#include <stdio.h>
#include <unistd.h>

#define N 4 // number of workers

typedef struct
{
  int i; // instance number
  unsigned int start, size; // search space: start ... start+size-1
  //...
}
Data;

Data D[N];

void *f( void *v) // worker function
{
  int i = *(int *) v;

  printf( "f %i start = %u, size = %u\n", i, D[i].start, D[i].size);

  while( D[i].size > 0) { sleep(1); --D[i].size; } // simulate work

  printf( "f %i done\n", i);

  return 0;
}

int main( void)
{
 // initialize data
 //
  for( int i = 0; i < N; ++i)
  {
    D[i].i = i; D[i].start = 10*i; D[i].size = 6-i; // simulate parameters
  }