02-27-2010
I didn't study OS design, but shouldn't the malloc() function be part of the C library, not the kernel?
That aside, I'd write it in assembly language (after all, it's pretty CPU specific, and might even be time-critical). Also, it might help flipping through Tannenbaums
Operating Systems Design and Implementation, as I'm sure that there's some information in there.
Minix is the implementation of the theories put forth there.
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1 . Thanks everyone who read the post.
2 . the programe is that :
#include <stdio.h>
#include <string.h>
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{
p = (char *) malloc(100);
(void )strcpy(p,"1234");
}
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{
char *p;
do_it(p);
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hello sir
since by mentioning a integer pointer and storing the integers
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Hello
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MALLOC(3) Library Functions Manual MALLOC(3)
NAME
malloc, free, realloc, calloc - main memory allocator
SYNOPSIS
char *malloc(size)
unsigned size;
free(ptr)
char *ptr;
char *realloc(ptr, size)
char *ptr;
unsigned size;
char *calloc(nelem, elsize)
unsigned nelem, elsize;
DESCRIPTION
Malloc and free provide a simple general-purpose memory allocation package. Malloc returns a pointer to a block of at least size bytes
beginning on a word boundary.
The argument to free is a pointer to a block previously allocated by malloc; this space is made available for further allocation, but its
contents are left undisturbed.
Needless to say, grave disorder will result if the space assigned by malloc is overrun or if some random number is handed to free.
Malloc allocates the first big enough contiguous reach of free space found in a circular search from the last block allocated or freed,
coalescing adjacent free blocks as it searches. It calls sbrk (see break(2)) to get more memory from the system when there is no suitable
space already free.
Realloc changes the size of the block pointed to by ptr to size bytes and returns a pointer to the (possibly moved) block. The contents
will be unchanged up to the lesser of the new and old sizes.
Realloc also works if ptr points to a block freed since the last call of malloc, realloc or calloc; thus sequences of free, malloc and
realloc can exploit the search strategy of malloc to do storage compaction.
Calloc allocates space for an array of nelem elements of size elsize. The space is initialized to zeros.
Each of the allocation routines returns a pointer to space suitably aligned (after possible pointer coercion) for storage of any type of
object.
DIAGNOSTICS
Malloc, realloc and calloc return a null pointer (0) if there is no available memory or if the arena has been detectably corrupted by stor-
ing outside the bounds of a block. Malloc may be recompiled to check the arena very stringently on every transaction; see the source code.
BUGS
When realloc returns 0, the block pointed to by ptr may be destroyed.
MALLOC(3)