From 957a513fd64f4ca5daa6e6bf08df65e6c469e08a Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Sat, 1 Jul 2017 11:17:29 -0400
Subject: [PATCH] More changes to threading model.

---
 core/vm.c          | 42 +++++++++++++++++++++++++++++++-----------
 gsttests/basic.gst | 17 ++++++++++-------
 2 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/core/vm.c b/core/vm.c
index a434a938..ce806bf4 100644
--- a/core/vm.c
+++ b/core/vm.c
@@ -40,6 +40,7 @@ int gst_continue(Gst *vm) {
 #define gst_assert(vm, cond, e) do {if (!(cond)){gst_error((vm), (e));}} while (0)
 
     /* Intialize local state */
+    vm->thread->status = GST_THREAD_ALIVE;
     stack = gst_thread_stack(vm->thread);
     pc = gst_frame_pc(stack);
 
@@ -356,14 +357,20 @@ int gst_continue(Gst *vm) {
         case GST_OP_TRN: /* Transfer */
             temp = stack[pc[2]]; /* The thread */
             v1 = stack[pc[3]]; /* The value to pass in */
-            if (temp.type != GST_THREAD)
+            if (temp.type != GST_THREAD && temp.type != GST_NIL)
                 gst_error(vm, "expected thread");
-            if (temp.data.thread->status == GST_THREAD_DEAD ||
-                temp.data.thread->status == GST_THREAD_ERROR)
-                gst_error(vm, "cannot enter dead thread");
+            if (temp.type == GST_THREAD) {
+                if (temp.data.thread->status == GST_THREAD_DEAD ||
+                    temp.data.thread->status == GST_THREAD_ERROR)
+                    gst_error(vm, "cannot enter dead thread");
+            }
             gst_frame_ret(stack) = pc[1];
             vm->thread->status = GST_THREAD_PENDING;
             gst_frame_pc(stack) = pc + 4;
+            if (temp.type == GST_NIL) {
+                vm->ret = v1;
+                return GST_RETURN_OK;
+            }
             temp.data.thread->status = GST_THREAD_ALIVE;
             vm->thread = temp.data.thread;
             stack = gst_thread_stack(temp.data.thread);
@@ -423,22 +430,35 @@ int gst_continue(Gst *vm) {
 /* Run the vm with a given function. This function is
  * called to start the vm. */
 int gst_run(Gst *vm, GstValue callee) {
-    if (vm->thread == NULL) {
-        vm->thread = gst_thread(vm, callee, 64);
-    } else {
+    int result;
+    if (vm->thread &&
+        (vm->thread->status == GST_THREAD_DEAD ||
+         vm->thread->status == GST_THREAD_ALIVE)) {
         /* Reuse old thread */
         gst_thread_reset(vm, vm->thread, callee);
+    } else {
+        /* Create new thread */
+        vm->thread = gst_thread(vm, callee, 64);
+        if (vm->thread == NULL)
+            return GST_RETURN_CRASH;
     }
-    if (vm->thread == NULL)
-        return GST_RETURN_CRASH;
     if (callee.type == GST_CFUNCTION) {
         vm->ret.type = GST_NIL;
-        return callee.data.cfunction(vm);
+        result = callee.data.cfunction(vm);
     } else if (callee.type == GST_FUNCTION) {
-        return gst_continue(vm);
+        result = gst_continue(vm);
     } else {
         return GST_RETURN_CRASH;
     }
+    /* Handle yields */
+    while (result == GST_RETURN_OK && vm->thread->status == GST_THREAD_PENDING) {
+        /* Send back in the value yielded - TODO - do something useful with this */
+        GstValue *stack = gst_thread_stack(vm->thread);
+        stack[gst_frame_ret(stack)] = vm->ret;
+        /* Resume */
+        result = gst_continue(vm);
+    }
+    return result;
 }
 
 /* Get an argument from the stack */
diff --git a/gsttests/basic.gst b/gsttests/basic.gst
index fdce7ab0..5a067765 100644
--- a/gsttests/basic.gst
+++ b/gsttests/basic.gst
@@ -1,14 +1,17 @@
 (print "Running basic tests...")
 
-(var numTestsPassed 0)
-(def assert (fn [x e] 
+(var num-tests-passed 0)
+(var num-tests-run 0)
+(def assert (fn [x e]
+	(varset! num-tests-run (+ 1 num-tests-run)) 
 	(if x 
 		(do 
 			(print "  \e[32m✔\e[0m" e) 
-			(varset! numTestsPassed (+ 1 numTestsPassed)) x)
+			(varset! num-tests-passed (+ 1 num-tests-passed))
+			x)
 		(do 
-			(print e)
-			(exit! (+ numTestsPassed 1))))))
+			(print "  \e[31m✘\e[0m" e)
+			x))))
 
 (assert (= 10 (+ 1 2 3 4)) "addition")
 (assert (= -8 (- 1 2 3 4)) "subtraction")
@@ -77,7 +80,7 @@
 (assert (= athread-result "hello, world!") "thread error result")
 (assert (= (status athread) "error") "thread error status")
 
-"All tests passed"
+"report"
 
-(print "All" numTestsPassed "tests passed")
+(print num-tests-passed "of" num-tests-run "tests passed")
 (exit! 0)
\ No newline at end of file