Initializes the virtual memory manager.
#include <vmemory.h>
int __far _vheapinit( unsigned int dosmin, unsigned int dosmax,
unsigned int swaparea );
| dosmin | Minimum amount of DOS memory that must be available for the virtual memory manager to install itself, in paragraphs | |
| dosmax | Maximum amount of DOS memory that the virtual memory manager can use, in paragraphs | |
| swaparea | Type of auxiliary memory to use |
The _vheapinit routine initializes the virtual memory manager in preparation for future allocations. It must be called before any virtual memory blocks are requested.
The _vheapinit function may round up the minimum value specified. After rounding, if the minimum amount of DOS memory is not available, _vheapinit does not initialize the virtual memory manager and returns 0. The virtual memory manager requires several kilobytes to function effectively.
If _VM_ALLDOS is specified for the dosmax argument, the virtual memory manager uses all available DOS memory.
The swaparea argument specifies which types of auxiliary memory the virtual memory manager can use to hold blocks of memory that are swapped out. The argument can be one or more of the following manifest constants, combined with the bitwise-OR operator (|):
| Value | Meaning |
| _VM_EMS | Use expanded memory |
| _VM_XMS | Use extended memory |
| _VM_DISK | Use disk space |
| _VM_ALLSWAP | ( _VM_EMS | _VM_XMS | _VM_DISK ) |
If not all of the specified forms of storage are available, the virtual memory manager uses what is available.
After the program is done using virtual memory, it must call _vheapterm to terminate the virtual memory manager. A program can contain multiple pairs of _vheapinit /_vheapterm calls.
Warning!:
If the program terminates without a call to _vheapterm, various system memory resources may not be available to subsequent programs.
To specify that no minimum amount of memory is required for installation of the virtual memory manager and to use all available DOS memory in the virtual heap and all auxiliary storage, use the following command:
if( _vheapinit( 0, _VM_ALLDOS, _VM_ALLSWAP) == 0 )
/* Error */
The _vheapinit function returns a nonzero value if the virtual memory manager was successfully initialized. Otherwise, it returns 0.
Standards:None
16-Bit:DOS
32-Bit:None
See the example for _vmalloc.