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// Myio.cpp
// Simple I/O class to demonstrate use of C++ iostream
// facilities in a customised environment
// Written by David L Nugent, June 1993
# include <iostream.h>
# include <string.h>
# include "Myio.h"
# include "Mystream.h"
Myio::Myio (int sz)
: bufsize(sz), bufchars(0), bufidx(0),
bufaddr(new char[bufsize]), mystream(0)
{}
Myio::~Myio (void)
{
delete bufaddr;
delete mystream;
}
iostream &
Myio::stream (void)
{
if (!mystream) // Create a stream if required
mystream = new Mystream(this);
return *mystream;
}
int // Simple write function into a circular buffer
Myio::write (char const * buf, int len)
{
int avail = (bufsize - bufchars); // See how many fit
if (len > avail)
{
len = avail;
stat |= Myio::overflow; // Only partial write
}
else
stat &= ~Myio::overflow;
avail = bufsize - bufidx; // Caculate room at end
if (avail > len)
avail = len;
if (avail)
{
memcpy (bufaddr + bufidx, buf, avail);
bufidx += avail; // Update the put index
buf += avail; // And the input pointer
}
if (bufidx >= bufsize) // Wrap buffer to start
bufidx = 0;
avail = len - avail; // See if there is any more to go
if (avail)
{
memcpy (bufaddr + bufidx, buf, avail);
bufidx += avail; // Update the put index
}
bufchars += len;
return (_pcount = len);
}
int // Simple read function from a circular buffer
Myio::read (char * buf, int len)
{
if (len > bufchars) // Adjust for available bytes
{
len = bufchars;
stat |= Myio::underflow; // Got an underflow (partial read)
}
else
stat &= ~Myio::underflow; // Clear underflow flag
int startidx = bufidx - bufchars; // Determine start get position
if (startidx < 0)
startidx += bufsize; // Adjust for wrap
int avail = bufsize - startidx; // Check room at end of buffer
if (avail > len) // Adjust down if necessary
avail = len;
if (avail) // Copy first section
{
memcpy (buf, bufaddr + startidx, avail);
startidx += avail; // Adjust start index
buf += avail; // Adjust output pointer
}
if (startidx >= bufsize) // Wrap buffer to start
startidx = 0;
avail = len - avail; // See if there is any more to go
if (avail) // If so, copy the rest
memcpy (buf, bufaddr + startidx, avail);
bufchars -= len; // Adjust character count
return (_gcount = len);
}
Myio &
operator<< (Myio & m, char const * ptr)
{
m.write (ptr, strlen (ptr));
return m;
}
int
Myio::dump (void) const
{
if (bufchars)
{
char * tmp = new char[bufchars + 2];
int idx = bufidx - bufchars;
if (idx < 0)
idx += bufsize;
for (int i = 0; i < bufchars; )
{
if (idx >= bufsize)
idx = 0;
tmp[i++] = bufaddr[idx++];
}
if (i)
{
if (tmp[i-1] != '\n') // Terminate with NL
tmp[i++] = '\n';
tmp[i] = 0;
cout << "---\n"
<< tmp
<< "---\n";
}
delete tmp;
}
return bufchars;
}
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