Watcom C Library : _memmax, memmove, _fmemmove, memset, _fmemset, min, mkdir, MK_FP
Watcom C Reference/K - L- M - N 2021. 8. 3. 19:56
Watcom C Library Reference : _memmax, memmove, _fmemmove, memset, _fmemset, min, mkdir, MK_FP
_memmax
Synopsis : #include <malloc.h>
size_t _memmax( void );
Description : The _memmax function returns the size of the largest contiguous block of memory available for dynamic memory allocation in the near heap (the default data segment). In the tiny, small and medium memory models, the default data segment is only extended as needed to satisfy requests for memory allocation. Therefore, you will need to call _nheapgrow in these memory models before calling _memmax in order to get a meaningful result.
Returns : The _memmax function returns the size of the largest contiguous block of memory available for dynamic memory allocation in the near heap. If 0 is returned, then there is no more memory available in the near heap.
See Also : calloc, _freect, _memavl, _heapgrow, malloc
Example :
#include <stdio.h>
#include <malloc.h>
void main( )
{
char *p;
size_t size;
size = _memmax( );
printf( "Maximum memory available is %u\n", size );
_nheapgrow( );
size = _memmax( );
printf( "Maximum memory available is %u\n", size );
p = (char *) _nmalloc( size );
size = _memmax( );
printf( "Maximum memory available is %u\n", size );
}
produces the following :
Maximum memory available is 0
Maximum memory available is 62700
Maximum memory available is 0
Classification : WATCOM
Systems : All
memmove, _fmemmove
Synopsis : #include <string.h>
void *memmove( void *dst, const void *src, size_t length);
void __far *_fmemmove( void __far *dst, const void __far *src, size_t length );
Description : The memmove and _fmemmove functions copy length characters from the buffer pointed to by src to the buffer pointed to by dst. Copying of overlapping objects will take place properly. See the memcpy or _fmemcpy functions to copy objects that do not overlap.
The _fmemmove function is a data model independent form of the memmove function. It accepts far pointer arguments and returns a far pointer. It is most useful in mixed memory model applications.
Returns : The memmove and _fmemmove functions return dst.
See Also : memcpy, memset
Example :
#include <string.h>
void main( )
{
char buffer[80];
memmove( buffer+1, buffer, 79 );
buffer[0] = '*';
}
Classification : memmove is ANSI, _fmemmove is not ANSI
Systems : memmove - All
_fmemmove - All
memset, _fmemset
Synopsis : #include <string.h>
void *memset( void *dst, int c, size_t length );
void __far * _fmemset( void __far *dst, int c, size_t length );
Description : The memset and _fmemset functions fill the first length characters of the object pointed to by s with the value c.
The _fmemset function is a data model independent form of the memset function. It accepts far pointer arguments and returns a far pointer. It is most useful in mixed memory model applications.
Returns : The memset and _fmemset functions return the pointer s.
See Also : memchr, memcmp, memcpy, memmove
Example :
#include <string.h>
void main( )
{
char buffer[80];
memset( buffer, '=', 80 );
}
Classification : memset is ANSI, _fmemset is not ANSI
Systems : memset - All
_fmemset - All
min
Synopsis : #include <stdlib.h>
#define min(a, b) (( (a) < (b) ) ? (a) : (b) )
Description : The min macro will evaluate to be the lesser of two values. It is implemented as follows.
#define min(a, b) (( (a) < (b) ) ? (a) : (b) )
Returns : The min macro will evaluate to the smaller of the two values passed.
See Also : max
Example :
#include <stdio.h>
#include <stdlib.h>
void main( )
{
int a;
/* The following line will set the variable "a" to 1 * since 10 is greater than 1. */
a = min( 1, 10 );
printf( "The value is : %d\n", a );
}
Classification : WATCOM
Systems : All
mkdir
Synopsis : #include <sys\types.h>
#include <direct.h>
int mkdir( const char *path );
Description : The mkdir function creates a new subdirectory with name path. The path can be either relative to the current working directory or it can be an absolute path name.
Returns : The mkdir function returns zero if successful, and a non-zero value otherwise.
Errors : When an error has occurred, errno contains a value indicating the type of error that has been detected.
| Constant | Meaning |
| EACCES | Search permission is denied for a component of path or write permission is denied on the parent directory of the directory to be created. |
| ENOENT | The specified path does not exist or path is an empty string. |
See Also : chdir, chmod, getcwd, rmdir, stat, umask
Example :
To make a new directory called \watcom on drive C:
#include <sys\types.h>
#include <direct.h>
void main( )
{
mkdir( "C:\\watcom" );
}
Note the use of two adjacent backslash characters(\) within character-string constants to signify a single backslash.
Classification : POSIX 1003.1
Systems : All
MK_FP
Synopsis : #include <i86.h>
void __far *MK_FP( unsigned int segment, unsigned int offset );
Description : The MK_FP macro can be used to obtain the far pointer value given by the segment segment
value and the offset offset value. These values may be obtained by using the FP_SEG and FP_OFF macros.
Returns : The MK_FP macro returns a far pointer.
See Also : FP_OFF, FP_SEG, segread
Example :
#include <i86.h>
#include <stdio.h>
void main( )
{
unsigned short __far *bios_prtr_port_1;
bios_prtr_port_1 = (unsigned short __far *) MK_FP( 0x40, 0x8 );
printf( "Port address is %x\n", *bios_prtr_port_1 );
}
Classification : Intel
Systems : MACRO
This manual describes the WATCOM C library for DOS, Windows, and OS/2, It includes the Standard C Library (as defined in the ANSI C Standard).
WATCOM C Language Reference manual describes the ANSI C Programming language and extensions to it which are supported by WATCOM C/C++ (32bit)
