memory.h File Reference

Memory management API. More...

#include <muteki/common.h>

Go to the source code of this file.

Functions
void *	lmalloc (size_t size)
	Allocate heap memory.
void *	lcalloc (size_t nmemb, size_t size)
	Allocate and clear data units on the heap.
void *	lrealloc (void *ptr, size_t size)
	Resize or reallocate memory.
void	_lfree (void *ptr)
	Free previously allocated memory.
void *	AllocBlock (size_t size, unsigned short tag, bool new_segment)
	Allocate memory on the secondary heap.
void	FreeBlock (void *ptr)
	Free memory previously allocated with AllocBlock().
size_t	GetFreeMemory (void)
	Return the size of available memory.

Detailed Description

Memory management API.

In Besta RTOS, heap memory management is entirely done in the OS kernel. All applications share a single heap managed by the OS and can be accessed through the malloc series API. Conventional address-space based heap memory management such as sbrk() is not supported due to the absence of MMU support in the OS kernel.

The simplest way to get heap memory support in a custom libc is to redirect malloc(), calloc(), realloc() and free() to the corresponding functions provided here.

Function Documentation

_lfree()

void _lfree ( void *  ptr )

extern

Free previously allocated memory.

Parameters

ptr	Pointer to previously allocated memory.

Returns

None.

AllocBlock()

void * AllocBlock ( size_t  size, unsigned short  tag, bool  new_segment  )

extern

Allocate memory on the secondary heap.

This allocates a block of memory on a secondary heap, that may be backed by a large block of memory on the primary heap. This secondary heap is usually 64KiB in size.

This seems to have a tie to the UI subsystem as UI-related syscalls seem to use this extensively.

Warning

Memory allocated with this function has to be freed with the FreeBlock() call.

Syscall Number

0x10145

Parameters

size	Size of the memory.
tag	Write this value to <allocated address> + 0x30 when the allocated memory is located on a fresh chunk (i.e. allocated on previously unused memory directly following the last chunk). Seems to be used in UI subsystem to differentiate components in some circumstances.
new_segment	Set to true to start a new segment. This will prevent this chunk and all chunks above from being reused until this memory is freed.

Returns

The allocated memory.

FreeBlock()

void FreeBlock ( void *  ptr )

extern

Free memory previously allocated with AllocBlock().

If a segment chunk is freed, everything below it will also be implicitly freed.

Syscall Number

0x10146

Parameters

ptr	Pointer to previously allocated memory.

Returns

None.

GetFreeMemory()

size_t GetFreeMemory ( void  )

extern

Return the size of available memory.

Requires -lkrnllib when dynamically linking with the shims.

Parameters

None.

Returns

Size of available memory.

lcalloc()

void * lcalloc ( size_t  nmemb, size_t  size  )

extern

Allocate and clear data units on the heap.

Parameters

nmemb	Number of data units to allocate.
size	Size of each data unit.

Returns

Pointer to allocated memory, or NULL if allocation fails.

lmalloc()

void * lmalloc ( size_t  size )

extern

Allocate heap memory.

Parameters

size	Size of the allocation in bytes.

Returns

Pointer to allocated memory, or NULL if allocation fails.

lrealloc()

void * lrealloc ( void *  ptr, size_t  size  )

extern

Resize or reallocate memory.

Parameters

ptr	Pointer to previously allocated memory.
size	New size in bytes.

Returns

Pointer to the newly allocated memory, or NULL if allocation fails.