bool CFat32Device::ReadFromCache(unsigned long sector, unsigned char *buffer)
{
// round sector size down to page size
unsigned long page = sector & ~(FAT_PAGE_SIZE / m_sectorsize - 1);
FATCACHE::iterator it = m_cache.find(page);
if (it != m_cache.end())
{
cacheHit++;
CSector *cacheSector = (*it).second;
cacheSector->IncrementUsage(timeGetTime());
fast_memcpy(buffer, cacheSector->Get() + (sector - page)*m_sectorsize, m_sectorsize);
return true;
}
return false;
}
void CFat32Device::CachePage(unsigned long page, unsigned char *buffer)
{
DWORD time = timeGetTime();
if (m_cache.size() >= CACHE_SIZE)
{ // remove the last used cache
FATCACHE::iterator lastUsed = m_cache.begin();
//CStdString usage;
unsigned long smallest = 0;
for (FATCACHE::iterator it = m_cache.begin(); it != m_cache.end(); ++it)
{
if ((*it).second->Usage(time) > (*lastUsed).second->Usage(time))
lastUsed = it;
if ((*it).second->Usage(time) < smallest)
smallest = (*it).second->Usage(time);
/* CStdString log;
if ((*it).second->Usage(time) > 0xFF)
log = "FF ";
else
log.Format("%02x ", (*it).second->Usage());
usage += log;*/
}
//CLog::Log(LOGDEBUG, "%s", usage.c_str());
// lastUsed is the one we remove
unsigned long oldpage = (*lastUsed).first;
CSector *sector = (*lastUsed).second;
m_cache.erase(lastUsed);
// CLog::Log(LOGDEBUG, "Swapping page %i for page %i, oldest usage: %d (%d)", oldpage, page, sector->Usage(time), smallest);
#ifdef FAT32_ALLOW_WRITING
// write it out to disk if dirty
if (sector->IsDirty())
WritePage(oldpage, sector->Get());
#endif
delete sector;
}
// cache our page
m_cache.insert(pair<unsigned int, CSector *>(page, new CSector(buffer, time)));
}