From c2c03f41e078481921bad82487eded0fc51ebb59 Mon Sep 17 00:00:00 2001
From: Michal Idziorek <m.i@gmx.at>
Date: Tue, 2 Dec 2014 01:02:49 +0100
Subject: further work on fork and friends

---
 kernel/task.c | 77 +++++++++++++++++++++++++++++++++++++++++++----------------
 1 file changed, 57 insertions(+), 20 deletions(-)

(limited to 'kernel/task.c')

diff --git a/kernel/task.c b/kernel/task.c
index 6ea9b79..ac54dbe 100644
--- a/kernel/task.c
+++ b/kernel/task.c
@@ -17,7 +17,7 @@
 
 #define MAX_TASKS 10
 
-static volatile int current_task=-2;
+static volatile int current_task=-1;
 
 static volatile struct task_list_struct
 {
@@ -25,6 +25,8 @@ static volatile struct task_list_struct
     bool active;
     uint32_t esp; // stack pointer of the task;
     uint32_t vmem; // number of virtual memory table to switch to
+    bool waiting;
+    bool skipwait;
     
 }volatile task_list[MAX_TASKS];
 
@@ -40,6 +42,8 @@ int add_task(uint32_t esp, uint32_t vmem)
 	    task_list[i].vmem=vmem;
 	    task_list[i].esp=esp;
 	    task_list[i].active=true;
+	    task_list[i].waiting=false;
+	    task_list[i].skipwait=false;
 
 	    return i;
 	}
@@ -48,22 +52,19 @@ int add_task(uint32_t esp, uint32_t vmem)
     panic(FOOLOS_MODULE_NAME,"out of task slots!");
 }
 
-// this gets called by our clock interrupt regularly!
-uint32_t task_switch_next(uint32_t oldesp)
+uint32_t my_scheduler(uint32_t oldesp)
 {
-    timer_tick();
-
-    if(current_task==-2)return oldesp;
-    
     task_list[current_task].esp=oldesp;
-    
+
     for(int i=0;i<MAX_TASKS;i++)
     {
 	int pid=(current_task+1+i)%MAX_TASKS; // schedule round robin style
 
-	if(task_list[pid].active)
+	if(task_list[pid].active && !task_list[pid].waiting)
 	{
-	  //  log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"switch from %d to pid: %d (0x%08X) vmem: %d ", current_task,pid,task_list[pid].esp,task_list[pid].vmem);
+	  //  if(current_task!=pid)
+	//	    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"switch from %d to %d", current_task, pid);
+
 	    current_task=pid;
 
 	    vmem_set_dir(task_list[pid].vmem);
@@ -72,34 +73,68 @@ uint32_t task_switch_next(uint32_t oldesp)
 
     }
 
-    return oldesp;
+    panic(FOOLOS_MODULE_NAME,"nothing to schedule!");
+}
+
+// this gets called by our clock interrupt regularly!
+uint32_t task_switch_next(uint32_t oldesp)
+{
+    timer_tick();
+
+    // check if multitasking has been started
+    if(current_task<0)return oldesp; 
+
+    return my_scheduler(oldesp);
 
 }
 
+
 //TODO: free vmem too!
+//TODO: notify waiting parent when child finished;
 uint32_t task_exit(uint32_t oldesp)
 { 
     task_list[current_task].active=false;
+    int parent_pid=task_list[current_task].parent;
 
-    for(int i=0;i<MAX_TASKS;i++)
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"[%d] exit ", current_task);
+    if(task_list[parent_pid].active)
     {
-	int pid=(current_task+1+i)%MAX_TASKS; // schedule round robin style
-
-	if(task_list[pid].active)
+	if(task_list[parent_pid].waiting)
 	{
-	  //  log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"switch from %d to pid: %d (0x%08X) vmem: %d ", current_task,pid,task_list[pid].esp,task_list[pid].vmem);
-	    current_task=pid;
-
-	    vmem_set_dir(task_list[pid].vmem);
-	    return task_list[pid].esp;
+    
+	   log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"wakeing up %d ", parent_pid);
+	   task_list[parent_pid].waiting=false;
+	}
+	else
+	{
+	   log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"set skipwait on %d ", parent_pid);
+	   task_list[parent_pid].skipwait=true;
 	}
+	
+    }
+
+    return my_scheduler(oldesp);
+
+}
 
+uint32_t task_wait(uint32_t oldesp)
+{ 
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"[%d] wait", current_task);
+    if(task_list[current_task].skipwait)
+    {
+	task_list[current_task].skipwait=false;
+    }
+    else
+    {
+	task_list[current_task].waiting=true;
     }
+    return my_scheduler(oldesp);
 }
 
 uint32_t task_fork(uint32_t oldesp)
 { 
    int pid=add_task(oldesp,vmem_new_space_dir(task_list[current_task].vmem));
+   log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"[%d] forked -> [%d]", current_task, pid);
    return pid;
 }
 
@@ -107,7 +142,9 @@ uint32_t task_fork(uint32_t oldesp)
 void task_init()
 {
     // this is our main task on slot 0 
+    task_list[0].parent=0;
     task_list[0].active=true;
+    task_list[0].waiting=false;
     task_list[0].vmem=0;
     task_list[0].esp = 0; // will be set by next task_switch_next() call.
     current_task=0;
-- 
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