#include <stdio.h>
#include <malloc.h>
#include <time.h>

#define TEST(f,x)	(*(f+(x)/16)&(1<<(((x)%16L)/2)))
#define SET(f,x)	*(f+(x)/16)|=1<<(((x)%16L)/2)

int
main(int argc, char *argv[])
{
    unsigned char *ptr=NULL;
    unsigned long max, mom, s=0, e=1;
    register unsigned long test=1;
    register unsigned long count=1;
    time_t begin;
    
    max = ( argc>1 ) ? atol(argv[1]) : 0xFFFFFFL;
    ptr = (unsigned char *) calloc( ((max>>4)+1L), sizeof(char) );
    if ( ! ptr ) {
        printf( "Can't allocate enough memory!\n" );
        system("pause");
      return 1;
    }

    printf( "Searching prime numbers to : %ld\n", max );
    
    begin = time (NULL);
    while ( (test+=2) < max) if (!TEST(ptr, test) ) {
        if  ( ++count%0xFFL==0 ) {
            printf ( "%ld prime number\x0d", count );
            fflush(stdout);
        }
        for ( mom=3L*test; mom<max; mom+=test<<1 ) SET (ptr, mom);
    }

    printf( " %ld prime numbers found in %ld secs.\n\n", count, time(NULL)-begin);

    printf( "Show prime numbers ( Enter end < start to exit )" );
    while ( s<e ) {
        printf ("\n\nStart of Area : "); 
        fflush (stdout); scanf ("%ld", &s);
        printf ("End of Area   : ");     
        fflush (stdout); scanf ("%ld", &e);
        count = s-2;
        if ( s%2==0 ) count++;
        while ((count+=2)<e) if (!TEST(ptr,count)) printf ("%ld\t", count);
    }

    free(ptr);
  return 0;
}

/*

Searching prime numbers to : 16777215
 1077871 prime numbers found in 1 secs.

Show prime numbers ( Enter end < start to exit )

Start of Area : 1
End of Area   : 1000
1       3       5       7       11      13      17      19      23      29
31      37      41      43      47      53      59      61      67      71
73      79      83      89      97      101     103     107     109     113
127     131     137     139     149     151     157     163     167     173
179     181     191     193     197     199     211     223     227     229
233     239     241     251     257     263     269     271     277     281
283     293     307     311     313     317     331     337     347     349
353     359     367     373     379     383     389     397     401     409
419     421     431     433     439     443     449     457     461     463
467     479     487     491     499     503     509     521     523     541
547     557     563     569     571     577     587     593     599     601
607     613     617     619     631     641     643     647     653     659
661     673     677     683     691     701     709     719     727     733
739     743     751     757     761     769     773     787     797     809
811     821     823     827     829     839     853     857     859     863
877     881     883     887     907     911     919     929     937     941
947     953     967     971     977     983     991     997

Start of Area :

*/