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sortix--sortix/kernel/textbuffer.cpp
2014-03-01 14:37:39 +01:00

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/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012, 2013.
This file is part of Sortix.
Sortix is free software: you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation, either version 3 of the License, or (at your option) any later
version.
Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
details.
You should have received a copy of the GNU General Public License along with
Sortix. If not, see <http://www.gnu.org/licenses/>.
textbuffer.cpp
Provides a indexable text buffer for used by text mode terminals.
*******************************************************************************/
#include <assert.h>
#include <sortix/kernel/kernel.h>
#include <sortix/kernel/kthread.h>
#include <sortix/kernel/refcount.h>
#include <sortix/kernel/textbuffer.h>
namespace Sortix {
TextBufferHandle::TextBufferHandle(TextBuffer* textbuf, bool deletebuf,
TextBuffer* def, bool deletedef)
{
this->textbuf = textbuf;
this->deletebuf = deletebuf;
this->def = def;
this->deletedef = deletedef;
this->numused = 0;
this->mutex = KTHREAD_MUTEX_INITIALIZER;
this->unusedcond = KTHREAD_COND_INITIALIZER;
}
TextBufferHandle::~TextBufferHandle()
{
if ( deletebuf )
delete textbuf;
if ( deletedef )
delete def;
}
TextBuffer* TextBufferHandle::Acquire()
{
ScopedLock lock(&mutex);
numused++;
if ( textbuf )
return textbuf;
if ( !def )
numused--;
return def;
}
void TextBufferHandle::Release(TextBuffer* textbuf)
{
assert(textbuf);
ScopedLock lock(&mutex);
assert(numused);
if ( !--numused )
kthread_cond_signal(&unusedcond);
}
bool TextBufferHandle::EmergencyIsImpaired()
{
if ( !kthread_mutex_trylock(&mutex) )
return true;
kthread_mutex_unlock(&mutex);
return false;
}
bool TextBufferHandle::EmergencyRecoup()
{
if ( !EmergencyIsImpaired() )
return true;
mutex = KTHREAD_MUTEX_INITIALIZER;
return true;
}
void TextBufferHandle::EmergencyReset()
{
}
TextBuffer* TextBufferHandle::EmergencyAcquire()
{
// This is during a kernel emergency where preemption has been disabled and
// this is the only thread running.
return textbuf ? textbuf : def;
}
void TextBufferHandle::EmergencyRelease(TextBuffer* textbuf)
{
// This is during a kernel emergency where preemption has been disabled and
// this is the only thread running. We don't maintain the reference count
// during this state, so this is a no-operation.
(void) textbuf;
}
void TextBufferHandle::Replace(TextBuffer* newtextbuf, bool deletebuf)
{
ScopedLock lock(&mutex);
while ( numused )
kthread_cond_wait(&unusedcond, &mutex);
if ( deletebuf )
delete textbuf;
this->textbuf = newtextbuf;
this->deletebuf = deletebuf;
}
} // namespace Sortix