progress: ImGui Port - Desktop UI + ImGui rendering performance overhaul

Full ImGui desktop environment (desktop.pas):
- Gradient wallpaper, taskbar with clock, start menu
- Desktop icons with click-to-open
- Windowed apps: System Info, Terminal, File Browser, Task Manager
- Terminal dispatches to registered kernel commands with output capture

Performance: Software rasterizer rewrite (imgui.pas, imgbridge.c)
- Quad detection: merge consecutive triangle pairs into fast rect fills
- 3 new fast-path rect fillers (solid/gradient/textured) using REP STOSD
  and 16.16 fixed-point integer inner loops
- Triangle rasterizer rewritten with fixed-point edge functions
- Back-buffer clear: DrawPixel loop -> REP STOSD (~200x faster)
- Render stat debug counters added

ISR-safe input buffering (imgbridge.c)
- Keyboard/mouse events buffered in lock-free ring buffers from ISR context
- Drained once per frame from main loop to prevent data races

Other changes:
- imguitypes.pas: InputTextFlags renumbered for cimgui 1.91+
- video.pas: backBufferLocation getter added
- kernel.pas: VFS init moved earlier, main loop uses desktop_frame,
  mouse hook uses ISR-safe buffering
- lmemorymanager.pas: kalloc/kfree exported with public aliases for C linkage
- scheduler.pas: Root_Task moved to interface for desktop task manager
- terminal.pas: freeParams exposed in interface

src/console.pas

@@ -838,6 +838,18 @@ const
 	MAX_WINDOWS = 255; //< Maximum number of Windows open.
     DefaultWND  = 0;   //< The Window assigned for output when no Window is specified. (Default).
 
+type
+    TWNDCaptureCallback = procedure(s: pchar);
+
+var
+    WND_CaptureActive   : boolean = false;
+    WND_CaptureHWND     : uint32 = 0;
+    WND_CaptureBuf      : array[0..511] of char;
+    WND_CaptureBufIdx   : uint32 = 0;
+    WND_CaptureCallback : TWNDCaptureCallback = nil;
+
+procedure flushCapture;
+
 implementation
 
 uses
@@ -2259,6 +2271,7 @@ var
    x,y: Byte;
 
 begin
+     if WND_CaptureActive and (WND = WND_CaptureHWND) then exit;
      if WindowManager.Windows[WND] <> nil then begin
         for y:=0 to Console_Properties.MAX_CELL_Y do begin
             for x:=0 to Console_Properties.MAX_CELL_X do begin
@@ -2419,8 +2432,26 @@ begin
      console.writeintlnexWND(i, Console_Properties.Default_Attribute, WND);
 end;
 
+procedure flushCapture;
+begin
+    if WND_CaptureActive and (WND_CaptureCallback <> nil) and (WND_CaptureBufIdx > 0) then begin
+        WND_CaptureBuf[WND_CaptureBufIdx] := #0;
+        WND_CaptureCallback(@WND_CaptureBuf[0]);
+        WND_CaptureBufIdx := 0;
+        WND_CaptureBuf[0] := #0;
+    end;
+end;
+
 procedure writecharexWND(character: char; attributes: uint32; WND : uint32); 
 begin
+    if WND_CaptureActive and (WND = WND_CaptureHWND) and (WND_CaptureCallback <> nil) then begin
+        if WND_CaptureBufIdx < 511 then begin
+            WND_CaptureBuf[WND_CaptureBufIdx] := character;
+            inc(WND_CaptureBufIdx);
+            WND_CaptureBuf[WND_CaptureBufIdx] := #0;
+        end;
+        exit;
+    end;
     if WindowManager.Windows[WND] <> nil then begin
         WindowManager.Windows[WND]^.Buffer[WindowManager.Windows[WND]^.Cursor.Y][WindowManager.Windows[WND]^.Cursor.X].Character:= character;
         WindowManager.Windows[WND]^.Buffer[WindowManager.Windows[WND]^.Cursor.Y][WindowManager.Windows[WND]^.Cursor.X].Attributes:= attributes;
@@ -2603,6 +2634,13 @@ end;
 
