,
* build basic types from bytes.
*/
class StreamUtil
{
private:
    // current position at bytes.
    char* p;
    // the bytes data for stream to read or write.
    char* bytes;
    // the total number of bytes.
    int nb_bytes;
public:
    StreamUtil();
    virtual ~StreamUtil();
public:
    /**
    * initialize the stream from bytes.
    * @b, the bytes to convert from/to basic types.
    * @nb, the size of bytes, total number of bytes for stream.
    * @remark, stream never free the bytes, user must free it.
    * @remark, return error when bytes NULL.
    * @remark, return error when size is not positive.
    */
    virtual int initialize(char* b, int nb);
// get the status of stream
public:
    /**
    * get data of stream, set by initialize.
    * current bytes = data() + pos()
    */
    virtual char* data();
    /**
    * the total stream size, set by initialize.
    * left bytes = size() - pos().
    */
    virtual int size();
    /**
    * tell the current pos.
    */
    virtual int pos();
    /*
     * tell left bytes
     */
    virtual int left();
    /**
    * whether stream is empty.
    * if empty, user should never read or write.
    */
    virtual bool empty();
    /**
    * whether required size is ok.
    * @return true if stream can read/write specified required_size bytes.
    * @remark assert required_size positive.
    */
    virtual bool require(int required_size);
// to change stream.
public:
    /**
    * to skip some size.
    * @param size can be any value. positive to forward; nagetive to backward.
    * @remark to skip(pos()) to reset stream.
    * @remark assert initialized, the data() not NULL.
    */
    virtual void skip(int size);
public:
    /**
    * get 1bytes char from stream.
    */
    virtual int8_t read_1bytes();
    /**
    * get 2bytes int from stream.
    */
    virtual int16_t read_2bytes();
    /**
    * get 3bytes int from stream.
    */
    virtual int32_t read_3bytes();
    /**
    * get 4bytes int from stream.
    */
    virtual int32_t read_4bytes();
    /**
    * get 8bytes int from stream.
    */
    virtual int64_t read_8bytes();
    /**
    * get string from stream, length specifies by param len.
    */
    virtual std::string read_string(int len);
    /**
    * get bytes from stream, length specifies by param len.
    */
    virtual void read_bytes(char* data, int size);
public:
    /**
    * write 1bytes char to stream.
    */
    virtual void write_1bytes(int8_t value);
    /**
    * write 2bytes int to stream.
    */
    virtual void write_2bytes(int16_t value);
    /**
    * write 4bytes int to stream.
    */
    virtual void write_4bytes(int32_t value);
    /**
    * write 3bytes int to stream.
    */
    virtual void write_3bytes(int32_t value);
    /**
    * write 8bytes int to stream.
    */
    virtual void write_8bytes(int64_t value);
    /**
    * write string to stream
    */
    virtual void write_string(std::string value);
    /**
    * write bytes to stream
    */
    virtual void write_bytes(char* data, int size);
};


#endif //GB28181_HIKVISION_JAIN_SIP_STREAMUTIL_H