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/*-------------------------------------------------------------------------
memcpyx.c
Copyright (C) 2003, Kevin Vigor
This library 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.
This library 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 this library; see the file COPYING. If not, write to the
Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
As a special exception, if you link this library with other files,
some of which are compiled with SDCC, to produce an executable,
this library does not by itself cause the resulting executable to
be covered by the GNU General Public License. This exception does
not however invalidate any other reasons why the executable file
might be covered by the GNU General Public License.
-------------------------------------------------------------------------*/
#include <string.h>
// FIXME: can optimize even further on '400 with auto-increment/auto-toggle.
void __xdata * memcpyx (
void __xdata * dst,
void __xdata * src,
int count
) __naked
{
/* Shut compiler up about unused parameters. */
dst; src; count;
__asm
; Destination is in DPTR. Save it on stack so we can return it at end.
push dpx
push dph
push dpl
mov dps, #0x1 ; Alternate DPTR.
; count is in _memcpyx_PARM_3
mov dptr, #_memcpyx_PARM_3
movx a, @dptr
inc dptr
mov r2, a
movx a, @dptr
mov r3, a
; src is in _memcpyx_PARM_2
mov dptr, #_memcpyx_PARM_2
movx a, @dptr
inc dptr
push acc
movx a, @dptr
inc dptr
push acc
movx a, @dptr
mov dpx1, a
pop dph1
pop dpl1
mov dps, #0x21 ; Current DPTR is alt DPTR, toggle after each op.
; src is in alt DPTR, dst is in normal DPTR, count is in r2/r3.
; If we have zero bytes to copy, quick out.
mov a, r2
orl a, r3
jz _memcpy_done
; increment r3 if r2 != 0 (makes djnz end-of-loop sequence possible).
inc r3
cjne r2, #0x0, _memcpyx_loopTop
dec r3
_memcpyx_loopTop:
movx a, @dptr
movx @dptr, a
inc dptr
inc dptr
djnz r2, _memcpyx_loopTop
djnz r3, _memcpyx_loopTop
_memcpy_done:
mov dps, #0x0
pop dpl
pop dph
pop dpx
ret
__endasm;
}
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