1 /*****************************************************************************/ 2 // StreamBuffer 3 // Written by Michael Wilber, OBOS Translation Kit Team 4 // 5 // StreamBuffer.h 6 // 7 // This class is for buffering data from a BPositionIO object in order to 8 // improve performance for cases when small amounts of data are frequently 9 // read from a BPositionIO object. 10 // 11 // 12 // Copyright (c) 2003 OpenBeOS Project 13 // 14 // Permission is hereby granted, free of charge, to any person obtaining a 15 // copy of this software and associated documentation files (the "Software"), 16 // to deal in the Software without restriction, including without limitation 17 // the rights to use, copy, modify, merge, publish, distribute, sublicense, 18 // and/or sell copies of the Software, and to permit persons to whom the 19 // Software is furnished to do so, subject to the following conditions: 20 // 21 // The above copyright notice and this permission notice shall be included 22 // in all copies or substantial portions of the Software. 23 // 24 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS 25 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 26 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL 27 // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 28 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 29 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 30 // DEALINGS IN THE SOFTWARE. 31 /*****************************************************************************/ 32 33 #ifndef STREAM_BUFFER_H 34 #define STREAM_BUFFER_H 35 36 #include <DataIO.h> 37 38 #define MIN_BUFFER_SIZE 512 39 40 class StreamBuffer { 41 public: 42 StreamBuffer(BPositionIO *pstream, size_t nbuffersize, bool binitialread); 43 ~StreamBuffer(); 44 45 status_t InitCheck(); 46 // Determines whether the constructor failed or not 47 48 ssize_t Read(uint8 *pinto, size_t nbytes); 49 // copy nbytes from the stream into pinto 50 51 bool Seek(off_t position); 52 // seek the stream to the given position 53 54 private: 55 ssize_t ReadStream(); 56 // Load the stream buffer from the stream 57 58 BPositionIO *fpStream; 59 // stream object this object is buffering 60 uint8 *fpBuffer; 61 // buffered data from fpStream 62 size_t fnBufferSize; 63 // number of bytes of memory allocated for fpBuffer 64 size_t fnLen; 65 // number of bytes of actual data in fpBuffer 66 size_t fnPos; 67 // current position in the buffer 68 }; 69 70 #endif 71