SectorAccessibleDisk.cc

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#include "SectorAccessibleDisk.hh"
#include "DiskImageUtils.hh"
#include "EmptyDiskPatch.hh"
#include "IPSPatch.hh"
#include "DiskExceptions.hh"
#include "sha1.hh"
#include "xrange.hh"
#include <memory>
 
namespace openmsx {
 
SectorAccessibleDisk::SectorAccessibleDisk()
        : patch(std::make_unique<EmptyDiskPatch>(*this))
{
}
 
SectorAccessibleDisk::~SectorAccessibleDisk() = default;
 
void SectorAccessibleDisk::readSector(size_t sector, SectorBuffer& buf)
{
        readSectors(&buf, sector, 1);
}
 
void SectorAccessibleDisk::readSectors(
        SectorBuffer* buffers, size_t startSector, size_t nbSectors)
{
        auto last = startSector + nbSectors - 1;
        if (!isDummyDisk() && // in that case we want DriveEmptyException
            (last > 1) && // allow reading sector 0 and 1 without calling
                          // getNbSectors() because this potentially calls
                          // detectGeometry() and that would cause an
                          // infinite loop
            (getNbSectors() <= last)) {
                throw NoSuchSectorException("No such sector");
        }
        try {
                // in the end this calls readSectorsImpl()
                patch->copyBlock(startSector * sizeof(SectorBuffer),
                                 buffers[0].raw,
                                 nbSectors * sizeof(SectorBuffer));
        } catch (MSXException& e) {
                throw DiskIOErrorException("Disk I/O error: ", e.getMessage());
        }
}
 
void SectorAccessibleDisk::readSectorsImpl(
        SectorBuffer* buffers, size_t startSector, size_t nbSectors)
{
        // Default implementation reads one sector at a time. But subclasses can
        // override this method if they can do it more efficiently.
        for (auto i : xrange(nbSectors)) {
                readSectorImpl(startSector + i, buffers[i]);
        }
}
 
void SectorAccessibleDisk::readSectorImpl(size_t /*sector*/, SectorBuffer& /*buf*/)
{
        // subclass should override exactly one of
        //    readSectorImpl() or readSectorsImpl()
        assert(false);
}
 
void SectorAccessibleDisk::writeSector(size_t sector, const SectorBuffer& buf)
{
        if (isWriteProtected()) {
                throw WriteProtectedException();
        }
        if (!isDummyDisk() && (getNbSectors() <= sector)) {
                throw NoSuchSectorException("No such sector");
        }
        try {
                writeSectorImpl(sector, buf);
        } catch (MSXException& e) {
                throw DiskIOErrorException("Disk I/O error: ", e.getMessage());
        }
        flushCaches();
}
 
void SectorAccessibleDisk::writeSectors(
        const SectorBuffer* buffers, size_t startSector, size_t nbSectors)
{
        // Simply write one-at-a-time. There's no possibility (nor any need) yet
        // to allow to optimize this
        for (auto i : xrange(nbSectors)) {
                writeSector(startSector + i, buffers[i]);
        }
}
 
 
size_t SectorAccessibleDisk::getNbSectors() const
{
        return getNbSectorsImpl();
}
 
void SectorAccessibleDisk::applyPatch(Filename patchFile)
{
        patch = std::make_unique<IPSPatch>(std::move(patchFile), std::move(patch));
}
 
std::vector<Filename> SectorAccessibleDisk::getPatches() const
{
        return patch->getFilenames();
}
 
bool SectorAccessibleDisk::hasPatches() const
{
        return !patch->isEmptyPatch();
}
 
Sha1Sum SectorAccessibleDisk::getSha1Sum(FilePool& filePool)
{
        checkCaches();
        if (sha1cache.empty()) {
                sha1cache = getSha1SumImpl(filePool);
        }
        return sha1cache;
}
 
Sha1Sum SectorAccessibleDisk::getSha1SumImpl(FilePool& /*filePool*/)
{
        try {
                setPeekMode(true);
                SHA1 sha1;
 
                constexpr size_t MAX_CHUNK = 32;
                SectorBuffer buf[MAX_CHUNK];
                size_t total = getNbSectors();
                size_t sector = 0;
                while (sector < total) {
                        auto chunk = std::min(MAX_CHUNK, total - sector);
                        readSectors(buf, sector, chunk);
                        sha1.update({buf[0].raw, chunk * sizeof(SectorBuffer)});
                        sector += chunk;
                }
 
                setPeekMode(false);
                return sha1.digest();
        } catch (MSXException&) {
                setPeekMode(false);
                throw;
        }
}
 
bool SectorAccessibleDisk::isWriteProtected() const
{
        return forcedWriteProtect || isWriteProtectedImpl();
}
 
void SectorAccessibleDisk::forceWriteProtect()
{
        // can't be undone
        forcedWriteProtect = true;
}
 
bool SectorAccessibleDisk::isDummyDisk() const
{
        return false;
}
 
void SectorAccessibleDisk::checkCaches()
{
        // nothing
}
 
void SectorAccessibleDisk::flushCaches()
{
        sha1cache.clear();
}
 
} // namespace openmsx