RtlUInt8Sub - NtDoc

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

//=============================================================================
// Subtraction functions
//=============================================================================

//
// UINT8 subtraction
//
_Must_inspect_result_
__inline
NTSTATUS
RtlUInt8Sub(
    _In_ UINT8 u8Minuend,
    _In_ UINT8 u8Subtrahend,
    _Out_ _Deref_out_range_(==, u8Minuend - u8Subtrahend) UINT8* pu8Result)
{
    NTSTATUS status;
    
    if (u8Minuend >= u8Subtrahend)
    {
        *pu8Result = (UINT8)(u8Minuend - u8Subtrahend);
        status = STATUS_SUCCESS;
    }
    else
    {
        *pu8Result = UINT8_ERROR;
        status = STATUS_INTEGER_OVERFLOW;
    }
    
    return status;
}

#endif
#endif
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