ignore ovmf vars, improve build script

.gitignore

@@ -1,3 +1,4 @@
-*.obj
+obj/
 fatroot/
-*.efi
+BootX64.efi
+OVMF/OVMF_VARS_4M.fd

build.bat

@@ -1,5 +1,42 @@
 @echo off
-cl /c /GS- /GR- /Oi /EHs-c- /nologo /Zc:threadSafeInit- /I include /Fo:main.obj main.cpp || pause && exit /b
-echo linking..
-link /NODEFAULTLIB /ENTRY:efi_main /NOLOGO /SUBSYSTEM:EFI_APPLICATION /OUT:BootX64.efi main.obj efilib.lib || pause && exit /b
+setlocal enabledelayedexpansion
+
+rem === Input files ===
+set cfiles=
+set afiles=
+
+rem === Flags ===
+set cflags=/c /GS- /GR- /Oi /EHs-c- /nologo /Zc:threadSafeInit- /I include /Fo:obj\
+set lflags=/NODEFAULTLIB /ENTRY:efi_main /NOLOGO /SUBSYSTEM:EFI_APPLICATION /LIBPATH:obj /OUT:BootX64.efi efilib.lib
+
+rem === Ensure obj\ directory exists ===
+if not exist "obj\" (
+    mkdir "obj"
+)
+
+rem === Dynamically generate object list ===
+set objects=
+
+for %%f in (%cfiles%) do (
+    set "base=%%~nf"
+    set "objects=!objects!!base!.obj "
+)
+
+for %%f in (%afiles%) do (
+    set "base=%%~nf"
+    set "objects=!objects!!base!.obj "
+)
+
+rem === Assemble all .asm files ===
+for %%f in (%afiles%) do (
+    ml64 /c /nologo /Foobj\%%~nf.obj %%f || pause && exit /b
+)
+
+rem === Compile all .cpp files ===
+cl %cflags% %cfiles% || pause && exit /b
+
+rem === Link all objects ===
+link %lflags% !objects! || pause && exit /b
+
+rem === Copy output to EFI folder ===
 copy /B /Y BootX64.efi fatroot\EFI\Boot\