04-12-2011
The dd function you posted would actually copy three times a junk of 1024 bytes, ie. 3K bytes in total.
But I understand your question in such a way that you want to read 3 bytes in at once and do that same 300 times, right?
memcpy() is not the right function when you want to store it into a file. You simply need to store 3 bytes in a buffer of char buf[3]; and then use fwrite to write this buffer into a file. Wrap a loop around it so it gets done until 1024bytes are written and you're done
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LEARN ABOUT DEBIAN
zipios_backbuffer
zipios::BackBuffer(3) Library Functions Manual zipios::BackBuffer(3)
NAME
zipios::BackBuffer -
A BackBuffer 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.
SYNOPSIS
#include <backbuffer.h>
Inherits vector< unsigned char >.
Public Member Functions
BackBuffer (istream &is, VirtualSeeker vs=VirtualSeeker(), int chunk_size=1024)
BackBuffer constructor.
int readChunk (int &read_pointer)
Reads another chunk and returns the size of the chunk that has been read.
Detailed Description
A BackBuffer 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.
BackBuffer 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 BackBuffer instance is associated with a file and a chunksize can be specified. To read a chunk of
the file into the BackBuffer call readChunk().
Definition at line 32 of file backbuffer.h.
Constructor & Destructor Documentation
zipios::BackBuffer::BackBuffer (istream &is, VirtualSeekervs = VirtualSeeker(), intchunk_size = 1024) [inline, explicit]
BackBuffer constructor. Parameters:
is The istream to read the data from. The stream must be seekable, as BackBuffer will reposition the file position to read chunks from
the back of the file.
chunk_size specifies the size of the chunks to read the file into the BackBuffer in.
Exceptions:
FCollException Thrown if the VirtualSeeker vs that has been specified is invalid for the istream is.
Definition at line 61 of file backbuffer.h.
Member Function Documentation
int zipios::BackBuffer::readChunk (int &read_pointer) [inline]
Reads another chunk and returns the size of the chunk that has been read. Returns 0 on I/O failure.
Parameters:
read_pointer When a new chunk is read in the already stored bytes change position in the BackBuffer. read_pointer is assumed by
readChunk() to be a pointer into a position in the BackBuffer, and is updated to point to the same position in the file as it pointed
to before the new chunk was read.
Definition at line 75 of file backbuffer.h.
Author
Generated automatically by Doxygen for Zipios++ from the source code.
Zipios++ Mon Oct 10 2011 zipios::BackBuffer(3)