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 reinterpret_cast<const void*>(&(head->begin()[m_headUsed]));
}
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 = reinterpret_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());
}
}
}
bool Heap::deallocate(void *ptr, size_t sz) {
if (ptr < mHeap || ptr >= end()) {
return false;
}
mUsedSize -= sz;
Chunk chunk = {ptr, sz};
ChunkList::iterator it = std::lower_bound(mChunks.begin(), mChunks.end(), chunk);
if (it != mChunks.begin()) {
// have a previous chunk
ChunkList::iterator pit = it;
--pit;
if (it == mChunks.end()) {
// no next chunk
if (pit->end() == ptr) {
PrintDebug("Merge with prev free chunk");
pit->size += sz;
} else {
PrintDebug("Add new free chunk");
mChunks.insert(it, chunk);
}
} else {
// also have next chunk
if (pit->end() == ptr) {
PrintDebug("Merge with prev free chunk");
pit->size += sz;
if (pit->end() == it->start) {
PrintDebug("Merge with next free chunk");
pit->size += it->size;
mChunks.erase(it);
}
} else {
if (offset(ptr, sz) == it->start) {
PrintDebug("Merge with next free chunk");
it->start = ptr;
it->size += sz;
} else {
PrintDebug("Add new free chunk");
mChunks.insert(it, chunk);
}
}
}
} else {
// no previous chunk
if (it == mChunks.end()) {
// no next chunk
PrintDebug("Add new free chunk");
mChunks.insert(it, chunk);
} else {
// have next chunk
if (offset(ptr, sz) == it->start) {
PrintDebug("Merge with next free chunk");
it->start = ptr;
it->size += sz;
} else {
PrintDebug("Add new free chunk");
mChunks.insert(it, chunk);
}
}
}
/*
ChunkList::iterator it = std::lower_bound(mChunks.begin(), mChunks.end(), chunk);
if (it != mChunks.begin()) {
// have a previous chunk
ChunkList::iterator pit = it;
--pit;
if (it == mChunks.end()) {
// no next chunk
} else {
// also have next chunk
}
} else {
// no previous chunk
if (it == mChunks.end()) {
// no next chunk
} else {
// have next chunk
}
}
if (it != mChunks.end()) {
// it points to next available chunk
if (offset(ptr, sz) < it->start) {
if (it != mChunks.begin()) {
// theres also a previous chunck
ChunkList::iterator pit = it;
--pit;
if (ptr > pit->end()) {
#ifdef _DEBUG
std::cerr << "### Add new free chunk" << std::endl;
#endif
mChunks.insert(it, chunk);
} else {
#ifdef _DEBUG
std::cerr << "### Merge with previous free chunk" << std::endl;
#endif
// merge with prev
pit->size += sz;
}
} else {
mChunks.insert(it, chunk);
}
} else {
// merge with next
#ifdef _DEBUG
std::cerr << "### Merge with next free chunk" << std::endl;
#endif
it->start = ptr;
it->size += sz;
}
} else {
ChunkList::iterator pit = it;
--pit;
if (ptr > pit->end()) {
#ifdef _DEBUG
std::cerr << "### Add new free chunk" << std::endl;
#endif
mChunks.insert(it, chunk);
} else {
// merge with prev
#ifdef _DEBUG
std::cerr << "### Merge with previous free chunk" << std::endl;
#endif
pit->size += sz;
}
}
*/
return true;
}