1 files changed, 54 insertions, 2 deletions

diff --git a/src/undo.cpp b/src/undo.cpp
index ec85530..38c22ef 100644
--- a/src/undo.cpp
+++ b/src/undo.cpp
@@ -1,3 +1,7 @@
+#if SPECIAL
+#include "main.h"
+#endif
+
 struct history_info {
     uint16 ActionCount_Total;
     uint16 ActionCount_EndOfPlayhead;
@@ -11,7 +15,7 @@ struct history_info {
 };
 
 static uint64
-History_GetActionSize(history_entry_list *History, int i, uint16 ActionCount_EndOfPlayhead)
+History_GetActionSize(history_entry_list *History, int i)
 {
     history_action *Action = &History->Action[i];
     if (Action->Type == action_type_swap || Action->Type == action_type_swap_bitmap)
@@ -44,7 +48,7 @@ History_GetTreeInfo(history_entry_list *History, uint16 SampleIndex)
 
     for (int i = 0; i < Info.ActionCount_Total; i++)
     {
-        uint64 Size = History_GetActionSize(History, i, Info.ActionCount_EndOfPlayhead);
+        uint64 Size = History_GetActionSize(History, i);
         Info.ActionOffset_Total += Size;
         if (i < Info.ActionCount_EndOfPlayhead)
             Info.ActionOffset_EndOfPlayhead += Size;
@@ -202,6 +206,9 @@ void History_Entry_Commit(memory *Memory, char *Name)
     history_entry *Entry = &History->Entry[History->EntryPlayhead];
     Entry->Name = Name;
     Entry->NumberOfActions = 0;
+    if (History->NumberOfEntries > MAX_HISTORY_ENTRIES) {
+        Assert(0);
+    }
     // Effectively deletes entries in front if we're beginning out of an undo.
     if (History->NumberOfEntries != History->EntryPlayhead)
         History->NumberOfEntries = History->EntryPlayhead;
@@ -223,6 +230,42 @@ void History_Entry_End(memory *Memory)
 #endif
 }
 
+static void
+History_Purge(memory *Memory, history_entry_list *History, uint64 ActionCount_Total, uint64 ActionOffset_Total, uint64 PurgeSize) 
+{
+    int Size = 0;
+    int EntryIndex = 0;
+    int ActionIndex = 0;
+    int ActionCount = 0;
+    while (Size < PurgeSize) {
+        history_entry *Entry = &History->Entry[EntryIndex];
+        ActionCount += Entry->NumberOfActions;
+        while (ActionIndex < ActionCount) {
+            Size += History_GetActionSize(History, ActionIndex);
+            ActionIndex++;
+        }
+        EntryIndex++;
+    }
+    int EntryCount = (EntryIndex + 1);
+    {
+        uint8 *Address_Start = (uint8 *)Memory_AddressAtOffset(Memory, P_UndoBuffer, Size);
+        uint8 *Address_End = (uint8 *)Memory_AddressAtOffset(Memory, P_UndoBuffer, ActionOffset_Total);
+        Arbitrary_ShiftData(Address_Start, Address_End, Size, -1);
+    }
+    {
+        uint8 *Address_Start = (uint8 *)&History->Entry[EntryCount];
+        uint8 *Address_End = (uint8 *)&History->Entry[History->NumberOfEntries];
+        Arbitrary_ShiftData(Address_Start, Address_End, sizeof(history_entry) * EntryCount, -1);
+    }
+    {
+        uint8 *Address_Start = (uint8 *)&History->Action[ActionCount];
+        uint8 *Address_End = (uint8 *)&History->Action[ActionCount_Total];
+        Arbitrary_ShiftData(Address_Start, Address_End, sizeof(history_action) * ActionCount, -1);
+    }
+    History->NumberOfEntries -= EntryCount;
+    History->EntryPlayhead -= EntryCount;
+}
+
 // NOTE(fox): Shift is the only action that additionally changes the data after
 // the info is put on the tree, since it's always the same function used.
 
@@ -233,6 +276,15 @@ static void History_Action_Add(memory *Memory, history_action ActionData, void *
 
     history_info Info = History_GetTreeInfo(History, History->EntryPlayhead - 1);
 
+    if ((Info.ActionOffset_EndOfPlayhead + ActionData.Size) > Memory->Slot[P_UndoBuffer].Size) {
+        History_Purge(Memory, History, Info.ActionCount_Total, Info.ActionOffset_Total, ActionData.Size * 4);
+        Entry = &History->Entry[History->EntryPlayhead - 1];
+        Info = History_GetTreeInfo(History, History->EntryPlayhead - 1);
+    }
+    if (Info.ActionCount_Total > MAX_HISTORY_ACTIONS) {
+        Assert(0);
+    }
+
     history_action *Action = &History->Action[Info.ActionCount_Total];
     *Action = ActionData;