;
; File:
;			  fmemcmp.asm
; Description:
;		memory comparison primitive - no mmu support
;
;			Copyright (c) 1995
;			Pasquale J. Villani
;			All Rights Reserved
;
; This file is part of DOS-C.
;
; DOS-C is free software; you can redistribute it and/or
; modify it under the terms of the GNU General Public License
; as published by the Free Software Foundation; either version
; 2, or (at your option) any later version.
;
; DOS-C is distributed in the hope that it will be useful, but
; WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
; the GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public
; License along with DOS-C; see the file COPYING.  If not,
; write to the Free Software Foundation, 675 Mass Ave,
; Cambridge, MA 02139, USA.
;
; $Logfile:   C:/dos-c/src/drivers/fmemcmp.asv  $
;
; $Header:   C:/dos-c/src/drivers/fmemcmp.asv   1.1   01 Sep 1995 18:50:36   patv  $
;
; $Log:   C:/dos-c/src/drivers/fmemcmp.asv  $
;
;   Rev 1.1   01 Sep 1995 18:50:36   patv
;Initial GPL release.
;
;   Rev 1.0   02 Jul 1995  7:58:38   patv
;Initial revision.
;

		page	60,132
		title	memory comparison primitive - no mmu support

IFDEF ??version
_TEXT		segment	byte public 'CODE'
DGROUP		group	_DATA,_BSS,_BSSEND		; small model
		assume	cs:_TEXT,ds:DGROUP,ss:DGROUP
_TEXT		ends

_DATA		segment word public 'DATA'
_DATA		ends

_BSS		segment word public 'BSS'
_BSS		ends

_BSSEND		segment byte public 'STACK'
_BSSEND		ends

ELSE
_TEXT		segment	byte public 'CODE'
_TEXT		ends

_DATA		segment word public 'DATA'
_DATA		ends

CONST		segment word public 'CONST'
CONST		ends

_BSS		segment word public 'BSS'
_BSS		ends

_BSSEND		segment byte public 'STACK'
_BSSEND		ends

DGROUP		group	CONST,_DATA,_BSS,_BSSEND	; small/tiny model
		assume	ds:DGROUP, ss:DGROUP
ENDIF


_TEXT      segment
	assume	CS: _TEXT
_fmemcmp	proc	near
		public	_fmemcmp
  
		push	bp
		mov	bp,sp
		push	si
		push	di
		push	ds
		push	es
		cld				; Clear direction
		lds	si,dword ptr [bp+8]	; Load 32 bit ptr
		mov	ax,ds
		xor	dx,dx			; Zero register
		mov	cx,4
  
fmemcmp1:
		shl	ax,1			; Shift w/zeros fill
		rcl	dx,1			; Rotate thru carry
		loop	fmemcmp1		; Loop if cx > 0
  
		add	ax,si
		adc	dx,0
		mov	si,ax
		and	si,0Fh
		mov	cx,4
  
fmemcmp2:
		clc				; Clear carry flag
		rcr	dx,1			; Rotate thru carry
		rcr	ax,1			; Rotate thru carry
		loop	fmemcmp2		; Loop if cx > 0
  
		mov	ds,ax
		les	di,dword ptr [bp+4]	; Load 32 bit ptr
		mov	ax,es
		xor	dx,dx			; Zero register
		mov	cx,4
  
fmemcmp3:
		shl	ax,1			; Shift w/zeros fill
		rcl	dx,1			; Rotate thru carry
		loop	fmemcmp3		; Loop if cx > 0
  
		add	ax,di
		adc	dx,0
		mov	di,ax
		and	di,0Fh
		mov	cx,4
  
fmemcmp4:
		clc				; Clear carry flag
		rcr	dx,1			; Rotate thru carry
		rcr	ax,1			; Rotate thru carry
		loop	fmemcmp4		; Loop if cx > 0
  
		mov	es,ax
		mov	ax,0FFF0h
		and	ax,[bp+0Ch]
		cmp	ax,0FFF0h
		jne	fmemcmp5		; Jump if not equal
		push	si
		push	di
		mov	cx,ax
		repe	cmpsb			; Rept zf=1+cx>0 Cmp [si] to es:[di]
		jnz	fmemcmp7		; Jump if not zero
		mov	ax,es
		add	ax,0FFFh
		mov	es,ax
		mov	ax,ds
		add	ax,0FFFh
		mov	ds,ax
		mov	cx,0Fh
		and	cx,[bp+0Ch]
		pop	di
		pop	si
		jmp	short fmemcmp6		; (0083)
fmemcmp5:
		mov	cx,[bp+0Ch]
fmemcmp6:
		repe	cmpsb			; Rept zf=1+cx>0 Cmp [si] to es:[di]
fmemcmp7:
		pushf				; Push flags
		xor	ax,ax			; Zero register
		popf				; Pop flags
		jz	fmemcmp8			; Jump if zero
		pushf				; Push flags
		inc	ax
		popf				; Pop flags
		jc	fmemcmp8		; Jump if carry Set
		dec	ax
		dec	ax
fmemcmp8:
		pop	es
		pop	ds
		pop	di
		pop	si
		pop	bp
		retn
  
_fmemcmp	endp
  
_TEXT		ends

		end