distrib/jpeg-6b/jmemdosa.asm - emulator-unstable-refactoring - Git at Google

 ;
 ; jmemdosa.asm
 ;
 ; Copyright (C) 1992, Thomas G. Lane.
 ; This file is part of the Independent JPEG Group's software.
 ; For conditions of distribution and use, see the accompanying README file.
 ;
 ; This file contains low-level interface routines to support the MS-DOS
 ; backing store manager (jmemdos.c).  Routines are provided to access disk
 ; files through direct DOS calls, and to access XMS and EMS drivers.
 ;
 ; This file should assemble with Microsoft's MASM or any compatible
 ; assembler (including Borland's Turbo Assembler).  If you haven't got
 ; a compatible assembler, better fall back to jmemansi.c or jmemname.c.
 ;
 ; To minimize dependence on the C compiler's register usage conventions,
 ; we save and restore all 8086 registers, even though most compilers only
 ; require SI,DI,DS to be preserved.  Also, we use only 16-bit-wide return
 ; values, which everybody returns in AX.
 ;
 ; Based on code contributed by Ge' Weijers.
 ;

 JMEMDOSA_TXT	segment byte public 'CODE'

 		assume	cs:JMEMDOSA_TXT

 		public	_jdos_open
 		public	_jdos_close
 		public	_jdos_seek
 		public	_jdos_read
 		public	_jdos_write
 		public	_jxms_getdriver
 		public	_jxms_calldriver
 		public	_jems_available
 		public	_jems_calldriver

 ;
 ; short far jdos_open (short far * handle, char far * filename)
 ;
 ; Create and open a temporary file
 ;
 _jdos_open	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	cx,0			; normal file attributes
 		lds	dx,dword ptr [bp+10]	; get filename pointer
 		mov	ah,3ch			; create file
 		int	21h
 		jc	open_err		; if failed, return error code
 		lds	bx,dword ptr [bp+6]	; get handle pointer
 		mov	word ptr [bx],ax	; save the handle
 		xor	ax,ax			; return zero for OK
 open_err:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jdos_open	endp


 ;
 ; short far jdos_close (short handle)
 ;
 ; Close the file handle
 ;
 _jdos_close	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	bx,word ptr [bp+6]	; file handle
 		mov	ah,3eh			; close file
 		int	21h
 		jc	close_err		; if failed, return error code
 		xor	ax,ax			; return zero for OK
 close_err:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jdos_close	endp


 ;
 ; short far jdos_seek (short handle, long offset)
 ;
 ; Set file position
 ;
 _jdos_seek	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	bx,word ptr [bp+6]	; file handle
 		mov	dx,word ptr [bp+8]	; LS offset
 		mov	cx,word ptr [bp+10]	; MS offset
 		mov	ax,4200h		; absolute seek
 		int	21h
 		jc	seek_err		; if failed, return error code
 		xor	ax,ax			; return zero for OK
 seek_err:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jdos_seek	endp


 ;
 ; short far jdos_read (short handle, void far * buffer, unsigned short count)
 ;
 ; Read from file
 ;
 _jdos_read	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	bx,word ptr [bp+6]	; file handle
 		lds	dx,dword ptr [bp+8]	; buffer address
 		mov	cx,word ptr [bp+12]	; number of bytes
 		mov	ah,3fh			; read file
 		int	21h
 		jc	read_err		; if failed, return error code
 		cmp	ax,word ptr [bp+12]	; make sure all bytes were read
 		je	read_ok
 		mov	ax,1			; else return 1 for not OK
 		jmp	short read_err
 read_ok:	xor	ax,ax			; return zero for OK
 read_err:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jdos_read	endp


 ;
 ; short far jdos_write (short handle, void far * buffer, unsigned short count)
 ;
 ; Write to file
 ;
 _jdos_write	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	bx,word ptr [bp+6]	; file handle
 		lds	dx,dword ptr [bp+8]	; buffer address
 		mov	cx,word ptr [bp+12]	; number of bytes
 		mov	ah,40h			; write file
 		int	21h
 		jc	write_err		; if failed, return error code
 		cmp	ax,word ptr [bp+12]	; make sure all bytes written
 		je	write_ok
 		mov	ax,1			; else return 1 for not OK
 		jmp	short write_err
 write_ok:	xor	ax,ax			; return zero for OK
 write_err:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jdos_write	endp


