dmmlib/sys_alloc.c

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

static void *borderPtr = NULL;

void setHeaders(void *ptr, size_t 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(size_t size) {
	size_t allocation_size;
	void *ptr;

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

	if (borderPtr == NULL) {

		ptr = sbrk((intptr_t) (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((char *) ptr + HDR_SIZE, 0);
		markPrevInUse((char *) ptr + HDR_SIZE);
		borderPtr = ptr;

	} else {

		ptr = sbrk((intptr_t) allocation_size);

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


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

	sbrk_unlock();
	return (void *) ptr;

}