#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// ULONG_PTR subtraction
//
#ifdef _WIN64

#define RtlULongPtrSub RtlULongLongSub

#endif
#endif
#endif
View code on GitHub

#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)
//
// ULONG_PTR subtraction
//
#ifdef _WIN64
// ...
#else

_Must_inspect_result_
__inline
NTSTATUS
RtlULongPtrSub(
    _In_ ULONG_PTR ulMinuend,
    _In_ ULONG_PTR ulSubtrahend,
    _Out_ _Deref_out_range_(==, ulMinuend - ulSubtrahend) ULONG_PTR* pulResult)
{
    NTSTATUS status;

    if (ulMinuend >= ulSubtrahend)
    {
        *pulResult = (ulMinuend - ulSubtrahend);
        status = STATUS_SUCCESS;
    }
    else
    {
        *pulResult = ULONG_PTR_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }

    return status;
}

#endif
#endif
#endif
View code on GitHub

// ntintsafe.h

NTSTATUS RtlULongPtrSub(
  [in]  ULONG_PTR ulMinuend,
  [in]  ULONG_PTR ulSubtrahend,
  [out] ULONG_PTR *pulResult
);
View the official Windows Driver Kit DDI reference

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Windows Driver Kit DDI reference (nf-ntintsafe-rtlulongptrsub)

RtlULongPtrSub function

Description

Subtracts one value of type ULONG_PTR from another.

Parameters

`ulMinuend` [in]

The value from which ulSubtrahend is subtracted.

`ulSubtrahend` [in]

The value to subtract from ulMinuend.

`pulResult` [out]

A pointer to the result. If the operation results in a value that overflows or underflows the capacity of the type, the function returns STATUS_INTEGER_OVERFLOW and this parameter is not valid.

Return value

Returns STATUS_SUCCESS if the operation is successful.

See the implementation of this helper function in ntintsafe.h in the WDK for possible error return values.

Remarks

This is one of a set of inline functions designed to provide arithmetic operations and perform validity checks with minimal impact on performance.

View the official Windows Driver Kit DDI reference