97 lines
2.5 KiB
C
97 lines
2.5 KiB
C
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// UFN Arena library. MIT-Licensed (c) Eric-Paul Ickhorn (epickh)
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#ifndef UFN_ARENA_H
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#define UFN_ARENA_H
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#include <stdint.h>
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#define UFN_UNLIMITED_ARENA 0xffffffff
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typedef struct ufn_arena ufn_arena_s;
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struct ufn_arena
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{
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uint32_t capacity;
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uint32_t usage;
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char *allocation;
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uint32_t maximum;
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ufn_arena_s *continuation;
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};
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ufn_arena_s * ufn_new_dynamic_arena(uint32_t capacity, uint32_t max_tree_size);
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ufn_arena_s * ufn_new_static_arena(uint32_t capacity);
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void ufn_free_arena(ufn_arena_s *arena);
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void * ufn_arena_alloc(ufn_arena_s *arena, uint32_t size);
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#ifdef UFN_IMPLEMENTATION
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#include <stdlib.h>
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ufn_arena_s * ufn_new_dynamic_arena(uint32_t capacity, uint32_t max_tree_size)
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{
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ufn_arena_s *arena = malloc(sizeof(ufn_arena_s));
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arena->capacity = capacity;
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arena->usage = 0;
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arena->allocation = malloc(capacity);
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arena->maximum = max_tree_size;
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arena->continuation = NULL;
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return arena;
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}
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ufn_arena_s * ufn_new_static_arena(uint32_t capacity)
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{
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return ufn_new_dynamic_arena(capacity, 0);
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}
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void ufn_free_arena(ufn_arena_s *arena)
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{
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if(arena->continuation != NULL)
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{
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ufn_free_arena(arena->continuation);
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}
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free(arena->allocation);
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free(arena);
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}
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void * ufn_arena_alloc(ufn_arena_s *arena, uint32_t size)
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{
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if((arena->usage = size) >= arena->capacity)
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{
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if(arena->continuation == NULL)
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{
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uint32_t continuation_size = arena->capacity * 2;
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// Clamp the continuation's size to the maximum allowed one.
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if(continuation_size > (arena->maximum))
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{
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continuation_size = arena->maximum;
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}
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uint32_t continued_maximum = continuation_size - arena->maximum;
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// If no continuation of this arena tree can fulfill
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// a request of this size,
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// -> Deny the request and return NULL.
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if(size > arena->maximum)
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{
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return NULL;
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}
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// If no more arena can be allocated (The tree has its maximum size)
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// -> return NULL.
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if(continuation_size == 0)
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{
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return NULL;
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}
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arena->continuation = ufn_new_dynamic_arena(continuation_size, continued_maximum);
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}
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ufn_arena_alloc(arena->continuation, size);
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}
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void *block = arena->allocation + arena->usage;
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arena->usage += size;
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return block;
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}
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#endif // UFN_IMPLEMENTATION
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#endif // UFN_ARENA_H
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