yandex_arm_2_proc

yandex_arm_2_proc.c

#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdio.h>

#define BATCH_SIZE 10

void calc_stat_for(char *batch, int sz, int *stat){
  int i;
	print_batch(batch,sz);
  for(i=0; i<sz; i++) stat[batch[i]]++;
}

void calc(char *str, int size, int *stat, int idx)
{
      int j,l,
        k = size/BATCH_SIZE/2;

      for(j=0; j<k-1; j++){
		  printf("pid=%d, processing batch: %d\n",getpid(), (j+idx)*BATCH_SIZE);
        calc_stat_for(&str[j*BATCH_SIZE+idx],BATCH_SIZE,stat);
      }
}

int merge_stat(int *st1, int *st2)
{
  int i,m=1;
	
  for(i=2; i<256; i++) {
    st1[i]+=st2[i];
    if(st1[i]>st1[m]) m = i;
  }

  return m;
}

char mostFrequentCharacter(char *str, int size)
{
  int stat[256] = {0};
  if(size > 2*BATCH_SIZE){
    int fd[2];
    pipe(fd);
    int p = fork();
    if(p>0){ // calc for odd
		close(fd[1]);
		printf("forked parent: %d\n",getpid());

      calc(str, size, stat, 0);
      int stat2[256],t;
      read(fd[0],stat2,256*sizeof(int));
      wait(&t);

      int max = merge_stat(stat, stat2);
		print_stat(stat2);

      return (char)max;
    }else if(p == 0){ // calc for even
		close(fd[0]);
		printf("forked child: %d\n",getpid());
      calc(str, size, stat, 1);

      write(fd[1],stat,256*sizeof(int));
    }
  }
  return 0;
}

int main(int argc, char *argv[])
{
	if(argc!=2){
		printf("Usage: %s filename\n",argv[0]);
		return 0;
	}
	
	FILE *f = fopen(argv[1],"r");
	char str[1024*1024], buf[1024];
	int i,k=0;
	while (fread(buf,sizeof(char),1024,f)) {
		for(i=0; i<1024; i++, k++)
			str[k] = buf[i];
	}
	printf("size: %d\n",k);
	char c = mostFrequentCharacter(str, k);
	printf("mostFrequentCharacter => %d\n", c);
	return 0;
}