RtlInsertAsLeftChild - NtDoc

Native API online documentation, based on the System Informer (formerly Process Hacker) phnt headers
#ifndef _NTRTL_H

#define RtlInsertAsLeftChild(ParentLinks, ChildLinks) \
{ \
    PRTL_SPLAY_LINKS _SplayParent; \
    PRTL_SPLAY_LINKS _SplayChild; \
    _SplayParent = (PRTL_SPLAY_LINKS)(ParentLinks); \
    _SplayChild = (PRTL_SPLAY_LINKS)(ChildLinks); \
    _SplayParent->LeftChild = _SplayChild; \
    _SplayChild->Parent = _SplayParent; \
}

#endif

View code on GitHub

This function is documented in Windows Driver Kit.