kvm/user/x86/sieve.c

   1 #include "vm.h"
   2
   3 void print(const char *text);
   4
   5 void printi(int n)
   6 {
   7     char buf[10], *p = buf;
   8     int s = 0, i;
   9
  10     if (n < 0) {
  11         n = -n;
  12         s = 1;
  13     }
  14
  15     while (n) {
  16         *p++ = '0' + n % 10;
  17         n /= 10;
  18     }
  19
  20     if (s)
  21         *p++ = '-';
  22
  23     if (p == buf)
  24         *p++ = '0';
  25
  26     for (i = 0; i < (p - buf) / 2; ++i) {
  27         char tmp;
  28
  29         tmp = buf[i];
  30         buf[i] = p[-1-i];
  31         p[-1-i] = tmp;
  32     }
  33
  34     *p = 0;
  35
  36     print(buf);
  37 }
  38
  39 int sieve(char* data, int size)
  40 {
  41     int i, j, r = 0;
  42
  43     for (i = 0; i < size; ++i)
  44         data[i] = 1;
  45
  46     data[0] = data[1] = 0;
  47
  48     for (i = 2; i < size; ++i)
  49         if (data[i]) {
  50             ++r;
  51             for (j = i*2; j < size; j += i)
  52                 data[j] = 0;
  53         }
  54     return r;
  55 }
  56
  57 void test_sieve(const char *msg, char *data, int size)
  58 {
  59     int r;
  60
  61     print(msg);
  62     print(": ");
  63     r = sieve(data, size);
  64     printi(r);
  65     print("\n");
  66 }
  67
  68 #define STATIC_SIZE 1000000
  69 #define VSIZE 100000000
  70 char static_data[STATIC_SIZE];
  71
  72 int main()
  73 {
  74     void *v;
  75     int i;
  76
  77     print("starting sieve\n");
  78     test_sieve("static", static_data, STATIC_SIZE);
  79     setup_vm();
  80     print("mapped: ");
  81     test_sieve("mapped", static_data, STATIC_SIZE);
  82     for (i = 0; i < 30; ++i) {
  83         v = vmalloc(VSIZE);
  84         test_sieve("virtual", v, VSIZE);
  85         vfree(v);
  86     }
  87
  88     return 0;
  89 }