Centre Blaise Pascal » Bench4GPU

//

// Estimation of Pi using Monte Carlo exploration process

// Cecill v2 Emmanuel QUEMENER <emmanuel.quemener@gmail.com>

// gcc -std=c99 -O3 -o Pi Pi.c -lm

//

#include <math.h>

#include <stdio.h>

#include <stdlib.h>

#include <omp.h>

#include <limits.h>

// Marsaglia RNG very simple implementation

#define znew  ((z=36969*(z&65535)+(z>>16))<<16)

#define wnew  ((w=18000*(w&65535)+(w>>16))&65535)

#define MWC   (znew+wnew)

#define SHR3  (jsr=(jsr=(jsr=jsr^(jsr<<17))^(jsr>>13))^(jsr<<5))

#define CONG  (jcong=69069*jcong+1234567)

#define KISS  ((MWC^CONG)+SHR3)

#define MWCfp MWC * 2.328306435454494e-10f

#define KISSfp KISS * 2.328306435454494e-10f

#define SHR3fp SHR3 * 2.328306435454494e-10f

#define CONGfp CONG * 2.328306435454494e-10f

#define ITERATIONS 1000000000

#define PROCESS 4

#ifdef LONG

#define LENGTH long long

#else

#define LENGTH int

#endif

LENGTH MainLoopGlobal(LENGTH iterations,unsigned int seed_w,unsigned int seed_z)

{

#if defined TCONG

   unsigned int jcong=seed_z;

#elif defined TSHR3

   unsigned int jsr=seed_w;

#elif defined TMWC

   unsigned int z=seed_z;

   unsigned int w=seed_w;

#elif defined TKISS

   unsigned int jcong=seed_z;

   unsigned int jsr=seed_w;

   unsigned int z=seed_z;

   unsigned int w=seed_w;

#endif

   LENGTH total=0;

   for (LENGTH i=0;i<iterations;i++) {

#if defined TINT32

    #define THEONE 1073741824

    #if defined TCONG

        unsigned int x=CONG>>17 ;

        unsigned int y=CONG>>17 ;

    #elif defined TSHR3

        unsigned int x=SHR3>>17 ;

        unsigned int y=SHR3>>17 ;

    #elif defined TMWC

        unsigned int x=MWC>>17 ;

        unsigned int y=MWC>>17 ;

    #elif defined TKISS

        unsigned int x=KISS>>17 ;

        unsigned int y=KISS>>17 ;

    #endif

#elif defined TINT64

    #define THEONE 4611686018427387904

    #if defined TCONG

        unsigned long x=(unsigned long)(CONG>>1) ;

        unsigned long y=(unsigned long)(CONG>>1) ;

    #elif defined TSHR3

        unsigned long x=(unsigned long)(SHR3>>1) ;

        unsigned long y=(unsigned long)(SHR3>>1) ;

    #elif defined TMWC

        unsigned long x=(unsigned long)(MWC>>1) ;

        unsigned long y=(unsigned long)(MWC>>1) ;

    #elif defined TKISS

        unsigned long x=(unsigned long)(KISS>>1) ;

        unsigned long y=(unsigned long)(KISS>>1) ;

    #endif

#elif defined TFP32

    #define THEONE 1.0f

    #if defined TCONG

        float x=CONGfp ;

        float y=CONGfp ;

    #elif defined TSHR3

        float x=SHR3fp ;

        float y=SHR3fp ;

    #elif defined TMWC

        float x=MWCfp ;

        float y=MWCfp ;

    #elif defined TKISS

      float x=KISSfp ;

      float y=KISSfp ;

    #endif

#elif defined TFP64

    #define THEONE 1.0f

    #if defined TCONG

        double x=(double)CONGfp ;

        double y=(double)CONGfp ;

    #elif defined TSHR3

        double x=(double)SHR3fp ;

        double y=(double)SHR3fp ;

    #elif defined TMWC

        double x=(double)MWCfp ;

        double y=(double)MWCfp ;

    #elif defined TKISS

        double x=(double)KISSfp ;

        double y=(double)KISSfp ;

    #endif

#endif

      unsigned long inside=((x*x+y*y) < THEONE) ? 1:0;

      total+=inside;

   }

   return(total);

}

LENGTH splitter(LENGTH iterations,unsigned int process,

                unsigned int seed_w,unsigned int seed_z)

{

  // Trashy static allocation...

  LENGTH inside[4096],insides=0;

#pragma omp parallel for

  for (int i=0 ; i<process; i++) {

    inside[i]=MainLoopGlobal(iterations/process,seed_w+process,seed_z+process);

    printf("\tFound %lld for process %i\n",(long long)inside[i],i);

  }

  printf("\n");

  for (int i=0 ; i<process; i++) {

    insides+=inside[i];

  }

  return(insides);

}

int main(int argc, char *argv[]) {

  unsigned int seed_w=10,seed_z=10,process=PROCESS;

  LENGTH iterations=ITERATIONS,insides=0;

  if (argc > 1) {

    iterations=(LENGTH)atoll(argv[1]);

    process=atoi(argv[2]);

  }

  else {

    printf("\n\tPi : Estimate Pi with Monte Carlo exploration\n\n");

    printf("\t\t#1 : number of iterations (default 1 billion)\n");

    printf("\t\t#2 : number of process (default 4)\n\n");

  }

  printf ("\n\tInformation about architecture:\n\n");

  printf ("\tSizeof int = %lld bytes.\n", (long long)sizeof(int));

  printf ("\tSizeof long = %lld bytes.\n", (long long)sizeof(long));

  printf ("\tSizeof long long = %lld bytes.\n\n", (long long)sizeof(long long));

  printf ("\tMax int = %u\n", INT_MAX);

  printf ("\tMax long = %ld\n", LONG_MAX);

  printf ("\tMax long long = %lld\n\n", LLONG_MAX);

  insides=splitter(iterations,process,seed_w,seed_z);

  float pi=4.*(float)insides/(float)iterations;

  printf("\tPi=%f with error %f and %lld iterations\n\n",pi,

         fabs(pi-4*atan(1))/pi,(long long)iterations);

}