audk/OvmfPkg/XenBusDxe/X64/TestAndClearBit.nasm

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DEFAULT REL
SECTION .text
; INT32
; EFIAPI
; TestAndClearBit (
; IN INT32 Bit, // rcx
; IN volatile VOID* Address // rdx
; );
global ASM_PFX(TestAndClearBit)
ASM_PFX(TestAndClearBit):
lock
btr [rdx], ecx
sbb eax, eax
ret