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// Myio.h
// Specialised I/O class to demonstrate use of C++ iostream
// facilities in a customised environment
// Written by David L Nugent, June 1993.
//
# if !defined(_Myio_h)
# define _Myio_h 1
// Foward declare classes
class Myio;
class Mystreambuf;
class Mystreambase;
class Mystream;
// Forward declare iostream classes
class iostream;
//
// class Myio
// This is a simplistic class which simply fields
// input and output to a simulated stream device.
//
// In fact, it doesn't really do much at all other
// than read input from and send output to a
// circular queue, as though talking via a loopback
// pipe to itself.
//
class Myio
{
friend class Mystreambuf;
public:
Myio (int sz =2048); // sz = buffer size to allocate
virtual ~Myio (void);
iostream & stream (void); // Return (or create) stream
int readok (void) const; // Underflow check
int writeok (void) const; // Overflow check
int gcount (void) const; // Get # of chrs last read
int pcount (void) const; // Get # of chrs last written
int count (void) const; // Get # of chrs in buffer
int size (void) const; // Get size of buffer
int dump (void) const; // Debugging - dumps buffer
int write (char const * buf, int len); // Put data into 'pipe'
int read (char * buf, int max); // Read data from our 'pipe'
private:
enum
{
overflow = 0x0001, // Last write only partial
underflow = 0x0002 // Last read only partial
};
unsigned stat; // Last read/write status
int _pcount; // Last write count
int _gcount; // Last read count
int bufsize; // Size of our buffer
int bufchars; // Chrs in buffer now
int bufidx; // Index into buffer (next put)
char * bufaddr; // Pointer to buffer
Mystream * mystream; // Stream assocated with this object
};
inline int
Myio::readok (void) const
{ return ((stat & Myio::underflow) == 0); }
inline int
Myio::writeok (void) const
{ return ((stat & Myio::overflow) == 0); }
inline int
Myio::gcount (void) const
{ return _gcount; }
inline int
Myio::pcount (void) const
{ return _pcount; }
inline int
Myio::count (void) const
{ return bufchars; }
inline int
Myio::size (void) const
{ return bufsize; }
# endif // _Myio_h
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