.TH "zipios::BackBuffer" 3 "Tue May 9 2017" "Zipios++" \" -*- nroff -*-
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.SH NAME
zipios::BackBuffer \- A \fBBackBuffer\fP instance is useful for reading the last part of a file in an efficient manner, when it is not known exactly how far back (towards the front!) to go, to find the start of the desired data block\&.  

.SH SYNOPSIS
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.PP
.PP
\fC#include <backbuffer\&.h>\fP
.PP
Inherits vector< unsigned char >\&.
.SS "Public Member Functions"

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.RI "\fBBackBuffer\fP (istream &is, \fBVirtualSeeker\fP vs=\fBVirtualSeeker\fP(), int chunk_size=1024)"
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.RI "\fBBackBuffer\fP constructor\&. "
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.RI "int \fBreadChunk\fP (int &read_pointer)"
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.RI "Reads another chunk and returns the size of the chunk that has been read\&. "
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.SH "Detailed Description"
.PP 
A \fBBackBuffer\fP instance is useful for reading the last part of a file in an efficient manner, when it is not known exactly how far back (towards the front!) to go, to find the start of the desired data block\&. 

\fBBackBuffer\fP is a vector< unsigned char > that fills itself with data from a file by reading chunks from the end of the file progressing towards the start\&. Upon construction the \fBBackBuffer\fP instance is associated with a file and a chunksize can be specified\&. To read a chunk of the file into the \fBBackBuffer\fP call \fBreadChunk()\fP\&. 
.PP
Definition at line 32 of file backbuffer\&.h\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "zipios::BackBuffer::BackBuffer (istream & is, \fBVirtualSeeker\fP vs = \fC\fBVirtualSeeker\fP()\fP, int chunk_size = \fC1024\fP)\fC [inline]\fP, \fC [explicit]\fP"

.PP
\fBBackBuffer\fP constructor\&. 
.PP
\fBParameters:\fP
.RS 4
\fIis\fP The istream to read the data from\&. The stream must be seekable, as \fBBackBuffer\fP will reposition the file position to read chunks from the back of the file\&. 
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\fIchunk_size\fP specifies the size of the chunks to read the file into the \fBBackBuffer\fP in\&. 
.RE
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\fBExceptions:\fP
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\fI\fBFCollException\fP\fP Thrown if the \fBVirtualSeeker\fP vs that has been specified is invalid for the istream is\&. 
.RE
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.PP
Definition at line 61 of file backbuffer\&.h\&.
.SH "Member Function Documentation"
.PP 
.SS "int zipios::BackBuffer::readChunk (int & read_pointer)\fC [inline]\fP"

.PP
Reads another chunk and returns the size of the chunk that has been read\&. Returns 0 on I/O failure\&. 
.PP
\fBParameters:\fP
.RS 4
\fIread_pointer\fP When a new chunk is read in the already stored bytes change position in the \fBBackBuffer\fP\&. read_pointer is assumed by \fBreadChunk()\fP to be a pointer into a position in the \fBBackBuffer\fP, and is updated to point to the same position in the file as it pointed to before the new chunk was read\&. 
.RE
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.PP
Definition at line 75 of file backbuffer\&.h\&.

.SH "Author"
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Generated automatically by Doxygen for Zipios++ from the source code\&.