boot/freeldr/freeldr/arch/i386/i386pxe.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 2011  Hervé Poussineau
   4  *
   5  *  This program is free software; you can redistribute it and/or modify
   6  *  it under the terms of the GNU General Public License as published by
   7  *  the Free Software Foundation; either version 2 of the License, or
   8  *  (at your option) any later version.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13  *  GNU General Public License for more details.
  14  *
  15  *  You should have received a copy of the GNU General Public License along
  16  *  with this program; if not, write to the Free Software Foundation, Inc.,
  17  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  18  */
  19
  20         .text
  21         .code16
  22
  23 #define ASM
  24
  25 #include <arch.h>
  26
  27 /*
  28  * U16 PxeCallApi(U16 Segment, U16 Offset, U16 Service, VOID *Parameter);
  29  *
  30  * RETURNS:
  31  */
  32 _pxe_function:
  33         .word   0
  34 _pxe_entry_point:
  35         .long   0
  36 _pxe_buffer_segment:
  37         .word   0
  38 _pxe_buffer_offset:
  39         .word   0
  40 _pxe_result:
  41         .word   0
  42
  43 EXTERN(_PxeCallApi)
  44         .code32
  45         pushl   %ebp
  46         movl    %esp,%ebp
  47
  48         pushal
  49         push    %es
  50
  51         /* copy entry point */
  52         movl    0x08(%ebp),%eax
  53         shll    $16,%eax
  54         movw    0x0C(%ebp),%ax
  55         movl    %eax,_pxe_entry_point
  56
  57         /* copy function */
  58         movw    0x10(%ebp),%ax
  59         movw    %ax,_pxe_function
  60
  61         /* convert pointer to data buffer to segment/offset */
  62         movl    0x14(%ebp),%eax
  63         shrl    $4,%eax
  64         andl    $0xf000,%eax
  65         movw    %ax,_pxe_buffer_segment
  66         movl    0x14(%ebp),%eax
  67         andl    $0xffff,%eax
  68         movw    %ax,_pxe_buffer_offset
  69
  70         call    switch_to_real
  71         .code16
  72
  73         movw    _pxe_buffer_segment,%ax
  74         push    %ax
  75         movw    _pxe_buffer_offset,%ax
  76         push    %ax
  77         movw    _pxe_function,%ax
  78         push    %ax
  79         lcall   *_pxe_entry_point
  80         addw    $6,%sp
  81         movw    %ax,_pxe_result
  82
  83         call    switch_to_prot
  84         .code32
  85
  86         pop     %es
  87         popal
  88
  89         movl    %ebp,%esp
  90         popl    %ebp
  91
  92         movw    _pxe_result,%ax
  93
  94         ret
  95
  96 /* EOF */
  97