Memory Manager Library

This library provides routines for manipulating dynamic memory allocation. Dynamic memory allocation (also known as heap-based memory allocation) is the allocation of memory storage for use in a program during the runtime of that program.
Dynamically allocated memory exists until it is released. This is in contrast to static memory allocation, which has a fixed duration. It is said that an object so allocated has a dynamic lifetime.

The heap memory size can be configured in the Edit Project window. Also, user can override heap memory size in the code, by setting the HEAP_SIZE constant.

MM_Init

Prototype	procedure MM_Init();
Description	Initializes the memory manager.
Parameters	None.
Returns	Nothing.
Requires	Nothing.
Example	MM_Init(); // Initializes memory manager
Notes	None.

GetMem

Prototype	procedure GetMem(var P: ^byte; Size: dword);
Description	Allocates a block of memory from the memory Heap.
Parameters	`P:` pointer to the allocated memory block. `Size:` Size of the memory block to be allocated.
Returns	Returns a pointer to the fetched memory (of "Size" bytes) in P, if success; Otherwise 0 (no free blocks of memory are large enough).
Requires	Nothing.
Example	GetMem(ptr,20sizeof(PBuffer)); // ptr will point to a memory block where PBuffer is allocated*
Notes	Following alignments are assumed : for size in bytes >= 4, alignment is set to 4. for size in bytes = 2, alignment is set to 2. else, alignment is set to 1. It is recommended to use New routine instead.

GetMemAlign

Prototype	procedure GetMemAlign(var P: ^byte; Size: dword; alignment: byte);
Description	Allocates a block of memory from the memory Heap.
Parameters	`P:` pointer to the allocated memory block. `Size:` Size of the memory block to be allocated. `alignment:` desired address alignment
Returns	Returns a pointer to the fetched memory (of "Size" bytes) in P if success; Otherwise 0 (no free blocks of memory are large enough).
Requires	Nothing.
Example	GetMemAlign(ptr,20sizeof(PBuffer)); // ptr will point to a memory block where PBuffer is allocated*
Notes	User must take care when specifing alignment parameter, as the compiler assumes that certain data types must be properly aligned. Having that in mind, it is advisable to use GetMem and New routines instead.

Malloc

Prototype	function Malloc(Size: dword) : ^byte;
Description	Allocates a block of size bytes of memory, returning a pointer to the beginning of the block. The content of the newly allocated block of memory is not initialized, remaining with indeterminate values..
Parameters	`Size:` Size of the memory block, in bytes.
Returns	Returns a pointer to the memory block allocated by the function. If the function failed to allocate the requested block of memory, a null pointer is returned.
Requires	Nothing.
Example	var p : ^dword; // pointer to byte var a : array[100] of dword; // array of dwords p := dword(Malloc(sizeof(a))); // p will point to a memory block where the array is allocated
Notes	None.

FreeMem

Prototype	procedure FreeMem(var P: ^byte; Size: dword);
Description	This function is used to free memory block allocated by GetMem or Malloc.
Parameters	`P:` variable of any pointer type previously assigned by the Getmem procedure. `Size:` specifies the size in bytes of the dynamic variable to dispose of and should be the same as the one used to Getmem.
Returns	Nothing.
Requires	Nothing.
Example	FreeMem(ptr,20sizeof(PBuffer)); // ptr will point to a memory block where PBuffer is allocated*
Notes	None.

Free

Prototype	procedure Free(var P: ^byte; Size: dword);
Description	This function is used to free memory block allocated by Malloc.
Parameters	`P:` pointer to the memory block `Size:` actual size of the memory block.
Returns	Nothing.
Requires	Nothing.
Example	var p : ^dword; // pointer to byte var a : array[100] of dword; // array of dwords p := dword(Malloc(sizeof(a))); // p will point to a memory block where the array is allocated Free(p, sizeof(p)); // frees memory block from the Heap allocated by Malloc, pointed to by the p pointer
Notes	None.

MM_LargestFreeMemBlock

Prototype	function MM_LargestFreeMemBlock() : dword;
Description	This function is used to determine largest available free memory of contiguous memory on the heap.
Parameters	None.
Returns	Returns, after defragmentation of the freelist the size (in bytes) of the largest free block of contiguous memory on the heap.
Requires	Nothing.
Example	var block : dword; begin block := MM_LargestFreeMemBlock(); end;
Notes	None.

MM_TotalFreeMemSize

Prototype	function MM_TotalFreeMemSize() : dword;
Description	This function is used to determine total free memory size on the heap.
Parameters	None.
Returns	Returns the size (in bytes) of the total free memory on the heap.
Requires	Nothing.
Example	var total : dword; begin total := MM_TotalFreeMemSize(); end;
Notes	None.

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