mirror of
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111 lines
2.7 KiB
C++
111 lines
2.7 KiB
C++
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2015.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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textbuffer.cpp
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Provides a indexable text buffer for used by text mode terminals.
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*******************************************************************************/
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#include <assert.h>
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#include <errno.h>
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#include <sortix/kernel/kernel.h>
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#include <sortix/kernel/kthread.h>
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#include <sortix/kernel/refcount.h>
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#include <sortix/kernel/textbuffer.h>
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namespace Sortix {
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TextBufferHandle::TextBufferHandle(TextBuffer* textbuf)
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{
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this->textbuf = textbuf;
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this->numused = 0;
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this->mutex = KTHREAD_MUTEX_INITIALIZER;
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this->unusedcond = KTHREAD_COND_INITIALIZER;
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}
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TextBufferHandle::~TextBufferHandle()
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{
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delete textbuf;
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}
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TextBuffer* TextBufferHandle::Acquire()
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{
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ScopedLock lock(&mutex);
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if ( !textbuf )
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return errno = EINIT, (TextBuffer*) NULL;
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numused++;
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return textbuf;
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}
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void TextBufferHandle::Release(TextBuffer* textbuf)
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{
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assert(textbuf);
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ScopedLock lock(&mutex);
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assert(numused);
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numused--;
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if ( numused == 0 )
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kthread_cond_signal(&unusedcond);
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}
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bool TextBufferHandle::EmergencyIsImpaired()
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{
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if ( !kthread_mutex_trylock(&mutex) )
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return true;
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kthread_mutex_unlock(&mutex);
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return false;
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}
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bool TextBufferHandle::EmergencyRecoup()
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{
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if ( !EmergencyIsImpaired() )
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return true;
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mutex = KTHREAD_MUTEX_INITIALIZER;
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return true;
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}
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void TextBufferHandle::EmergencyReset()
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{
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}
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TextBuffer* TextBufferHandle::EmergencyAcquire()
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{
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// This is during a kernel emergency where preemption has been disabled and
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// this is the only thread running.
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return textbuf;
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}
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void TextBufferHandle::EmergencyRelease(TextBuffer* textbuf)
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{
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// This is during a kernel emergency where preemption has been disabled and
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// this is the only thread running. We don't maintain the reference count
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// during this state, so this is a no-operation.
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(void) textbuf;
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}
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void TextBufferHandle::Replace(TextBuffer* newtextbuf)
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{
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ScopedLock lock(&mutex);
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while ( 0 < numused )
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kthread_cond_wait(&unusedcond, &mutex);
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delete textbuf;
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textbuf = newtextbuf;
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}
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} // namespace Sortix
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