From b8cc2491d8d2f239df29a6f85ad8b21e0221e8d1 Mon Sep 17 00:00:00 2001
From: johannst <johannes.stoelp@gmail.com>
Date: Sat, 19 Sep 2020 19:16:39 +0200
Subject: added basic executor

---
 example/test.cc     | 25 +++++++++++++++++--------
 lib/matcha.cc       | 15 +++++----------
 lib/matcha.h        | 38 ++++++++++++++++++++++++++++++++++----
 lib/thread_create.s |  6 +++---
 4 files changed, 59 insertions(+), 25 deletions(-)

diff --git a/example/test.cc b/example/test.cc
index b436708..1a40958 100644
--- a/example/test.cc
+++ b/example/test.cc
@@ -1,21 +1,30 @@
 #include "lib/matcha.h"
 
-#include <cassert>
 #include <cstdio>
+#include <memory>
+
+struct TestThread : public Thread {
+    TestThread(const char* name) : Thread(), mName(name) {}
 
-struct Thread1 : public Thread {
     virtual void threadFn() override {
-        puts("start threadFn -> yield()");
+        printf("[%s] starting up TestThread -> yield()\n", mName);
         yield();
-        puts("return from yield() -> finish threadFn");
+        printf("[%s] yield() -> finishing TestThreads\n", mName);
     }
-} gThread1;
+
+  private:
+    const char* mName;
+};
 
 int main() {
-    puts("start main thread");
+    puts("[main] start main thread");
 
-    gThread1.yield_to();
+    Executor e;
+    e.spawn(std::make_unique<TestThread>("Thread1"));
+    e.spawn(std::make_unique<TestThread>("Thread2"));
+    e.spawn(std::make_unique<TestThread>("Thread3"));
+    e.run();
 
-    puts("finish main thread");
+    puts("[main] finish main thread");
     return 0;
 }
diff --git a/lib/matcha.cc b/lib/matcha.cc
index 561a08f..6e73a5e 100644
--- a/lib/matcha.cc
+++ b/lib/matcha.cc
@@ -2,13 +2,12 @@
 
 #include <cassert>
 #include <cstdint>
-#include <cstdio>
 #include <sys/mman.h>
 #include <unistd.h>  // sysconf
 
 // asm fns
 extern "C" void thread_create();
-extern "C" void yield(void* new_stack, void** old_stack);
+extern "C" void yield(const void* new_stack, void* const* old_stack);
 
 long get_pagesize() {
     return sysconf(_SC_PAGESIZE);
@@ -51,18 +50,14 @@ Thread::Thread() {
 
 void Thread::entry(void* obj) {
     Thread* t = static_cast<Thread*>(obj);
-
-    puts("thread entry");
     t->threadFn();
-    puts("thread done");
 }
 
-void* gOriginalStack;
-
 void Thread::yield() {
-    ::yield(gOriginalStack, &mStackPtr);
+    assert(mExecutor);
+    ::yield(mExecutor->getStackPtr(), &mStackPtr);
 }
 
-void Thread::yield_to() const {
-    ::yield(mStackPtr, &gOriginalStack);
+void Executor::yield_to(const Thread* t) const {
+    ::yield(t->mStackPtr, &mStackPtr);
 }
diff --git a/lib/matcha.h b/lib/matcha.h
index 1506081..9fed7c2 100644
--- a/lib/matcha.h
+++ b/lib/matcha.h
@@ -1,18 +1,48 @@
+#include <memory>
+#include <vector>
+
+struct Executor;
+
 struct Thread {
     Thread(const Thread&) = delete;
     Thread& operator=(const Thread&) = delete;
     Thread();
+    virtual ~Thread() {}
 
     virtual void threadFn() = 0;
 
-    // use from executor
-    void yield_to() const;
-
   protected:
-    // use in thread
     void yield();
 
   private:
     static void entry(void* obj);
     void* mStackPtr;
+
+    friend struct Executor;
+    const Executor* mExecutor;
+};
+
+
+struct Executor {
+    Executor(const Executor&) = delete;
+    Executor& operator=(const Executor&) = delete;
+    Executor() = default;
+
+    const void* getStackPtr() const { return mStackPtr; }
+
+    void spawn(std::unique_ptr<Thread> t) {
+        mThreads.push_back(std::move(t));
+        mThreads.back()->mExecutor = this;
+    }
+    void run() {
+        for (const std::unique_ptr<Thread>& t : mThreads) {
+            yield_to(t.get());
+        }
+    }
+
+  private:
+    void* mStackPtr;
+    std::vector<std::unique_ptr<Thread>> mThreads;
+
+    void yield_to(const Thread* t) const;
 };
diff --git a/lib/thread_create.s b/lib/thread_create.s
index 6ebcd86..d5dd092 100644
--- a/lib/thread_create.s
+++ b/lib/thread_create.s
@@ -23,9 +23,9 @@ thread_create:
     .size thread_create, .-thread_create
 
 
-    # extern "C" void yield(void* new_stack, void** old_stack);
-    #                             ^^^^^^^^^         ^^^^^^^^^
-    #                             rdi               rsi
+    # extern "C" void yield(const void* new_stack, void* const* old_stack);
+    #                                   ^^^^^^^^^               ^^^^^^^^^
+    #                                   rdi                     rsi
     .global yield
     .type   yield, @function
 yield:
-- 
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