none/tests/x86/lzcnt32.c

   1
   2 #include <stdio.h>
   3
   4 typedef  unsigned long long int  ULong;
   5 typedef  unsigned int            UInt;
   6
   7 __attribute__((noinline))
   8 void do_lzcnt32 ( /*OUT*/UInt* flags, /*OUT*/UInt* res, UInt arg )
   9 {
  10   UInt block[3] = { arg, 0, 0 };
  11   __asm__ __volatile__(
  12     "movl $0x55555555, %%esi" "\n\t"
  13     "lzcntl 0(%0), %%esi"     "\n\t"
  14     "movl %%esi, 4(%0)"       "\n\t"
  15     "pushfl"                  "\n\t"
  16     "popl %%esi"              "\n\t"
  17     "movl %%esi, 8(%0)"       "\n"
  18     : : "r"(&block[0]) : "esi","cc","memory"
  19   );
  20   *res = block[1];
  21   *flags = block[2] & 0x8d5;
  22 }
  23
  24 __attribute__((noinline))
  25 void do_lzcnt16 ( /*OUT*/UInt* flags, /*OUT*/UInt* res, UInt arg )
  26 {
  27   UInt block[3] = { arg, 0, 0 };
  28   __asm__ __volatile__(
  29     "movl $0x55555555, %%esi" "\n\t"
  30     "lzcntw 0(%0), %%si"      "\n\t"
  31     "movl %%esi, 4(%0)"       "\n\t"
  32     "pushfl"                  "\n\t"
  33     "popl %%esi"              "\n\t"
  34     "movl %%esi, 8(%0)"       "\n"
  35     : : "r"(&block[0]) : "esi","cc","memory"
  36   );
  37   *res = block[1];
  38   *flags = block[2] & 0x8d5;
  39 }
  40
  41 int main ( void )
  42 {
  43    UInt w;
  44
  45    w = 0xFEDC1928;
  46    while (1) {
  47       UInt res;
  48       UInt flags;
  49       do_lzcnt32(&flags, &res, w);
  50       printf("lzcntl %08x -> %08x %04x\n", w, res, flags);
  51       if (w == 0) break;
  52       w = ((w >> 2) | (w >> 1)) + (w / 17);
  53    }
  54
  55    w = 0xFEDC1928;
  56    while (1) {
  57       UInt res;
  58       UInt flags;
  59       do_lzcnt16(&flags, &res, w);
  60       printf("lzcntw %08x -> %08x %04x\n", w, res, flags);
  61       if (w == 0) break;
  62       w = ((w >> 2) | (w >> 1)) + (w / 17);
  63    }
  64
  65    return 0;
  66 }