// os.c
// Runs on LM4F120/TM4C123/MSP432
// Lab 3 starter file.
// Daniel Valvano
// March 24, 2016

#include <stdint.h>
#include "os.h"
#include "CortexM.h"
#include "BSP.h"

// function definitions in osasm.s
void StartOS(void);

#define NUMTHREADS  6        // maximum number of threads
#define NUMPERIODIC 2        // maximum number of periodic threads
#define STACKSIZE   100      // number of 32-bit words in stack per thread
struct tcb{
  int32_t *sp;       // pointer to stack (valid for threads not running
  struct tcb *next;  // linked-list pointer
   // nonzero if blocked on this semaphore
   // nonzero if this thread is sleeping
//*FILL THIS IN****
};
typedef struct tcb tcbType;
tcbType tcbs[NUMTHREADS];
tcbType *RunPt;
int32_t Stacks[NUMTHREADS][STACKSIZE];


// ******** OS_Init ************
// Initialize operating system, disable interrupts
// Initialize OS controlled I/O: periodic interrupt, bus clock as fast as possible
// Initialize OS global variables
// Inputs:  none
// Outputs: none
void OS_Init(void){
  DisableInterrupts();
  BSP_Clock_InitFastest();// set processor clock to fastest speed
  // perform any initializations needed
}

void SetInitialStack(int i){
  // **Same as Lab 2****
	tcbs[i].sp = &Stacks[i][STACKSIZE - 16];
	
	Stacks[i][STACKSIZE-1] = 0x01000000; // Thumb bit
	//Stacks[i][STACKSIZE-2] is reserved for PC
	//and is initialized with start address of task
	Stacks[i][STACKSIZE-3] = 0x14141414; // R14 = LR
	Stacks[i][STACKSIZE-4] = 0x12121212; // R12
	Stacks[i][STACKSIZE-5] = 0x03030303; // R3
	Stacks[i][STACKSIZE-6] = 0x02020202; // R2
	Stacks[i][STACKSIZE-7] = 0x01010101; // R1
	Stacks[i][STACKSIZE-8] = 0x00000000; // R0
	Stacks[i][STACKSIZE-9] = 0x11111111; // R11
	Stacks[i][STACKSIZE-10] = 0x10101010; // R10
	Stacks[i][STACKSIZE-11] = 0x09090909; // R9
	Stacks[i][STACKSIZE-12] = 0x08080808; // R8
	Stacks[i][STACKSIZE-13] = 0x07070707; // R7
	Stacks[i][STACKSIZE-14] = 0x06060606; // R6
	Stacks[i][STACKSIZE-15] = 0x05050505; // R5
	Stacks[i][STACKSIZE-16] = 0x04040404; // R4
}

//******** OS_AddThreads ***************
// Add six main threads to the scheduler
// Inputs: function pointers to six void/void main threads
// Outputs: 1 if successful, 0 if this thread can not be added
// This function will only be called once, after OS_Init and before OS_Launch
int OS_AddThreads(void(*thread0)(void),
                  void(*thread1)(void),
                  void(*thread2)(void),
                  void(*thread3)(void),
                  void(*thread4)(void),
                  void(*thread5)(void)){
  // **similar to Lab 2. initialize as not blocked, not sleeping****

  return 1;               // successful
}

//******** OS_AddPeriodicEventThread ***************
// Add one background periodic event thread
// Typically this function receives the highest priority
// Inputs: pointer to a void/void event thread function
//         period given in units of OS_Launch (Lab 3 this will be msec)
// Outputs: 1 if successful, 0 if this thread cannot be added
// It is assumed that the event threads will run to completion and return
// It is assumed the time to run these event threads is short compared to 1 msec
// These threads cannot spin, block, loop, sleep, or kill
// These threads can call OS_Signal
// In Lab 3 this will be called exactly twice
int OS_AddPeriodicEventThread(void(*thread)(void), uint32_t period){
// ****IMPLEMENT THIS****
  return 1;

}

void static runperiodicevents(void){
// ****IMPLEMENT THIS****
// **RUN PERIODIC THREADS, DECREMENT SLEEP COUNTERS

}

//******** OS_Launch ***************
// Start the scheduler, enable interrupts
// Inputs: number of clock cycles for each time slice
// Outputs: none (does not return)
// Errors: theTimeSlice must be less than 16,777,216
void OS_Launch(uint32_t theTimeSlice){
  STCTRL = 0;                  // disable SysTick during setup
  STCURRENT = 0;               // any write to current clears it
  SYSPRI3 =(SYSPRI3&0x00FFFFFF)|0xE0000000; // priority 7
  STRELOAD = theTimeSlice - 1; // reload value
  STCTRL = 0x00000007;         // enable, core clock and interrupt arm
  StartOS();                   // start on the first task
}
// runs every ms
void Scheduler(void){ // every time slice
// ROUND ROBIN, skip blocked and sleeping threads
}

//******** OS_Suspend ***************
// Called by main thread to cooperatively suspend operation
// Inputs: none
// Outputs: none
// Will be run again depending on sleep/block status
void OS_Suspend(void){
  STCURRENT = 0;        // any write to current clears it
  INTCTRL = 0x04000000; // trigger SysTick
// next thread gets a full time slice
}

// ******** OS_Sleep ************
// place this thread into a dormant state
// input:  number of msec to sleep
// output: none
// OS_Sleep(0) implements cooperative multitasking
void OS_Sleep(uint32_t sleepTime){
// set sleep parameter in TCB
// suspend, stops running
}

// ******** OS_InitSemaphore ************
// Initialize counting semaphore
// Inputs:  pointer to a semaphore
//          initial value of semaphore
// Outputs: none
void OS_InitSemaphore(int32_t *semaPt, int32_t value){
//***IMPLEMENT THIS***
}

// ******** OS_Wait ************
// Decrement semaphore and block if less than zero
// Lab2 spinlock (does not suspend while spinning)
// Lab3 block if less than zero
// Inputs:  pointer to a counting semaphore
// Outputs: none
void OS_Wait(int32_t *semaPt){
//***IMPLEMENT THIS***
}

// ******** OS_Signal ************
// Increment semaphore
// Lab2 spinlock
// Lab3 wakeup blocked thread if appropriate
// Inputs:  pointer to a counting semaphore
// Outputs: none
void OS_Signal(int32_t *semaPt){
//***IMPLEMENT THIS***
}

#define FSIZE 10    // can be any size
uint32_t PutI;      // index of where to put next
uint32_t GetI;      // index of where to get next
uint32_t Fifo[FSIZE];
int32_t CurrentSize;// 0 means FIFO empty, FSIZE means full
uint32_t LostData;  // number of lost pieces of data

// ******** OS_FIFO_Init ************
// Initialize FIFO.  
// One event thread producer, one main thread consumer
// Inputs:  none
// Outputs: none
void OS_FIFO_Init(void){
//***IMPLEMENT THIS***
}

// ******** OS_FIFO_Put ************
// Put an entry in the FIFO.  
// Exactly one event thread puts,
// do not block or spin if full
// Inputs:  data to be stored
// Outputs: 0 if successful, -1 if the FIFO is full
int OS_FIFO_Put(uint32_t data){
//***IMPLEMENT THIS***

  return 0;   // success

}

// ******** OS_FIFO_Get ************
// Get an entry from the FIFO.   
// Exactly one main thread get,
// do block if empty
// Inputs:  none
// Outputs: data retrieved
uint32_t OS_FIFO_Get(void){uint32_t data;
//***IMPLEMENT THIS***

  return data;
}