C / C++ / MFC

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#include <windows.h><br />
#include "ssHeap.h"<br />
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typedef struct _HEAP_STRUCT<br />
{<br />
	DWORD size;<br />
	struct _HEAP_STRUCT *next;<br />
}HEAP_STRUCT;<br />
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HEAP_STRUCT *front;<br />
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HEAP_STRUCT *temp, *prevNode;<br />
HEAP_STRUCT *node;<br />
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char HeapSpace[4096];<br />
LPVOID beginOfTheHeap;<br />
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void ssInit(void)<br />
{<br />
	<br />
	front = new HEAP_STRUCT;<br />
	beginOfTheHeap = malloc(sizeof(HeapSpace));<br />
	front = (HEAP_STRUCT*)beginOfTheHeap;<br />
	<br />
	front->next = NULL;<br />
	front->size = 0;<br />
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	node = new HEAP_STRUCT;<br />
	node->next = NULL;<br />
	node->size = 0;<br />
	<br />
	<br />
};<br />
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LPVOID ssAlloc(LONG nBytes)<br />
{<br />
	HEAP_STRUCT *alloc = new HEAP_STRUCT;<br />
	int allocated = false;<br />
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	while(nBytes % 8 != 0)	//make this multiple of 8.<br />
		nBytes++;	//if this is not multiple of 8, increase it <br />
	//for example if 31%8 =7, then it will allocate 32bytes.<br />
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	if(front->next == NULL)	// this only happen if ssAlloc is called the first time<br />
	{<br />
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		node = new HEAP_STRUCT;	//create a new node<br />
		node->next = NULL;	//new node ->next points to NULL		<br />
		node = front + nBytes;	//this node address is nBytes away from the front<br />
		<br />
		<br />
		front->size = nBytes;	//this new node's size is what is left off	<br />
		front->next = node;	<br />
		return node;<br />
	}<br />
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	<br />
	<br />
	while(front->next != NULL)<br />
	{<br />
		long freeSpace = ((int)front->next - (int)(front + front->size))/sizeof(char);  //the free space between block<br />
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		if( freeSpace> nBytes)	//if the size is greater than nBytes<br />
		{<br />
			<br />
			while(freeSpace != nBytes)	//the size must be multiple of 8<br />
			{<br />
				freeSpace = freeSpace / 2;	//divide the free space to two<br />
			}<br />
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			node = new HEAP_STRUCT;		//create a new node<br />
			node = front + front->size;	//the mem location of the new node;<br />
			node->size = nBytes;<br />
			node->next = front->next ;	//point to the next free space that temp point to<br />
			front->next = node;	//now this one is point to the node that is new allocated <br />
			alloc = node;				//for returning purpose.<br />
			<br />
			allocated = true;	//set the allocated flag.<br />
		}<br />
		else <br />
		{<br />
			front = front->next;<br />
		}<br />
	}<br />
			<br />
	<br />
	if(allocated)		//if the space is allocated <br />
		return LPVOID(alloc);<br />
	else				//if there is not allocated space<br />
		return NULL;<br />
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};<br />
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void ssFree(LPVOID p)<br />
{<br />
		<br />
	if(front == (HEAP_STRUCT*)p)	//First node can not deleted<br />
	{<br />
		front->size = 0;<br />
	}<br />
	else<br />
	{<br />
		prevNode = new HEAP_STRUCT;<br />
		temp = new HEAP_STRUCT;<br />
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		<br />
		while(front->next->next != NULL)<br />
		{<br />
			prevNode = front;	//keep track of the previous node;<br />
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			if(front->next ==(HEAP_STRUCT*)p)<br />
			{	<br />
				temp = front->next->next;<br />
				prevNode = temp;<br />
				delete front->next;<br />
			}<br />
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			front->next = front->next->next ;	//go to the next of next node;<br />
		}<br />
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	}<br />
};<br />
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