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#include <pch.cxx>
#define _NTAPI_ULIB_
#define _IFSUTIL_MEMBER_
#include "ulib.hxx"
#include "ifsutil.hxx"
#include "rcache.hxx"
DEFINE_EXPORTED_CONSTRUCTOR( READ_CACHE, DRIVE_CACHE, IFSUTIL_EXPORT );
READ_CACHE::~READ_CACHE(
)
/*++
Routine Description:
Destructor for READ_CACHE.
Arguments:
None.
Return Value:
None.
--*/
{
Destroy();
}
VOID
READ_CACHE::Construct (
)
/*++
Routine Description:
Contructor for READ_CACHE.
Arguments:
None.
Return Value:
None.
--*/
{
}
VOID
READ_CACHE::Destroy(
)
/*++
Routine Description:
Destructor for READ_CACHE.
Arguments:
None.
Return Value:
None.
--*/
{
}
IFSUTIL_EXPORT
BOOLEAN
READ_CACHE::Initialize(
IN OUT PIO_DP_DRIVE Drive,
IN ULONG NumberOfCacheBlocks
)
/*++
Routine Description:
This routine initializes a READ_CACHE object.
Arguments:
Drive - Supplies the drive to cache for.
Return Value:
FALSE - Failure.
TRUE - Success.
--*/
{
Destroy();
if (!DRIVE_CACHE::Initialize(Drive)) {
Destroy();
return FALSE;
}
if (!_cache.Initialize(Drive->QuerySectorSize(),
NumberOfCacheBlocks)) {
Destroy();
return FALSE;
}
return TRUE;
}
BOOLEAN
READ_CACHE::Read(
IN BIG_INT StartingSector,
IN SECTORCOUNT NumberOfSectors,
OUT PVOID Buffer
)
/*++
Routine Description:
This routine reads the requested sectors.
Arguments:
StartingSector - Supplies the first sector to be read.
NumberOfSectors - Supplies the number of sectors to be read.
Buffer - Supplies the buffer to read the run of sectors to.
Return Value:
FALSE - Failure.
TRUE - Success.
--*/
{
ULONG i, j;
ULONG sector_size;
PCHAR buf;
// Bypass the cache for large reads.
if (NumberOfSectors > _cache.QueryMaxNumBlocks()) {
return HardRead(StartingSector, NumberOfSectors, Buffer);
}
sector_size = _cache.QueryBlockSize();
buf = (PCHAR) Buffer;
for (i = 0; i < NumberOfSectors; i++) {
for (j = i; j < NumberOfSectors; j++) {
if (_cache.Read(StartingSector + j, &buf[j*sector_size])) {
break;
}
}
// Now do a hard read on everything from i to j and add these
// blocks to the cache.
if (j - i) {
if (!HardRead(StartingSector + i, j - i, &buf[i*sector_size])) {
return FALSE;
}
for (; i < j; i++) {
_cache.AddBlock(StartingSector + i, &buf[i*sector_size]);
}
}
}
return TRUE;
}
BOOLEAN
READ_CACHE::Write(
IN BIG_INT StartingSector,
IN SECTORCOUNT NumberOfSectors,
IN PVOID Buffer
)
/*++
Routine Description:
This routine writes the requested sectors directly to the disk.
Arguments:
StartingSector - Supplies the first sector to be written.
NumberOfSectors - Supplies the number of sectors to be written.
Buffer - Supplies the buffer to write the run of sectors from.
Return Value:
FALSE - Failure.
TRUE - Success.
--*/
{
_cache.Empty();
return HardWrite(StartingSector, NumberOfSectors, Buffer);
}
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