please dont rip this site

Hi-Tech memcpy

by Isaac Marino Bavaresco

This routine is a substitution for the one in the Hi-Tech PICC compiler library.

The original has some limitations that I wanted to overcome:
1 - The data destination must always be in bank 0 or bank 1.
2 - If the data source is in program memory (retlw table) it must be 256 entries long or less, and it must not cross a 256 instruction address boundary.

My version can copy data to any RAM bank, from any RAM bank or a retlw table, without any size or alignment restriction. Besides, it is over twice as fast as the original.

There are draw-backs tough:
1 - The parameter 'Dst' is declared 'const void *', when it should be declared 'void *', but a non-const pointer can point only to banks 0 and 1 or to banks 2 and 3, never to all banks. It's no problem if the programmer is a bit careful.
2 - the function returns 'void', where it should return 'void *'. I did this to save some RAM and execution time (I personally never used the return from memcpy, as it is the same destination pointer I already have). If one needs it the right way, it is easy to fix.

Note:
If a pointer to program memory is passed to 'Dst', the function returns without doing nothing.

;==============================================================================
; Copyright (c) 2008, Isaac Marino Bavaresco
; All rights reserved.
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions are met:
;     * Redistributions of source code must retain the above copyright
;       notice, this list of conditions and the following disclaimer.
;     * Neither the name of the author nor the
;       names of its contributors may be used to endorse or promote products
;       derived from this software without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY THE AUTHOR ''AS IS'' AND ANY
; EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
; WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
; DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
; DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
; (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
; ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
; SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
;==============================================================================
; isaacbavaresco@yahoo.com.br
;==============================================================================
INDF		equ	0
PCL		equ	2
STATUS		equ	3
FSR		equ	4
PCLATH		equ	10
;===============================================================================
_memcpy$Dst	set	?_memcpy+0
_memcpy$DstBnk	set	?_memcpy+1
_memcpy$Src	set	?_memcpy+2
_memcpy$SrcBnk	set	?_memcpy+3
_memcpy$Len	set	?_memcpy+4
;===============================================================================
; void memcpy( const void *Dst, const void *Src, unsigned char Len )

		psect	text0,local,class=CODE,delta=2

		global	_memcpy
		signat	_memcpy,0x3078
		fnsize	_memcpy,0,5
		global	?_memcpy

_memcpy:	clrf	STATUS
		;---------------------------------------------------------------
		btfss	_memcpy$DstBnk,7	; if( !( Dst & 0x8000 ))
DstInROM:	return				;    return;

		incf	_memcpy$Len,f
		;---------------------------------------------------------------
DstInRAM:	btfsc	_memcpy$SrcBnk,7	; if( Src & 0x8000 )
		goto	SrcInRAMTest
		;---------------------------------------------------------------
SrcInROM:	btfsc	_memcpy$DstBnk,0
		bsf	STATUS,7
		movf	_memcpy$Dst,w
		movwf	FSR
		
		goto	SrcInROMTest
		;---------------------------------------------------------------
SrcInROMLoop:	call	LookUp

		movwf	INDF

		pagesel	$

		incfsz	_memcpy$Src,f
		goto	$+2
		incf	_memcpy$SrcBnk,f

		incf	FSR,f

SrcInROMTest:	decfsz	_memcpy$Len,f
		goto	SrcInROMLoop
		return
		;---------------------------------------------------------------
LookUp:		movf	_memcpy$SrcBnk,w
		movwf	PCLATH
		movf	_memcpy$Src,w
		movwf	PCL
		;---------------------------------------------------------------
SrcInRAM:	bcf	STATUS,7
		btfsc	_memcpy$SrcBnk,0
		bsf	STATUS,7
		movf	_memcpy$Src,w
		movwf	FSR

		movf	INDF,w
		movwf	btemp+0

		bcf	STATUS,7
		btfsc	_memcpy$DstBnk,0
		bsf	STATUS,7
		movf	_memcpy$Dst,w
		movwf	FSR

		movf	btemp+0,w
		movwf	INDF

		incf	_memcpy$Src,f
		incf	_memcpy$Dst,f

SrcInRAMTest:	decfsz	_memcpy$Len,f
		goto	SrcInRAM
		return
;===============================================================================
		psect	temp,ovrld,class=BANK0,space=1
btemp		ds	1
;===============================================================================

file: /Techref/member/IMB-yahoo-J86/hi-techmemcpy.htm, 5KB, , updated: 2009/7/9 09:02, local time: 2018/11/17 18:57, owner: IMB-yahoo-J86,
TOP NEW HELP FIND: 
54.159.44.54:LOG IN

 ©2018 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE! / 

<A HREF="http://www.piclist.com/Techref/member/IMB-yahoo-J86/hi-techmemcpy.htm"> Hi-Tech memcpy</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?