Example TOP-C Application

There are several example `TOP-C' programs in the `topc/examples' subdirectory. We include one example in this manual. It does not contain any UPDATE actions, and therefore illustrates only a trivial form of parallelism (with no interaction among the slaves).

The program produces an array of 10,000,000 random integers in one pass, and then finds the maximum value in a second pass. It would be compiled by: topcc MODE file.out, where MODE is one of -seq, -mpi, or -pthread. One can control the number of slaves by executing: ./a.out --TOPC_num_slaves=num.

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <topc.h>

#define MAX 10000000
#define INCR MAX/10 /* We assume INCR divides MAX exactly */

int array[MAX];
int idx;
int max_int;

TOPC_BUF GenerateTaskInput() {
  static int input_task;
  if (idx >= MAX) return NOTASK;
  input_task = idx;
  idx = idx + INCR;
  return TOPC_MSG( &input_task, sizeof(input_task) );
}
TOPC_BUF DoTaskRandom( void *input ) {
  static int rand_int[INCR];
  int i;
  for ( i = 0; i < INCR; i++)
    rand_int[i] = rand();
  return TOPC_MSG( rand_int, INCR * sizeof(int) );
}
TOPC_ACTION CheckTaskRandom( void *input, void *output ) {
  int curr_idx = *(int *)input;
  int *rand_vals = output;
  memcpy( array+curr_idx, rand_vals, INCR * sizeof(int) );
  return NO_ACTION;
}

TOPC_BUF GenerateTaskInMax() {
  int *input_task;
  if (idx >= MAX) return NOTASK;
  input_task = array + idx;
  idx = idx + INCR;
  return TOPC_MSG( input_task, INCR * sizeof(int) );
}
TOPC_BUF DoTaskMax( void *input ) {
  int i, *subarray = input;
  static max=0;
  for ( i = 0; i < INCR; i++)
    if ( subarray[i] > max )
      max = subarray[i];
  return TOPC_MSG( &max, sizeof(max) );
}
TOPC_ACTION CheckTaskMax( void *input, void *output ) {
  int curr_max = *(int *)output;
  if ( curr_max > max_int )
    max_int = curr_max;
  return NO_ACTION;
}

int main( int argc, char **argv ) {
  TOPC_init( &argc, &argv );
  idx = 0; /* Initialize idx, and randomize values of array[] */
  TOPC_master_slave( GenerateTaskInput, DoTaskRandom, CheckTaskRandom, NULL );
  printf("Finished randomizing integers.\n");
  idx = 0; /* Re-initialize idx to 0, and find max. value in array[] */
  TOPC_master_slave( GenerateTaskInMax, DoTaskMax, CheckTaskMax, NULL );
  TOPC_finalize();
  printf("The maximum integer is:  %d\n", max_int);
}

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