source: soft/giet_vm/libs/libsrl/srl_barrier.c @ 177

#include "srl_barrier.h"
/*
int srl_barrier_init(srl_barrier_t barrier)
{

    register int* pinit         = (int*)&barrier->init_val;
    register int* pcount        = (int*)&barrier->count;

    // parallel initialisation using atomic instructions LL/SC
    asm volatile ("_barrier_init_test:                  \n"
                  "ll   $2,     0(%0)                   \n"     // read initial value
                  "bnez $2,     _barrier_init_done      \n"
                  "move $3,     %2                      \n"
                  "sc   $3,     0(%0)                   \n"     // try to write initial value
                  "beqz $3,     _barrier_init_test      \n"
                  "move $3,     %2                      \n"
                  "sw   $3,     0(%1)                   \n"     // write count
                                  "sync"
                  "_barrier_init_done:                  \n"
                  ::"r"(pinit),"r"(pcount),"r"(value):"$2","$3");
    return 0 ;
}
*/

void srl_barrier_wait( srl_barrier_t barrier)
{
    register int* pcount        = (int*)&barrier->count;
    register int  maxcount      = (int)barrier->init_val;
    register int  count;

    // parallel decrement barrier counter using atomic instructions LL/SC
    // input : pointer on the barrier counter 
    // output : counter value 
    asm volatile ("_barrier_decrement:                          \n"
                  "ll   %0,     0(%1)                           \n"
                  "addi $3,     %0,     -1                      \n"
                  "sc   $3,     0(%1)                           \n"
                  "beqz $3,     _barrier_decrement              \n"
                  :"=r"(count):"r"(pcount):"$2","$3");

    // the last task re-initializes the barrier counter 
    // to the max value, waking up all other waiting tasks

//TODO:check it out
    if ( count == 0 )    // last task
    {
        //*pcount = maxcount;
                asm volatile( "sw %0,   (%1)\n"
                                          "sync                 \n"
                                          ::"r"(maxcount),"r"(pcount));
        return ;
    }
    else                // other tasks
    {
//        while ( *pcount != maxcount )         { }     // busy waiting 
                srl_sched_wait_eq(pcount, maxcount);    // busy waiting 
        return ;
    }

}