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sortix--sortix/kernel/linebuffer.cpp
2014-03-01 14:37:41 +01:00

138 lines
3.2 KiB
C++

/*******************************************************************************
Copyright(C) Jonas 'Sortie' Termansen 2012, 2013, 2014.
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/>.
linebuffer.cpp
Provides a simple queue-like line buffering for terminals.
*******************************************************************************/
#include <stddef.h>
#include <stdint.h>
#include <string.h>
#include <sortix/kernel/kernel.h>
#include "linebuffer.h"
namespace Sortix {
static size_t OffsetIndex(size_t offset, size_t index, size_t length)
{
// TODO: Possible overflow here.
return (offset + index) % length;
}
LineBuffer::LineBuffer()
{
buffer = NULL;
bufferlength = 0;
bufferoffset = 0;
buffercommitted = 0;
bufferfrozen = 0;
bufferused = 0;
}
LineBuffer::~LineBuffer()
{
delete[] buffer;
}
bool LineBuffer::Push(uint32_t unicode)
{
// Check if we need to allocate or resize the circular queue.
if ( bufferused == bufferlength )
{
size_t newbufferlength = (bufferlength) ? bufferlength * 2 : 32UL;
uint32_t* newbuffer = new uint32_t[newbufferlength];
if ( !newbuffer )
return false;
size_t elemsize = sizeof(*buffer);
size_t leadingavai = bufferlength-bufferoffset;
size_t leading = (leadingavai < bufferused) ? leadingavai : bufferused;
size_t trailing = bufferused - leading;
memcpy(newbuffer, buffer + bufferoffset, leading * elemsize);
memcpy(newbuffer + leading, buffer, trailing * elemsize);
delete[] buffer;
buffer = newbuffer;
bufferlength = newbufferlength;
bufferoffset = 0;
}
size_t index = OffsetIndex(bufferoffset, bufferused++, bufferlength);
buffer[index] = unicode;
return true;
}
uint32_t LineBuffer::Pop()
{
if ( !CanPop() )
return 0;
uint32_t result = Peek();
bufferoffset = (bufferoffset+1) % bufferlength;
buffercommitted--;
bufferfrozen--;
bufferused--;
return result;
}
uint32_t LineBuffer::Peek() const
{
if ( !CanPop() )
return 0;
size_t index = OffsetIndex(bufferoffset, 0, bufferlength);
return buffer[index];
}
uint32_t LineBuffer::Backspace()
{
if ( !CanBackspace() )
return 0;
size_t index = OffsetIndex(bufferoffset, --bufferused, bufferlength);
return buffer[index];
}
uint32_t LineBuffer::WouldBackspace() const
{
if ( !CanBackspace() )
return 0;
size_t index = OffsetIndex(bufferoffset, bufferused-1, bufferlength);
return buffer[index];
}
void LineBuffer::Commit()
{
buffercommitted = bufferfrozen = bufferused;
}
void LineBuffer::Freeze()
{
bufferfrozen = bufferused;
}
bool LineBuffer::CanPop() const
{
return buffercommitted;
}
bool LineBuffer::CanBackspace() const
{
return bufferused - bufferfrozen;
}
} // namespace Sortix