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prefix_sum.c
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prefix_sum.c
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#include "simple.h"
#include <values.h>
/* this is used for block prefix sum. Based on the idea that just to keep all the threads busy. */
int prefix_sum(int *buff, int n, THREADED)
{
int * result,i,start,t=0;
result = node_malloc(sizeof(int)*THREADS,TH);
/*now run prefix-sum on buff*/
pardo(i,0,n,1) {
start=i;
break;
}
pardo(i,0,n,1){
if(i!=start) buff[i]+=buff[i-1];
t=buff[i];
}
node_Barrier();
result[MYTHREAD]=t;
node_Barrier();
on_one_thread{
for(i=1;i<THREADS;i++) result[i]+=result[i-1];
for(i=THREADS-1;i>0;i--) result[i]=result[i-1];
result[0]=0;
}
node_Barrier();
t = result[MYTHREAD];
pardo(i,0,n,1)
if(MYTHREAD!=0) buff[i]+=t;
node_Barrier();
node_free(result,TH);
}
int prefix_sum_max(int *buff, int n, THREADED)
{
int * result,i,start,t=0;
result = node_malloc(sizeof(int)*THREADS,TH);
/*now run prefix-sum on buff*/
pardo(i,0,n,1) {
start=i;
break;
}
pardo(i,0,n,1){
if(i!=start) buff[i]=max(buff[i],buff[i-1]);
t=buff[i];
}
node_Barrier();
result[MYTHREAD]=t;
node_Barrier();
on_one_thread{
for(i=1;i<THREADS;i++) result[i]=max(result[i],result[i-1]);
for(i=THREADS-1;i>0;i--) result[i]=result[i-1];
result[0]=-MAXINT;
}
node_Barrier();
t = result[MYTHREAD];
pardo(i,0,n,1)
if(MYTHREAD!=0) buff[i]=max(t,buff[i]);
node_Barrier();
node_free(result,TH);
}