mem_io_channel.h

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#include <string>
#include "io_channel.h"
#include "file_io_channel.h"

#ifndef MEM_IO_CHANNEL
#define MEM_IO_CHANNEL

class MemIO: public IOChannel<MemIO> { public:
    char * buffer = nullptr;
    int size = 0;
    int read_pos = 0;
    int cap;

    MemIO(int _cap=1024*1024) {
        this->cap = _cap;
        buffer = new char[cap];
        size = 0;
    }
    ~MemIO(){
        if(buffer!=nullptr)
            delete[] buffer;
    }
    void load_from_file(FileIO * fio, uint64_t size) {
        delete[] buffer;
        buffer = new char[size];
        this->cap = size;
        this->read_pos = 0;
        this->size = size;
        fio->recv_data(buffer, size);
    }
    void clear(){
        size = 0;
    }
    void send_data_impl(const void * data, int len) {
        if(size + len >= cap){
            char * new_buffer = new char[2*(cap+len)];
            memcpy(new_buffer, buffer, size);
            delete[] buffer;
            buffer = new_buffer;
            cap = 2*(cap + len);
        }
        memcpy(buffer + size, data, len);
        size += len;
    }

    void recv_data_impl(void  * data, int len) {
        if(read_pos + len <= size) {
            memcpy(data, buffer + read_pos, len);
            read_pos += len;
        } else {
            fprintf(stderr,"error: mem_recv_data\n");
        }
    }
};
#endif//MEM_IO_CHANNEL_H__