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/*
* barrier -- mouse and keyboard sharing utility
* Copyright (C) 2012-2016 Symless Ltd.
* Copyright (C) 2002 Chris Schoeneman
*
* This package is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* found in the file LICENSE that should have accompanied this file.
*
* This package 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 this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "io/StreamBuffer.h"
//
// StreamBuffer
//
#include <cassert>
const UInt32 StreamBuffer::kChunkSize = 4096;
StreamBuffer::StreamBuffer() :
m_size(0),
m_headUsed(0)
{
// do nothing
}
StreamBuffer::~StreamBuffer()
{
// do nothing
}
const void*
StreamBuffer::peek(UInt32 n)
{
assert(n <= m_size);
// if requesting no data then return NULL so we don't try to access
// an empty list.
if (n == 0) {
return NULL;
}
// reserve space in first chunk
ChunkList::iterator head = m_chunks.begin();
head->reserve(n + m_headUsed);
// consolidate chunks into the first chunk until it has n bytes
ChunkList::iterator scan = head;
++scan;
while (head->size() - m_headUsed < n && scan != m_chunks.end()) {
head->insert(head->end(), scan->begin(), scan->end());
scan = m_chunks.erase(scan);
}
return static_cast<const void*>(&(head->begin()[m_headUsed]));
}
void
StreamBuffer::pop(UInt32 n)
{
// discard all chunks if n is greater than or equal to m_size
if (n >= m_size) {
m_size = 0;
m_headUsed = 0;
m_chunks.clear();
return;
}
// update size
m_size -= n;
// discard chunks until more than n bytes would've been discarded
ChunkList::iterator scan = m_chunks.begin();
assert(scan != m_chunks.end());
while (scan->size() - m_headUsed <= n) {
n -= (UInt32)scan->size() - m_headUsed;
m_headUsed = 0;
scan = m_chunks.erase(scan);
assert(scan != m_chunks.end());
}
// remove left over bytes from the head chunk
if (n > 0) {
m_headUsed += n;
}
}
void
StreamBuffer::write(const void* vdata, UInt32 n)
{
assert(vdata != NULL);
// ignore if no data, otherwise update size
if (n == 0) {
return;
}
m_size += n;
// cast data to bytes
const UInt8* data = static_cast<const UInt8*>(vdata);
// point to last chunk if it has space, otherwise append an empty chunk
ChunkList::iterator scan = m_chunks.end();
if (scan != m_chunks.begin()) {
--scan;
if (scan->size() >= kChunkSize) {
++scan;
}
}
if (scan == m_chunks.end()) {
scan = m_chunks.insert(scan, Chunk());
}
// append data in chunks
while (n > 0) {
// choose number of bytes for next chunk
assert(scan->size() <= kChunkSize);
UInt32 count = kChunkSize - (UInt32)scan->size();
if (count > n)
count = n;
// transfer data
scan->insert(scan->end(), data, data + count);
n -= count;
data += count;
// append another empty chunk if we're not done yet
if (n > 0) {
++scan;
scan = m_chunks.insert(scan, Chunk());
}
}
}
UInt32
StreamBuffer::getSize() const
{
return m_size;
}
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