Add 'libco/' from commit '7871e50f7d48444f1a6333128308acb0a1c8ad2b'

git-subtree-dir: libco
git-subtree-mainline: c5b39e2dfc
git-subtree-split: 7871e50f7d

libco/fiber.c

@@ -0,0 +1,55 @@
+#define LIBCO_C
+#include "libco.h"
+#include "settings.h"
+
+#define WINVER 0x0400
+#define _WIN32_WINNT 0x0400
+#include <windows.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+static thread_local cothread_t co_active_ = 0;
+
+static void __stdcall co_thunk(void* coentry) {
+  ((void (*)(void))coentry)();
+}
+
+cothread_t co_active() {
+  if(!co_active_) {
+    ConvertThreadToFiber(0);
+    co_active_ = GetCurrentFiber();
+  }
+  return co_active_;
+}
+
+cothread_t co_derive(void* memory, unsigned int heapsize, void (*coentry)(void)) {
+  //Windows fibers do not allow users to supply their own memory
+  return (cothread_t)0;
+}
+
+cothread_t co_create(unsigned int heapsize, void (*coentry)(void)) {
+  if(!co_active_) {
+    ConvertThreadToFiber(0);
+    co_active_ = GetCurrentFiber();
+  }
+  return (cothread_t)CreateFiber(heapsize, co_thunk, (void*)coentry);
+}
+
+void co_delete(cothread_t cothread) {
+  DeleteFiber(cothread);
+}
+
+void co_switch(cothread_t cothread) {
+  co_active_ = cothread;
+  SwitchToFiber(cothread);
+}
+
+int co_serializable() {
+  return 0;
+}
+
+#ifdef __cplusplus
+}
+#endif