/* Taken from Wine ntdll/sync.c */

#include <rtl_vista.h>
#include <wine/config.h>
#include <wine/port.h>

/******************************************************************
 *              RtlRunOnceInitialize (NTDLL.@)
 */
void WINAPI RtlRunOnceInitialize( RTL_RUN_ONCE *once )
{
    once->Ptr = NULL;
}

/******************************************************************
 *              RtlRunOnceBeginInitialize (NTDLL.@)
 */
DWORD WINAPI RtlRunOnceBeginInitialize( RTL_RUN_ONCE *once, ULONG flags, void **context )
{
    if (flags & RTL_RUN_ONCE_CHECK_ONLY)
    {
        ULONG_PTR val = (ULONG_PTR)once->Ptr;

        if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
        if ((val & 3) != 2) return STATUS_UNSUCCESSFUL;
        if (context) *context = (void *)(val & ~3);
        return STATUS_SUCCESS;
    }

    for (;;)
    {
        ULONG_PTR next, val = (ULONG_PTR)once->Ptr;

        switch (val & 3)
        {
        case 0:  /* first time */
            if (!interlocked_cmpxchg_ptr( &once->Ptr,
                                          (flags & RTL_RUN_ONCE_ASYNC) ? (void *)3 : (void *)1, 0 ))
                return STATUS_PENDING;
            break;

        case 1:  /* in progress, wait */
            if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
            next = val & ~3;
            if (interlocked_cmpxchg_ptr( &once->Ptr, (void *)((ULONG_PTR)&next | 1),
                                         (void *)val ) == (void *)val)
                NtWaitForKeyedEvent( 0, &next, FALSE, NULL );
            break;

        case 2:  /* done */
            if (context) *context = (void *)(val & ~3);
            return STATUS_SUCCESS;

        case 3:  /* in progress, async */
            if (!(flags & RTL_RUN_ONCE_ASYNC)) return STATUS_INVALID_PARAMETER;
            return STATUS_PENDING;
        }
    }
}

/******************************************************************
 *              RtlRunOnceComplete (NTDLL.@)
 */
DWORD WINAPI RtlRunOnceComplete( RTL_RUN_ONCE *once, ULONG flags, void *context )
{
    if ((ULONG_PTR)context & 3) return STATUS_INVALID_PARAMETER;

    if (flags & RTL_RUN_ONCE_INIT_FAILED)
    {
        if (context) return STATUS_INVALID_PARAMETER;
        if (flags & RTL_RUN_ONCE_ASYNC) return STATUS_INVALID_PARAMETER;
    }
    else context = (void *)((ULONG_PTR)context | 2);

    for (;;)
    {
        ULONG_PTR val = (ULONG_PTR)once->Ptr;

        switch (val & 3)
        {
        case 1:  /* in progress */
            if (interlocked_cmpxchg_ptr( &once->Ptr, context, (void *)val ) != (void *)val) break;
            val &= ~3;
            while (val)
            {
                ULONG_PTR next = *(ULONG_PTR *)val;
                NtReleaseKeyedEvent( 0, (void *)val, FALSE, NULL );
                val = next;
            }
            return STATUS_SUCCESS;

        case 3:  /* in progress, async */
            if (!(flags & RTL_RUN_ONCE_ASYNC)) return STATUS_INVALID_PARAMETER;
            if (interlocked_cmpxchg_ptr( &once->Ptr, context, (void *)val ) != (void *)val) break;
            return STATUS_SUCCESS;

        default:
            return STATUS_UNSUCCESSFUL;
        }
    }
}

/******************************************************************
 *              RtlRunOnceExecuteOnce (NTDLL.@)
 */
DWORD WINAPI RtlRunOnceExecuteOnce( RTL_RUN_ONCE *once, PRTL_RUN_ONCE_INIT_FN func,
                                    void *param, void **context )
{
    DWORD ret = RtlRunOnceBeginInitialize( once, 0, context );

    if (ret != STATUS_PENDING) return ret;

    if (!func( once, param, context ))
    {
        RtlRunOnceComplete( once, RTL_RUN_ONCE_INIT_FAILED, NULL );
        return STATUS_UNSUCCESSFUL;
    }

    return RtlRunOnceComplete( once, 0, context ? *context : NULL );
}