Generic Allocator Interface

Classes
struct	Allocator
	A generic allocator backed by function pointers (vtable). More...

Typedefs
typedef void *(*	AllocFn) (void *ctx, usize size)
	Function pointer type for an allocation operation.
typedef void(*	FreeFn) (void *ctx, void *ptr, usize size)
	Function pointer type for a free operation.
typedef void *(*	ReallocFn) (void *ctx, void *ptr, usize old_size, usize new_size)
	Function pointer type for a realloc operation.
typedef struct Allocator	Allocator
	A generic allocator backed by function pointers (vtable).

Functions
function void *	allocator_alloc (Allocator *a, usize size)
	Allocates size zero-initialized bytes through the allocator.
function void	allocator_free (Allocator *a, void *ptr, usize size)
	Frees a previously allocated block through the allocator.
function void *	allocator_realloc (Allocator *a, void *ptr, usize old_size, usize new_size)
	Resizes a previously allocated block through the allocator.
function Allocator	arena_allocator (Arena *arena)
	Constructs an Allocator interface backed by an existing Arena.

Detailed Description

Typedef Documentation

Allocator

typedef struct Allocator Allocator

A generic allocator backed by function pointers (vtable).

Pass by pointer to any function that needs to allocate memory without caring about the concrete allocator type.

Note

Passing by pointer is preferred over by value to allow the callee to observe state changes (e.g., arena pos advancing).

AllocFn

typedef void *(* AllocFn) (void *ctx, usize size)

Function pointer type for an allocation operation.

Parameters

ctx	Opaque allocator context (e.g., a pointer to an Arena).
size	Number of bytes to allocate.

Returns

Pointer to zero-initialized memory, or NULL on OOM.

Definition at line 70 of file mem_allocator.h.

FreeFn

typedef void(* FreeFn) (void *ctx, void *ptr, usize size)

Function pointer type for a free operation.

For allocators that do not support individual frees (e.g., Arena), this may be a no-op. size is provided so implementations can track usage without storing it internally.

Parameters

ctx	Opaque allocator context.
ptr	Pointer previously returned by AllocFn.
size	The size that was originally requested.

Definition at line 83 of file mem_allocator.h.

ReallocFn

typedef void *(* ReallocFn) (void *ctx, void *ptr, usize old_size, usize new_size)

Function pointer type for a realloc operation.

For arena allocators, this always performs a fresh allocation (the old block is not freed).

Parameters

ctx	Opaque allocator context.
ptr	Existing allocation to resize (may be NULL for a fresh alloc).
old_size	Size of the existing allocation.
new_size	Desired size of the new allocation.

Returns

Pointer to the resized allocation, or NULL on OOM.

Definition at line 97 of file mem_allocator.h.

Function Documentation

allocator_alloc()

function void * allocator_alloc ( Allocator * a, usize size )

inline

Allocates size zero-initialized bytes through the allocator.

Parameters

a	Pointer to the Allocator.
size	Number of bytes to allocate.

Returns

Pointer to zero-initialized memory, or NULL on OOM.

Definition at line 124 of file mem_allocator.h.

allocator_free()

function void allocator_free ( Allocator * a, void * ptr, usize size )

inline

Frees a previously allocated block through the allocator.

No-op for arena-backed allocators. Always safe to call.

Parameters

a	Pointer to the Allocator.
ptr	Pointer to free.
size	The size originally requested.

Definition at line 140 of file mem_allocator.h.

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allocator_realloc()

function void * allocator_realloc ( Allocator * a, void * ptr, usize old_size, usize new_size )

inline

Resizes a previously allocated block through the allocator.

Falls back to fresh alloc + memcpy + free if .realloc == NULL.

Parameters

a	Pointer to the Allocator.
ptr	Existing allocation to resize (may be NULL).
old_size	Size of the existing allocation.
new_size	Desired new size.

Returns

Pointer to resized allocation, or NULL on OOM.

Definition at line 160 of file mem_allocator.h.

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arena_allocator()

function Allocator arena_allocator ( Arena * arena )

inline

Constructs an Allocator interface backed by an existing Arena.

The returned Allocator holds a pointer to arena the arena must outlive any use of the returned Allocator.

Example:

Arena     arena = arena_create(MB(64));
Allocator ally  = arena_allocator(&arena);
build_scene(&ally);

Parameters

arena

Pointer to an initialized Arena.

Returns

An Allocator whose alloc/free/realloc functions delegate to arena.

Definition at line 220 of file mem_allocator.h.