Allocates a based heap.
| #include <malloc.h> | Required only for function declarations |
__segment _bheapseg( size_t size );
| size | Segment size to allocate |
The _bheapseg function allocates a based-heap segment of at least size bytes. (The block may be larger than size bytes because of space required for alignment and for maintenance information.)
The value returned by _bheapseg is the identifier of the based-heap segment. This value should be saved and used in subsequent calls to other based-heap functions. If the original block of memory is depleted (e.g., by calls to _bmalloc and _brealloc), the run-time code will try to enlarge the heap as necessary.
The _bheapseg function can be called repeatedly. For each call, the run-time library will allocate a new based-heap segment.
The _bheapseg function returns the newly allocated segment selector; save this value for use in subsequent based-heap functions. A return value of _NULLSEG indicates failure.
Always check the return from the _bheapseg function (especially when it is used in real mode), even if the amount of memory requested is small.
Standards:None
16-Bit:DOS, QWIN, WIN, WIN DLL
32-Bit:None
calloc functions, free functions, malloc functions, realloc functions
/* BHEAPSEG.C: This program C illustrates dynamic allocation of based
* memory using functions _bheapseg, _bfreeseg, _bmalloc, and _bfree.
*/
#include <stdio.h>
#include <malloc.h>
#include <stdlib.h>
#include <string.h>
void main( void )
{
__segment seg;
char __based( seg ) *outstr, __based( seg ) *instr;
char __based( seg ) *pout, __based( seg ) *pin;
char tmpstr[80];
int len;
printf( "Enter a string: " );
gets( tmpstr );
/* Request a based heap. Use based so that memory won't be taken from
* near heap.
*/
if( (seg = _bheapseg( 1000 )) == _NULLSEG )
exit( 1 );
/* Allocate based memory for two strings. */
len = strlen( tmpstr );
if( ((instr = _bmalloc( seg, len + 1 )) == _NULLOFF) ||
((outstr = _bmalloc( seg, len + 1 )) == _NULLOFF) )
exit( 1 );
/* Copy a lowercased string to dynamic memory. The based memory is
* far when addressed as a whole.
*/
_fstrlwr( _fstrcpy( (char __far *)instr, (char __far *)tmpstr ) );
/* Copy input string to output string in reversed order. When reading
* and writing individual characters from a based heap, the compiler will
* try to process them as near, thus speeding up the processing.
*/
for( pin = instr + len - 1, pout = outstr;
pout < outstr + len; pin--, pout++ )
*pout = *pin;
*pout = '\0';
/* Display strings. Again, strings as a whole are far. */
printf( "Input: %Fs\n", (char __far *)instr );
printf( "Output: %Fs\n", (char __far *)outstr );
/* Free blocks and release based heap. */
_bfree( seg, instr );
_bfree( seg, outstr );
_bfreeseg( seg );
}
Enter a string: Was I god
Input: was i god
Output: dog i saw