51 lines
1.2 KiB
C
51 lines
1.2 KiB
C
#ifndef ARENA_H
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#define ARENA_H
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#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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typedef enum {
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ARENA_ZERO = 1 << 0,
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ARENA_SOFTFAIL = 1 << 1,
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} arena_flags_t;
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// More or less taken from https://nullprogram.com/blog/2023/09/27/
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typedef struct {
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uint8_t *begin;
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uint8_t *end;
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} arena_t;
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arena_t arena_create(ptrdiff_t capacity)
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{
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arena_t a = {0};
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a.begin = malloc(capacity);
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a.end = a.begin ? a.begin + capacity : 0;
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return a;
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}
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void *arena_alloc(arena_t *a, ptrdiff_t size, ptrdiff_t align, ptrdiff_t count, arena_flags_t flags)
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{
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ptrdiff_t padding = -(uintptr_t)a->begin & (align - 1);
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ptrdiff_t available = a->end - a->begin - padding;
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if (available < 0 || count > available/size)
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{
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// TODO: Decide what to do on oom
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if (flags & ARENA_SOFTFAIL)
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return 0;
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else
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abort();
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}
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void *p = a->begin + padding;
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a->begin += padding + count*size;
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return flags & ARENA_ZERO ? p : memset(p, 0, count*size);
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}
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#define arena_reserve(arena, type, count, flags) (type *)arena_alloc(arena, sizeof(type), _Alignof(type), count, flags)
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#define KB 1024
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#define MB 1024*KB
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#define GB 1024*MB
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#endif
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