2 files changed, 102 insertions, 0 deletions
diff --git a/coroutine/ucontext/Context.c b/coroutine/ucontext/Context.c
new file mode 100644
index 0000000000..5d728d554d
--- /dev/null
+++ b/coroutine/ucontext/Context.c
@@ -0,0 +1,23 @@
+/*
+ *  This file is part of the "Coroutine" project and released under the MIT License.
+ *
+ *  Created by Samuel Williams on 24/6/2019.
+ *  Copyright, 2019, by Samuel Williams.
+*/
+
+/* According to Solaris' ucontext.h, makecontext, etc. are removed in SUSv4.
+ * To enable the prototype declarations, we need to define __EXTENSIONS__.
+ */
+#if defined(__sun) && !defined(__EXTENSIONS__)
+#define __EXTENSIONS__
+#endif
+
+#include "Context.h"
+
+void coroutine_trampoline(void * _start, void * _context)
+{
+    coroutine_start start = (coroutine_start)_start;
+    struct coroutine_context * context = _context;
+
+    start(context->from, context);
+}
diff --git a/coroutine/ucontext/Context.h b/coroutine/ucontext/Context.h
new file mode 100644
index 0000000000..d338d8de60
--- /dev/null
+++ b/coroutine/ucontext/Context.h
@@ -0,0 +1,79 @@
+#ifndef COROUTINE_UCONTEXT_CONTEXT_H
+#define COROUTINE_UCONTEXT_CONTEXT_H 1
+
+/*
+ *  This file is part of the "Coroutine" project and released under the MIT License.
+ *
+ *  Created by Samuel Williams on 24/6/2019.
+ *  Copyright, 2019, by Samuel Williams.
+*/
+
+#pragma once
+
+#include <assert.h>
+#include <stddef.h>
+#include <ucontext.h>
+
+#define COROUTINE __attribute__((noreturn)) void
+
+#ifdef HAVE_STDINT_H
+#include <stdint.h>
+#if INTPTR_MAX <= INT32_MAX
+#define COROUTINE_LIMITED_ADDRESS_SPACE
+#endif
+#endif
+
+struct coroutine_context
+{
+    ucontext_t state;
+    struct coroutine_context * from;
+    void *argument;
+};
+
+typedef COROUTINE(* coroutine_start)(struct coroutine_context *from, struct coroutine_context *self);
+
+COROUTINE coroutine_trampoline(void * _start, void * _context);
+
+static inline void coroutine_initialize_main(struct coroutine_context * context) {
+    context->from = NULL;
+    getcontext(&context->state);
+}
+
+static inline void coroutine_initialize(
+    struct coroutine_context *context,
+    coroutine_start start,
+    void *stack,
+    size_t size
+) {
+    assert(start && stack && size >= 1024);
+
+    coroutine_initialize_main(context);
+
+    context->state.uc_stack.ss_size = size;
+    // Despite what it's called, this is not actually a stack pointer. It points to the address of the stack allocation (the lowest address).
+    context->state.uc_stack.ss_sp = (char*)stack;
+    context->state.uc_stack.ss_flags = 0;
+    context->state.uc_link = NULL;
+
+    makecontext(&context->state, (void(*)(void))coroutine_trampoline, 2, (void*)start, (void*)context);
+}
+
+static inline struct coroutine_context * coroutine_transfer(struct coroutine_context * current, struct coroutine_context * target)
+{
+    struct coroutine_context * previous = target->from;
+
+    target->from = current;
+    swapcontext(&current->state, &target->state);
+    target->from = previous;
+
+    return target;
+}
+
+static inline void coroutine_destroy(struct coroutine_context * context)
+{
+    context->state.uc_stack.ss_sp = NULL;
+    context->state.uc_stack.ss_size = 0;
+    context->from = NULL;
+}
+
+#endif /* COROUTINE_UCONTEXT_CONTEXT_H */