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#ifndef ARENA_H
#define ARENA_H
#include "typ.h"
typedef struct {
char *beg, *end;
} Arena;
#define new(a, t)\
zeroed(alloc(a, sizeof(t), _Alignof(t)), sizeof(t))
#define new_arr(a, t, n)\
alloc(a, sizeof(t) * n, _Alignof(t))
#define resize(a, p, old, new)\
re_alloc(a, p, (old) * sizeof(*(p)), (new) * sizeof(*(p)),\
_Alignof(__typeof__(*(p))))
void *alloc(Arena *a, isize n, isize align);
void *re_alloc(Arena *a, void *ptr, isize old, isize new, isize align);
void *zeroed(void *p, usize n);
#ifdef ARENA_IMPL
#include <stdio.h>
#include <stdlib.h>
void *alloc(Arena *a, isize n, isize align) {
char *p = a->beg + (-(uintptr_t)a->beg & (align - 1));
if (p + n >= a->end) {
fprintf(stderr, "out of arena memory!\n");
abort();
}
a->beg = p + n;
return p;
}
void *zeroed(void *p, usize n) {
memset(p, 0, n);
return p;
}
void *re_alloc(Arena *a, void *ptr, isize old, isize new, isize align) {
if (ptr && a->beg - old == ptr && a->beg - old + new < a->end) {
a->beg = a->beg - old + new;
return ptr;
} else {
void *p = alloc(a, new, align);
if (ptr) memcpy(p, ptr, old);
return p;
}
}
#endif
#endif
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