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Added: Arena allocator improvements

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This commit is contained in:
rhuibertsjr 2024-06-04 11:25:55 +02:00
parent bcebc14b5a
commit 3866404505
2 changed files with 87 additions and 19 deletions

View File

@ -1,40 +1,93 @@
internal Arena *
arena_initialize(u64 size)
arena_initialize(u64 size, b8 growable)
{
Arena *result = 0;
void *backing_buffer = malloc(size);
void *backing_buffer = platform_memory_reserve(size);
if (backing_buffer != NULL)
{
result = (Arena*) backing_buffer;
platform_memory_commit(backing_buffer, ARENA_INITIAL_COMMIT_SIZE);
result->buffer = backing_buffer;
result->offset = sizeof(Arena);
result->size = sizeof(Arena) + size;
result = (Arena*) backing_buffer;
result->backing_buffer = (u64*) backing_buffer;
result->current = result;
result->prev = 0;
// rhjr: immutable arena header
result->base_pos =
memory_align(sizeof(Arena), ARENA_DEFAULT_ALIGNMENT);
result->offset = result->base_pos;
result->growable = growable;
result->size = size;
}
// rhjr: arenas should be instantiated early on in the programs lifetime, that
// is why this assertion will also be used in production.
ASSERT(result != 0);
return result;
}
internal Arena *
arena_initialize_default()
{
Arena *result = arena_initialize(ARENA_DEFAULT_RESERVE_SIZE, 1);
return result;
}
internal void *
arena_allocate(Arena *arena, u64 size)
{
void *result = 0;
Arena *current = arena->current;
u64 pos_cur = current->base_pos + current->offset;
u64 pos_mem = memory_align(pos_cur, ARENA_DEFAULT_ALIGNMENT);
u64 pos_new = pos_mem + size;
if (arena->offset + size <= arena->size)
if (current->size < pos_new && current->growable)
{
result = (void*)((u64) arena->buffer + (u64) arena->offset);
arena->offset += size;
Arena *new_memory_bock;
memset(result, 0, size);
if (size > ARENA_DEFAULT_RESERVE_SIZE)
{
// rhjr: TODO add support for allocations larger then a single page, in a
// single allocation call.
ASSERT(0);
}
else
{
new_memory_bock = arena_initialize_default();
if (new_memory_bock)
{
stack_push(arena->current, new_memory_bock, prev);
current = new_memory_bock;
pos_mem =
memory_align(current->offset, ARENA_DEFAULT_ALIGNMENT);
pos_new = current->offset + size;
}
return result;
}
}
void *memory = (void*)((u64) current->backing_buffer + pos_mem);
arena->offset = pos_new;
platform_memory_commit(memory, size);
memset(memory, 0, size);
return memory;
}
internal void
arena_release(Arena *arena)
{
arena->offset = 0;
for (Arena *node = arena->current, *prev = 0; node != 0; node = prev)
{
prev = node->prev;
platform_memory_release(node, node->size);
}
}

View File

@ -1,19 +1,30 @@
#ifndef ARENA_H
#define ARENA_H
#define ARENA_INITIAL_COMMIT_SIZE sizeof(struct Arena)
#define ARENA_DEFAULT_ALIGNMENT 0
#ifndef ARENA_DEFAULT_RESERVE_SIZE
# define ARENA_DEFAULT_RESERVE_SIZE KB(4)
#endif // ARENA_DEFAULT_RESERVE_SIZE
typedef struct Arena Arena;
struct Arena {
u64 *buffer;
struct Arena *current;
struct Arena *prev;
u64 *backing_buffer;
u64 base_pos;
u64 offset;
u64 size;
b8 growable;
};
internal Arena * arena_initialize(u64 size);
//= rhjr: arenas
internal Arena * arena_initialize(u64 size, b8 growable);
internal Arena * arena_initialize_default();
internal void * arena_allocate(Arena *arena, u64 size);
internal void arena_release(Arena *arena);
//= rhjr: arena helpers
#define arena_push_array(arena, type, count) \
(type*) arena_allocate((arena), sizeof(type) * (count))
@ -21,8 +32,12 @@ internal void arena_release(Arena *arena);
#define arena_push(arena, type) \
(type*) arena_allocate((arena), sizeof(type))
internal void arena_release(Arena *arena);
//= rhjr: memory helpers
#define memory_align(x, b) ((b != 0) ? (((x) + (b) - 1) & (~(b - 1))) : (x))
#define memory_zero(s,z) memset((s), 0, (z))
#define memory_zero_struct(s) memory_zero((s), sizeof(*(s)))