Ruby: coroutine/ucontext/Context.h Source File

Ruby 4.0.5p0 (2026-05-20 revision 64336ffd0ee9e1f4c05891695a3d7b49cb709721)

Context.h
1#ifndef COROUTINE_UCONTEXT_CONTEXT_H
2#define COROUTINE_UCONTEXT_CONTEXT_H 1
3
4/*
5 * This file is part of the "Coroutine" project and released under the MIT License.
6 *
7 * Created by Samuel Williams on 24/6/2019.
8 * Copyright, 2019, by Samuel Williams.
9*/
10
11#pragma once
12
13#include <assert.h>
14#include <stddef.h>
15#include <ucontext.h>
16
17#define COROUTINE __attribute__((noreturn)) void
18
19#ifdef HAVE_STDINT_H
20#include <stdint.h>
21#if INTPTR_MAX <= INT32_MAX
22#define COROUTINE_LIMITED_ADDRESS_SPACE
23#endif
24#endif
25
26struct coroutine_context
27{
28 ucontext_t state;
29 struct coroutine_context * from;
30 void *argument;
31};
32
33typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
34
35COROUTINE coroutine_trampoline(void * _start, void * _context);
36
37static inline void coroutine_initialize_main(struct coroutine_context * context) {
38 context->from = NULL;
39 getcontext(&context->state);
40}
41
42static inline void coroutine_initialize(
43 struct coroutine_context *context,
44 coroutine_start start,
45 void *stack,
46 size_t size
47) {
48 assert(start && stack && size >= 1024);
49
50 coroutine_initialize_main(context);
51
52 context->state.uc_stack.ss_size = size;
53 // Despite what it's called, this is not actually a stack pointer. It points to the address of the stack allocation (the lowest address).
54 context->state.uc_stack.ss_sp = (char*)stack;
55 context->state.uc_stack.ss_flags = 0;
56 context->state.uc_link = NULL;
57
58 makecontext(&context->state, (void(*)(void))coroutine_trampoline, 2, (void*)start, (void*)context);
59}
60
61static inline struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target)
62{
63 struct coroutine_context * previous = target->from;
64
65 target->from = current;
66 swapcontext(&current->state, &target->state);
67 target->from = previous;
68
69 return target;
70}
71
72static inline void coroutine_destroy(struct coroutine_context * context)
73{
74 context->state.uc_stack.ss_sp = NULL;
75 context->state.uc_stack.ss_size = 0;
76 context->from = NULL;
77}
78
79#endif /* COROUTINE_UCONTEXT_CONTEXT_H */
assert.h
coroutine_context
Definition Context.h:36