 ;
 ; void far jxms_getdriver (XMSDRIVER far *)
 ;
 ; Get the address of the XMS driver, or NULL if not available
 ;
 _jxms_getdriver	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov 	ax,4300h		; call multiplex interrupt with
 		int	2fh			; a magic cookie, hex 4300
 		cmp 	al,80h			; AL should contain hex 80
 		je	xmsavail
 		xor 	dx,dx			; no XMS driver available
 		xor 	ax,ax			; return a nil pointer
 		jmp	short xmsavail_done
 xmsavail:	mov 	ax,4310h		; fetch driver address with
 		int	2fh			; another magic cookie
 		mov 	dx,es			; copy address to dx:ax
 		mov 	ax,bx
 xmsavail_done:	les 	bx,dword ptr [bp+6]	; get pointer to return value
 		mov	word ptr es:[bx],ax
 		mov	word ptr es:[bx+2],dx
 		pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop	bp
 		ret
 _jxms_getdriver	endp


 ;
 ; void far jxms_calldriver (XMSDRIVER, XMScontext far *)
 ;
 ; The XMScontext structure contains values for the AX,DX,BX,SI,DS registers.
 ; These are loaded, the XMS call is performed, and the new values of the
 ; AX,DX,BX registers are written back to the context structure.
 ;
 _jxms_calldriver 	proc	far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		les 	bx,dword ptr [bp+10]	; get XMScontext pointer
 		mov 	ax,word ptr es:[bx]	; load registers
 		mov 	dx,word ptr es:[bx+2]
 		mov 	si,word ptr es:[bx+6]
 		mov 	ds,word ptr es:[bx+8]
 		mov 	bx,word ptr es:[bx+4]
 		call	dword ptr [bp+6]	; call the driver
 		mov	cx,bx			; save returned BX for a sec
 		les 	bx,dword ptr [bp+10]	; get XMScontext pointer
 		mov 	word ptr es:[bx],ax	; put back ax,dx,bx
 		mov 	word ptr es:[bx+2],dx
 		mov 	word ptr es:[bx+4],cx
 		pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jxms_calldriver 	endp


 ;
 ; short far jems_available (void)
 ;
 ; Have we got an EMS driver? (this comes straight from the EMS 4.0 specs)
 ;
 _jems_available	proc	far
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		mov	ax,3567h		; get interrupt vector 67h
 		int	21h
 		push	cs
 		pop	ds
 		mov	di,000ah		; check offs 10 in returned seg
 		lea	si,ASCII_device_name	; against literal string
 		mov	cx,8
 		cld
 		repe cmpsb
 		jne	no_ems
 		mov	ax,1			; match, it's there
 		jmp	short avail_done
 no_ems:		xor	ax,ax			; it's not there
 avail_done:	pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		ret

 ASCII_device_name	db	"EMMXXXX0"

 _jems_available	endp


 ;
 ; void far jems_calldriver (EMScontext far *)
 ;
 ; The EMScontext structure contains values for the AX,DX,BX,SI,DS registers.
 ; These are loaded, the EMS trap is performed, and the new values of the
 ; AX,DX,BX registers are written back to the context structure.
 ;
 _jems_calldriver	proc far
 		push	bp			; linkage
 		mov 	bp,sp
 		push	si			; save all registers for safety
 		push	di
 		push	bx
 		push	cx
 		push	dx
 		push	es
 		push	ds
 		les 	bx,dword ptr [bp+6]	; get EMScontext pointer
 		mov 	ax,word ptr es:[bx]	; load registers
 		mov 	dx,word ptr es:[bx+2]
 		mov 	si,word ptr es:[bx+6]
 		mov 	ds,word ptr es:[bx+8]
 		mov 	bx,word ptr es:[bx+4]
 		int	67h			; call the EMS driver
 		mov	cx,bx			; save returned BX for a sec
 		les 	bx,dword ptr [bp+6]	; get EMScontext pointer
 		mov 	word ptr es:[bx],ax	; put back ax,dx,bx
 		mov 	word ptr es:[bx+2],dx
 		mov 	word ptr es:[bx+4],cx
 		pop	ds			; restore registers and exit
 		pop	es
 		pop	dx
 		pop	cx
 		pop	bx
 		pop	di
 		pop	si
 		pop 	bp
 		ret
 _jems_calldriver	endp

