Ruby  3.1.4p223 (2023-03-30 revision HEAD)
Context.h
1 #ifndef COROUTINE_EMSCRIPTEN_CONTEXT_H
2 #define COROUTINE_EMSCRIPTEN_CONTEXT_H 1
3 
4 /* An experimental coroutine wrapper for emscripten
5  * Contact on Yusuke Endoh if you encounter any problem about this
6  */
7 
8 #pragma once
9 
10 #include <assert.h>
11 #include <stddef.h>
12 #include <emscripten/fiber.h>
13 
14 #define COROUTINE __attribute__((noreturn)) void
15 
16 #if INTPTR_MAX <= INT32_MAX
17 #define COROUTINE_LIMITED_ADDRESS_SPACE
18 #endif
19 
20 struct coroutine_context;
21 
22 typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
23 
24 struct coroutine_context
25 {
26  emscripten_fiber_t state;
27  coroutine_start entry_func;
28  struct coroutine_context * from;
29  void *argument;
30 };
31 
32 COROUTINE coroutine_trampoline(void * _context);
33 
34 #define MAIN_ASYNCIFY_STACK_SIZE 65536
35 static inline void coroutine_initialize_main(struct coroutine_context * context) {
36  static char asyncify_stack[MAIN_ASYNCIFY_STACK_SIZE];
37  emscripten_fiber_init_from_current_context(&context->state, asyncify_stack, MAIN_ASYNCIFY_STACK_SIZE);
38 }
39 #undef MAIN_ASYNCIFY_STACK_SIZE
40 
41 static inline void coroutine_initialize(
42  struct coroutine_context *context,
43  coroutine_start start,
44  void *stack,
45  size_t size
46 ) {
47  assert(start && stack && size >= 1024);
48 
49  uintptr_t addr = (uintptr_t)stack;
50  size_t offset = addr & 0xF;
51  void *c_stack = (void*)((addr + 0xF) & ~0xF);
52  size -= offset;
53  size_t c_stack_size = (size / 2) & ~0xF;
54  void *asyncify_stack = (void*)((uintptr_t)c_stack + c_stack_size);
55  size_t asyncify_stack_size = size - c_stack_size;
56  context->entry_func = start;
57 
58  emscripten_fiber_init(&context->state, coroutine_trampoline, context, c_stack, c_stack_size, asyncify_stack, asyncify_stack_size);
59 }
60 
61 static 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  emscripten_fiber_swap(&current->state, &target->state);
67  target->from = previous;
68 
69  return target;
70 }
71 
72 static inline void coroutine_destroy(struct coroutine_context * context)
73 {
74  context->from = NULL;
75 }
76 
77 #endif /* COROUTINE_EMSCRIPTEN_CONTEXT_H */