1
2 #include <stdio.h>
3
4 typedef unsigned long long int ULong;
5 typedef unsigned int UInt;
6
7 __attribute__((noinline))
do_lzcnt32(UInt * flags,UInt * res,UInt arg)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))
do_lzcnt16(UInt * flags,UInt * res,UInt arg)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
main(void)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 }
67