 JMEMDOSA_TXT	ends

 		end
	;
	; jmemdosa.asm
	;
	; Copyright (C) 1992, Thomas G. Lane.
	; This file is part of the Independent JPEG Group's software.
	; For conditions of distribution and use, see the accompanying README file.
	;
	; This file contains low-level interface routines to support the MS-DOS
	; backing store manager (jmemdos.c). Routines are provided to access disk
	; files through direct DOS calls, and to access XMS and EMS drivers.
	;
	; This file should assemble with Microsoft's MASM or any compatible
	; assembler (including Borland's Turbo Assembler). If you haven't got
	; a compatible assembler, better fall back to jmemansi.c or jmemname.c.
	;
	; To minimize dependence on the C compiler's register usage conventions,
	; we save and restore all 8086 registers, even though most compilers only
	; require SI,DI,DS to be preserved. Also, we use only 16-bit-wide return
	; values, which everybody returns in AX.
	;
	; Based on code contributed by Ge' Weijers.
	;

	JMEMDOSA_TXT segment byte public 'CODE'

	assume cs:JMEMDOSA_TXT

	public _jdos_open
	public _jdos_close
	public _jdos_seek
	public _jdos_read
	public _jdos_write
	public _jxms_getdriver
	public _jxms_calldriver
	public _jems_available
	public _jems_calldriver

	;
	; short far jdos_open (short far * handle, char far * filename)
	;
	; Create and open a temporary file
	;
	_jdos_open proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov cx,0 ; normal file attributes
	lds dx,dword ptr [bp+10] ; get filename pointer
	mov ah,3ch ; create file
	int 21h
	jc open_err ; if failed, return error code
	lds bx,dword ptr [bp+6] ; get handle pointer
	mov word ptr [bx],ax ; save the handle
	xor ax,ax ; return zero for OK
	open_err: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jdos_open endp


	;
	; short far jdos_close (short handle)
	;
	; Close the file handle
	;
	_jdos_close proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov bx,word ptr [bp+6] ; file handle
	mov ah,3eh ; close file
	int 21h
	jc close_err ; if failed, return error code
	xor ax,ax ; return zero for OK
	close_err: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jdos_close endp


	;
	; short far jdos_seek (short handle, long offset)
	;
	; Set file position
	;
	_jdos_seek proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov bx,word ptr [bp+6] ; file handle
	mov dx,word ptr [bp+8] ; LS offset
	mov cx,word ptr [bp+10] ; MS offset
	mov ax,4200h ; absolute seek
	int 21h
	jc seek_err ; if failed, return error code
	xor ax,ax ; return zero for OK
	seek_err: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jdos_seek endp


	;
	; short far jdos_read (short handle, void far * buffer, unsigned short count)
	;
	; Read from file
	;
	_jdos_read proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov bx,word ptr [bp+6] ; file handle
	lds dx,dword ptr [bp+8] ; buffer address
	mov cx,word ptr [bp+12] ; number of bytes
	mov ah,3fh ; read file
	int 21h
	jc read_err ; if failed, return error code
	cmp ax,word ptr [bp+12] ; make sure all bytes were read
	je read_ok
	mov ax,1 ; else return 1 for not OK
	jmp short read_err
	read_ok: xor ax,ax ; return zero for OK
	read_err: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jdos_read endp


	;
	; short far jdos_write (short handle, void far * buffer, unsigned short count)
	;
	; Write to file
	;
	_jdos_write proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov bx,word ptr [bp+6] ; file handle
	lds dx,dword ptr [bp+8] ; buffer address
	mov cx,word ptr [bp+12] ; number of bytes
	mov ah,40h ; write file
	int 21h
	jc write_err ; if failed, return error code
	cmp ax,word ptr [bp+12] ; make sure all bytes written
	je write_ok
	mov ax,1 ; else return 1 for not OK
	jmp short write_err
	write_ok: xor ax,ax ; return zero for OK
	write_err: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jdos_write endp


