169 lines
3.9 KiB
C++
169 lines
3.9 KiB
C++
#ifndef HGL_IO_MEMORY_INPUT_STREAM_INCLUDE
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#define HGL_IO_MEMORY_INPUT_STREAM_INCLUDE
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#include<hgl/io/InputStream.h>
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namespace hgl
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{
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namespace io
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{
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/**
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* 内存数据输入流，从内存块中取得数据。
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*/
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class MemoryInputStream:public InputStream ///内存数据输入流
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{
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protected:
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const uint8 *buf;
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int64 buf_size;
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int64 cur_pos;
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public:
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MemoryInputStream()
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{
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buf=0;
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buf_size=0;
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cur_pos=0;
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}
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virtual ~MemoryInputStream()
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{
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}
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/**
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* 关联一个数据区到当前输入流
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* @param data 数据指针
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* @param size 数据长度字节数
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* @return 是否成功
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*/
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bool Link(const void *data,const int64 size)
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{
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if(!data)
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return(false);
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buf=(uint8 *)data;
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buf_size=size;
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cur_pos=0;
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return(true);
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}
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/**
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* 更新关联的数据区长度，不复位cur_pos
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* @param data 数据指针
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* @param size 数据长度字节数
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* @return 是否成功
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*/
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bool Update(void *data,int64 size)
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{
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if(!data)
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return(false);
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buf=(uint8 *)data;
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buf_size=size;
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return(true);
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}
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void Unlink()
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{
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buf=0;
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}
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void Close()
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{
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Unlink();
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}
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int64 Read(void *data,int64 size)
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{
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const int result=Peek(data,size);
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if(result>0)
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cur_pos+=result;
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return result;
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}
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int64 Peek(void *data,int64 size)
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{
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if(!buf||!data||size<0)
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return(-1);
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if(cur_pos+size>buf_size)
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size=buf_size-cur_pos;
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if(size<=0)
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return(0);
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memcpy(data,buf+cur_pos,size);
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return size;
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}
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bool CanRestart()const{return true;}
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bool CanSeek()const{return true;}
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bool CanSize()const{return true;}
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bool CanPeek()const{return true;}
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bool Restart()
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{
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cur_pos=0;
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return(true);
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}
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int64 Skip(int64 bytes)
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{
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return Seek(bytes,SeekOrigin::Current);
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}
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int64 Seek(int64 off,SeekOrigin so)
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{
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if(!CanSeek())return(-1);
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if(so==SeekOrigin::Current)
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{
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off+=cur_pos;
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}
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else
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if(so==SeekOrigin::End)
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{
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off+=buf_size;
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}
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if(off<0||off>=buf_size)
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return(-1);
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cur_pos=off;
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return cur_pos;
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}
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int64 Tell()const
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{
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if(!buf)return(-1);
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return cur_pos;
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}
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const void *TellPointer()const
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{
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if(!buf)return(nullptr);
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return buf+cur_pos;
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}
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int64 GetSize()const
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{
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if(!buf)return(-1);
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return buf_size;
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}
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int64 Available()const
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{
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if(!buf)return(-1);
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return buf_size-cur_pos;
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}
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};//class MemoryInputStream
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}//namespace io
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}//namespace hgl
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#endif//HGL_IO_MEMORY_INPUT_STREAM_INCLUDE
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