kc3-lang/libjpeg-turbo/jmemdosa.asm

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• Hash : 4a6b7303
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  Date : 1992-03-17T00:00:00
  

  The Independent JPEG Group's JPEG software v3
  

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• jmemdosa.asm

• ;
  ; 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
  

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