_pm.asm

BIOS emulator and interface to Realmode X86 Emulator Library Can emulate a PCI Graphic Controller V

;****************************************************************************
;*
;*					SciTech OS Portability Manager Library
;*
;*  ========================================================================
;*
;*    The contents of this file are subject to the SciTech MGL Public
;*    License Version 1.0 (the "License"); you may not use this file
;*    except in compliance with the License. You may obtain a copy of
;*    the License at http://www.scitechsoft.com/mgl-license.txt
;*
;*    Software distributed under the License is distributed on an
;*    "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
;*    implied. See the License for the specific language governing
;*    rights and limitations under the License.
;*
;*    The Original Code is Copyright (C) 1991-1998 SciTech Software, Inc.
;*
;*    The Initial Developer of the Original Code is SciTech Software, Inc.
;*    All Rights Reserved.
;*
;*  ========================================================================
;*
;* Language:	80386 Assembler, TASM 4.0 or NASM
;* Environment:	IBM PC Real mode and 16/32 bit protected mode
;*
;* Description:	Low level assembly support for the PM library specific to
;*				MSDOS.
;*
;****************************************************************************

		IDEAL

include	"scitech.mac"				; Memory model macros

header    	_pmdos             		; Set up memory model

begdataseg	_pmdos

ifndef 	flatmodel

struc   rmregs_s
ax      	dw	?
ax_high		dw	?
bx			dw	?
bx_high		dw	?
cx			dw	?
cx_high		dw	?
dx			dw	?
dx_high		dw	?
si			dw	?
si_high		dw	?
di			dw	?
di_high		dw	?
cflag		dw	?
cflag_high	dw	?
ends	rmregs_s
RMREGS	= (rmregs_s PTR es:bx)

struc	rmsregs_s
es		dw	?
cs		dw	?
ss		dw	?
ds		dw	?
ends	rmsregs_s
RMSREGS	= (rmsregs_s PTR es:bx)

endif	; !flatmodel

ifdef flatmodel
	cextern	_PM_savedDS,USHORT
endif
intel_id		db	"GenuineIntel"	; Intel vendor ID

enddataseg	_pmdos

begcodeseg  _pmdos					; Start of code segment

ifndef 	flatmodel

;----------------------------------------------------------------------------
; void PM_callRealMode(unsigned s,unsigned o, RMREGS *regs,
;	RMSREGS *sregs)
;----------------------------------------------------------------------------
; Calls a real mode procedure, loading the appropriate registers values
; from the passed in structures. Only the DS and ES register are loaded
; from the SREGS structure.
;----------------------------------------------------------------------------
cprocstart	PM_callRealMode

		ARG     s:WORD, o:WORD, regs:DWORD, sregs:DWORD

		LOCAL	addr:DWORD, bxVal:WORD, esVal:WORD, flags:WORD = LocalSize

		enter_c
		push	ds
		push	es

		mov		ax,[o]				; Build the address to call in 'addr'
		mov		[WORD addr],ax
		mov		ax,[s]
		mov		[WORD addr+2],ax

		les		bx,[sregs]
		mov     ax,[RMSREGS.ds]
		mov     ds,ax				; DS := passed in value
		mov		ax,[RMSREGS.es]
		mov		[esVal],ax
		les		bx,[regs]
		mov		ax,[RMREGS.bx]
		mov		[bxVal],ax
		mov		ax,[RMREGS.ax]		; AX := passed in value
		mov		cx,[RMREGS.cx]		; CX := passed in value
		mov		dx,[RMREGS.dx]		; DX := passed in value
		mov		si,[RMREGS.si] 		; SI := passed in value
		mov		di,[RMREGS.di]		; DI := passed in value
		push	bp
		push	[esVal]
		pop		es					; ES := passed in value
		mov		bx,[bxVal]			; BX := passed in value

		call	[addr]				; Call the specified routine

		pushf						; Save flags for later
		pop		[flags]

		pop		bp
		push	es
		pop		[esVal]
		push	bx
		pop		[bxVal]
		les		bx,[sregs]
		push	ds
		pop		[RMSREGS.ds]		; Save value of DS
		push	[esVal]
		pop		[RMSREGS.es]		; Save value of ES
		les		bx,[regs]
		mov		[RMREGS.ax],ax		; Save value of AX
		mov		[RMREGS.cx],cx		; Save value of CX
		mov		[RMREGS.dx],dx		; Save value of DX
		mov		[RMREGS.si],si		; Save value of SI
		mov		[RMREGS.di],di		; Save value of DI
		mov		ax,[flags]			; Return flags
		and		ax,1h				; Isolate carry flag
		mov		[RMREGS.cflag],ax	; Save carry flag status
		mov		ax,[bxVal]
		mov     [RMREGS.bx],ax		; Save value of BX

		pop		es
		pop		ds
		leave_c
		ret

cprocend

endif

;----------------------------------------------------------------------------
; void PM_segread(PMSREGS *sregs)
;----------------------------------------------------------------------------
; Read the current value of all segment registers
;----------------------------------------------------------------------------
cprocstartdll16	PM_segread