	;
	; void far jxms_getdriver (XMSDRIVER far *)
	;
	; Get the address of the XMS driver, or NULL if not available
	;
	_jxms_getdriver proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov ax,4300h ; call multiplex interrupt with
	int 2fh ; a magic cookie, hex 4300
	cmp al,80h ; AL should contain hex 80
	je xmsavail
	xor dx,dx ; no XMS driver available
	xor ax,ax ; return a nil pointer
	jmp short xmsavail_done
	xmsavail: mov ax,4310h ; fetch driver address with
	int 2fh ; another magic cookie
	mov dx,es ; copy address to dx:ax
	mov ax,bx
	xmsavail_done: les bx,dword ptr [bp+6] ; get pointer to return value
	mov word ptr es:[bx],ax
	mov word ptr es:[bx+2],dx
	pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jxms_getdriver endp


	;
	; void far jxms_calldriver (XMSDRIVER, XMScontext far *)
	;
	; The XMScontext structure contains values for the AX,DX,BX,SI,DS registers.
	; These are loaded, the XMS call is performed, and the new values of the
	; AX,DX,BX registers are written back to the context structure.
	;
	_jxms_calldriver proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	les bx,dword ptr [bp+10] ; get XMScontext pointer
	mov ax,word ptr es:[bx] ; load registers
	mov dx,word ptr es:[bx+2]
	mov si,word ptr es:[bx+6]
	mov ds,word ptr es:[bx+8]
	mov bx,word ptr es:[bx+4]
	call dword ptr [bp+6] ; call the driver
	mov cx,bx ; save returned BX for a sec
	les bx,dword ptr [bp+10] ; get XMScontext pointer
	mov word ptr es:[bx],ax ; put back ax,dx,bx
	mov word ptr es:[bx+2],dx
	mov word ptr es:[bx+4],cx
	pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jxms_calldriver endp


	;
	; short far jems_available (void)
	;
	; Have we got an EMS driver? (this comes straight from the EMS 4.0 specs)
	;
	_jems_available proc far
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	mov ax,3567h ; get interrupt vector 67h
	int 21h
	push cs
	pop ds
	mov di,000ah ; check offs 10 in returned seg
	lea si,ASCII_device_name ; against literal string
	mov cx,8
	cld
	repe cmpsb
	jne no_ems
	mov ax,1 ; match, it's there
	jmp short avail_done
	no_ems: xor ax,ax ; it's not there
	avail_done: pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	ret

	ASCII_device_name db "EMMXXXX0"

	_jems_available endp


	;
	; void far jems_calldriver (EMScontext far *)
	;
	; The EMScontext structure contains values for the AX,DX,BX,SI,DS registers.
	; These are loaded, the EMS trap is performed, and the new values of the
	; AX,DX,BX registers are written back to the context structure.
	;
	_jems_calldriver proc far
	push bp ; linkage
	mov bp,sp
	push si ; save all registers for safety
	push di
	push bx
	push cx
	push dx
	push es
	push ds
	les bx,dword ptr [bp+6] ; get EMScontext pointer
	mov ax,word ptr es:[bx] ; load registers
	mov dx,word ptr es:[bx+2]
	mov si,word ptr es:[bx+6]
	mov ds,word ptr es:[bx+8]
	mov bx,word ptr es:[bx+4]
	int 67h ; call the EMS driver
	mov cx,bx ; save returned BX for a sec
	les bx,dword ptr [bp+6] ; get EMScontext pointer
	mov word ptr es:[bx],ax ; put back ax,dx,bx
	mov word ptr es:[bx+2],dx
	mov word ptr es:[bx+4],cx
	pop ds ; restore registers and exit
	pop es
	pop dx
	pop cx
	pop bx
	pop di
	pop si
	pop bp
	ret
	_jems_calldriver endp

	JMEMDOSA_TXT ends

	end