1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
|
#include <lcq/pit/arena.h>
#include <lcq/pit/utils.h>
pit_arena *pit_arena_new(u8 *buf, i64 buf_len, i64 elem_size) {
uintptr_t base = (uintptr_t) buf;
uintptr_t aligned = pit_align_up(base, sizeof(void *));
pit_arena *a = (pit_arena *) aligned;
uintptr_t data = aligned + sizeof(pit_arena);
i64 offset = (i64) data - (i64) base;
i64 remaining = (i64) pit_align_down((uintptr_t) (buf_len - offset), sizeof(void *));
if (!a || remaining <= 0) return NULL;
a->elem_size = elem_size;
a->capacity = remaining;
a->next = 0;
a->back = remaining;
return a;
}
void pit_arena_reset(pit_arena *a) {
a->next = 0;
a->back = a->capacity;
}
static i64 pit_arena_byte_idx(pit_arena *a, pit_arena_index idx) {
i64 byte_idx = 0; pit_mul(&byte_idx, a->elem_size, idx);
return byte_idx;
}
pit_arena_index pit_arena_alloc_index(pit_arena *a) {
i64 ret = a->next;
i64 byte_idx = pit_arena_byte_idx(a, ret);
if (byte_idx + a->elem_size >= a->back) { return -1; }
a->next += 1;
return ret;
}
pit_arena_index pit_arena_alloc_array_index(pit_arena *a, i64 num) {
i64 ret = a->next;
i64 byte_idx = pit_arena_byte_idx(a, ret);
i64 byte_len = 0; pit_mul(&byte_len, a->elem_size, num);
if (byte_idx + byte_len > a->back) { return -1; }
a->next += num;
return ret;
}
void *pit_arena_alloc(pit_arena *a) {
return pit_arena_get(a, pit_arena_alloc_index(a));
}
void *pit_arena_alloc_array(pit_arena *a, i64 num) {
return pit_arena_get(a, pit_arena_alloc_array_index(a, num));
}
void *pit_arena_get(pit_arena *a, pit_arena_index idx) {
i64 byte_idx = pit_arena_byte_idx(a, idx);
if (byte_idx < 0 || byte_idx + a->elem_size >= a->back) { return NULL; }
return &a->data[byte_idx];
}
void *pit_arena_alloc_back(pit_arena *a, i64 sz) {
i64 next_byte = pit_arena_byte_idx(a, a->next);
i64 back_byte = (i64) pit_align_down((uintptr_t) (a->back - sz), sizeof(void *));
if (back_byte < next_byte) return NULL;
a->back = back_byte;
return &a->data[a->back];
}
|
