Category : C++ Source Code
Archive   : VMEMPP.ZIP
Filename : DISK.CPP

 
Output of file : DISK.CPP contained in archive : VMEMPP.ZIP
#include "memory.h"
#include
#include
#include
#include

char DefaultDiskMemDir[MAXPATH] = ".";
int DiskFrameOrder = 0;
// 0 = conventional, EMS
// 1 = EMS, conventional

int DiskMemory::handle = -1;
int DiskMemory::isInitialized = 0;
DiskMemory *DiskMemory::head = 0;
long DiskMemory::lastAddr = 0;

void ClearDisk()
{
if( DiskMemory::handle != 0 )
{
_dos_close(DiskMemory::handle);
unlink( DefaultDiskMemDir );
}
}

#pragma exit ClearDisk

DiskMemory::DiskMemory()
{
init();
}

DiskMemory::DiskMemory( size_t sz )
{
init();
allocate(sz);
}

DiskMemory::~DiskMemory()
{
free();
}

int DiskMemory::allocate( size_t sz )
{
if( handle < 0 || memsize != 0 || sz == 0 )
return 0;

memsize = 0;
long aAddr = 0;
DiskMemory *parent = head;
if( head != 0 )
{
aAddr = parent->addr+parent->memsize;
while( parent->next != 0 )
{
aAddr = parent->addr + parent->memsize;
if( fitsInto( aAddr, parent->next->addr, sz) )
break;
parent = parent->next;
aAddr = parent->addr+parent->memsize;
}
}
if( (parent == 0 || parent->next == 0) && !fitsInto(aAddr, lastAddr, sz) )
{
lseek(handle, aAddr+sz-1, SEEK_SET);
char ch = ' ';
unsigned nwritten;
_dos_write( handle, &ch, 1, &nwritten );
lastAddr = filelength(handle);
if( !fitsInto(aAddr, lastAddr, sz) )
return 0;
}

if( parent == 0 )
{
next = 0;
head = this;
}
else
{
next = parent->next;
parent->next = this;
}
addr = aAddr;
memsize = sz;
return sz;
}

void DiskMemory::free()
{
DiskMemory *ptr;

if( memsize == 0 || lockflag != 0 )
return;

if( head == this )
head = head->next;
else
for( ptr = head; ptr->next; ptr = ptr->next )
if( ptr->next == this )
{
ptr->next = ptr->next->next;
break;
}
addr = 0;
next = 0;
memsize = 0;
}

void far *DiskMemory::lock()
{
unsigned nread;

if( memsize == 0 )
return 0;

if( !lockflag )
{
if( DiskFrameOrder == 0 )
{
frame = new ConvMemory( memsize );
if( !frame || frame->memSize() != memsize )
{
delete frame;
frame = new EmsMemory( memsize );
if( !frame || frame->memSize() != memsize )
{
delete frame;
frame = 0;
return 0;
}
}
}
else
{
frame = new EmsMemory( memsize );
if( !frame || frame->memSize() != memsize )
{
delete frame;
frame = new ConvMemory( memsize );
if( !frame || frame->memSize() != memsize )
{
delete frame;
frame = 0;
return 0;
}
}
}
frameBuf = frame->lock();
if( frameBuf == 0 )
{
frame->unlock();
frame->free();
delete frame;
frame = 0;
return 0;
}
lseek( handle, addr, SEEK_SET );
_dos_read( handle, frameBuf, memsize, &nread );
}
lockflag++;
return frameBuf;
}

void DiskMemory::unlock()
{
unsigned nwritten;
if( !lockflag )
return;

lockflag--;
if( lockflag == 0 )
{
lseek( handle, addr, SEEK_SET );
_dos_write( handle, frameBuf, memsize, &nwritten );
frame->unlock();
frame->free();
delete frame;
frame = 0;
}
}

long DiskMemory::memAvail()
{
if( handle < 0 ) return 0;
long l = lastAddr;
DiskMemory *ptr;

for( ptr = head; ptr != 0; ptr = ptr->next )
l -= ptr->memsize;
return l;
}

long DiskMemory::maxAvail()
{
if( handle < 0 ) return 0;
long tmp, l = 0;
DiskMemory *ptr;

if( head == 0 )
l = lastAddr;
else
{
for( ptr = head; ptr->next != 0; ptr = ptr->next )
{
tmp = ptr->next->addr - ptr->addr - ptr->memsize;
if( tmp > l )
l = tmp;
}
tmp = lastAddr - ptr->addr - ptr->memsize;
if( tmp > l )
l = tmp;
}
return l;
}

void DiskMemory::init()
{
if( !isInitialized )
{
isInitialized++;
char *ptr = DefaultDiskMemDir;
while( *ptr ) ptr++;
for( ptr--; *ptr != '\\' && ptr >= DefaultDiskMemDir; ptr-- );
ptr[1] = 0;
int i = strlen(DefaultDiskMemDir);
if( i > 0 && DefaultDiskMemDir[i-1] != '\\' )
DefaultDiskMemDir[i++] = '\\';
strcpy( DefaultDiskMemDir+i, "TXXXXXX" );
mktemp( DefaultDiskMemDir+i );
if( _dos_creat(DefaultDiskMemDir, 0, &handle) )
handle = -1;
if( handle < 0 )
return;
lastAddr = 0;
memsize = 0;
}
}

int DiskMemory::fitsInto( long addr, long next, size_t sz )
{
return (next >= addr+sz);
}



  3 Responses to “Category : C++ Source Code
Archive   : VMEMPP.ZIP
Filename : DISK.CPP

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