Generic Allocator Interface

A vtable structure for passing allocators dynamically. More...

Classes
struct	MemAllocator
	An abstract allocator interface. More...

Typedefs
typedef enum MemAllocMode	MemAllocMode
	Describes the type of memory operation being requested.
typedef void *(*	MemAllocFn) (MemAllocMode mode, void *ctx, usize size, void *old_ptr)
	The core function signature for an abstract allocator.
typedef struct MemAllocator	MemAllocator
	An abstract allocator interface.

Enumerations
enum	MemAllocMode { MEM_ALLOC_MODE_ALLOC , MEM_ALLOC_MODE_FREE , MEM_ALLOC_MODE_REALLOC , MEM_ALLOC_MODE_FREE_ALL }
	Describes the type of memory operation being requested. More...

Functions
function void *	mem_alloc (MemAllocator *alloc, usize size)
	Allocator Helper Functions.
function void *	mem_realloc (MemAllocator *alloc, void *old_ptr, usize old_size, usize new_size)
	Resizes a previously allocated block through the allocator.
function void	mem_free (MemAllocator *alloc, void *ptr, usize size)
	Frees a previously allocated block through the allocator.
function void	mem_free_all (MemAllocator *alloc)
	Clears the entire allocator in one shot (e.g. arena reset, pool reset).

Detailed Description

A vtable structure for passing allocators dynamically.

Typedef Documentation

MemAllocFn

typedef void *(* MemAllocFn) (MemAllocMode mode, void *ctx, usize size, void *old_ptr)

The core function signature for an abstract allocator.

• Parameters

  mode	The memory operation being requested.
  ctx	The internal context/state of the allocator (e.g., pointer to an Arena).
  size	The size of the requested allocation.
  old_ptr	A pointer to existing memory (used during FREE and REALLOC modes).

  Returns

  A pointer to the newly allocated memory, or NULL on failure or FREE.

Definition at line 80 of file mem_allocator.h.

Enumeration Type Documentation

MemAllocMode

enum MemAllocMode

Describes the type of memory operation being requested.

Enumerator
MEM_ALLOC_MODE_ALLOC	Request new memory.
MEM_ALLOC_MODE_FREE	Free existing memory.
MEM_ALLOC_MODE_REALLOC	Resize existing memory.
MEM_ALLOC_MODE_FREE_ALL	Clear the entire allocator (if supported).

Definition at line 65 of file mem_allocator.h.

Function Documentation

mem_alloc()

function void * mem_alloc ( MemAllocator * alloc, usize size )

inline

Allocator Helper Functions.

Allocates size zero-initialized bytes through the allocator.

Example:

MemAllocator alloc = mem_arena_allocator(&arena);
int *nums = (int *)mem_alloc(&alloc, sizeof(int) * 64);
// nums[0..63] are all zero

Parameters

alloc	Pointer to the allocator.
size	Number of bytes to allocate.

Returns

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

Definition at line 105 of file mem_allocator.h.

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mem_free()

function void mem_free ( MemAllocator * alloc, void * ptr, usize size )

inline

Frees a previously allocated block through the allocator.

No-op for arena allocators. Always safe to call regardless of allocator type.

Example:

MemAllocator alloc = mem_gpalloc();
MyStruct *s = MAKE_STRUCT(MyStruct, &alloc);
// ... use s ...
mem_free(&alloc, s, sizeof(MyStruct));

Parameters

alloc	Pointer to the allocator.
ptr	Pointer to free.
size	The size originally requested.

Definition at line 166 of file mem_allocator.h.

mem_free_all()

function void mem_free_all ( MemAllocator * alloc )

inline

Clears the entire allocator in one shot (e.g. arena reset, pool reset).

For arena allocators this resets pos to 0. For heap allocators this is a no-op. Use this instead of manually calling mem_arena_clear() so that code stays allocator-agnostic.

Parameters

alloc

Pointer to the allocator to clear.

Definition at line 181 of file mem_allocator.h.

mem_realloc()

function void * mem_realloc ( MemAllocator * alloc, void * old_ptr, usize old_size, usize new_size )

inline

Resizes a previously allocated block through the allocator.

For arena allocators this always allocates a fresh block and copies the old data — the old block is not freed since arenas don't support individual frees. For heap allocators this maps to realloc.

Example:

MemAllocator alloc = mem_gpalloc();
int *buf = (int *)mem_alloc(&alloc, sizeof(int) * 4);
buf[0] = 1; buf[3] = 4;
 
// Grow to 8 elements — old data is preserved:
buf = (int *)mem_realloc(&alloc, buf, sizeof(int) * 4, sizeof(int) * 8);
// buf[0] == 1, buf[3] == 4, buf[4..7] == 0

Parameters

alloc	Pointer to the allocator.
old_ptr	Existing allocation to resize.
old_size	Size of the existing allocation in bytes.
new_size	Desired new size in bytes.

Returns

Pointer to the resized allocation, or NULL on OOM.

Definition at line 135 of file mem_allocator.h.