reactos/boot/freeldr/freeldr/arch/realmode/helpers.inc

   1
   2 Empty8042:
   3     .word HEX(00eb), HEX(00eb)          // jmp $+2, jmp $+2
   4     in al, HEX(64)
   5     cmp al, HEX(0ff)                            // legacy-free machine without keyboard
   6     jz Empty8042_ret                    // controllers on Intel Macs read back 0xFF
   7     test al, 2
   8     jnz Empty8042
   9 Empty8042_ret:
  10         ret
  11
  12 EnableA20:
  13     pusha
  14     call Empty8042
  15     mov al, HEX(0D1)                            // command write
  16     out HEX(064), al
  17     call Empty8042
  18     mov al, HEX(0DF)                            // A20 on
  19     out HEX(060), al
  20     call Empty8042
  21     popa
  22     ret
  23
  24 /*
  25  * writestr
  26  * si = pointer to zero terminated string
  27  */
  28 writestr:
  29         pushfd
  30         pushad
  31 writestr_top:
  32         lodsb
  33         and     al, al
  34         jz      writestr_end
  35         call    writechr
  36         jmp     short writestr_top
  37 writestr_end:
  38         popad
  39         popfd
  40         ret
  41
  42 /*
  43  * writechr
  44  * al = character to output
  45  */
  46 writechr:
  47         pushf
  48         pusha
  49         mov     ah, HEX(0E)
  50         xor     bx, bx
  51         int     HEX(10)
  52         popa
  53         popf
  54         ret
  55
  56 //
  57 // writehex[248]: Write a hex number in (AL, AX, EAX) to the console
  58 //
  59 writehex2:
  60     pushfd
  61     pushad
  62     shl    eax, 24
  63     mov cx, 2
  64     jmp    short writehex_common
  65 writehex4:
  66     pushfd
  67     pushad
  68     shl    eax, 16
  69     mov cx, 4
  70     jmp    short writehex_common
  71 writehex8:
  72     pushfd
  73     pushad
  74     mov cx, 8
  75 writehex_common:
  76 .loop:
  77     rol    eax, 4
  78     push    eax
  79     and    al, HEX(0F)
  80     cmp al, 10
  81     jae    .high
  82 .low:
  83     add    al, '0'
  84     jmp    short .ischar
  85 .high:
  86     add    al, 'A'-10
  87 .ischar:
  88     call writechr
  89     pop    eax
  90     loop    .loop
  91     popad
  92     popfd
  93     ret
  94
  95 SoftReboot:
  96         mov ax, HEX(40)
  97         mov ds, ax
  98         mov si, HEX(72)
  99
 100         /* Set the word at location 40:72 to 1234h */
 101         mov word ptr [si], HEX(1234)
 102
 103         /* and jump to location FFFF:0 in ROM */
 104         ljmp16  HEX(0FFFF), HEX(0000)
 105
 106
 107 ChainLoadBiosBootSectorCode:
 108
 109     /* Load segment registers */
 110     cli
 111     xor ax, ax
 112     mov ds, ax
 113     mov es, ax
 114     mov fs, ax
 115     mov gs, ax
 116     mov ss, ax
 117     mov esp, HEX(7C00)
 118
 119     /* Jump to the bootsector code */
 120     ljmp16      HEX(0000), HEX(7C00)