From 6c926175afbf1f9ec2715fb007acc28588b36c4a Mon Sep 17 00:00:00 2001
From: Miguel <m.i@gmx.at>
Date: Tue, 21 Aug 2018 17:54:28 +0200
Subject: cleaning up multitasking

---
 kernel/task.c | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 61 insertions(+), 6 deletions(-)

(limited to 'kernel/task.c')

diff --git a/kernel/task.c b/kernel/task.c
index c281821..395c196 100644
--- a/kernel/task.c
+++ b/kernel/task.c
@@ -45,7 +45,6 @@ volatile int add_task(uint32_t esp, uint32_t vmem)
 	    task_list[i].waiting=false;
 	    task_list[i].skipwait=false;
 	    task_list[i].brk=task_list[current_task].brk;
-
 	    return i;
 	}
     }
@@ -53,9 +52,29 @@ volatile int add_task(uint32_t esp, uint32_t vmem)
     panic(FOOLOS_MODULE_NAME,"out of task slots!");
 }
 
+//
+// REMEMBER WE ARE INSIDE AN INTERRUPT HERE - DON'T WASTE TIME!
+//
+// oldesp - is the adress of the stack pointer when pit_interrupt_handler was entered.
+// registers have been pushed with pusha to this old stack.
+//
+// stack pointer was moved to the 16kb stack we have from multiboot.s
+//
+// we need to return a NEW stack pointer where popa will get the registers the new task requires
+//
+static int first=1;
 volatile uint32_t my_scheduler(uint32_t oldesp)
 {
-    task_list[current_task].esp=oldesp;
+
+    // allows skipping scheduling from gdb 
+    volatile int skippy=0;
+    if(skippy)return oldesp;
+
+    if(!first)
+    {
+	task_list[current_task].esp=oldesp;
+    }
+	first=0;
 
     for(int i=0;i<MAX_TASKS;i++)
     {
@@ -89,6 +108,7 @@ volatile uint32_t task_switch_next(uint32_t oldesp)
 //TODO: notify waiting parent when child finished;
 volatile uint32_t task_exit(uint32_t oldesp)
 { 
+
     task_list[current_task].active=false;
     int parent_pid=task_list[current_task].parent;
 
@@ -140,16 +160,51 @@ volatile uint32_t task_fork(uint32_t oldesp)
 // init task (root of all other tasks / processes) //
 volatile void task_init(pdirectory *dir)
 {
-
+    current_task=0;
+    
     // 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=dir;
-    task_list[0].esp = 0; // will be set by next task_switch_next() call.
+    task_list[0].esp = kballoc(4); //  0; // will be set by next task_switch_next() call.
+
+    task_list[1].parent=0;
+    task_list[1].active=true;
+    task_list[1].waiting=false;
+    task_list[1].vmem=dir;
+    task_list[1].esp = kballoc(4); // fresh 16kb stack from here.
+
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"fresh esp on: 0x%08X",1,task_list[1].esp);
+    log(FOOLOS_MODULE_NAME,FOOLOS_LOG_INFO,"fresh esp on: 0x%08X",0,task_list[0].esp);
+
+    task_pusha(task_list[1].esp); // pusha but to alternative location
+    task_pusha(task_list[0].esp); // pusha but to alternative location
+
+    /*
     current_task=0;
-    
-    switch_to_user_mode();
+    unsigned esp, ebp, eax, ebx, ecx, edx;
+
+    asm(
+        "movl %%esp, %0;"
+        "movl %%ebp, %1;"
+        "movl %%eax, %2;"
+        "movl %%ebx, %3;"
+        "movl %%ecx, %4;"
+        "movl %%edx, %5;"
+        :"=r"(esp), "=r"(ebp), "=r"(eax), "=r"(ebx), "=r"(ecx), "=r"(edx)
+        );
+
+    // TODO: prepare stack so popa get's what it wants!
+    int i=task_fork(esp);
+    */
+
+    // finally enable interrrupts so the scheduler is called (by timer)
+    x86_sti(); 
+
+    // loop until scheduler kicks in and reschedules us...
+    while(1);
+
 }
 
 volatile int task_get_current_pid()
-- 
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