/*
* Main
*/
int main(void) {
init_tlb();
enable_tlb();
printf("Hello from Nios II!\n");
mutex = altera_avalon_mutex_open(MUTEX_0_NAME); // Initialize the hardware mutex
mbox = OSSemCreate(0); // Initialize the message box
CriticalFunctionPointers* cp = (CriticalFunctionPointers*)SHARED_MEMORY_BASE;
// Wait for monitor to be done initialization of shared variables before retrieving their values
while(cp->init_complete == 0);
init_cpu1_isr(); // Initialize the ISR
// Set the task(only one in this example)
int arg_5 = CRITICAL_TASK_PRIORITY;
OSTaskCreateExt(preemption_task, &arg_5, &critical_task_stk[TASK_STACKSIZE - 1],
CRITICAL_TASK_PRIORITY, CRITICAL_TASK_PRIORITY,
critical_task_stk, TASK_STACKSIZE, NULL,0);
// Signal that the core has finished initializing
altera_avalon_mutex_lock(mutex, 1); // Acquire the hardware mutex
{
cp->core_ready[1] = 1;
}
altera_avalon_mutex_unlock(mutex); // Memory
// Start OS
OSStart();
return 0;
}
/*
* This is the wrapper for the task that executes rendundantly on both cores
* There is one VERY important thing to note. When the critical task begins executing
* the value of the stack pointer MUST be the same on both cores. This means that
* the wrapper must have the same number of variables declared within its scope (i.e.
* onto its stack) before calling the critical task (pt() in this example)
*/
void preemption_task(void* pdata){
int done = 0;
int first = 0;
int t_os;
CriticalFunctionPointers* cp =
(CriticalFunctionPointers*) SHARED_MEMORY_BASE;
pt = cp->task[1];
while(1){
// Get initial time, then wait for 2 ticks
t_os = OSTimeGet();
OSTimeDly(2 - t_os);
//This is a crude way of synchronizing the beginning of the task
//on both cores
while (done == 0) {
altera_avalon_mutex_lock(mutex, 1); //Acquire the hardware mutex
{
if(first == 0){
cp->checkout[1] = 1;
first = 1;
}
if( cp->checkout[0] == 1){
cp->checkout[0] = 0;
done = 1;
}
}
altera_avalon_mutex_unlock(mutex);
}
// Set default block size for fingerprinting
fprint_set_block_size(cp->blocksize[1]);
//Context switch is necessary to clear the callee saved registers
long registers[8];
context_switch(registers);
//Set the global pointer in case of compilation issues related
//to global variables
set_gp();
//call the critical task
pt(cp->args[1]);
//restore the original global pointer
restore_gp();
//Restore the callee saved registers
context_restore(registers);
//Get the end time
alt_u64 t = alt_timestamp();
//store the end time
cp->core_time[1] = t;
}
}
/*
* If CPU1 interrupt goes off, we assume that it has been sent
* by the monitor for now and that a task must be executed.
* The identity of the task is retrieved from the shared_memory
* using the CriticalFunctionPointers data structure. The task is then executed
*/
static void handle_cpu1_interrupt(void* context) {
unsigned short priority;
altera_avalon_mutex_lock(mutex, 1);
{
CriticalFunctionPointers* cp = (CriticalFunctionPointers*)SHARED_MEMORY_BASE;
priority = cp->priority[1];
*isr_1_ptr = 0;
}
altera_avalon_mutex_unlock(mutex);
if(priority == CRITICAL_TASK_PRIORITY)
OSSemPost(mbox);
}
int main()
{
printf("Hello from cpu_3!\n");
alt_mutex_dev* mutex = altera_avalon_mutex_open( "/dev/mutex_1" );
while(TRUE) {
altera_avalon_mutex_lock( mutex, 1 );
if (IORD_8DIRECT(FLAG,0) == 1) {
value=IORD_8DIRECT(VALUE,0);
printf("Reading from shared memory (safe): %d\n",value);
IOWR_8DIRECT(VALUE,0,++value);
IOWR_8DIRECT(FLAG,0,0);
printf("\tWriting to shared memory (safe): %d\n",value);
}
altera_avalon_mutex_unlock( mutex );
delay(10);
}
return 0;
}
