freeldr/freeldr/arch/i386/mem.S

   1 /*
   2  *  FreeLoader
   3  *  Copyright (C) 1998-2002  Brian Palmer  <brianp@sginet.com>
   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
  16  *  along with this program; if not, write to the Free Software
  17  *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18  */
  19
  20         .text
  21         .code16
  22
  23 #define ASM
  24 #include "arch.h"
  25 #include "multiboot.h"
  26
  27
  28
  29         .code32
  30 EXTERN(_GetExtendedMemorySize)
  31
  32         //
  33         // get extended memory size in KB
  34         //
  35         pushl   %edx
  36         pushl   %ecx
  37         pushl   %ebx
  38
  39         call    switch_to_real
  40         .code16
  41
  42         movw    $0xe801,%ax
  43         int             $0x15
  44         jc              .oldstylemem
  45
  46         cmpw    $0,%ax
  47         je              .cmem
  48
  49         movzwl  %bx,%ebx
  50         shll    $6,%ebx
  51         movzwl  %ax,%eax
  52         addl    %ebx,%eax
  53         jmp             .done_mem
  54
  55 .cmem:
  56         cmpw    $0,%cx
  57         je              .oldstylemem
  58
  59         movzwl  %dx,%edx
  60         shll    $6,%edx
  61         movzwl  %cx,%ecx
  62         addl    %ecx,%edx
  63         movl    %edx,%eax
  64         jmp             .done_mem
  65
  66 .oldstylemem:
  67         // int 15h opt e801 don't work , try int 15h, option 88h
  68         movb    $0x88,%ah
  69         int             $0x15
  70         cmp             $0,%ax
  71         je              .cmosmem
  72         movzwl  %ax,%eax
  73         jmp             .done_mem
  74
  75 .cmosmem:
  76         // int 15h opt 88h don't work , try read cmos
  77         xorl    %eax,%eax
  78         movb    $0x31,%al
  79         outb    %al,$0x70
  80         inb             $0x71,%al
  81         andl    $0xffff,%eax    // clear carry
  82         shll    $8,%eax
  83
  84 .done_mem:
  85
  86
  87         /* Save return value */
  88         movl    %eax,%edx
  89
  90         call    switch_to_prot
  91
  92         .code32
  93
  94         /* Restore return value */
  95         movl    %edx,%eax
  96
  97         popl    %ebx
  98         popl    %ecx
  99         popl    %edx
 100
 101         ret
 102
 103
 104
 105         .code32
 106 EXTERN(_GetConventionalMemorySize)
 107
 108         //
 109         // Get conventional memory size in KB
 110         //
 111         pushl   %edx
 112
 113         call    switch_to_real
 114         .code16
 115
 116         xorl    %eax,%eax
 117         int             $0x12
 118
 119         /*xorl  %eax,%eax
 120         movb    $0x30,%al
 121         outb    %al,$0x70
 122         inb             $0x71,%al
 123         andl    $0xffff,%eax*/  // clear carry
 124
 125         /* Save return value */
 126         movzwl  %ax,%edx
 127
 128         call    switch_to_prot
 129
 130         .code32
 131
 132         /* Restore return value */
 133         movl    %edx,%eax
 134
 135         popl    %edx
 136
 137         ret
 138
 139
 140
 141         .code32
 142 _gbmm_mem_map_length:
 143         .long 0
 144 _gbmm_memory_map_addr:
 145         .long 0
 146 EXTERN(_GetBiosMemoryMap)
 147         //
 148         // Retrieve BIOS memory map if available
 149         //
 150         pushl   %edx
 151         pushl   %ecx
 152         pushl   %ebx
 153         pushl   %edi
 154
 155         movl    $0,_gbmm_mem_map_length
 156
 157         /* Get memory map address off stack */
 158         movl    0x10(%esp),%eax
 159         movl    %eax,_gbmm_memory_map_addr
 160
 161         call    switch_to_real
 162         .code16
 163
 164         xorl    %ebx,%ebx
 165         movl    _gbmm_memory_map_addr,%edi
 166
 167 .mmap_next:
 168
 169         movl    $0x534D4150,%edx        // 'SMAP'
 170         movl    $/*sizeof(memory_map_t)*/24,%ecx
 171         movl    0xE820,%eax
 172         int             $0x15
 173         jc              .done_mmap
 174
 175         cmpl    $0x534D4150,%eax        // 'SMAP'
 176         jne             .done_mmap
 177
 178         addl    $/*sizeof(memory_map_t)*/24,%edi
 179         addl    $/*sizeof(memory_map_t)*/24,_gbmm_mem_map_length
 180
 181         cmpl    $0,%ebx
 182         jne             .mmap_next
 183
 184 .done_mmap:
 185
 186         call    switch_to_prot
 187
 188         .code32
 189
 190         /* Get return value */
 191         movl    _gbmm_mem_map_length,%eax
 192
 193         popl    %edi
 194         popl    %ebx
 195         popl    %ecx
 196         popl    %edx
 197
 198         ret