Memory Slab APIs

Macros
#define	K_MEM_SLAB_DEFINE(name, slab_block_size, slab_num_blocks, slab_align)
	Statically define and initialize a memory slab. More...

Functions
int	k_mem_slab_init (struct k_mem_slab *slab, void *buffer, size_t block_size, uint32_t num_blocks)
	Initialize a memory slab. More...
int	k_mem_slab_alloc (struct k_mem_slab *slab, void **mem, k_timeout_t timeout)
	Allocate memory from a memory slab. More...
void	k_mem_slab_free (struct k_mem_slab *slab, void **mem)
	Free memory allocated from a memory slab. More...
static uint32_t	k_mem_slab_num_used_get (struct k_mem_slab *slab)
	Get the number of used blocks in a memory slab. More...
static uint32_t	k_mem_slab_max_used_get (struct k_mem_slab *slab)
	Get the number of maximum used blocks so far in a memory slab. More...
static uint32_t	k_mem_slab_num_free_get (struct k_mem_slab *slab)
	Get the number of unused blocks in a memory slab. More...

Detailed Description

Macro Definition Documentation

K_MEM_SLAB_DEFINE

#define K_MEM_SLAB_DEFINE	(		name,
			slab_block_size,
			slab_num_blocks,
			slab_align
	)

#include <include/kernel.h>

Value:

        char __noinit_named(k_mem_slab_buf_##name) \
           __aligned(WB_UP(slab_align)) \
           _k_mem_slab_buf_##name[(slab_num_blocks) * WB_UP(slab_block_size)]; \
        STRUCT_SECTION_ITERABLE(k_mem_slab, name) = \
                Z_MEM_SLAB_INITIALIZER(name, _k_mem_slab_buf_##name, \
                                        WB_UP(slab_block_size), slab_num_blocks)

Statically define and initialize a memory slab.

The memory slab's buffer contains slab_num_blocks memory blocks that are slab_block_size bytes long. The buffer is aligned to a slab_align -byte boundary. To ensure that each memory block is similarly aligned to this boundary, slab_block_size must also be a multiple of slab_align.

The memory slab can be accessed outside the module where it is defined using:

extern struct k_mem_slab <name>; 

Parameters

name	Name of the memory slab.
slab_block_size	Size of each memory block (in bytes).
slab_num_blocks	Number memory blocks.
slab_align	Alignment of the memory slab's buffer (power of 2).

Function Documentation

k_mem_slab_alloc()

int k_mem_slab_alloc	(	struct k_mem_slab *	slab,
		void **	mem,
		k_timeout_t	timeout
	)

#include <include/kernel.h>

Allocate memory from a memory slab.

This routine allocates a memory block from a memory slab.

Note

timeout must be set to K_NO_WAIT if called from ISR.

When CONFIG_MULTITHREADING=n any timeout is treated as K_NO_WAIT.

Function properties (list may not be complete)

isr-ok

Parameters

slab	Address of the memory slab.
mem	Pointer to block address area.
timeout	Non-negative waiting period to wait for operation to complete. Use K_NO_WAIT to return without waiting, or K_FOREVER to wait as long as necessary.

Return values

0	Memory allocated. The block address area pointed at by mem is set to the starting address of the memory block.
-ENOMEM	Returned without waiting.
-EAGAIN	Waiting period timed out.
-EINVAL	Invalid data supplied

k_mem_slab_free()

void k_mem_slab_free	(	struct k_mem_slab *	slab,
		void **	mem
	)

#include <include/kernel.h>

Free memory allocated from a memory slab.

This routine releases a previously allocated memory block back to its associated memory slab.

Parameters

slab	Address of the memory slab.
mem	Pointer to block address area (as set by k_mem_slab_alloc()).

Returns

N/A

k_mem_slab_init()

int k_mem_slab_init	(	struct k_mem_slab *	slab,
		void *	buffer,
		size_t	block_size,
		uint32_t	num_blocks
	)

#include <include/kernel.h>

Initialize a memory slab.

Initializes a memory slab, prior to its first use.

The memory slab's buffer contains slab_num_blocks memory blocks that are slab_block_size bytes long. The buffer must be aligned to an N-byte boundary matching a word boundary, where N is a power of 2 (i.e. 4 on 32-bit systems, 8, 16, ...). To ensure that each memory block is similarly aligned to this boundary, slab_block_size must also be a multiple of N.

Parameters

slab	Address of the memory slab.
buffer	Pointer to buffer used for the memory blocks.
block_size	Size of each memory block (in bytes).
num_blocks	Number of memory blocks.

Return values

0	on success
-EINVAL	invalid data supplied

k_mem_slab_max_used_get()

static uint32_t k_mem_slab_max_used_get ( struct k_mem_slab *  slab )

inlinestatic

#include <include/kernel.h>

Get the number of maximum used blocks so far in a memory slab.

This routine gets the maximum number of memory blocks that were allocated in slab.

Parameters

slab	Address of the memory slab.

Returns

Maximum number of allocated memory blocks.

k_mem_slab_num_free_get()

static uint32_t k_mem_slab_num_free_get ( struct k_mem_slab *  slab )

inlinestatic

#include <include/kernel.h>

Get the number of unused blocks in a memory slab.

This routine gets the number of memory blocks that are currently unallocated in slab.

Parameters

slab	Address of the memory slab.

Returns

Number of unallocated memory blocks.

k_mem_slab_num_used_get()

static uint32_t k_mem_slab_num_used_get ( struct k_mem_slab *  slab )

inlinestatic

#include <include/kernel.h>

Get the number of used blocks in a memory slab.

This routine gets the number of memory blocks that are currently allocated in slab.

Parameters

slab	Address of the memory slab.

Returns

Number of allocated memory blocks.