format pe64 dll efi
entry main

section '.text' code executable readable



;for 32/64 portability and automatic natural align in structure definitions

struc int8 {
  . db ?
}
struc int16 {
  align 2
  . dw ?
}
struc int32 {
  align 4
  . dd ?
}
struc int64 {
  align 8
  . dq ?
}
struc intn {
  align 8
  . dq ?
}
struc dptr {
  align 8
  . dq ?
}

;symbols

EFIERR = 0x8000000000000000
EFI_SUCCESS			= 0
EFI_LOAD_ERROR			= EFIERR or 1
EFI_INVALID_PARAMETER		= EFIERR or 2
EFI_UNSUPPORTED 		= EFIERR or 3
EFI_BAD_BUFFER_SIZE		= EFIERR or 4
EFI_BUFFER_TOO_SMALL		= EFIERR or 5
EFI_NOT_READY			= EFIERR or 6
EFI_DEVICE_ERROR		= EFIERR or 7
EFI_WRITE_PROTECTED		= EFIERR or 8
EFI_OUT_OF_RESOURCES		= EFIERR or 9
EFI_VOLUME_CORRUPTED		= EFIERR or 10
EFI_VOLUME_FULL 		= EFIERR or 11
EFI_NO_MEDIA			= EFIERR or 12
EFI_MEDIA_CHANGED		= EFIERR or 13
EFI_NOT_FOUND			= EFIERR or 14
EFI_ACCESS_DENIED		= EFIERR or 15
EFI_NO_RESPONSE 		= EFIERR or 16
EFI_NO_MAPPING			= EFIERR or 17
EFI_TIMEOUT			= EFIERR or 18
EFI_NOT_STARTED 		= EFIERR or 19
EFI_ALREADY_STARTED		= EFIERR or 20
EFI_ABORTED			= EFIERR or 21
EFI_ICMP_ERROR			= EFIERR or 22
EFI_TFTP_ERROR			= EFIERR or 23
EFI_PROTOCOL_ERROR		= EFIERR or 24

;helper macro for definition of relative structure member offsets

macro struct name
{
  virtual at 0
    name name
  end virtual
}

;structures

struc EFI_TABLE_HEADER {
 .Signature    int64
 .Revision     int32
 .HeaderSize   int32
 .CRC32        int32
 .Reserved     int32
}
struct EFI_TABLE_HEADER

struc EFI_SYSTEM_TABLE {
 .Hdr		       EFI_TABLE_HEADER
 .FirmwareVendor       dptr
 .FirmwareRevision     int32
 .ConsoleInHandle      dptr
 .ConIn 	       dptr
 .ConsoleOutHandle     dptr
 .ConOut	       dptr
 .StandardErrorHandle  dptr
 .StdErr	       dptr
 .RuntimeServices      dptr
 .BootServices	       dptr
 .NumberOfTableEntries intn
 .ConfigurationTable   dptr
}
struct EFI_SYSTEM_TABLE

struc SIMPLE_TEXT_OUTPUT_INTERFACE {
 .Reset 	    dptr
 .OutputString	    dptr
 .TestString	    dptr
 .QueryMode	    dptr
 .SetMode	    dptr
 .SetAttribute	    dptr
 .ClearScreen	    dptr
 .SetCursorPosition dptr
 .EnableCursor	    dptr
 .Mode		    dptr
}
struct SIMPLE_TEXT_OUTPUT_INTERFACE



main:
 sub rsp, 4*8              ; reserve space for 4 arguments

 mov [Handle], rcx         ; ImageHandle
 mov [SystemTable], rdx    ; pointer to SystemTable

 lea rdx, [_hello]
 mov rcx, [SystemTable]
 mov rcx, [rcx + EFI_SYSTEM_TABLE.ConOut]
 push rcx rdx
 call [rcx + SIMPLE_TEXT_OUTPUT_INTERFACE.ClearScreen]  ;; TODO : what calling convention? clobbers rcx, what else?  
 ; TODO: use more modern UEFI.inc like stuff
 ; TODO: update scripts build run. maybe makefile, also generating iso? 
 ; TODO: what is NvVars who generates it why it need
 ; TODO: print some info provided by eufi like versions etc..
 ; TODO: print memory map
 ; TODO: how to load kernel . See https://github.com/BrianOtto/nasm-uefi 
 pop rdx rcx
 call [rcx + SIMPLE_TEXT_OUTPUT_INTERFACE.OutputString]

 jmp $

 add rsp, 4*8
 mov eax, EFI_SUCCESS
 retn


section '.data' data readable writeable

Handle      dq ?
SystemTable dq ?
_hello      du 'Hello World',13,10,0

section '.reloc' fixups data discardable