Implement arch-specific atomic singly-linked list functions

xtoskrnl/rtl/i686/atomic.cc

@@ -0,0 +1,178 @@
+/**
+ * PROJECT:         ExectOS
+ * COPYRIGHT:       See COPYING.md in the top level directory
+ * FILE:            xtoskrnl/rtl/i686/atomic.cc
+ * DESCRIPTION:     Atomic operations support
+ * DEVELOPERS:      Aiken Harris <harraiken91@gmail.com>
+ */
+
+#include <xtos.hh>
+
+
+/**
+ * Removes all entries from single linked list.
+ *
+ * @param Header
+ *        Supplies a pointer to the header of linked list.
+ *
+ * @return This routine returns a pointer to the original list, or NULLPTR if the list was already empty.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+PSINGLE_LIST_ENTRY
+RTL::Atomic::FlushSingleList(IN PSINGLE_LIST_HEADER ListHead)
+{
+    SINGLE_LIST_HEADER ExpectedHeader, NewHeader;
+    PSINGLE_LIST_ENTRY FirstEntry;
+    ULONG64 ResultValue;
+
+    /* Load the initial state of the header */
+    ExpectedHeader.Alignment = *(VOLATILE PULONGLONG)&ListHead->Alignment;
+
+    /* Enter the CAS loop */
+    while(TRUE)
+    {
+        /* Extract the entry address */
+        FirstEntry = ExpectedHeader.Next.Next;
+
+        /* Check if list is empty */
+        if(FirstEntry == NULLPTR)
+        {
+            /* Return NULLPTR */
+            return NULLPTR;
+        }
+
+        /* Prepare the new header state */
+        NewHeader.Next.Next = NULLPTR;
+        NewHeader.Depth = 0;
+        NewHeader.Sequence = ExpectedHeader.Sequence;
+
+        /* Perform the compare and swap operation */
+        ResultValue = CompareExchange64((VOLATILE PLONG_PTR)&ListHead->Alignment,
+                                        (LONG_PTR)ExpectedHeader.Alignment,
+                                        (LONG_PTR)NewHeader.Alignment);
+
+        /* Evaluate the CAS result */
+        if(ResultValue == ExpectedHeader.Alignment)
+        {
+            /* Swap succeeded, return the original first entry */
+            return FirstEntry;
+        }
+
+        /* Collision detected, retry */
+        ExpectedHeader.Alignment = ResultValue;
+    }
+}
+
+/**
+ * Removes and returns the first entry from single linked list.
+ *
+ * @param Header
+ *        Supplies a pointer to the header of a single linked list.
+ *
+ * @return This routine returns a pointer to the removed element, or NULLPTR if the list was empty.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+PSINGLE_LIST_ENTRY
+RTL::Atomic::PopEntrySingleList(IN PSINGLE_LIST_HEADER ListHead)
+{
+    SINGLE_LIST_HEADER ExpectedHeader, NewHeader;
+    PSINGLE_LIST_ENTRY FirstEntry;
+    ULONGLONG ResultValue;
+
+    /* Load the initial state of the header */
+    ExpectedHeader.Alignment = *(VOLATILE PULONGLONG)&ListHead->Alignment;
+
+    /* Enter the CAS loop */
+    while(TRUE)
+    {
+        /* Extract the entry address */
+        FirstEntry = ExpectedHeader.Next.Next;
+
+        /* Check if list is empty */
+        if(FirstEntry == NULLPTR)
+        {
+            /* Return NULLPTR */
+            return NULLPTR;
+        }
+
+        /* Prepare the new header state */
+        NewHeader.Next.Next = FirstEntry->Next;
+        NewHeader.Depth = ExpectedHeader.Depth - 1;
+        NewHeader.Sequence = ExpectedHeader.Sequence;
+
+        /* Perform the compare and swap operation */
+        ResultValue = CompareExchange64((VOLATILE PLONG_PTR)&ListHead->Alignment,
+                                        (LONG_PTR)ExpectedHeader.Alignment,
+                                        (LONG_PTR)NewHeader.Alignment);
+
+        /* Evaluate the CAS result */
+        if(ResultValue == ExpectedHeader.Alignment)
+        {
+            /* Swap succeeded, return the original first entry */
+            return FirstEntry;
+        }
+
+        /* Collision detected, retry */
+        ExpectedHeader.Alignment = ResultValue;
+    }
+}
+
+/**
+ * Inserts new entry at the beginning of single linked list.
+ *
+ * @param Header
+ *        Supplies a pointer to the header of linked list.
+ *
+ * @param Entry
+ *        Supplies a pointer to entry, that will be inserted into linked list.
+ *
+ * @return This routine returns a pointer to original heading, or NULLPTR if the list was originally empty.
+ *
+ * @since XT 1.0
+ */
+XTFASTCALL
+PSINGLE_LIST_ENTRY
+RTL::Atomic::PushEntrySingleList(IN PSINGLE_LIST_HEADER ListHead,
+                                 IN PSINGLE_LIST_ENTRY Entry)
+{
+    SINGLE_LIST_HEADER ExpectedHeader, NewHeader;
+    PSINGLE_LIST_ENTRY FirstEntry;
+    ULONGLONG ResultValue;
+
+    /* Load the initial state of the header */
+    ExpectedHeader.Alignment = *(VOLATILE PULONGLONG)&ListHead->Alignment;
+
+    /* Enter the CAS loop */
+    while(TRUE)
+    {
+        /* Extract the entry address */
+        FirstEntry = ExpectedHeader.Next.Next;
+
+        /* Set next entry to the previous first */
+        Entry->Next = FirstEntry;
+
+        /* Prepare the new header state */
+        NewHeader.Next.Next = Entry;
+        NewHeader.Depth = ExpectedHeader.Depth + 1;
+        NewHeader.Sequence = ExpectedHeader.Sequence + 1;
+
+        /* Perform the compare and swap operation */
+        ResultValue = CompareExchange64((VOLATILE PLONG_PTR)&ListHead->Alignment,
+                                        (LONG_PTR)ExpectedHeader.Alignment,
+                                        (LONG_PTR)NewHeader.Alignment);
+
+        /* Evaluate the CAS result */
+        if(ResultValue == ExpectedHeader.Alignment)
+        {
+            /* Swap succeeded, return the original first entry */
+            return FirstEntry;
+        }
+
+        /* Collision detected, retry */
+        ExpectedHeader.Alignment = ResultValue;
+    }
+}