146 lines
3.3 KiB
C++
146 lines
3.3 KiB
C++
/*
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* Copyright (c) 2012, 2013, 2014 Jonas 'Sortie' Termansen.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* linebuffer.cpp
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* Provides a simple queue-like line buffering for terminals.
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*/
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#include <stddef.h>
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#include <stdint.h>
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#include <string.h>
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#include <sortix/kernel/kernel.h>
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#include "linebuffer.h"
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namespace Sortix {
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static size_t OffsetIndex(size_t offset, size_t index, size_t length)
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{
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// TODO: Possible overflow here.
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return (offset + index) % length;
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}
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LineBuffer::LineBuffer()
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{
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buffer = NULL;
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bufferlength = 0;
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bufferoffset = 0;
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buffercommitted = 0;
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bufferfrozen = 0;
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bufferused = 0;
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}
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LineBuffer::~LineBuffer()
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{
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delete[] buffer;
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}
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bool LineBuffer::Push(uint32_t unicode)
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{
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// TODO: An infinite line buffer seems like a bad idea.
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// Check if we need to allocate or resize the circular queue.
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if ( bufferused == bufferlength )
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{
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size_t newbufferlength = (bufferlength) ? bufferlength * 2 : 32UL;
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uint32_t* newbuffer = new uint32_t[newbufferlength];
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if ( !newbuffer )
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return false;
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size_t elemsize = sizeof(*buffer);
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size_t leadingavai = bufferlength-bufferoffset;
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size_t leading = (leadingavai < bufferused) ? leadingavai : bufferused;
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size_t trailing = bufferused - leading;
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if ( buffer )
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{
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memcpy(newbuffer, buffer + bufferoffset, leading * elemsize);
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memcpy(newbuffer + leading, buffer, trailing * elemsize);
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delete[] buffer;
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}
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buffer = newbuffer;
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bufferlength = newbufferlength;
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bufferoffset = 0;
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}
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size_t index = OffsetIndex(bufferoffset, bufferused++, bufferlength);
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buffer[index] = unicode;
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return true;
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}
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uint32_t LineBuffer::Pop()
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{
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if ( !CanPop() )
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return 0;
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uint32_t result = Peek();
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bufferoffset = (bufferoffset+1) % bufferlength;
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buffercommitted--;
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bufferfrozen--;
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bufferused--;
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return result;
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}
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uint32_t LineBuffer::Peek() const
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{
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if ( !CanPop() )
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return 0;
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size_t index = OffsetIndex(bufferoffset, 0, bufferlength);
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return buffer[index];
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}
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uint32_t LineBuffer::Backspace()
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{
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if ( !CanBackspace() )
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return 0;
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size_t index = OffsetIndex(bufferoffset, --bufferused, bufferlength);
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return buffer[index];
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}
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uint32_t LineBuffer::WouldBackspace() const
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{
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if ( !CanBackspace() )
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return 0;
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size_t index = OffsetIndex(bufferoffset, bufferused-1, bufferlength);
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return buffer[index];
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}
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void LineBuffer::Commit()
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{
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buffercommitted = bufferfrozen = bufferused;
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}
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void LineBuffer::Freeze()
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{
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bufferfrozen = bufferused;
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}
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bool LineBuffer::CanPop() const
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{
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return buffercommitted;
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}
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bool LineBuffer::CanBackspace() const
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{
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return bufferused - bufferfrozen;
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}
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void LineBuffer::Flush()
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{
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bufferoffset = 0;
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buffercommitted = 0;
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bufferfrozen = 0;
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bufferused = 0;
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}
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} // namespace Sortix
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