vdr-plugin-streamdev/tools/select.h
2004-12-30 22:43:55 +00:00

76 lines
2.2 KiB
C++

#ifndef TOOLBOX_SELECT_H
#define TOOLBOX_SELECT_H
#include "tools/tools.h"
#include <sys/types.h>
/* cTBSelect provides an interface for polling UNIX-like file descriptors. */
class cTBSelect {
private:
int m_MaxFiled;
fd_set m_Rfds;
fd_set m_Wfds;
public:
cTBSelect(void);
virtual ~cTBSelect();
/* Clear() resets the object for use in a new Select() call. All file
descriptors and their previous states are invalidated. */
virtual void Clear(void);
/* Add() adds a file descriptor to be polled in the next Select() call.
That call polls if the file is readable if Output is set to false,
writeable otherwise. */
virtual bool Add(int Filed, bool Output = false);
/* Select() polls all descriptors added by Add() and returns as soon as
one of those changes state (gets readable/writeable), or after
TimeoutMs milliseconds, whichever happens first. It returns the number
of filedescriptors that have changed state. On error, -1 is returned
and errno is set appropriately. */
virtual int Select(uint TimeoutMs);
/* Select() polls all descriptors added by Add() and returns as soon as
one of those changes state (gets readable/writeable). It returns the
number of filedescriptors that have changed state. On error, -1 is
returned and errno is set appropriately. */
virtual int Select(void);
/* CanRead() returns true if the descriptor has changed to readable during
the last Select() call. Otherwise false is returned. */
virtual bool CanRead(int FileNo) const;
/* CanWrite() returns true if the descriptor has changed to writeable
during the last Select() call. Otherwise false is returned. */
virtual bool CanWrite(int FileNo) const;
};
inline void cTBSelect::Clear(void) {
FD_ZERO(&m_Rfds);
FD_ZERO(&m_Wfds);
m_MaxFiled = -1;
}
inline bool cTBSelect::Add(int Filed, bool Output /* = false */) {
if (Filed < 0) return false;
FD_SET(Filed, Output ? &m_Wfds : &m_Rfds);
if (Filed > m_MaxFiled) m_MaxFiled = Filed;
return true;
}
inline bool cTBSelect::CanRead(int FileNo) const {
if (FileNo < 0) return false;
return FD_ISSET(FileNo, &m_Rfds);
}
inline bool cTBSelect::CanWrite(int FileNo) const {
if (FileNo < 0) return false;
return FD_ISSET(FileNo, &m_Wfds);
}
#endif // TOOLBOX_SELECT_H