215 lines
4.4 KiB
NASM
215 lines
4.4 KiB
NASM
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page ,160
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title MS-DOS BIOS int 2f handler
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;
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;----------------------------------------------------------------------------
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;
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; Modification history
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;
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; 26-Feb-1991 sudeepb Ported for NT DOSEm
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;----------------------------------------------------------------------------
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; THIS FILE SHOULD BE NAMED INT2f.ASM RATHER THAN INT13.ASM AS I HAVE RIPPED
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; THE INT 13 SUPPORT. TO REDUCE CONFUSION WHEN PICKING FIXES FROM DOS 5.1
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; THE NAME IS RETAINED AS IT IS.
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include version.inc ; set build flags
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include biosseg.inc ; establish bios segment structure
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include msequ.inc
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include biostruc.inc
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include msgroup.inc ; establish Bios_Data segment
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include vint.inc
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multMULT equ 4ah
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multMULTGETHMAPTR equ 1
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multMULTALLOCHMA equ 2
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Win386_RelTS equ 80h
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NT_WAIT_BOP equ 5Ah
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bop MACRO callid
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db 0c4h,0c4h,callid
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endm
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;SR;
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; Include file for WIN386 support
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;
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include win386.inc
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extrn SysinitPresent:byte
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extrn FreeHMAPtr:word
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extrn MoveDOSIntoHMA:dword
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;SR;
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;New variables for Win386 support
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;
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extrn IsWin386:byte
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extrn Win386_SI:byte
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extrn SI_Next:dword
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; close data, open Bios_code segment
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tocode
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extrn Bios_Data_Word:word
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; Int 2f functions to support communication of external block device
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; drivers with msdisk are not supported. It also does'nt support
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; function 13h which replaces the int 13 vector.
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;
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public i2f_handler
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i2f_handler proc far
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assume ds:nothing,es:nothing
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cmp ah,13h
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jz i2f_iret
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cmp ah,8
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jz i2f_iret
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;
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;Check for WIN386 startup and return the BIOS instance data
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;
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cmp ah,MULTWIN386
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jz win386call
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cmp ah, multMULT
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jne i2f_iret
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jmp handle_multmult
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i2f_iret:
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FIRET
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;WIN386 startup stuff is done here. If starting up we set our WIN386 present
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;flag and return instance data. If exiting, we reset the WIN386 present flag
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;NOTE: We assume that the BIOS int 2fh is at the bottom of the chain.
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win386call:
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push ds
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mov ds,cs:Bios_Data_Word
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assume ds:Bios_Data
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cmp al, Win386_Init ; is it win386 initializing?
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je Win386Init
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cmp al, Win386_Exit ; is it win386 exiting?
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je Win386Exit
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cmp al, Win386_RelTS ; is it app release timeslice call?
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jne win_iret ; if not, continue int2f chain
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push ax ; It's the idling case - call MS BOP A
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xor ax,ax ; with AX = 0
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bop NT_WAIT_BOP
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pop ax
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xor al, al
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jmp short win_iret
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Win386Exit:
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test dx, 1 ; is it win386 or win286 dos extender?
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jnz win_iret ; if not win386, then continue
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and [IsWin386], 0 ; indicate that win386 is not present
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jmp short win_iret
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Win386Init:
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test dx, 1 ; is it win386 or win286 dos extender?
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jnz win_iret ; if not win386, then continue
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or [IsWin386], 1 ; Indicate WIN386 present
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mov word ptr [SI_Next], bx ; Hook our structure into chain
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mov word ptr [SI_Next + 2], es
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mov bx, offset Win386_SI ; point ES:BX to Win386_SI
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push ds
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pop es
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win_iret:
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pop ds
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assume ds:nothing
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jmp i2f_iret ;return back up the chain
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handle_multmult:
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cmp al, multMULTGETHMAPTR
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jne try_2
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push ds
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call HMAPtr ; get offset of free HMA
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mov bx, 0ffffh
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mov es, bx ; seg of HMA
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mov bx, di
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not bx
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or bx, bx
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jz @f
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inc bx
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@@:
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pop ds
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jmp i2f_iret
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try_2:
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cmp al, multMULTALLOCHMA
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jne try_3
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push ds
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mov di, 0ffffh ; assume not enough space
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mov es, di
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call HMAPtr ; get offset of free HMA
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assume ds:Bios_Data
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cmp di, 0ffffh
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je InsuffHMA
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neg di ; free space in HMA
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cmp bx, di
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jbe @f
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mov di, 0ffffh
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jmp short InsuffHMA
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@@:
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mov di, FreeHMAPtr
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add bx, 15
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and bx, 0fff0h
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add FreeHMAPtr, bx ; update the free pointer
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jnz InsuffHMA
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mov FreeHMAPtr, 0ffffh ; no more HMA if we have wrapped
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InsuffHMA:
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pop ds
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assume ds:nothing
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jmp i2f_iret
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try_3:
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jmp i2f_iret
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i2f_handler endp
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;
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;--------------------------------------------------------------------------
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;
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; procedure : HMAPtr
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;
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; Gets the offset of the free HMA area ( with respect to
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; seg ffff )
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; If DOS has not moved high, tries to move DOS high.
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; In the course of doing this, it will allocate all the HMA
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; and set the FreeHMAPtr to past the end of the BIOS and
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; DOS code. The call to MoveDOSIntoHMA (which is a pointer)
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; enters the routine in sysinit1 called FTryToMoveDOSHi.
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;
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; RETURNS : offset of free HMA in DI
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; BIOS_DATA, seg in DS
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;
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;--------------------------------------------------------------------------
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;
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HMAPtr proc near
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mov ds, Bios_Data_Word
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assume ds:Bios_Data
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mov di, FreeHMAPtr
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cmp di, 0ffffh
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jne @f
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cmp SysinitPresent, 0
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je @f
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call MoveDOSIntoHMA
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mov di, FreeHMAPtr
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@@:
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ret
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HMAPtr endp
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Bios_Code ends
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end
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