1/* @title: One-time atomic tokens */
2#pragma once
3#include <atomic.h>
4#include <compiler/core.h>
5#include <stdbool.h>
6
7#define ONCE_TOKEN_DEFINE(type, name) \
8 struct { \
9 atomic(type) state; \
10 } name
11
12#define ONCE_TOKEN_INIT(val) {.state = ATOMIC_VAR_INIT(val)}
13
14/* ===== typecheck ===== */
15#define once_token_typecheck_internal(tok) ((void) sizeof((tok)->state))
16
17#define once_token_typecheck_internal_type(tok, type) \
18 ct_typecheck(type, atomic_load_rlx(&(tok)->state))
19
20#define once_token_typecheck_internal_bool(tok) \
21 once_token_typecheck_internal_type(tok, bool)
22
23#define once_token_typecheck_internal_same(tok1, tok2) \
24 ct_typecheck_same(atomic_load_rlx(&(tok1)->state), \
25 atomic_load_rlx(&(tok2)->state))
26
27/* ===== init ===== */
28#define once_token_init_1(tok) \
29 ({ \
30 __auto_type __ot_tok = (tok); \
31 once_token_typecheck_internal_bool(__ot_tok); \
32 static_assert(cc_generic((__ot_tok->state), bool : 1, default : 0), \
33 "once_token_init_1 requires a boolean token"); \
34 atomic_init(&__ot_tok->state, false); \
35 })
36
37#define once_token_init_2(tok, val) \
38 ({ \
39 __auto_type __ot_tok = (tok); \
40 once_token_typecheck_internal(__ot_tok); \
41 typeof(atomic_load_rlx(&__ot_tok->state)) __ot_val = (val); \
42 atomic_init(&__ot_tok->state, __ot_val); \
43 })
44
45#define once_token_init(...) PP_CALL(once_token_init, __VA_ARGS__)
46
47/* ===== claim ===== */
48/* The 2 and 4 argument versions return what was actually there, which
49 * can be used to inspect whether something unexpected happened */
50#define once_token_claim_4(tok, from, to, out) \
51 ({ \
52 __auto_type __ot_tok = (tok); \
53 once_token_typecheck_internal(__ot_tok); \
54 ct_typecheck_same(from, to); \
55 typeof(atomic_load_rlx(&__ot_tok->state)) __ot_exp = (from); \
56 typeof(__ot_exp) __ot_to = (to); \
57 __auto_type __ot_out = (out); \
58 static_assert(ct_is_type(typeof(__ot_exp) *, out) || \
59 (ct_is_const(out) && (out) == NULL), \
60 "once_token_claim out must point to the token state " \
61 "type or be NULL"); \
62 bool ret = atomic_cas_strong(&__ot_tok->state, &__ot_exp, __ot_to, \
63 mo_acq_rel, mo_acquire); \
64 if (__ot_out) \
65 *((typeof(__ot_exp) *) __ot_out) = __ot_exp; \
66 ret; \
67 })
68
69#define once_token_claim_3(tok, from, to) \
70 once_token_claim_4(tok, from, to, NULL)
71
72#define once_token_claim_2(tok, out) \
73 ({ \
74 once_token_typecheck_internal_bool(tok); \
75 static_assert(cc_generic(((tok)->state), bool : 1, default : 0), \
76 "once_token_claim_1 argument requires a boolean token"); \
77 once_token_claim_4(tok, false, true, out); \
78 })
79
80#define once_token_claim_1(tok) once_token_claim_2(tok, NULL)
81
82#define once_token_claim(...) PP_CALL(once_token_claim, __VA_ARGS__)
83
84/* ===== claimed ===== */
85#define once_token_claimed_1(tok) \
86 ({ \
87 __auto_type __ot_tok = (tok); \
88 once_token_typecheck_internal_bool(__ot_tok); \
89 static_assert(cc_generic((__ot_tok->state), bool : 1, default : 0), \
90 "once_token_claimed_1 requires a boolean token"); \
91 \
92 atomic_load_acq(&__ot_tok->state); \
93 })
94
95#define once_token_claimed_2(tok, val) \
96 ({ \
97 __auto_type __ot_tok = (tok); \
98 once_token_typecheck_internal(__ot_tok); \
99 typeof(atomic_load_rlx(&__ot_tok->state)) __ot_val = (val); \
100 \
101 atomic_load_acq(&__ot_tok->state) == __ot_val; \
102 })
103
104#define once_token_claimed(...) PP_CALL(once_token_claimed, __VA_ARGS__)
105
106/* ===== reset ===== */
107#define once_token_reset_1(tok) \
108 ({ \
109 __auto_type __ot_tok = (tok); \
110 once_token_typecheck_internal_bool(__ot_tok); \
111 static_assert(cc_generic((__ot_tok->state), bool : 1, default : 0), \
112 "once_token_reset_1 requires a boolean token"); \
113 atomic_store_release(&__ot_tok->state, false); \
114 })
115
116#define once_token_reset_2(tok, val) \
117 ({ \
118 __auto_type __ot_tok = (tok); \
119 once_token_typecheck_internal(__ot_tok); \
120 typeof(atomic_load_rlx(&__ot_tok->state)) __ot_val = (val); \
121 atomic_store_release(&__ot_tok->state, __ot_val); \
122 })
123
124#define once_token_reset(...) PP_CALL(once_token_reset, __VA_ARGS__)
125
126#define once_token_read(tok) \
127 ({ \
128 __auto_type __ot_tok = (tok); \
129 once_token_typecheck_internal(__ot_tok); \
130 atomic_load_acq(&__ot_tok->state); \
131 })
132