diff --git a/src/arena_allocator.c b/src/arena_allocator.c index e5b6b9c..d543d4a 100644 --- a/src/arena_allocator.c +++ b/src/arena_allocator.c @@ -3,30 +3,55 @@ #include #include -#define DEFAULT_ARENA_SIZE 1048576 /* 8 * 1024 * 1024 = 8MB */ +#define DEFAUL_REGION_SIZE 1048576 /* 8 * 1024 * 1024 = 8MB */ + +Region *new_region(size_t capacity) { + if (capacity == 0) { + capacity = DEFAUL_REGION_SIZE; + } + Region *region = malloc(capacity); + assert(region != NULL); + *region = (Region){.next = NULL, + .capacity = capacity + sizeof(Region), + .cursor = sizeof(Region) - 1}; + return region; +} Arena arena_init(size_t capacity) { - if (capacity == 0) { - capacity = DEFAULT_ARENA_SIZE; - } - Arena result = {.capacity = capacity, .size = 0, .data = malloc(capacity)}; - assert(result.data != NULL); - return result; + Region *region = new_region(capacity); + Arena arena = {.begin = region, .end = region}; + return arena; } void arena_deinit(Arena *arena) { - free(arena->data); - *arena = (Arena){.capacity = 0, .size = 0, .data = NULL}; + assert(arena->begin != NULL && arena->end != NULL); + Region *region = arena->begin; + while (region != NULL) { + Region *next_region = region->next; + free(region); + region = next_region; + } + *arena = (Arena){.begin = NULL, .end = NULL}; } void *arena_alloc(Arena *arena, size_t size) { - assert(arena->size + size <= arena->capacity); - void *result = &arena->data[arena->size]; - arena->size += size; + Region *region = arena->end; + assert(region != NULL); + + if (region->cursor + size > region->capacity) { + if (size < DEFAUL_REGION_SIZE) + size = DEFAUL_REGION_SIZE; + region->next = new_region(size); + arena->end = region->next; + region = region->next; + } + + void *result = ®ion->data[region->cursor]; + region->cursor += size; return result; } -void *arena_clear(Arena *arena) { - arena->size = 0; - return arena->data; -} +//void *arena_clear(Arena *arena) { +// arena->size = 0; +// return arena->data; +//} diff --git a/src/arena_allocator.h b/src/arena_allocator.h index 981f76c..3300084 100644 --- a/src/arena_allocator.h +++ b/src/arena_allocator.h @@ -1,15 +1,23 @@ #pragma once #include +#include + +typedef struct Region_s Region; +struct Region_s { + Region *next; + size_t capacity; + size_t cursor; + uintptr_t data[]; +}; typedef struct { - size_t capacity; - size_t size; - unsigned char *data; + Region *begin; + Region *end; } Arena; Arena arena_init(size_t capacity); void arena_deinit(Arena *arena); void *arena_alloc(Arena *arena, size_t size); -void *arena_clear(Arena *arena); +//void *arena_clear(Arena *arena);