arena_template.h File Reference

Arena allocator. More...

#include <assert.h>
#include <stdalign.h>
#include <stdbool.h>
#include <stddef.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include "align.h"

Go to the source code of this file.

Classes
struct	arena
	Arena data struct. More...
struct	arena_state
	Tempory arena state struct. More...

Macros
#define	FUNCTION_DEFINITIONS
	Define the functions.
#define	TYPE_DEFINITIONS
	Define the types.
#define	FUNCTION_LINKAGE
	Specify function linkage e.g. static inline.
#define	PASTE(a, b)
	Paste two tokens together.
#define	XPASTE(a, b)
	First expand tokens, then paste them together.
#define	JOIN(a, b)
	First expand tokens, then paste them together with a _ in between.
#define	IS_POW2(X)
	Macro to check if a number is a power of two.

Functions
arena_state_type	arena_state_save (arena_type *arena_ptr)
	Save the arena state temporarily.
void	arena_state_restore (arena_state_type prev_state)
	Restore the arena state.
void	arena_init (arena_type *self, const size_t len, unsigned char *backing_buf)
	Initialize the arena.
void	arena_deallocate_all (arena_type *self)
	Deallocate all allocations in the arena.
void *	arena_allocate_aligned (arena_type *self, const size_t alignment, const size_t size)
	Get the pointer to a chunk of the arena. With specific alignment.
void *	arena_allocate (arena_type *self, const size_t size)
	Get the pointer to a chunk of the arena.
void *	arena_reallocate_aligned (arena_type *self, void *old_ptr_, const size_t alignment, const size_t old_size, const size_t new_size)
	Reallocate a previously allocated chunk in the arena. With specific aligment.
void *	arena_reallocate (arena_type *self, void *old_ptr, const size_t old_size, const size_t new_size)
	Reallocate a previously allocated chunk in the arena.

Detailed Description

Arena allocator.

For a comprehensive source, read:

• https://www.gingerbill.org/article/2019/02/08/memory-allocation-strategies-002/

Macro Definition Documentation

IS_POW2

#define IS_POW2

(

X

)

Value:

((X) != 0 && ((X) & ((X) - 1)) == 0)

Macro to check if a number is a power of two.

Parameters

[in]

X

The number at hand.

Returns

A boolean value indicating whether the number is a power of two.

JOIN

#define JOIN	(		a,
			b )

Value:

XPASTE(a, XPASTE(_, b))

First expand tokens, then paste them together with a _ in between.

PASTE

#define PASTE	(		a,
			b )

Value:

a##b

Paste two tokens together.

XPASTE

#define XPASTE	(		a,
			b )

Value:

PASTE(a, b)

First expand tokens, then paste them together.

Function Documentation

arena_allocate()

void * arena_allocate	(	arena_type *	self,
		const size_t	size )

Get the pointer to a chunk of the arena.

Parameters

[in]	self	The arena pointer.
[in]	size	The section size in bytes.

Returns

A pointer to a zeroed-out memory chunk.

Return values

NULL	If the arena doesn't have enough memory for the allocation.

Examples

arena_example.c.

arena_allocate_aligned()

void * arena_allocate_aligned	(	arena_type *	self,
		const size_t	alignment,
		const size_t	size )

Get the pointer to a chunk of the arena. With specific alignment.

Parameters

[in]	self	arena pointer.
[in]	alignment	alignment size
[in]	size	chunk size

Returns

A pointer to a zeroed-out memory chunk.

Return values

NULL	If the arena doesn't have enough memory for the allocation.

Examples

arena_example.c.

arena_deallocate_all()

void arena_deallocate_all

(

arena_type *

self

)

Deallocate all allocations in the arena.

Parameters

[in]

self

Arena pointer.

Examples

arena_example.c.

arena_init()

void arena_init	(	arena_type *	self,
		const size_t	len,
		unsigned char *	backing_buf )

Initialize the arena.

Parameters

[in]	self	Arena pointer.
[in]	len	Backing buffer length.
[in]	backing_buf	Backing buffer.

Examples

arena_example.c.

arena_reallocate()

void * arena_reallocate	(	arena_type *	self,
		void *	old_ptr,
		const size_t	old_size,
		const size_t	new_size )

Reallocate a previously allocated chunk in the arena.

Parameters

[in]	self	The arena pointer.
[in]	old_ptr	Pointer to the buffer to reallocate
[in]	old_size	Old size.
[in]	new_size	New size to grow/shrink to.

Returns

A pointer to the reallocated memory chunk.

Return values

NULL	If arena doesn't have enough memory for the reallocation or invalid parameters are given.

Examples

arena_example.c.

arena_reallocate_aligned()

void * arena_reallocate_aligned	(	arena_type *	self,
		void *	old_ptr_,
		const size_t	alignment,
		const size_t	old_size,
		const size_t	new_size )

Reallocate a previously allocated chunk in the arena. With specific aligment.

Parameters

[in]	self	Arena pointer.
[in]	old_ptr_	Pointer to the buffer to reallocate
[in]	alignment	Alignment size.
[in]	old_size	Old size.
[in]	new_size	New size to grow/shrink to.

Returns

A pointer to the reallocated memory chunk.

Return values

NULL	If arena doesn't have enough memory for the reallocation or invalid parameters are given.

Examples

arena_example.c.

arena_state_restore()

void arena_state_restore

(

arena_state_type

prev_state

)

Restore the arena state.

Parameters

[in]

prev_state

Stored arena state.

Examples

arena_example.c.

arena_state_save()

arena_state_type arena_state_save

(

arena_type *

arena_ptr

)

Save the arena state temporarily.

Parameters

[in]

arena_ptr

The arena whose state to save.

Examples

arena_example.c.