Crivello ottimizzato di Eratostene con calcolo pi

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

#define RANGE 10000u
#define SCMAX (RANGE/3)
// compiled with cl65  -r -O -Cl crivello.c -o crivello.prg
typedef unsigned char uint_8;

uint_8 composite[RANGE];


int main(void) {
    clock_t Ticks, TicksDelta;
    unsigned int Sec;
    unsigned int Milli;

    unsigned int pi=0;
    unsigned int pr=0;
    register unsigned int i;
    register unsigned int j=2;
    register unsigned int ScopeMax;

    for(j=0,i=1; j<RANGE; ++j) {
        composite[j]=0;
        composite[i]=1;
        ++j;
        i+=2;
    }
    j=3;
    ScopeMax    = RANGE/j;

    printf("\nPress enter to start\n");
    //getchar();
    printf("\nComputing...\n");
    Ticks = clock();
    while(j<SCMAX) {
        pr=j+j+j-1;
        for (i=3; i<=ScopeMax; i+=2) {
            composite[pr]=1;
                pr+=j+j;
        }
        j+=2;
        ScopeMax=RANGE/j;
    }
    TicksDelta = clock() - Ticks;
    Sec = (unsigned short) (TicksDelta / CLOCKS_PER_SEC);
    Milli = ((TicksDelta % CLOCKS_PER_SEC) * 1000) / CLOCKS_PER_SEC;
    printf ("Time used: %u.%03u seconds = %u ticks\n", Sec, Milli, (unsigned short) TicksDelta);

    printf("Press enter to print the prime numbers\n");
    getchar();
    printf("\n");
    composite[0]=1;
    composite[1]=0;
    for(i=0; i<RANGE; ++i) {
        if(composite[i]==0) {
            ++pi;
            printf(" %u ", i+1);
        }
    }
    printf("\nPi = %u", pi);

    return 0;
}