From 8d157e1bcd6b31baaa3a38038f29da0a1523e5e3 Mon Sep 17 00:00:00 2001
From: Eggert Jung <eggert.s.jung@wischhof13.de>
Date: Mon, 23 Feb 2026 15:13:47 +0100
Subject: [PATCH] switch to linked list for alloc

---
 kernel/memory/pageframealloc.cc | 60 +++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 29 deletions(-)

diff --git a/kernel/memory/pageframealloc.cc b/kernel/memory/pageframealloc.cc
index 006ae41..e85e026 100644
--- a/kernel/memory/pageframealloc.cc
+++ b/kernel/memory/pageframealloc.cc
@@ -10,6 +10,8 @@
 
 //uint8_t PageFrameAllocator::bitmap[4294967296 / 4096 / 8];
 PageFrame PageFrameAllocator::PageFrames[4294967296 / 4096];
+Queue<PageFrame> user_memory_q;
+Queue<PageFrame> kernel_memory_q;
 
 void mark_pageframes(uintptr_t start, uintptr_t end, bool available){
    // DBG << "start: " << hex << start << " end: " << end;
@@ -19,16 +21,24 @@ void mark_pageframes(uintptr_t start, uintptr_t end, bool available){
         start = 4294967296;
     if(end > 4294967296)
         end = 4294967296;
+
+    if(start < 0x4000000 && end > 0x4000000){
+        mark_pageframes(start, 0x4000000, available);
+        mark_pageframes(0x4000000, end, available);
+    }
+
     //DBG << " page start: " << hex << start << " end: " << end << endl;
+    Queue<PageFrame>* q = start<0x4000000?&kernel_memory_q:&user_memory_q;
 
     for(uint64_t i = start; i < end; i += 4096){
         uint64_t pg = i/4096;
 
         PageFrameAllocator::PageFrames[pg].available = available;
-        //if(available)
-        //    PageFrameAllocator::bitmap[pg/8] |= (1 << pg%8);
-        //else
-        //    PageFrameAllocator::bitmap[pg/8] &= ~(1 << pg%8);
+
+        if(available)
+            q->enqueue(PageFrameAllocator::PageFrames[pg]);
+        else
+            q->remove(&PageFrameAllocator::PageFrames[pg]);
     }
 }
 
@@ -42,8 +52,12 @@ void PageFrameAllocator::init(){
         uintptr_t end =  (uintptr_t)memory_map_entry->getEndAddress();
         bool available = memory_map_entry->isAvailable();
 
-        if(available)
-            mark_pageframes(start, end, true);
+        if(available){
+            if(start < (uintptr_t)&___KERNEL_END___)
+                start = Page::ceil((uintptr_t)&___KERNEL_END___ +1);
+
+            mark_pageframes(start, end, available);
+        }
 
         memory_map_entry = memory_map_entry->getNext();
     }
@@ -55,8 +69,9 @@ void PageFrameAllocator::init(){
         uintptr_t end =  (uintptr_t)memory_map_entry->getEndAddress();
         bool available = memory_map_entry->isAvailable();
 
-        if(!available)
-            mark_pageframes(start, end, false);
+        if(!available){
+           mark_pageframes(start, end, available);
+        }
 
         memory_map_entry = memory_map_entry->getNext();
     }
@@ -113,31 +128,18 @@ void PageFrameAllocator::stats(){
 }
 
 void* PageFrameAllocator::alloc(bool kernel){
-    uintptr_t search_start;
-    uintptr_t search_end;
-    if(kernel){
-        search_start = Page::ceil((uintptr_t)&___KERNEL_END___);
-        search_end = 0x4000000;
-    }
-    else{
-        search_start = 0x4000000;
-        search_end = 0x8000000; //TODO find some appropriate value
-    }
-
-    uint64_t free_pageframe=0;
-    //TODO make this more efficent
-    for(uint64_t i=search_start/4096; i < search_end/4096; i++){
-        if(PageFrames[i].available){
-            free_pageframe = i;
-            break;
-        }
-    }
+    Queue<PageFrame>* q = kernel?&kernel_memory_q:&user_memory_q;
+    PageFrame* free_pageframe = q->dequeue();
 
     if(!free_pageframe)
         return 0;
 
-    mark_pageframes(free_pageframe*4096, (free_pageframe*4096)+1, false);
-    return (void*)(free_pageframe*4096);
+    free_pageframe->available = false;
+
+    uintptr_t addr = ((free_pageframe - &PageFrames[0]))<<12;
+
+    mark_pageframes(addr, addr+1, false);
+    return (void*)(addr);
 }
 
 void PageFrameAllocator::free(PageFrame* frame){