 procedure backspaceWND(WND : uint32);
 begin
+     if WND_CaptureActive and (WND = WND_CaptureHWND) then begin
+        if WND_CaptureBufIdx > 0 then begin
+            dec(WND_CaptureBufIdx);
+            WND_CaptureBuf[WND_CaptureBufIdx] := #0;
+        end;
+        exit;
+     end;
      if WindowManager.Windows[WND] <> nil then begin
         Dec(WindowManager.Windows[WND]^.Cursor.X);
         writecharWND(' ', WND);
@@ -2659,6 +2697,13 @@ end;
 
 procedure _safeincrement_y_WND(WND : uint32);
 begin
+     if WND_CaptureActive and (WND = WND_CaptureHWND) and (WND_CaptureCallback <> nil) then begin
+        WND_CaptureBuf[WND_CaptureBufIdx] := #0;
+        WND_CaptureCallback(@WND_CaptureBuf[0]);
+        WND_CaptureBufIdx := 0;
+        WND_CaptureBuf[0] := #0;
+        exit;
+     end;
      if WindowManager.Windows[WND] <> nil then begin
         WindowManager.Windows[WND]^.Cursor.Y:= WindowManager.Windows[WND]^.Cursor.Y+1;
         if WindowManager.Windows[WND]^.Cursor.Y > WindowManager.Windows[WND]^.WND_H-1 then begin

src/driver/storage/vfs.pas

@@ -92,6 +92,7 @@ var
     Root              : PVFSObject;
     CurrentDirectory  : pchar = nil;
     PushPopDirectory  : PLinkedListBase;
+    MountDepth        : uint32 = 0;
 
 procedure init();
 Function OpenFile(Filename : pchar; OpenMode : TOpenMode; WriteMode : TWriteMode; Lock : Boolean; Error : PError) : TFileHandle;
@@ -104,6 +105,7 @@ function GetDirectories(Handle : uint32; Path : pchar) : PHashMap;
 function PathValid(Path : pchar) : TIsPathValid;
 function changeDirectory(Path : pchar) : TIsPathValid;
 function getWorkingDirectory : pchar;
+function GetDirectoryListing(Path : pchar) : PHashMap;
 
 //VFS Functions
 function newVirtualDirectory(Path : pchar) : TError;
@@ -288,6 +290,7 @@ begin
             NewObj:= PVFSObject(hashmap.get(ht, item));                                            
             if NewObj = nil then begin                                                              
                 GetObjectFromPath:= nil;
+                STRLL_Free(SplitPath);
                 tracer.push_trace('vfs.GetObjectFromPath.shortexit_1');
                 exit;
             end;                                                                                    
@@ -304,6 +307,7 @@ begin
         end;
     end;                                                                                           
     GetObjectFromPath:= Obj;
+    STRLL_Free(SplitPath);
     tracer.push_trace('vfs.GetObjectFromPath.exit');
 end;
 
@@ -348,7 +352,17 @@ begin
                 GetDirectoryListing:= nil;
             end; 
             otMOUNT:begin
+                { Safety: cap mount-follow depth to prevent infinite recursion
+                  from circular mounts.  Use a simple static counter. }
+                if MountDepth < 16 then begin
+                    Inc(MountDepth);
                     GetDirectoryListing:= GetDirectoryListing(PVFSMount(Obj^.Reference)^.Path);
+                    Dec(MountDepth);
+                end else
+                    GetDirectoryListing:= nil;
+            end;
+            else begin
+                GetDirectoryListing:= nil;
             end;
         end;
     end else begin
@@ -420,7 +434,7 @@ begin
 
     NewObj^.Reference:= void(NewDev);
 
-    hashmap.add(ht, stringCopy(DeviceName), void(NewDev));
+    hashmap.add(ht, stringCopy(DeviceName), void(NewObj));
 end;
 
