mirror of https://github.com/akuker/RASCSI.git
101 lines
2.8 KiB
C++
101 lines
2.8 KiB
C++
//---------------------------------------------------------------------------
|
|
//
|
|
// SCSI Target Emulator RaSCSI (*^..^*)
|
|
// for Raspberry Pi
|
|
//
|
|
// Copyright (C) 2022-2023 akuker
|
|
//
|
|
// This method of file access will use the mmap() capabilities to 'map' the
|
|
// file into memory.
|
|
//
|
|
// This doesn't actually copy the file into RAM, but instead maps the file
|
|
// as virtual memory. Behind the scenes, the file is still being accessed.
|
|
//
|
|
// The operating system will do some caching of the data to prevent direct
|
|
// drive access for each read/write. So, instead of implementing our own
|
|
// caching mechanism (like in disk_track_cache.h), we just rely on the
|
|
// operating system.
|
|
//
|
|
// [ MmapFilehandle ]
|
|
//
|
|
//---------------------------------------------------------------------------
|
|
|
|
#include "mmap_file_handle.h"
|
|
#include "shared/log.h"
|
|
#include <sys/mman.h>
|
|
#include <errno.h>
|
|
#include <unistd.h>
|
|
|
|
//===========================================================================
|
|
//
|
|
// Direct file access that will map the file into virtual memory space
|
|
//
|
|
//===========================================================================
|
|
MmapFileHandle::MmapFileHandle(const string &path, int size, uint32_t blocks, off_t imgoff) : DiskImageHandle(path, size, blocks, imgoff)
|
|
{
|
|
assert(blocks > 0);
|
|
assert(imgoff >= 0);
|
|
|
|
fd = open(path.c_str(), O_RDWR);
|
|
if (fd < 0)
|
|
{
|
|
LOGWARN("Unable to open file %s. Errno:%d", path.c_str(), errno)
|
|
}
|
|
LOGINFO("%s opened %s", __PRETTY_FUNCTION__, path.c_str())
|
|
struct stat sb;
|
|
if (fstat(fd, &sb) < 0)
|
|
{
|
|
LOGWARN("Unable to run fstat. Errno:%d", errno)
|
|
}
|
|
printf("Size: %d\n", (unsigned int)sb.st_size);
|
|
|
|
LOGINFO("%s mmap-ed file of size: %d", __PRETTY_FUNCTION__, (unsigned int)sb.st_size)
|
|
|
|
memory_block = (const char *)mmap(NULL, sb.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
|
|
int errno_val = errno;
|
|
if (memory_block == MAP_FAILED)
|
|
{
|
|
LOGWARN("Unabled to memory map file %s", path.c_str());
|
|
LOGWARN(" Errno:%d", errno_val);
|
|
return;
|
|
}
|
|
initialized = true;
|
|
}
|
|
|
|
MmapFileHandle::~MmapFileHandle()
|
|
{
|
|
munmap((void *)memory_block, sb.st_size);
|
|
close(fd);
|
|
|
|
// Force the OS to save any cached data to the disk
|
|
sync();
|
|
}
|
|
|
|
bool MmapFileHandle::ReadSector(vector<uint8_t>& buf, int block)
|
|
{
|
|
assert(block < GetBlocksPerSector());
|
|
assert(memory_block);
|
|
|
|
int sector_size_bytes = (off_t)1 << GetSectorSize();
|
|
|
|
// Calculate offset into the image file
|
|
off_t offset = GetTrackOffset(block);
|
|
offset += GetSectorOffset(block);
|
|
|
|
memcpy(buf.data(), &memory_block[offset], sector_size_bytes);
|
|
|
|
return true;
|
|
}
|
|
|
|
bool MmapFileHandle::WriteSector(const vector<uint8_t>& buf, int block)
|
|
{
|
|
assert(block < GetBlocksPerSector());
|
|
assert(memory_block);
|
|
|
|
assert((block * GetSectorSize()) <= (sb.st_size + GetSectorSize()));
|
|
|
|
memcpy((void *)&memory_block[(block * GetSectorSize())], buf.data(), GetSectorSize());
|
|
|
|
return true;
|
|
}
|