/*
*********************************************************************************************************
*                                               uC/OS-II
*                                        The Real-Time Kernel
*
*                           (c) Copyright 1992-2003, Micrium, Inc., Weston, FL
*                                          All Rights Reserved
*
*                                               ARM7 Port
*
* File : OS_CPU_C.C
* By   : Jean J. Labrosse
*        Michael Anburaj        Email : michaelanburaj@hotmail.com
*                               Web   : http://geocities.com/michaelanburaj/
*********************************************************************************************************
*/

#define  OS_CPU_GLOBALS
#include "ucos_ii.h"

#define  ARM_SVC_MODE   0x00000013
#define  F_BIT          0x40
/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                            (BEGINNING)
*
* Description: This function is called by OSInit() at the beginning of OSInit().
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts should be disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSInitHookBegin (void)
{
    OSIntCtxSwFlag = 0;
}
#endif

/*
*********************************************************************************************************
*                                       OS INITIALIZATION HOOK
*                                               (END)
*
* Description: This function is called by OSInit() at the end of OSInit().
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts should be disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSInitHookEnd (void)
{
}
#endif

/*
*********************************************************************************************************
*                                          TASK CREATION HOOK
*
* Description: This function is called when a task is created.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being created.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 
void  OSTaskCreateHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}
#endif


/*
*********************************************************************************************************
*                                           TASK DELETION HOOK
*
* Description: This function is called when a task is deleted.
*
* Arguments  : ptcb   is a pointer to the task control block of the task being deleted.
*
* Note(s)    : 1) Interrupts are disabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 
void  OSTaskDelHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                       /* Prevent compiler warning                                     */
}
#endif

/*
*********************************************************************************************************
*                                             IDLE TASK HOOK
*
* Description: This function is called by the idle task.  This hook has been added to allow you to do  
*              such things as STOP the CPU to conserve power.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are enabled during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION >= 251
void  OSTaskIdleHook (void)
{
}
#endif

/*
*********************************************************************************************************
*                                           STATISTIC TASK HOOK
*
* Description: This function is called every second by uC/OS-II's statistics task.  This allows your 
*              application to add functionality to the statistics task.
*
* Arguments  : none
*********************************************************************************************************
*/

#if OS_CPU_HOOKS_EN > 0 
void  OSTaskStatHook (void)
{
}
#endif

/*
*********************************************************************************************************
*                                        INITIALIZE A TASK'S STACK
*
* Description: This function is called by either OSTaskCreate() or OSTaskCreateExt() to initialize the
*              stack frame of the task being created.  This function is highly processor specific.
*
* Arguments  : task          is a pointer to the task code
*
*              p_arg         is a pointer to a user supplied data area that will be passed to the task
*                            when the task first executes.
*
*              ptos          is a pointer to the top of stack.  It is assumed that 'ptos' points to
*                            a 'free' entry on the task stack.  If OS_STK_GROWTH is set to 1 then 
*                            'ptos' will contain the HIGHEST valid address of the stack.  Similarly, if
*                            OS_STK_GROWTH is set to 0, the 'ptos' will contains the LOWEST valid address
*                            of the stack.
*
*              opt           specifies options that can be used to alter the behavior of OSTaskStkInit().
*                            (see uCOS_II.H for OS_TASK_OPT_???).
*
* Returns    : Always returns the location of the new top-of-stack' once the processor registers have
*              been placed on the stack in the proper order.
*
* Note(s)    : 1) Interrupts are enabled when your task starts executing. 
*              2) All tasks run in SVC mode.
*********************************************************************************************************
*/

OS_STK *OSTaskStkInit (void (*task)(void *pd), void *p_arg, OS_STK *ptos, INT16U opt)
{
    OS_STK *stk;


    opt      = opt;                         /* 'opt' is not used, prevent warning                      */
    stk      = ptos;                        /* Load stack pointer                                      */
    *(stk)   = (OS_STK)task;                /* Entry Point                                             */
    *(--stk) = (INT32U)0x14141414;         /* LR                                                      */
    *(--stk) = (INT32U)0x12121212;         /* R12                                                     */
    *(--stk) = (INT32U)0x11111111;         /* R11                                                     */
    *(--stk) = (INT32U)0x10101010;         /* R10                                                     */
    *(--stk) = (INT32U)0x09090909;         /* R9                                                      */
    *(--stk) = (INT32U)0x08080808;         /* R8                                                      */
    *(--stk) = (INT32U)0x07070707;         /* R7                                                      */
    *(--stk) = (INT32U)0x06060606;         /* R6                                                      */
    *(--stk) = (INT32U)0x05050505;         /* R5                                                      */
    *(--stk) = (INT32U)0x04040404;         /* R4                                                      */
    *(--stk) = (INT32U)0x03030303;         /* R3                                                      */
    *(--stk) = (INT32U)0x02020202;         /* R2                                                      */
    *(--stk) = (INT32U)0x01010101;         /* R1                                                      */
    *(--stk) = (INT32U)p_arg;               /* R0 : argument                                           */
    *(--stk) = (INT32U)ARM_SVC_MODE|F_BIT;        /* CPSR  (Enable both IRQ and FIQ interrupts)              */
    *(--stk) = (INT32U)ARM_SVC_MODE|F_BIT;        /* SPSR                                                    */

    return (stk);
}

/*
*********************************************************************************************************
*                                           TASK SWITCH HOOK
*
* Description: This function is called when a task switch is performed.  This allows you to perform other
*              operations during a context switch.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts are disabled during this call.
*              2) It is assumed that the global pointer 'OSTCBHighRdy' points to the TCB of the task that
*                 will be 'switched in' (i.e. the highest priority task) and, 'OSTCBCur' points to the 
*                 task being switched out (i.e. the preempted task).
*********************************************************************************************************
*/
#if (OS_CPU_HOOKS_EN > 0) && (OS_TASK_SW_HOOK_EN > 0)
void  OSTaskSwHook (void)
{
}
#endif

/*
*********************************************************************************************************
*                                           OS_TCBInit() HOOK
*
* Description: This function is called by OS_TCBInit() after setting up most of the TCB.
*
* Arguments  : ptcb    is a pointer to the TCB of the task being created.
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if OS_CPU_HOOKS_EN > 0 && OS_VERSION > 203
void  OSTCBInitHook (OS_TCB *ptcb)
{
    ptcb = ptcb;                                           /* Prevent Compiler warning                 */
}
#endif


/*
*********************************************************************************************************
*                                               TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments  : none
*
* Note(s)    : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
#if (OS_CPU_HOOKS_EN > 0) && (OS_TIME_TICK_HOOK_EN > 0)
void  OSTimeTickHook (void)
{
}
#endif


/*
*********************************************************************************************************
*                                         ARM SPECIFIC CODE
*********************************************************************************************************
*/


/*
*********************************************************************************************************
*                                   INTERRUPT LEVEL CONTEXT SWITCH
*
* Description : This function is called by the OSIntExit() to perform a context switch at the completion
*               of an ISR.  However, instead of actually doing the context switch from within OSIntExit(),
*               we simply set a flag (OSIntCtxSwFlag) and defer the actual context switch until the actual
*               ISR completes (see OS_CPU_IRQ_ISR()).
*               
* Arguments   : none
*********************************************************************************************************
*/
void  OSIntCtxSw (void)
{
    OSIntCtxSwFlag = 1;                       /* Indicate that a context switch from ISR is needed  */
}