 { Filesystem Functions }

src/driver/video/doublebuffer.pas

@@ -54,13 +54,8 @@ end;
 
 procedure Flush(FrontBuffer : PVideoBuffer; BackBuffer : PVideoBuffer);
 var
-    idx : uint32;
     Back,Front : uint32;
-    BufferSize : uint32;
+    Count64 : uint32;
-
-const
-    //COPY_WIDTH = 64; //Use this for 64bit copies
-    COPY_WIDTH = 128; //Use this for SSE copies
 
 begin
     //tracer.push_trace('doublebuffer.Flush.enter');
@@ -68,11 +63,32 @@ begin
     if ((FrontBuffer^.Width > BackBuffer^.Width) or (FrontBuffer^.Height > BackBuffer^.Height)) then exit;
     Back:= BackBuffer^.Location;
     Front:= FrontBuffer^.Location;
-    BufferSize:= ( ( BackBuffer^.Width * BackBuffer^.Height * BackBuffer^.BitsPerPixel) div COPY_WIDTH ) - 1;
+    { Number of 64-byte blocks: total_bytes / 64 = (W * H * BPP/8) / 64 }
-    for idx:=0 to BufferSize do begin
+    Count64:= ( BackBuffer^.Width * BackBuffer^.Height * BackBuffer^.BitsPerPixel) div 512;
-        //Front[idx]:= Back[idx];
+    if Count64 = 0 then exit;
-        // -- TODO: Get SSE working here for 128bit copies --
+    { Bulk SSE copy: 4 x MOVAPS (64 bytes) per iteration.
-        __SSE_128_memcpy(Back + (idx * 16), Front + (idx * 16));  
+      4x fewer loop iterations than the old per-16-byte function-call loop. }
+    asm
+        PUSH ESI
+        PUSH EDI
+        MOV ESI, Back
+        MOV EDI, Front
+        MOV ECX, Count64
+    @sseloop:
+        MOVAPS XMM0, [ESI]
+        MOVAPS XMM1, [ESI + 16]
+        MOVAPS XMM2, [ESI + 32]
+        MOVAPS XMM3, [ESI + 48]
+        MOVAPS [EDI], XMM0
+        MOVAPS [EDI + 16], XMM1
+        MOVAPS [EDI + 32], XMM2
+        MOVAPS [EDI + 48], XMM3
+        ADD ESI, 64
+        ADD EDI, 64
+        DEC ECX
+        JNZ @sseloop
+        POP EDI
+        POP ESI
     end;
     //tracer.push_trace('doublebuffer.Flush.exit');
 end;

src/driver/video/imgui/crtshim.c

@@ -125,9 +125,11 @@ char* strcpy(char* dst, const char* src) {
 }
 
 char* strncpy(char* dst, const char* src, size_t n) {
-    char* d = dst;
+    size_t i;
-    while (n-- && (*d++ = *src++));
+    for (i = 0; i < n && src[i] != '\0'; i++)
-    while (n--) *d++ = '\0';
+        dst[i] = src[i];
+    for (; i < n; i++)
+        dst[i] = '\0';
     return dst;
 }
 
@@ -150,8 +152,8 @@ int strcmp(const char* a, const char* b) {
 }
 
 int strncmp(const char* a, const char* b, size_t n) {
-    while (n-- && *a && (*a == *b)) { a++; b++; }
     if (!n) return 0;
+    while (--n && *a && (*a == *b)) { a++; b++; }
     return (unsigned char)*a - (unsigned char)*b;
 }
 