		ARG		sregs:DPTR

		enter_c

		mov		ax,es
		_les	_si,[sregs]
		mov		[_ES _si],ax
		mov		[_ES _si+2],cs
		mov		[_ES _si+4],ss
		mov		[_ES _si+6],ds
		mov		[_ES _si+8],fs
		mov		[_ES _si+10],gs

		leave_c
		ret

cprocend

; Create a table of the 256 different interrupt calls that we can jump
; into

ifdef	USE_NASM

%assign	intno 0

intTable:
%rep	256
		db      0CDh
		db      intno
%assign intno	intno + 1
		ret
		nop
%endrep

else

intno = 0

intTable:
		REPT    256
		db      0CDh
		db      intno
intno = intno + 1
		ret
		nop
		ENDM

endif

;----------------------------------------------------------------------------
; _PM_genInt	- Generate the appropriate interrupt
;----------------------------------------------------------------------------
cprocnear	_PM_genInt

		push	_ax						; Save _ax
		push	_bx                 	; Save _bx
ifdef flatmodel
		mov    	ebx,[UINT esp+12]		; EBX := interrupt number
else
		mov		bx,sp					; Make sure ESP is zeroed
		mov    	bx,[UINT ss:bx+6]		; BX := interrupt number
endif
		mov     _ax,offset intTable		; Point to interrupt generation table
		shl     _bx,2					; _BX := index into table
		add     _ax,_bx					; _AX := pointer to interrupt code
ifdef flatmodel
		xchg	eax,[esp+4]				; Restore eax, and set for int
else
		mov		bx,sp
		xchg	ax,[ss:bx+2]			; Restore ax, and set for int
endif
		pop		_bx						; restore _bx
		ret

cprocend

;----------------------------------------------------------------------------
; int PM_int386x(int intno, PMREGS *in, PMREGS *out,PMSREGS *sregs)
;----------------------------------------------------------------------------
; Issues a software interrupt in protected mode. This routine has been
; written to allow user programs to load CS and DS with different values
; other than the default.
;----------------------------------------------------------------------------
cprocstartdll16	PM_int386x

		ARG		intno:UINT, inptr:DPTR, outptr:DPTR, sregs:DPTR

		LOCAL	flags:UINT, sv_ds:UINT, sv_esi:ULONG = LocalSize

		enter_c
		push	ds
		push	es					; Save segment registers
		push	fs
		push	gs

		_lds	_si,[sregs]			; DS:_SI -> Load segment registers
		mov		es,[_si]
		mov		bx,[_si+6]
		mov		[sv_ds],_bx			; Save value of user DS on stack
		mov		fs,[_si+8]
		mov		gs,[_si+10]

		_lds	_si,[inptr]			; Load CPU registers
		mov     eax,[_si]
		mov		ebx,[_si+4]
		mov		ecx,[_si+8]
		mov		edx,[_si+12]
		mov     edi,[_si+20]
		mov		esi,[_si+16]

		push	ds					; Save value of DS
		push	_bp					; Some interrupts trash this!
		clc							; Generate the interrupt
		push	[UINT intno]
		mov		ds,[WORD sv_ds]		; Set value of user's DS selector
		call	_PM_genInt
		pop		_bp					; Pop intno from stack (flags unchanged)
		pop		_bp					; Restore value of stack frame pointer
		pop		ds					; Restore value of DS

		pushf                       ; Save flags for later
		pop		[UINT flags]
		push	esi					; Save ESI for later
		pop		[DWORD sv_esi]
		push	ds					; Save DS for later
		pop		[UINT sv_ds]

		_lds	_si,[outptr]		; Save CPU registers
		mov     [_si],eax
		mov		[_si+4],ebx
		mov		[_si+8],ecx
		mov		[_si+12],edx
		push	[DWORD sv_esi]
		pop		[DWORD _si+16]
		mov     [_si+20],edi

		mov		_bx,[flags]			; Return flags
		and		ebx,1h				; Isolate carry flag
		mov		[_si+24],ebx		; Save carry flag status

