mem_alloc.c File Reference

Dynamic memory allocation implementation. More...

#include <stdio.h>
#include <string.h>
#include "exceptions.h"
#include "errors.h"
#include "os_helpers.h"
#include "os_math.h"
#include "os_print.h"
#include "os_utils.h"
#include "mem_alloc.h"

Include dependency graph for mem_alloc.c:

Go to the source code of this file.

Classes
struct	header_s
struct	heap_t

Macros
#define	PAYLOAD_ALIGNEMENT   4
#define	PAYLOAD_DATA_ALIGNEMENT   8
#define	ALLOC_CHUNK_HEADER_SIZE   4
#define	FREE_CHUNK_HEADER_SIZE   8
#define	HEAP_HEADER_SIZE    ((sizeof(heap_t) + PAYLOAD_DATA_ALIGNEMENT - 1) & ~(PAYLOAD_DATA_ALIGNEMENT - 1))
#define	NB_LINEAR_SEGMENTS   5
#define	NB_MAX_SEGMENTS   10
#define	NB_SUB_SEGMENTS   4
#define	GET_PTR(_heap, index)   ((header_t *) (((uint8_t *) _heap) + ((index) << 3)))
#define	GET_IDX(_heap, _ptr)   ((((uint8_t *) (_ptr)) - ((uint8_t *) _heap)) >> 3)
#define	GET_PREV(_heap, _ptr)   ((header_t *) (((uint8_t *) _heap) + ((_ptr)->fprev << 3)))
#define	GET_NEXT(_heap, _ptr)   ((header_t *) (((uint8_t *) _heap) + ((_ptr)->fnext << 3)))

Typedefs
typedef struct header_s	header_t

Functions
mem_ctx_t	mem_init (void *heap_start, size_t heap_size)
	initializes the heap for this allocator
void *	mem_alloc (mem_ctx_t ctx, size_t nb_bytes)
	allocates a buffer of the given size, if possible
void	mem_free (mem_ctx_t ctx, void *ptr)
	frees the given buffer
void	mem_parse (mem_ctx_t ctx, mem_parse_callback_t callback, void *data)
	parse the heap
void	mem_stat (mem_ctx_t *ctx, mem_stat_t *stat)
	function used to get statistics (nb chunks, nb allocated chunks, total size) about the heap

Detailed Description

Dynamic memory allocation implementation.

Definition in file mem_alloc.c.

Macro Definition Documentation

ALLOC_CHUNK_HEADER_SIZE

#define ALLOC_CHUNK_HEADER_SIZE   4

Definition at line 27 of file mem_alloc.c.

FREE_CHUNK_HEADER_SIZE

#define FREE_CHUNK_HEADER_SIZE   8

Definition at line 29 of file mem_alloc.c.

GET_IDX

#define GET_IDX	(		_heap,
			_ptr
	)		((((uint8_t *) (_ptr)) - ((uint8_t *) _heap)) >> 3)

Definition at line 54 of file mem_alloc.c.

GET_NEXT

#define GET_NEXT	(		_heap,
			_ptr
	)		((header_t *) (((uint8_t *) _heap) + ((_ptr)->fnext << 3)))

Definition at line 56 of file mem_alloc.c.

GET_PREV

#define GET_PREV	(		_heap,
			_ptr
	)		((header_t *) (((uint8_t *) _heap) + ((_ptr)->fprev << 3)))

Definition at line 55 of file mem_alloc.c.

GET_PTR

#define GET_PTR	(		_heap,
			index
	)		((header_t *) (((uint8_t *) _heap) + ((index) << 3)))

Definition at line 53 of file mem_alloc.c.

HEAP_HEADER_SIZE

#define HEAP_HEADER_SIZE    ((sizeof(heap_t) + PAYLOAD_DATA_ALIGNEMENT - 1) & ~(PAYLOAD_DATA_ALIGNEMENT - 1))

Definition at line 31 of file mem_alloc.c.

NB_LINEAR_SEGMENTS

#define NB_LINEAR_SEGMENTS   5

Definition at line 35 of file mem_alloc.c.

NB_MAX_SEGMENTS

#define NB_MAX_SEGMENTS   10

Definition at line 48 of file mem_alloc.c.

NB_SUB_SEGMENTS

#define NB_SUB_SEGMENTS   4

Definition at line 50 of file mem_alloc.c.

PAYLOAD_ALIGNEMENT

#define PAYLOAD_ALIGNEMENT   4

Definition at line 23 of file mem_alloc.c.

PAYLOAD_DATA_ALIGNEMENT

#define PAYLOAD_DATA_ALIGNEMENT   8

Definition at line 25 of file mem_alloc.c.

Typedef Documentation

header_t

typedef struct header_s header_t

Function Documentation

mem_alloc()

void * mem_alloc	(	mem_ctx_t	ctx,
		size_t	nb_bytes
	)

allocates a buffer of the given size, if possible

Note

this buffer should be free later with mem_free

Parameters

ctx	allocator context (returned by mem_init())
nb_bytes	size in bytes of the buffer to allocate (must be > 0)

Returns

either a valid address if successful, or NULL if failed (no more memory or invalid nb_bytes)

Definition at line 320 of file mem_alloc.c.

mem_free()

void mem_free	(	mem_ctx_t	ctx,
		void *	ptr
	)

frees the given buffer

Parameters

ctx	allocator context (returned by mem_init())
ptr	buffer previously allocated with mem_alloc

Definition at line 406 of file mem_alloc.c.

mem_init()

mem_ctx_t mem_init	(	void *	heap_start,
		size_t	heap_size
	)

initializes the heap for this allocator

Parameters

heap_start	address of the heap to use
heap_size	size in bytes of the heap to use. It must be a multiple of 8, and at least 200 bytes but less than 32kBytes (max is exactly 32856 bytes)

Returns

the context to use for further calls, or NULL if failling

Definition at line 283 of file mem_alloc.c.

mem_parse()

void mem_parse	(	mem_ctx_t	ctx,
		mem_parse_callback_t	callback,
		void *	data
	)

parse the heap

Parameters

ctx	allocator context (returned by mem_init())
ptr	buffer previously allocated with mem_alloc
data	context data, passed to given callback

Definition at line 439 of file mem_alloc.c.

mem_stat()

void mem_stat	(	mem_ctx_t *	ctx,
		mem_stat_t *	stat
	)

function used to get statistics (nb chunks, nb allocated chunks, total size) about the heap

Parameters

ctx	allocator context (returned by mem_init())
ptr	buffer previously allocated with mem_alloc

Definition at line 477 of file mem_alloc.c.