src/driver/video/imgui/imguitypes.pas

@@ -137,27 +137,33 @@ const
   ============================================================ }
 const
     ImGuiInputTextFlags_None                = 0;
+    { Character filters }
     ImGuiInputTextFlags_CharsDecimal        = 1 SHL 0;
     ImGuiInputTextFlags_CharsHexadecimal    = 1 SHL 1;
-    ImGuiInputTextFlags_CharsUppercase      = 1 SHL 2;
+    ImGuiInputTextFlags_CharsScientific     = 1 SHL 2;
-    ImGuiInputTextFlags_CharsNoBlank        = 1 SHL 3;
+    ImGuiInputTextFlags_CharsUppercase      = 1 SHL 3;
-    ImGuiInputTextFlags_AutoSelectAll       = 1 SHL 4;
+    ImGuiInputTextFlags_CharsNoBlank        = 1 SHL 4;
-    ImGuiInputTextFlags_EnterReturnsTrue    = 1 SHL 5;
+    { Inputs }
-    ImGuiInputTextFlags_CallbackCompletion  = 1 SHL 6;
+    ImGuiInputTextFlags_AllowTabInput       = 1 SHL 5;
-    ImGuiInputTextFlags_CallbackHistory     = 1 SHL 7;
+    ImGuiInputTextFlags_EnterReturnsTrue    = 1 SHL 6;
-    ImGuiInputTextFlags_CallbackAlways      = 1 SHL 8;
+    ImGuiInputTextFlags_EscapeClearsAll     = 1 SHL 7;
-    ImGuiInputTextFlags_CallbackCharFilter  = 1 SHL 9;
+    ImGuiInputTextFlags_CtrlEnterForNewLine = 1 SHL 8;
-    ImGuiInputTextFlags_AllowTabInput       = 1 SHL 10;
+    { Other options }
-    ImGuiInputTextFlags_CtrlEnterForNewLine = 1 SHL 11;
+    ImGuiInputTextFlags_ReadOnly            = 1 SHL 9;
-    ImGuiInputTextFlags_NoHorizontalScroll  = 1 SHL 12;
+    ImGuiInputTextFlags_Password            = 1 SHL 10;
-    ImGuiInputTextFlags_AlwaysOverwrite     = 1 SHL 13;
+    ImGuiInputTextFlags_AlwaysOverwrite     = 1 SHL 11;
-    ImGuiInputTextFlags_ReadOnly            = 1 SHL 14;
+    ImGuiInputTextFlags_AutoSelectAll       = 1 SHL 12;
-    ImGuiInputTextFlags_Password            = 1 SHL 15;
+    ImGuiInputTextFlags_ParseEmptyRefVal    = 1 SHL 13;
+    ImGuiInputTextFlags_DisplayEmptyRefVal  = 1 SHL 14;
+    ImGuiInputTextFlags_NoHorizontalScroll  = 1 SHL 15;
     ImGuiInputTextFlags_NoUndoRedo          = 1 SHL 16;
-    ImGuiInputTextFlags_CharsScientific     = 1 SHL 17;
+    { Callback features }
-    ImGuiInputTextFlags_CallbackResize      = 1 SHL 18;
+    ImGuiInputTextFlags_CallbackCompletion  = 1 SHL 17;
-    ImGuiInputTextFlags_CallbackEdit        = 1 SHL 19;
+    ImGuiInputTextFlags_CallbackHistory     = 1 SHL 18;
-    ImGuiInputTextFlags_EscapeClearsAll     = 1 SHL 20;
+    ImGuiInputTextFlags_CallbackAlways      = 1 SHL 19;
+    ImGuiInputTextFlags_CallbackCharFilter  = 1 SHL 20;
+    ImGuiInputTextFlags_CallbackResize      = 1 SHL 21;
+    ImGuiInputTextFlags_CallbackEdit        = 1 SHL 22;
 
 { ============================================================
   ImGuiTreeNodeFlags

src/driver/video/video.pas

@@ -40,6 +40,7 @@ function frontBufferBpp : uint8;
 function backBufferWidth : uint32;
 function backBufferHeight : uint32;
 function backBufferBpp : uint8;
+function backBufferLocation : uint32;
 
 Procedure basicFDrawTexture(Buffer : PVideoBuffer; X : uint32; Y : uint32; Texture : PTexture);
 
@@ -315,4 +316,9 @@ begin
     backBufferBpp:= VideoInterface.BackBuffer.BitsPerPixel;
 end;
 
+function backBufferLocation : uint32;
+begin
+    backBufferLocation:= VideoInterface.BackBuffer.Location;
+end;
+
 end.

src/kernel.pas

@@ -57,7 +57,7 @@ uses
      terminal,
      hashmap, vfs, 
      video, vesa, doublebuffer, color,
-     imgui, imguitypes;
+     imgui, imguitypes, desktop;
  
 procedure kmain(mbinfo: Pmultiboot_info_t; mbmagic: uint32); stdcall;
  
