MrSID Decode SDK for LiDAR Reference Manual
1.1.3.4427
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IO is the base class for binary input and output. More...
#include <IO.h>
Classes | |
struct | Location |
Location is a helper structure for holding the location of data in a IO object. More... | |
Public Types | |
typedef lt_int64 | offset_type |
Integer data type for file offsets and sizes. | |
Public Member Functions | |
virtual void | open (void)=0 |
Open the IO object. | |
virtual void | close (void)=0 |
Close the IO object. | |
virtual size_t | pread (offset_type offset, void *buffer, size_t nbytes) const =0 |
Read data. | |
virtual size_t | pwrite (offset_type offset, const void *buffer, size_t nbytes) const =0 |
Write data. | |
virtual offset_type | size (void) const =0 |
Get the size of the resource. | |
virtual void | truncate (offset_type length)=0 |
Set the size of the resource. | |
virtual void | unlink (void)=0 |
Delete the resource when the IO object is deleted. |
The IO class was designed to thread safe for reading and writing. The reading and writing functions do not have a internal file position, the offset is passed into pread() and pwrite(). This is based off the POSIX pread() and pwrite() interfaces. Unlike the libc's FILE structure the buffering is not part of the IO object. Buffering is handled by the StreamReader and the StreamWriter classes.
typedef lt_int64 IO::offset_type |
virtual void IO::close | ( | void | ) | [pure virtual] |
This method closes the IO object. open() and close() are reference counted so you must call close() the some number of times as open().
When subclassing IO, open() and close() must implement the reference counting and be thread safe because they can be called from multiple threads. close() should look something like the following:
{.cpp} void close(void) { MutexMonitor mon(m_openLock); m_openCount -= 1; if (m_openCount == 0) { // close the resource } }
virtual void IO::open | ( | void | ) | [pure virtual] |
This method opens the IO object. open() and close() are reference counted so you must call close() the some number of times as open().
When subclassing IO, open() and close() must implement the reference counting and be thread safe because they can be called from multiple threads. open() should look something like the following:
{.cpp} void open(void) { MutexMonitor mon(m_openLock); if (m_openCount == 0) { // open the resource } m_openCount += 1; }
virtual size_t IO::pread | ( | offset_type | offset, |
void * | buffer, | ||
size_t | nbytes | ||
) | const [pure virtual] |
This method tries to read nbytes bytes at the given offset.
offset | the file offset to read from |
buffer | the destination memory location |
nbytes | the number of bytes to read |
virtual size_t IO::pwrite | ( | offset_type | offset, |
const void * | buffer, | ||
size_t | nbytes | ||
) | const [pure virtual] |
This method tries to write nbytes bytes at the given offset.
offset | the file offset to write to |
buffer | the source memory location |
nbytes | the number of bytes to write |
virtual offset_type IO::size | ( | void | ) | const [pure virtual] |
This method returns the size of the resource.
virtual void IO::truncate | ( | offset_type | length | ) | [pure virtual] |
This method sets the size of the resource. If the new size is smaller the data is lost. If the new size is larger the resource padded with zeros.
virtual void IO::unlink | ( | void | ) | [pure virtual] |
This method marks the resource for deletion when the object goes away.
Implemented in FileIO.