//--------------------------------------------------------------------------------------
// FUNCTION: RCCE_barrier
//--------------------------------------------------------------------------------------
// very simple, linear barrier
//--------------------------------------------------------------------------------------
int RCCE_barrier(RCCE_COMM *comm) {
int counter, i, error;
int ROOT = 0;
t_vchar cyclechar[RCCE_LINE_SIZE];
t_vchar valchar [RCCE_LINE_SIZE];
t_vcharp gatherp, releasep;
RCCE_FLAG_STATUS cycle;
counter = 0;
gatherp = comm->gather.line_address;
if (RCCE_debug_synch)
fprintf(STDERR,"UE %d has checked into barrier\n", RCCE_IAM);
// flip local barrier variable
if (error = RCCE_get(cyclechar, gatherp, RCCE_LINE_SIZE, RCCE_IAM))
return(RCCE_error_return(RCCE_debug_synch,error));
cycle = RCCE_flip_bit_value(cyclechar, comm->gather.location);
if (error = RCCE_put(comm->gather.line_address, cyclechar, RCCE_LINE_SIZE, RCCE_IAM))
return(RCCE_error_return(RCCE_debug_synch,error));
if (RCCE_IAM==comm->member[ROOT]) {
// read "remote" gather flags; once all equal "cycle" (i.e counter==comm->size),
// we know all UEs have reached the barrier
while (counter != comm->size) {
// skip the first member (#0), because that is the ROOT
for (counter=i=1; i<comm->size; i++) {
// copy flag values out of comm buffer
if (error = RCCE_get(valchar, comm->gather.line_address, RCCE_LINE_SIZE,
comm->member[i]))
return(RCCE_error_return(RCCE_debug_synch,error));
if (RCCE_bit_value(valchar, comm->gather.location) == cycle) counter++;
}
}
// set release flags
for (i=1; i<comm->size; i++)
if (error = RCCE_flag_write(&(comm->release), cycle, comm->member[i]))
return(RCCE_error_return(RCCE_debug_synch,error));
}
else {
if (error = RCCE_wait_until(comm->release, cycle))
return(RCCE_error_return(RCCE_debug_synch,error));
}
if (RCCE_debug_synch) fprintf(STDERR,"UE %d has cleared barrier\n", RCCE_IAM);
return(RCCE_SUCCESS);
}
//--------------------------------------------------------------------------------------
// FUNCTION: RCCE_flag_free
//--------------------------------------------------------------------------------------
// free space for one flag. Since multiple fit on a single cache line, we only
// need to free claimed MPB space when the all existing lines are completely emptied.
//--------------------------------------------------------------------------------------
int RCCE_flag_free(RCCE_FLAG *flag) {
RCCE_FLAG_LINE *flagp, *flagpminus1 = NULL;
int loc;
// check wether flag exists, and whether the location field is valid
if (!flag || flag->location < 0)
return(RCCE_error_return(RCCE_debug_synch,RCCE_ERROR_FLAG_UNDEFINED));
// find flag line in globally maintained structure
flagp = &RCCE_flags;
while (flagp->next && flag->line_address != flagp->line_address) {
flagpminus1 = flagp;
flagp = flagp->next;
}
if (flag->line_address != flagp->line_address)
return(RCCE_error_return(RCCE_debug_synch,RCCE_ERROR_FLAG_UNDEFINED));
// error checking is done
flagp->members--;
loc = flag->location;
#ifdef SINGLEBITFLAGS
RCCE_flip_bit_value(flagp->flag+loc/RCCE_FLAGS_PER_BYTE,loc%RCCE_FLAGS_PER_BYTE);
#else
flagp->flag[flag->location] = (char) ((unsigned int) 0);
#endif
// something special happens if we've emptied an entire line
if (flagp->members==0) {
if (flagpminus1) {
// there is a predecessor; splice out current flag line from linked list
RCCE_free(flagp->line_address);
flagpminus1->next = flagp->next;
free(flagp);
}
// if there is a successor but no predecessor, do nothing
}
// invalidate location field to make sure we won't free again by mistake
flag->location = -1;
flag->line_address = NULL;
return(RCCE_SUCCESS);
}
