_interlockedbittestandset64 function (winnt.h)

Article
02/22/2024

Tests the specified bit of the specified LONG64 value and sets it to 1. The operation is atomic.

Syntax

BOOLEAN _interlockedbittestandset64(
  [in] LONG64 volatile *Base,
  [in] LONG64          Offset
);

Parameters

[in] Base

A pointer to a variable.

[in] Offset

The bit position to be tested.

Return value

The value of the specified bit before it is set.

Remarks

The interlocked functions provide a simple mechanism for synchronizing access to a variable that is shared by multiple threads. This function is atomic with respect to calls to other interlocked functions.

This function is implemented using a compiler intrinsic where possible. For more information, see the WinBase.h header file and _interlockedbittestandset64.

This function generates a full memory barrier (or fence) to ensure that memory operations are completed in order.

Requirements

Requirement	Value
Target Platform	Windows
Header	winnt.h (include Windows.h)