#ifndef _NTINTSAFE_H_INCLUDED_
#if WINAPI_FAMILY_PARTITION(WINAPI_PARTITION_APP | WINAPI_PARTITION_SYSTEM | WINAPI_PARTITION_GAMES)

//
// UINT subtraction
//
_Must_inspect_result_
__inline
NTSTATUS
RtlUIntSub(
    _In_ UINT uMinuend,
    _In_ UINT uSubtrahend,
    _Out_ _Deref_out_range_(==, uMinuend - uSubtrahend) UINT* puResult)
{
    NTSTATUS status;

    if (uMinuend >= uSubtrahend)
    {
        *puResult = (uMinuend - uSubtrahend);
        status = STATUS_SUCCESS;
    }
    else
    {
        *puResult = UINT_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }

    return status;
}

#endif
#endif
View code on GitHub

// ntintsafe.h

NTSTATUS RtlUIntSub(
  [in]  UINT uMinuend,
  [in]  UINT uSubtrahend,
  [out] UINT *puResult
);
View the official Windows Driver Kit DDI reference

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

RtlUIntSub function

Description

Subtracts one value of type UINT from another.

Parameters

`uMinuend` [in]

The value from which u8Subtrahend is subtracted.

`uSubtrahend` [in]

The value to subtract from u8Minuend.

`puResult` [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.

This function uses the following alternate name:

RtlUInt32Sub

View the official Windows Driver Kit DDI reference