1 2 #include <stdio.h> 3 4 typedef unsigned int UInt; 5 6 UInt test_jcxz ( UInt arg ) 7 { 8 UInt block[2]; 9 block[0] = arg; 10 block[1] = 0xdeadbeef; 11 __asm__ __volatile__( 12 "movl %0,%%ecx\n\t" 13 "movl $0,%%eax\n" 14 "0:\n\t" 15 "jcxz 1f\n\t" 16 "addl $1, %%eax\n\t" 17 "subl $1, %%ecx\n\t" 18 "jmp 0b\n" 19 "1:\n\t" 20 "movl %%eax, %1" 21 : /*out*/ : /*in*/ "m"(block[0]), 22 "m"(block[1]) : /*trash*/ "eax","ecx","cc","memory" 23 ); 24 return block[1]; 25 } 26 27 UInt test_jecxz ( UInt arg ) 28 { 29 UInt block[2]; 30 block[0] = arg; 31 block[1] = 0xdeadbeef; 32 __asm__ __volatile__( 33 "movl %0,%%ecx\n\t" 34 "movl $0,%%eax\n" 35 "0:\n\t" 36 "jecxz 1f\n\t" 37 "addl $1, %%eax\n\t" 38 "subl $1, %%ecx\n\t" 39 "jmp 0b\n" 40 "1:\n\t" 41 "movl %%eax, %1" 42 : /*out*/ : /*in*/ "m"(block[0]), 43 "m"(block[1]) : /*trash*/ "eax","ecx","cc","memory" 44 ); 45 return block[1]; 46 } 47 48 int main ( void ) 49 { 50 UInt arg = 0x01028374; 51 printf("test_jcxz(0x%x) = 0x%x\n", arg, test_jcxz(arg)); 52 printf("test_jecxz(0x%x) = 0x%x\n", arg, test_jecxz(arg)); 53 return 0; 54 } 55
