bool SectorReader::Read(u64 offset, u64 size, u8* out_ptr)
{
u64 remain = size;
u64 block = 0;
u32 position_in_block = static_cast<u32>(offset % m_block_size);
while (remain > 0)
{
block = offset / m_block_size;
const Cache* cache = GetCacheLine(block);
if (!cache)
return false;
// Cache entries are aligned chunks, we may not want to read from the start
u32 read_offset = static_cast<u32>(block - cache->block_idx) * m_block_size + position_in_block;
u32 can_read = m_block_size * cache->num_blocks - read_offset;
u32 was_read = static_cast<u32>(std::min<u64>(can_read, remain));
std::copy(cache->data.begin() + read_offset, cache->data.begin() + read_offset + was_read,
out_ptr);
offset += was_read;
out_ptr += was_read;
remain -= was_read;
position_in_block = 0;
}
return true;
}
/////////////////////////////////////////////////////////
// Description:
// flush content in IOBuffer to real hardware storage
//
// Input:
//
//
// output:
//
//
// Remarks:
//
// Returns:
void FAT_SectorCache::FlushSector( UINT32 sectorIndex )
{
FAT_CacheLine* cacheLine = GetCacheLine( sectorIndex );
if(cacheLine)
{
FlushSector( cacheLine );
}
}
void FAT_SectorCache::MarkSectorDirty( UINT32 sectorIndex )
{
FAT_CacheLine* cacheLine = GetCacheLine( sectorIndex );
if(cacheLine)
{
cacheLine->SetDirty( TRUE );
}
}
BYTE* FAT_SectorCache::GetSector( UINT32 sectorIndex, BOOL forWrite )
{
if(sectorIndex > m_sectorCount) //sectorIndex out of range of this device
return NULL;
FAT_CacheLine* cacheLine = GetCacheLine( sectorIndex );
if(!cacheLine)
{
cacheLine = GetUnusedCacheLine();
if(!cacheLine->m_buffer)
{
cacheLine->m_buffer = (BYTE*)private_malloc( SECTORCACHE_LINESIZE );
if(!cacheLine->m_buffer) return NULL;
}
cacheLine->m_begin = sectorIndex - (sectorIndex % m_sectorsPerLine);
cacheLine->m_bsByteAddress = m_baseByteAddress + cacheLine->m_begin * m_bytesPerSector;
cacheLine->m_flags = 0;
if(!m_blockStorageDevice->Read( cacheLine->m_bsByteAddress, SECTORCACHE_LINESIZE, cacheLine->m_buffer ))
{
private_free( cacheLine->m_buffer );
cacheLine->m_buffer = NULL;
return NULL;
}
}
if(forWrite) cacheLine->SetDirty( TRUE );
if((cacheLine->GetLRUCounter()) != m_LRUCounter)
{
m_LRUCounter++;
cacheLine->SetLRUCOunter( m_LRUCounter );
}
return cacheLine->m_buffer + (sectorIndex - cacheLine->m_begin) * m_bytesPerSector;
}
