Play-/Source/ISO9660/File.cpp
2023-01-18 15:30:45 -05:00

117 lines
2.6 KiB
C++

#include "File.h"
#include <cassert>
#include <cstring>
#include <climits>
#include <algorithm>
using namespace ISO9660;
CFile::CFile(CBlockProvider* blockProvider, uint64 start)
: m_blockProvider(blockProvider)
, m_start(start)
, m_end(ULLONG_MAX)
{
InitBlock();
}
CFile::CFile(CBlockProvider* blockProvider, uint64 start, uint64 size)
: m_blockProvider(blockProvider)
, m_start(start)
, m_end(start + size)
{
InitBlock();
}
void CFile::Seek(int64 amount, Framework::STREAM_SEEK_DIRECTION whence)
{
uint64 size = (m_end != ULLONG_MAX) ? (m_end - m_start) : ULLONG_MAX;
switch(whence)
{
case Framework::STREAM_SEEK_SET:
m_position = amount;
break;
case Framework::STREAM_SEEK_CUR:
m_position += amount;
break;
case Framework::STREAM_SEEK_END:
//Cannot seek from end with unbounded files
assert(m_end != ULLONG_MAX);
m_position = size + amount;
break;
}
m_position = std::max<int64>(m_position, 0);
m_position = std::min<uint64>(m_position, size);
m_isEof = false;
}
uint64 CFile::Tell()
{
return m_position;
}
uint64 CFile::Read(void* data, uint64 length)
{
if(length == 0) return 0;
//Pre-condition
assert(m_position <= (m_end - m_start));
//Check if we're at the end of the file
uint64 offset = m_start + m_position;
if(offset >= m_end)
{
m_isEof = true;
return 0;
}
uint64 remainFileSize = m_end - offset;
length = std::min<uint64>(length, remainFileSize);
uint64 total = length;
//Read what's remaining of this block
while(1)
{
SyncBlock();
uint64 blockPosition = (m_start + m_position) % CBlockProvider::BLOCKSIZE;
uint64 blockRemain = CBlockProvider::BLOCKSIZE - blockPosition;
uint64 toRead = (length > blockRemain) ? (blockRemain) : (length);
memcpy(data, m_block + blockPosition, static_cast<uint32>(toRead));
m_position += toRead;
length -= toRead;
data = reinterpret_cast<uint8*>(data) + toRead;
if(length == 0) break;
}
//Post-condition
assert(m_position <= (m_end - m_start));
return total;
}
uint64 CFile::Write(const void* pData, uint64 nLength)
{
return -1;
}
bool CFile::IsEOF()
{
return m_isEof;
}
void CFile::InitBlock()
{
m_blockPosition = static_cast<uint32>(m_start / CBlockProvider::BLOCKSIZE);
m_blockProvider->ReadBlock(m_blockPosition, m_block);
}
void CFile::SyncBlock()
{
uint32 position = static_cast<uint32>((m_start + m_position) / CBlockProvider::BLOCKSIZE);
if(position == m_blockPosition) return;
m_blockProvider->ReadBlock(position, m_block);
m_blockPosition = position;
}