OvmfPkg/XenBusDxe/Ia32/TestAndClearBit.nasm

   1 SECTION .text
   2
   3 ; INT32
   4 ; EFIAPI
   5 ; TestAndClearBit (
   6 ;   IN  INT32 Bit,
   7 ;   IN  volatile VOID* Address
   8 ;   );
   9 global ASM_PFX(TestAndClearBit)
  10 ASM_PFX(TestAndClearBit):
  11   mov ecx, [esp + 4]
  12   mov edx, [esp + 8]
  13   lock btr [edx], ecx
  14   sbb eax, eax
  15   ret
  16