		_lds	_si,[sregs]			; Save segment registers
		mov		[_si],es
		mov		_bx,[sv_ds]
		mov		[_si+6],bx			; Get returned DS from stack
		mov		[_si+8],fs
		mov		[_si+10],gs

		pop		gs					; Restore segment registers
		pop		fs
		pop		es
		pop		ds
		leave_c
		ret

cprocend

ifndef flatmodel
_PM_savedDS		dw	_DATA			; Saved value of DS
endif

;----------------------------------------------------------------------------
; void PM_saveDS(void)
;----------------------------------------------------------------------------
; Save the value of DS into a section of the code segment, so that we can
; quickly load this value at a later date in the PM_loadDS() routine from
; inside interrupt handlers etc. The method to do this is different
; depending on the DOS extender being used.
;----------------------------------------------------------------------------
cprocstartdll16	PM_saveDS

ifdef flatmodel
		mov		[_PM_savedDS],ds	; Store away in data segment
endif
		ret

cprocend

;----------------------------------------------------------------------------
; void PM_loadDS(void)
;----------------------------------------------------------------------------
; Routine to load the DS register with the default value for the current
; DOS extender. Only the DS register is loaded, not the ES register, so
; if you wish to call C code, you will need to also load the ES register
; in 32 bit protected mode.
;----------------------------------------------------------------------------
cprocstartdll16	PM_loadDS

		mov		ds,[cs:_PM_savedDS]	; We can access the proper DS through CS
		ret

cprocend

ifdef flatmodel

;----------------------------------------------------------------------------
; void DPMI_allocateCallback(void (*pmcode)(), void *rmregs, long *RMCB)
;----------------------------------------------------------------------------
cprocstart	_DPMI_allocateCallback

		ARG		pmcode:CPTR, rmregs:DPTR, RMCB:DPTR

		enter_c
		push	ds
		push	es

		push	cs
		pop		ds
		mov		esi,[pmcode]	; DS:ESI -> protected mode code to call
		mov		edi,[rmregs]	; ES:EDI -> real mode register buffer
		mov		ax,303h			; AX := allocate realmode callback function
		int		31h

		mov     eax,[RMCB]
		shl		ecx,16
		mov		cx,dx
		mov		[es:eax],ecx	; Return real mode address

		pop		es
		pop		ds
		leave_c
		ret

cprocend

;----------------------------------------------------------------------------
; void DPMI_freeCallback(long RMCB)
;----------------------------------------------------------------------------
cprocstart	_DPMI_freeCallback

		ARG		RMCB:ULONG

		enter_c

		mov     cx,[WORD RMCB+2]
		mov		dx,[WORD RMCB]	; CX:DX := real mode callback
		mov		ax,304h
		int		31h

		leave_c
		ret

cprocend

endif

; Macro to delay briefly to ensure that enough time has elapsed between
; successive I/O accesses so that the device being accessed can respond
; to both accesses even on a very fast PC.

ifdef	USE_NASM
%macro	DELAY 0
		jmp		short $+2
		jmp		short $+2
		jmp		short $+2
%endmacro
%macro	IODELAYN 1
%rep	%1
		DELAY
%endrep
%endmacro
else
macro	DELAY
		jmp		short $+2
		jmp		short $+2
		jmp	    short $+2
endm
macro	IODELAYN	N
	rept	N
		DELAY
	endm
endm
endif

;----------------------------------------------------------------------------
; uchar _PM_readCMOS(int index)
;----------------------------------------------------------------------------
; Read the value of a specific CMOS register. We do this with both
; normal interrupts and NMI disabled.
;----------------------------------------------------------------------------
cprocstart	_PM_readCMOS

		ARG		index:UINT

		push	_bp
		mov		_bp,_sp
		pushfd
		mov		al,[BYTE index]
		or		al,80h				; Add disable NMI flag
		cli
		out		70h,al
		IODELAYN 5
		in		al,71h
		mov		ah,al
		xor		al,al
		IODELAYN 5
		out		70h,al				; Re-enable NMI
		sti
		mov		al,ah				; Return value in AL
		popfd
		pop		_bp
		ret

cprocend

;----------------------------------------------------------------------------
; void _PM_writeCMOS(int index,uchar value)
;----------------------------------------------------------------------------
; Read the value of a specific CMOS register. We do this with both
; normal interrupts and NMI disabled.
;----------------------------------------------------------------------------
cprocstart	_PM_writeCMOS

		ARG		index:UINT, value:UCHAR

		push	_bp
		mov		_bp,_sp
		pushfd
		mov		al,[BYTE index]
		or		al,80h				; Add disable NMI flag
		cli
		out		70h,al
		IODELAYN 5
		mov		al,[value]
		out		71h,al
		xor		al,al
		IODELAYN 5
		out		70h,al				; Re-enable NMI
		sti
		popfd
		pop		_bp
		ret

cprocend

;----------------------------------------------------------------------------
; _PM_getPDB - Return the Page Table Directory Base address
;----------------------------------------------------------------------------
cprocstart	_PM_getPDB

ifdef	DOS4GW
		mov     ax,cs
		and   	eax,3
		jnz		@@Fail
		mov		eax,cr3
		and		eax,0FFFFF000h
		ret
endif
@@Fail:	xor		eax,eax
		ret

cprocend

;----------------------------------------------------------------------------
; _PM_flushTLB - Flush the Translation Lookaside buffer
;----------------------------------------------------------------------------
cprocstart	_PM_flushTLB

ifdef	DOS4GW
		mov		eax,cr3
		mov		cr3,eax
endif
		ret

cprocend

endcodeseg  _pmdos

		END						; End of module