Programs now start up and can write to the console, but crash when reading.
This commit is contained in:
David Given
parent
48398b072a
commit
cc356b5c75
8 changed files with 111 additions and 43 deletions
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@ -36,7 +36,7 @@ begtext:
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cseg mov (interrupt_ptr+0), esi
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cseg o16 mov (transfer_buffer_ptr), di
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mov eax, endbss
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mov eax, __end
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cseg callf (realloc_ptr)
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! Clear BSS.
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@ -161,7 +161,7 @@ empty_environment:
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add esp, 5*4
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! Bail out if something went wrong.
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test ax, ax
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test eax, eax
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jnz no_room
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! argc, argv, and envp are now at the stack top. Now go.
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@ -197,6 +197,7 @@ rmode: .space 2
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pmode_cs: .space 2
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pmode_ds: .space 2
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.define realloc_ptr
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.define interrupt_ptr
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.define rmode
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.define pmode_cs
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23
plat/msdos386/libsys/brk.s
Normal file
23
plat/msdos386/libsys/brk.s
Normal file
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@ -0,0 +1,23 @@
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! Declare segments (the order is important).
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.sect .text
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.sect .rom
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.sect .data
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.sect .bss
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.sect .text
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.extern realloc_ptr
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.define _brk
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_brk:
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enter 0, 0
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newsize = 2*4
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mov eax, newsize(ebp)
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callf (realloc_ptr)
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xor eax, eax
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leave
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ret
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@ -1,13 +1,14 @@
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acklibrary {
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name = "lib",
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srcs = {
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"./brk.c",
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"./_hol0.s",
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"./brk.s",
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"./close.s",
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"./errno.s",
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"./getpid.s",
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"./_hol0.s",
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"./isatty.s",
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"./rename.s",
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"./sbrk.c",
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"./sys_exists.s",
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"./sys_getdate.s",
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"./sys_gettime.s",
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@ -8,29 +8,9 @@
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#include <unistd.h>
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#include "libsys.h"
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#define STACK_BUFFER 128 /* number of bytes to leave for stack */
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extern char _end[1];
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static char* current = _end;
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int brk(void* newend)
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{
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/* This variable is used to figure out the current stack pointer,
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* by taking its address. */
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char dummy;
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char* p = newend;
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if ((p > (&dummy - STACK_BUFFER)) ||
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(p < _end))
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{
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errno = ENOMEM;
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return -1;
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}
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current = p;
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return 0;
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}
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void* sbrk(int increment)
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{
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char* old;
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@ -17,13 +17,13 @@
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.define __sys_isreadyr
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__sys_isreadyr:
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int 3
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mov bx, sp
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mov ax, 0x4406
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mov bx, 2(bx)
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mov ebx, sp
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mov eax, 0x4406
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mov ebx, 4(ebx)
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int 0x21
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jnc ok
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movb al, 0
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ok:
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cbw
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cwd
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ret
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@ -26,5 +26,60 @@
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.define __sys_rawread
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__sys_rawread:
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int 3
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enter 4, 0
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amount_transferred = -1*4
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file_handle = 2*4
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write_buffer = 3*4
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amount_to_read = 4*4
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mov amount_transferred(ebp), 0
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mainloop:
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mov eax, amount_to_read(ebp)
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test eax, eax
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jz exit
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mov ecx, 32*1024
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cmp eax, ecx
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jge 2f
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mov ecx, eax
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2:
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! Read from DOS into the transfer buffer.
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movb ah, 0x3f
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o16 mov dx, (transfer_buffer_ptr)
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o16 mov bx, file_handle(ebp)
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mov ecx, 0x80
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or ebx, 0x210000
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callf (interrupt_ptr)
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jc exit
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test eax, eax
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jz exit
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! Copy eax bytes out of the transfer buffer.
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mov ecx, eax
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push eax
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movzx esi, (transfer_buffer_ptr)
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mov edi, write_buffer(ebp)
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mov es, (pmode_ds)
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cld
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1:
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eseg lods
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movb (edi), al
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add edi, 4
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loop 1b
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pop eax
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add write_buffer(ebp), eax
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add amount_transferred(ebp), eax
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sub amount_to_read(ebp), eax
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jmp mainloop
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exit:
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mov eax, amount_transferred(ebp)
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leave
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ret
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@ -32,31 +32,39 @@ file_handle = 2*4
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read_buffer = 3*4
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amount_to_write = 4*4
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mov es, (pmode_ds)
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mov amount_transferred(ebp), 0
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mainloop:
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mov ecx, 32*1024
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cmp amount_to_write(ebp), ecx
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jge 2f
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mov ecx, amount_to_write(ebp)
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test ecx, ecx
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mov eax, amount_to_write(ebp)
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test eax, eax
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jz exit
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mov ecx, 32*1024
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cmp eax, ecx
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jge 2f
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mov ecx, eax
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2:
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! Copy ecx bytes into the transfer buffer.
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push ecx
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mov esi, read_buffer(ebp)
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movzx edi, (transfer_buffer_ptr)
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mov es, (pmode_ds)
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cld
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rep movsb
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pop ecx
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! Write from the transfer buffer to DOS.
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movb ah, 0x40
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o16 mov dx, (transfer_buffer_ptr)
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o16 mov bx, file_handle(ebp)
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or ebx, 0x210000
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callf (interrupt_ptr)
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movzx eax, ax
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jc exit
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! Update counters and go again.
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add read_buffer(ebp), eax
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add amount_transferred(ebp), eax
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@ -64,7 +72,7 @@ mainloop:
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jmp mainloop
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exit:
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mov eax, amount_to_write(ebp)
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mov eax, amount_transferred(ebp)
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leave
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ret
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@ -337,12 +337,12 @@ interrupt:
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pop ds
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pop es
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pushf
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mov ax, (dpmi_eax)
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mov bx, (dpmi_ebx)
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mov cx, (dpmi_ecx)
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mov dx, (dpmi_edx)
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mov si, (dpmi_esi)
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mov di, (dpmi_edi)
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o32 movzx eax, (dpmi_eax)
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o32 movzx ebx, (dpmi_ebx)
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o32 movzx ecx, (dpmi_ecx)
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o32 movzx edx, (dpmi_edx)
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o32 movzx esi, (dpmi_esi)
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o32 movzx edi, (dpmi_edi)
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popf
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ret
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