📄 os_cpu_c.c
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/*
**********************************************************************************************************
* uC/OS-II
* The Real-Time Kernel
*
* AVR Specific code
*
* File : OS_CPU_C.C
* By : Ole Saether
* Port Version : V1.01
*
* AVR-GCC port version : 1.0 2001-04-02 modified/ported to avr-gcc by Jesper Hansen (jesperh@telia.com)
*
*
*
**********************************************************************************************************
*/
#define OS_CPU_GLOBALS
#include "includes.h"
/*
**********************************************************************************************************
* 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
*
* pdata 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 the
* highest valid address on 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) : Interrupts are enabled when your task starts executing. You can change this by setting the
* SREG to 0x00 instead. In this case, interrupts would be disabled upon task startup. The
* application code would be responsible for enabling interrupts at the beginning of the task
* code. You will need to modify OSTaskIdle() and OSTaskStat() so that they enable
* interrupts. Failure to do this will make your system crash!
*
* The AVR return stack is placed 64 bytes above the start of the (512 byte) stack. This
* provides 32 levels of function call nesting which should be more than enough for most
* applications (see the "read.me" file for more info).
*
**********************************************************************************************************
*/
void *OSTaskStkInit (void (*task)(void *pd), void *pdata, void *ptos, INT16U opt)
{
INT8U *stk;
INT16U tmp;
opt = opt; /* 'opt' is not used, prevent warning */
stk = (INT8U *)ptos; /* AVR return stack ("hardware stack") */
tmp = (INT16U)task;
/* "push" initial register values onto the stack */
*stk-- = (INT8U)tmp; /* Put task start address on top of stack */
*stk-- = (INT8U)(tmp >> 8);
*stk-- = (INT8U)0x00; /* R0 = 0x00 */
*stk-- = (INT8U)0x00; /* R1 = 0x00 */
*stk-- = (INT8U)0x00; /* R2 = 0x00 */
*stk-- = (INT8U)0x00; /* R3 = 0x00 */
*stk-- = (INT8U)0x00; /* R4 = 0x00 */
*stk-- = (INT8U)0x00; /* R5 = 0x00 */
*stk-- = (INT8U)0x00; /* R6 = 0x00 */
*stk-- = (INT8U)0x00; /* R7 = 0x00 */
*stk-- = (INT8U)0x00; /* R8 = 0x00 */
*stk-- = (INT8U)0x00; /* R9 = 0x00 */
*stk-- = (INT8U)0x00; /* R10 = 0x00 */
*stk-- = (INT8U)0x00; /* R11 = 0x00 */
*stk-- = (INT8U)0x00; /* R12 = 0x00 */
*stk-- = (INT8U)0x00; /* R13 = 0x00 */
*stk-- = (INT8U)0x00; /* R14 = 0x00 */
*stk-- = (INT8U)0x00; /* R15 = 0x00 */
*stk-- = (INT8U)0x00; /* R16 = 0x00 */
*stk-- = (INT8U)0x00; /* R17 = 0x00 */
*stk-- = (INT8U)0x00; /* R18 = 0x00 */
*stk-- = (INT8U)0x00; /* R19 = 0x00 */
*stk-- = (INT8U)0x00; /* R20 = 0x00 */
*stk-- = (INT8U)0x00; /* R21 = 0x00 */
*stk-- = (INT8U)0x00; /* R22 = 0x00 */
*stk-- = (INT8U)0x00; /* R23 = 0x00 */
tmp = (INT16U)pdata;
*stk-- = (INT8U)tmp; /* Simulate call to function with argument */
*stk-- = (INT8U)(tmp >> 8); /* R24, R25 contains argument pointer pdata */
*stk-- = (INT8U)0x00; /* R26 = 0x00 */
*stk-- = (INT8U)0x00; /* R27 = 0x00 */
*stk-- = (INT8U)0x00; /* R28 = 0x00 */
*stk-- = (INT8U)0x00; /* R29 = 0x00 */
*stk-- = (INT8U)0x00; /* R30 = 0x00 */
*stk-- = (INT8U)0x00; /* R31 = 0x00 */
*stk-- = (INT8U)0x80; /* SREG = Interrupts enabled */
return ((void *)stk);
}
/*$PAGE*/
#if OS_CPU_HOOKS_EN
/*
*********************************************************************************************************
* 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.
*********************************************************************************************************
*/
void OSTaskCreateHook (OS_TCB *ptcb)
{
ptcb = ptcb; /* Prevent compiler warning */
}
/*
*********************************************************************************************************
* 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.
*********************************************************************************************************
*/
void OSTaskDelHook (OS_TCB *ptcb)
{
ptcb = ptcb; /* Prevent compiler warning */
}
/*
*********************************************************************************************************
* 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).
*********************************************************************************************************
*/
void OSTaskSwHook (void)
{
}
/*
*********************************************************************************************************
* 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
*********************************************************************************************************
*/
void OSTaskStatHook (void)
{
}
/*
*********************************************************************************************************
* TICK HOOK
*
* Description: This function is called every tick.
*
* Arguments : none
*
* Note(s) : 1) Interrupts may or may not be ENABLED during this call.
*********************************************************************************************************
*/
void OSTimeTickHook (void)
{
}
#endif
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