/*-------------------------------------------------------------------------
_divulong.c - routine for division of 32 bit unsigned long
Copyright (C) 1999, Jean-Louis Vern <jlvern AT gmail.com>
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.
-------------------------------------------------------------------------*/
/* Assembler-functions are provided for:
mcs51 small
mcs51 small stack-auto
*/
#include <stdbool.h>
#if !defined(__SDCC_USE_XSTACK) && !defined(_SDCC_NO_ASM_LIB_FUNCS)
# if defined(__SDCC_mcs51)
# if defined(__SDCC_MODEL_SMALL)
# if defined(__SDCC_STACK_AUTO) && !defined(__SDCC_PARMS_IN_BANK1)
# define _DIVULONG_ASM_SMALL_AUTO
# else
# define _DIVULONG_ASM_SMALL
# endif
# endif
# endif
#endif
#if defined _DIVULONG_ASM_SMALL
static void
_divlong_dummy
(void) __naked
{
__asm
.
globl __divulong
__divulong
:
#define count r2
#define x0 dpl
#define x1 dph
#define x2 b
#define x3 r3
#define reste0 r4
#define reste1 r5
#define reste2 r6
#define reste3 r7
#if !defined(__SDCC_PARMS_IN_BANK1)
#if defined(__SDCC_NOOVERLAY)
.
area DSEG
(DATA
)
#else
.
area OSEG
(OVR
,DATA
)
#endif
.
globl __divulong_PARM_2
.
globl __divslong_PARM_2
__divulong_PARM_2
:
__divslong_PARM_2
:
.
ds 4
.
area CSEG
(CODE
)
#define y0 (__divulong_PARM_2)
#define y1 (__divulong_PARM_2 + 1)
#define y2 (__divulong_PARM_2 + 2)
#define y3 (__divulong_PARM_2 + 3)
#else
#define y0 (b1_0)
#define y1 (b1_1)
#define y2 (b1_2)
#define y3 (b1_3)
#endif // !__SDCC_PARMS_IN_BANK1
; parameter x comes in a
, b
, dph
, dpl
mov x3
,a
; save parameter x3
mov count
,#32
clr a
mov reste0
,a
mov reste1
,a
mov reste2
,a
mov reste3
,a
; optimization loop in lp0 until the first bit is shifted into rest
lp0
: mov a
,x0
; x
<<= 1
add a
,x0
mov x0
,a
mov a
,x1
rlc a
mov x1
,a
mov a
,x2
rlc a
mov x2
,a
mov a
,x3
rlc a
mov x3
,a
jc in_lp
djnz count
,lp0
sjmp
exit
loop
: mov a
,x0
; x
<<= 1
add a
,x0
mov x0
,a
mov a
,x1
rlc a
mov x1
,a
mov a
,x2
rlc a
mov x2
,a
mov a
,x3
rlc a
mov x3
,a
in_lp
: mov a
,reste0
; reste
<<= 1
rlc a
; feed in carry
mov reste0
,a
mov a
,reste1
rlc a
mov reste1
,a
mov a
,reste2
rlc a
mov reste2
,a
mov a
,reste3
rlc a
mov reste3
,a
mov a
,reste0
; reste
- y
subb a
,y0
; carry is always clear here
, because
; reste
<<= 1 never overflows
mov a
,reste1
subb a
,y1
mov a
,reste2
subb a
,y2
mov a
,reste3
subb a
,y3
jc minus
; reste
>= y
?
; -> yes
; reste
-= y
;
mov a
,reste0
subb a
,y0
; carry is always clear here
(jc
)
mov reste0
,a
mov a
,reste1
subb a
,y1
mov reste1
,a
mov a
,reste2
subb a
,y2
mov reste2
,a
mov a
,reste3
subb a
,y3
mov reste3
,a
orl x0
,#1
minus
: djnz count
,loop
; -> no
exit: mov a
,x3
; prepare the
return value
ret
__endasm
;
}
#elif defined _DIVULONG_ASM_SMALL_AUTO
static void
_divlong_dummy
(void) __naked
{
__asm
.
globl __divulong
__divulong
:
#define count r2
#define x0 dpl
#define x1 dph
#define x2 b
#define x3 r3
#define reste0 r4
#define reste1 r5
#define reste2 r6
#define reste3 r7
.
globl __divlong
; entry point
for __divslong
#define y0 r1
; parameter x comes in a
, b
, dph
, dpl
mov x3
,a
; save parameter x3
mov a
,sp
add a
,#-2-3 ; 2 bytes return address, 3 bytes param y
mov r0
,a
; r0 points to y0
__divlong
: ; entry point
for __divslong
mov a
,@r0
; load y0
mov y0
,a
inc r0
; r0 points to y1
mov count
,#32
clr a
mov reste0
,a
mov reste1
,a
mov reste2
,a
mov reste3
,a
; optimization loop in lp0 until the first bit is shifted into rest
lp0
: mov a
,x0
; x
<<= 1
add a
,x0
mov x0
,a
mov a
,x1
rlc a
mov x1
,a
mov a
,x2
rlc a
mov x2
,a
mov a
,x3
rlc a
mov x3
,a
jc in_lp
djnz count
,lp0
sjmp
exit
loop
: mov a
,x0
; x
<<= 1
add a
,x0
mov x0
,a
mov a
,x1
rlc a
mov x1
,a
mov a
,x2
rlc a
mov x2
,a
mov a
,x3
rlc a
mov x3
,a
in_lp
: mov a
,reste0
; reste
<<= 1
rlc a
; feed in carry
mov reste0
,a
mov a
,reste1
rlc a
mov reste1
,a
mov a
,reste2
rlc a
mov reste2
,a
mov a
,reste3
rlc a
mov reste3
,a
mov a
,reste0
; reste
- y
subb a
,y0
; carry is always clear here
, because
; reste
<<= 1 never overflows
mov a
,reste1
subb a
,@r0
; y1
mov a
,reste2
inc r0
subb a
,@r0
; y2
mov a
,reste3
inc r0
subb a
,@r0
; y3
dec r0
dec r0
jc minus
; reste
>= y
?
; -> yes
; reste
-= y
;
mov a
,reste0
subb a
,y0
; carry is always clear here
(jc
)
mov reste0
,a
mov a
,reste1
subb a
,@r0
; y1
mov reste1
,a
mov a
,reste2
inc r0
subb a
,@r0
; y2
mov reste2
,a
mov a
,reste3
inc r0
subb a
,@r0
; y3
mov reste3
,a
dec r0
dec r0
orl x0
,#1
minus
: djnz count
,loop
; -> no
exit: mov a
,x3
; prepare the
return value
ret
__endasm
;
}
#else // _DIVULONG_ASM
#define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
unsigned long
_divulong
(unsigned long x
, unsigned long y
)
{
unsigned long reste
= 0L;
unsigned char count
= 32;
bool c
;
do
{
// reste: x <- 0;
c
= MSB_SET
(x
);
x
<<= 1;
reste
<<= 1;
if (c
)
reste
|= 1L;
if (reste
>= y
)
{
reste
-= y
;
// x <- (result = 1)
x
|= 1L;
}
}
while (--count
);
return x
;
}
#endif // _DIVULONG_ASM