Start implment os kernel

RidhaOs/Inc/ridhaOsKernel.h

@@ -0,0 +1,15 @@
+#ifndef __R_KERNEL_H__
+#define __R_KERNEL_H__
+
+#include "RIDHAOS_CONF.h"
+
+/* This Struct used to restore next thread and save the running thread */
+typedef struct tControlBlock
+{
+	int32_t * stackPt;
+	struct tControlBlock * nextPt;
+}tControlBlock_t;
+	
+
+
+#endif /* __R_THREAD_H__ */

RidhaOs/RIDHAOS_CONF.h

@@ -1,6 +1,7 @@
 #ifndef __R_CONFIGURATION_H__
 #define __R_CONFIGURATION_H__
 
+
 /* Here Define your MCU REGISTER MAP FILE */
 #include "fsl_device_registers.h"
 
@@ -8,8 +9,12 @@
 /* SysTick Configuration for TimeBase */
 extern uint32_t SystemCoreClock;
 
-#define CPU_CLOCK_HZ 		SystemCoreClock
-#define MAX_DELAY				0xFFFFFFFFU
-#define TICK_RATE_HZ 		1000
+#define CPU_CLOCK_HZ 		SystemCoreClock // Use Default System Clock in Hz
+#define MAX_DELAY				0xFFFFFFFFU // Max Wayt Delay
+#define TICK_RATE_HZ 		1000 // Getting SystemCoreClock divide by 1000 to get interrupt every 1ms
+
+/* Thread Configuration Size and Number Max for TCB */
+#define NUM_OF_THREADS	3
+#define STACKSIZE				100
 
 #endif /* __R_CONFIGURATION_H__ */

RidhaOs/Src/ridhaOsKernel.c

@@ -0,0 +1,16 @@
+#include "ridhaOsKernel.h"
+
+/* Define a fixed linked list of Stack */
+tControlBlock_t tcbs[NUM_OF_THREADS];
+
+/* Define current Pointer to point to first of the list of Stack*/
+tControlBlock_t * currentPt;
+
+/* Each Thread will have STACKSIZE * 4. */
+int32_t TCB_STACK[NUM_OF_THREADS][STACKSIZE];
+
+void ridhaOsKernalStackInit(int i)
+{
+	/* Set bit24 Thumb state bit to one, operate in thumb mode */
+	TCB_STACK[i][STACKSIZE-1] = (1U << 24); // PSR register
+}

RidhaOs/Src/timebase.c

@@ -47,7 +47,6 @@ uint32_t get_tick(void)
 void timebase_init(void)
 {
 	/* Reload the timer with number of cycles per second */
-	/* Getting SystemCoreClock divide by 1000 to get interrupt every 1ms */
 	SysTick->LOAD = (SystemCoreClock / 1000) - 1;
 	
 	/* Clear Systick current value register */

RidhaOs/note.txt

@@ -0,0 +1,46 @@
+For RidhaOs we will use Round Robin Scheduler to switch from thread to another.
+For Context switch we follow these steps:
+    1. Save execution of the running thread.
+    2. Restore execution of the next ready thread.
+
+For Kernel he will be manage :
+    - Thread Scheduling.
+    - Booting.
+    - Inter-thread communication.
+    - Synchronization.
+
+Steps to implement RidhaOs:
+    1. Configure timebase (by Default use systick).
+    2. Create our Thread Control Block for Round Robin design.
+
+For more information:
+
+Scheduling Algorithm Optimization :
+    The Keys to have a good RTOS design you need:
+    - Maximize Throughput.
+    - Minimize Turnaround Time.
+    - Minimize Response Time.
+    - Maximize CPU Utilization.
+    - Minimize Scheduling Overhead.
+
+Popular Scheduling Algorithm:
+* First Come First Serve Scheduler (FCFSS):
+    - Task are executed on first come, first server basis.
+    - Non-preemptive.
+    - Its implementation is based on FIFO queue.
+    - Poor in performance as average wait time is high.
+
+* Round Robin Scheduler (RRS):
+    - Preemptive.
+    - Employs time sharing, gives each thread a timeslice (quanta).
+    - When timesclice runs out OS preempts the thread.
+
+* Weighted Round Robin Scheduler (WRRS):
+    - Preemptive.
+    - Employs time sharing, gives each thread a timeslice (quanta).
+    - If quanta runs out OS preempts the thread.
+    - Threads have unequal weight.
+
+* Rate Monotonic Scheduler (RMS).
+* Shortest Job First (SJF).
+