@@ -122,11 +122,16 @@ begin
 end;
 
 procedure imgui_mouse_hook(x, y: sint32; lmb, rmb, mmb: boolean);
+var
+    fx, fy: Single;
 begin
-    imgui_feed_mouse_pos(Single(x), Single(y));
+    { Buffer mouse events — will be drained before next frame }
-    imgui_feed_mouse_button(0, lmb);
+    fx := x;
-    imgui_feed_mouse_button(1, rmb);
+    fy := y;
-    imgui_feed_mouse_button(2, mmb);
+    imgui_handle_mouse_pos(fx, fy);
+    imgui_handle_mouse_button(0, sint32(lmb));
+    imgui_handle_mouse_button(1, sint32(rmb));
+    imgui_handle_mouse_button(2, sint32(mmb));
 end;
 
 procedure kmain(mbinfo: Pmultiboot_info_t; mbmagic: uint32); stdcall; [public, alias: 'kmain'];   
@@ -235,6 +240,9 @@ begin
      { Call Tracer }
      tracer.init();
 
+     { Virtual File System }
+     vfs.init();
+
      video.init();
      vesa.init(@video.register);
      doublebuffer.init(@video.register);
@@ -282,6 +290,11 @@ begin
      imgui_init(video.frontBufferWidth, video.frontBufferHeight);
      console.outputln('KERNEL', 'ImGui: INIT END.');
 
+     { Initialize desktop }
+     console.outputln('KERNEL', 'Desktop: INIT BEGIN.');
+     desktop_init;
+     console.outputln('KERNEL', 'Desktop: INIT END.');
+
      { Initialize input drivers }
      console.outputln('KERNEL', 'Input: INIT BEGIN.');
      keyboard.init(keyboard_layout);
@@ -302,10 +315,10 @@ begin
 
      { Warm-up frames: ImGui needs 2+ frames for window layout }
      imgui_new_frame;
-     imgui_test_window;
+     desktop_frame;
      imgui_render;
      imgui_new_frame;
-     imgui_test_window;
+     desktop_frame;
      imgui_render;
 
      { Main interactive render loop }
@@ -321,8 +334,9 @@ begin
          else
              imgui_feed_delta_time(Single(0.001));
 
+         imgui_process_input;
          imgui_new_frame;
-         imgui_test_window;
+         desktop_frame;
          imgui_render;
      end;
 

src/lmemorymanager.pas

@@ -170,7 +170,7 @@ begin
     klalloc:= Address;
 end;
 
-function kalloc(size : uint32) : void;
+function kalloc(size : uint32) : void; [public, alias: 'kernel_kalloc'];
 var
    Heap_Entries : uint32;
    i, j         : uint32;
@@ -217,7 +217,7 @@ begin
     //pop_trace;
 end;
 
-procedure kfree(area : void);
+procedure kfree(area : void); [public, alias: 'kernel_kfree'];
 var
     hp : PHeapPage;
     entry : uint32;

src/prog/terminal.pas

@@ -72,6 +72,7 @@ procedure registerCommandEx(command : pchar; method : TCommandMethod; descriptio
 function getParams(buf : TCommandBuffer) : PParamList;
 function paramCount(params : PParamList) : uint32;
 function getParam(index : uint32; params : PParamList) : pchar;
+procedure freeParams(params : PParamList);
 procedure setWorkingDirectory(str : pchar);
 function getWorkingDirectory : pchar;
 function getTerminalHWND : uint32;

src/scheduler.pas

@@ -45,6 +45,7 @@ type
 
 var
     Active : Boolean;
+    Root_Task    : PScheduler_Entry;
 
 procedure init;
 procedure add_task(priority : uint8);
@@ -53,7 +54,6 @@ implementation
 
 var
    Tick         : uint32;
-   Root_Task    : PScheduler_Entry = nil;
    Current_Task : PScheduler_Entry = nil;
 
 procedure context_switch();