dmmlib/sys_alloc.c

#include <unistd.h>
#include <stdio.h>
#include "posix_lock.h"
#include "other.h"
#include "LeaHeader.h"

static char * borderPtr = NULL;

void setHeaders (char * ptr,unsigned int sz) {
	sz = req_padding(sz);
	setSize(ptr,sz);
	markInUse(ptr);
	setPrevSize(getNext(ptr),sz);
	setSize(getNext(ptr),0);//border block
	markInUse(getNext(ptr));//border block
}

void *sys_alloc(unsigned int size) {
	unsigned int allocation_size;
	void *ptr;

	sbrk_lock();
	allocation_size = req_padding(size) + HDR_SIZE;

	if (borderPtr == NULL) {

		ptr = sbrk(allocation_size + 2*HDR_SIZE); //extra space for coalescing support

		if (ptr == (void *) -1){
			printf("sbrk Fail\n");
			return NULL;
		}

		//printf("sbrk = %p\n",ptr);

		setPrevSize(ptr + HDR_SIZE,0);
		markPrevInUse(ptr + HDR_SIZE);
		borderPtr  = ptr;

	} else {

		ptr =  sbrk(allocation_size);

		if ((ptr == (char *) -1)){
			printf("sbrk Fail: out of Memory\n");
			return NULL;
		}
		if((ptr != borderPtr + 2*HDR_SIZE)){
			printf("sbrk Fail: Non-contiguous Memory\n");
			return NULL;
		}
	}


	ptr = borderPtr + HDR_SIZE;
	borderPtr += allocation_size;
	setHeaders(ptr,size);

	sbrk_unlock();
	return (void *) ptr;

}