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