1 files changed, 43 insertions, 0 deletions
diff --git a/wasm/fiber.h b/wasm/fiber.h
new file mode 100644
index 0000000000..0f3a336332
--- /dev/null
+++ b/wasm/fiber.h
@@ -0,0 +1,43 @@
+#ifndef RB_WASM_SUPPORT_FIBER_H
+#define RB_WASM_SUPPORT_FIBER_H
+
+#include <stdbool.h>
+
+#ifndef WASM_FIBER_STACK_BUFFER_SIZE
+# define WASM_FIBER_STACK_BUFFER_SIZE 6144
+#endif
+
+struct __rb_wasm_asyncify_fiber_ctx {
+    void* top;
+    void* end;
+    char buffer[WASM_FIBER_STACK_BUFFER_SIZE];
+};
+
+// Fiber execution context needed to perform context switch
+typedef struct {
+    // Fiber entry point called when the fiber started for the first time.
+    // NULL if the entry point is main
+    void (*entry_point)(void *, void *);
+    // Opaque argument pointers passed to the entry point function
+    void *arg0, *arg1;
+
+    // Internal asyncify buffer space
+    struct __rb_wasm_asyncify_fiber_ctx asyncify_buf;
+
+    bool is_rewinding;
+    bool is_started;
+} rb_wasm_fiber_context;
+
+// Initialize a given fiber context to be ready to pass to `rb_wasm_swapcontext`
+void rb_wasm_init_context(rb_wasm_fiber_context *fcp, void (*func)(void *, void *), void *arg0, void *arg1);
+
+// Swap the execution control with `target_fiber` and save the current context in `old_fiber`
+// NOTE: `old_fiber` must be the current executing fiber context
+void rb_wasm_swapcontext(rb_wasm_fiber_context *old_fiber, rb_wasm_fiber_context *target_fiber);
+
+// Returns the Asyncify buffer of next fiber if unwound for fiber context switch.
+// Used by the top level Asyncify handling in wasm/runtime.c
+void *rb_wasm_handle_fiber_unwind(void (**new_fiber_entry)(void *, void *),
+                                  void **arg0, void **arg1, bool *is_new_fiber_started);
+
+#endif