Boolean_T isRamDsk(unsigned char drive)
{
union REGS regs;
B_REC buffer;
regs.x.ax = 0x4408; /* Not if removable */
regs.h.bl = (unsigned)toupper(drive) - (unsigned char)'@';
intdos(®s, ®s);
if (0 == regs.x.ax)
return False_;
if (AbsDiskRead(toupper(drive) - 'A', 1, 0, &buffer))
return Error_;
return (1 == buffer.bsFATs);
}
int _cdecl CachedAbsDiskRead(int iDrive, DWORD dwSector, WORD wOffset,
WORD wLength, void *pBuf)
{
int err;
DEVICEPARAMS dpCache;
DEVICEPARAMS *pdp = &dpCache;
WORD wToCopy;
if (iDrive != iCachedDrive)
{
if (iCacheDirty) CachedAbsDiskFlush();
iCachedDrive = -1; /* Assume failure reading the drive parameters */
err = GetDeviceParams(iDrive, pdp);
if (err) return err; /* Access denied */
if (pdp->dpBytesPerSec > 1024) return 5; /* Prevent cache overflow */
wCachedSectorSize = pdp->dpBytesPerSec;
iCachedDrive = iDrive; /* Flag success: Drive parameters are valid. */
dwCachedSector = NO_SECTOR; // Force reading the new drive
}
/* Prevent errors */
if (wOffset >= wCachedSectorSize) return 5;
while (wLength)
{
if (dwSector != dwCachedSector) // Don't read twice the same sector
{
if (iCacheDirty) CachedAbsDiskFlush();
err = AbsDiskRead(iDrive, dwSector, 1, cSectorCache);
if (err) return err;
dwCachedSector = dwSector;
}
wToCopy = min(wLength, wCachedSectorSize - wOffset);
memcpy(pBuf, cSectorCache+wOffset, wToCopy);
dwSector += 1;
wOffset = 0;
wLength -= wToCopy;
(char *)pBuf += wToCopy;
}
return 0;
}
