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/*-------------------------------------------------------------------------
_memset.c - part of string library functions
Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
mcs51 assembler by Frieder Ferlemann (2007)
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 2.1, 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"
#undef memset /* Avoid conflict with builtin memset() in Z80 and some related ports */
#if defined (_SDCC_NO_ASM_LIB_FUNCS) || !defined (SDCC_mcs51) || \
(!defined (SDCC_MODEL_SMALL) && !defined (SDCC_MODEL_LARGE)) || \
(defined (SDCC_STACK_AUTO) || defined (SDCC_PARMS_IN_BANK1) )
#ifdef __SDCC_BROKEN_STRING_FUNCTIONS
void *memset (void *s, unsigned char c, size_t n)
#else
void *memset (void *s, int c, size_t n)
#endif
{
register unsigned char *ret = s;
while (n--)
{
*(unsigned char *) ret = c;
ret = ((unsigned char *) ret) + 1;
}
return s;
}
#else
/* assembler implementation for mcs51 */
static void dummy(void) __naked
{
__asm
/* assigning function parameters to registers.
SDCC_PARMS_IN_BANK1 or SDCC_STACK_AUTO not yet implemented. */
#if defined (SDCC_MODEL_SMALL)
#if defined(SDCC_NOOVERLAY)
.area DSEG (DATA)
#else
.area OSEG (OVR,DATA)
#endif
_memset_PARM_2::
.ds 1
_memset_PARM_3::
.ds 2
.area CSEG (CODE)
_memset::
; Assign buf (b holds memspace, no need to touch)
mov r4,dpl
mov r5,dph
;
; Assign count
mov r6,_memset_PARM_3
mov r7,(_memset_PARM_3 + 1)
;
; if (!count) return buf;
; check for count != 0 intermangled with gymnastic
; preparing djnz instructions
cjne r6,#0x00,COUNT_LSB_NOT_ZERO
mov a,r7
jz MEMSET_END
dec r7
COUNT_LSB_NOT_ZERO:
inc r7
;
; This was 8 byte overhead for preparing
; the count argument for an integer loop with two
; djnz instructions - it might make sense to
; let SDCC automatically generate this when
; it encounters a loop like:
; for(i=0;i<j;i++){...}
; (at least for option --opt-code-speed)
;
; Assign ch
mov a,_memset_PARM_2
#else
.area XSEG (XDATA)
_memset_PARM_2::
.ds 1
_memset_PARM_3::
.ds 2
.area CSEG (CODE)
_memset::
; Assign buf (b holds memspace, no need to touch)
mov r4,dpl
mov r5,dph
;
; Assign count
mov dptr,#_memset_PARM_3
movx a,@dptr
mov r6,a
inc dptr
movx a,@dptr
mov r7,a
;
; if (!count) return buf;
; check for count != 0 intermangled with gymnastic
; preparing djnz instructions
cjne r6,#0x00,COUNT_LSB_NOT_ZERO
; acc holds r7
jz MEMSET_END
dec r7
COUNT_LSB_NOT_ZERO:
inc r7
;
; Assign ch
mov dptr,#_memset_PARM_2
movx a,@dptr
; acc is precious now
;
; Restore dptr
mov dpl,r4
mov dph,r5
#endif
/* now independent of the parameter passing everything
should be in registers by now and the loop may start */
; _memset.c do {
MEMSET_LOOP:
; _memset.c *p = ch;
lcall __gptrput
; _memset.c p++;
inc dptr
; _memset.c } while(--count) ;
djnz r6,MEMSET_LOOP
djnz r7,MEMSET_LOOP
;
MEMSET_END:
; _memset.c return buf ;
; b was unchanged
mov dpl,r4
mov dph,r5
;
ret
__endasm;
}
#endif
|
