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/*-------------------------------------------------------------------------
_mulint.c - routine for (unsigned) int (16 bit) multiplication
Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
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.
-------------------------------------------------------------------------*/
/* Signed and unsigned multiplication are the same - as long as the output
has the same precision as the input.
Assembler-functions are provided for:
ds390
mcs51 small
mcs51 small stack-auto
mcs51 large
*/
#if !defined(__SDCC_USE_XSTACK) && !defined(_SDCC_NO_ASM_LIB_FUNCS)
# if defined(__SDCC_ds390)
# if !defined(__SDCC_STACK_AUTO)
# define _MULINT_ASM_LARGE
# endif
# elif defined(__SDCC_mcs51)
# if defined(__SDCC_MODEL_SMALL)
# if defined(__SDCC_STACK_AUTO) && !defined(__SDCC_PARMS_IN_BANK1)
# define _MULINT_ASM_SMALL_AUTO
# else
# define _MULINT_ASM_SMALL
# endif
# else // must be __SDCC_MODEL_LARGE
# if !defined(__SDCC_STACK_AUTO)
# define _MULINT_ASM_LARGE
# endif
# endif
# endif
#endif
#if defined(_MULINT_ASM_LARGE)
#pragma save
#pragma less_pedantic
int
_mulint (int a, int b)
{
a*b; // hush the compiler
/* mulint=
(int)(lsb_a*lsb_b) +
(char)(msb_a*lsb_b)<<8 +
(char)(lsb_a*msb_b)<<8
*/
__asm
mov r2,dph ; msb_a
mov r3,dpl ; lsb_a
mov b,r3 ; lsb_a
#if defined(__SDCC_PARMS_IN_BANK1)
mov a,b1_0
#else
mov dptr,#__mulint_PARM_2
movx a,@dptr ; lsb_b
#endif
mul ab ; lsb_a*lsb_b
mov r0,a
mov r1,b
mov b,r2 ; msb_a
#if defined(__SDCC_PARMS_IN_BANK1)
mov a,b1_0
#else
movx a,@dptr ; lsb_b
#endif
mul ab ; msb_a*lsb_b
add a,r1
mov r1,a
mov b,r3 ; lsb_a
#if defined(__SDCC_PARMS_IN_BANK1)
mov a,b1_1
#else
inc dptr
movx a,@dptr ; msb_b
#endif
mul ab ; lsb_a*msb_b
add a,r1
mov dph,a
mov dpl,r0
ret
__endasm;
}
#pragma restore
#elif defined(_MULINT_ASM_SMALL) || defined(_MULINT_ASM_SMALL_AUTO)
#pragma save
#pragma less_pedantic
int
_mulint_dummy (void) __naked
{
__asm
__mulint:
.globl __mulint
#if !defined(__SDCC_STACK_AUTO) || defined(__SDCC_PARMS_IN_BANK1)
#if defined(__SDCC_NOOVERLAY)
.area DSEG (DATA)
#else
.area OSEG (OVR,DATA)
#endif
#if defined(__SDCC_PARMS_IN_BANK1)
#define bl (b1_0)
#define bh (b1_1)
#else
#define bl (__mulint_PARM_2)
#define bh (__mulint_PARM_2 + 1)
__mulint_PARM_2:
.globl __mulint_PARM_2
.ds 2
#endif
.area CSEG (CODE)
; globbered registers none
mov a,dpl ; 1 al
mov b,bl ; 2 bl
mul ab ; 4 al * bl
xch a,dpl ; 1 store low-byte of return value, fetch al
push b ; 2
mov b,bh ; 2 bh
mul ab ; 4 al * bh
pop b ; 2
add a,b ; 1
xch a,dph ; 1 ah -> acc
mov b,bl ; 2 bl
mul ab ; 4 ah * bl
add a,dph ; 1
mov dph,a ; 1
ret ; 2
; 30
#else // __SDCC_STACK_AUTO
; globbered registers r0
mov a,#-2 ; 1 return address 2 bytes
add a,sp ; 1
mov r0,a ; 1 r0 points to bh
mov a,@r0 ; 1 bh
mov b,dpl ; 2 al
mul ab ; 4 al * bh
push acc ; 2
mov b,dpl ; 2 al
dec r0 ; 1
mov a,@r0 ; 1 bl
mul ab ; 4 al * bl
mov dpl,a ; 1 low-byte of return-value
pop acc ; 2
add a,b ; 1
xch a,dph ; 1 ah -> acc
mov b,@r0 ; 2 bl
mul ab ; 4 ah * bl
add a,dph ; 1
mov dph,a ; 1
ret
#endif // __SDCC_STACK_AUTO
__endasm;
}
#pragma restore
#else
#if defined(__SDCC_hc08) || defined(__SDCC_s08) || defined(__SDCC_stm8)
// Big-endian
union uu {
struct { unsigned char hi, lo ;} s;
unsigned int t;
};
#else
// Little-endian
union uu {
struct { unsigned char lo,hi ;} s;
unsigned int t;
};
#endif
int
_mulint (int a, int b)
{
#if !defined(__SDCC_STACK_AUTO) && (defined(__SDCC_MODEL_LARGE) || defined(__SDCC_ds390)) // still needed for large
union uu __xdata *x;
union uu __xdata *y;
union uu t;
x = (union uu __xdata *)&a;
y = (union uu __xdata *)&b;
#else
register union uu *x;
register union uu *y;
union uu t;
x = (union uu *)&a;
y = (union uu *)&b;
#endif
// sdcc is bad at handling union accesses. So we use (unsigned char)a instead of x->s.lo here.
t.t = (unsigned char)a * (unsigned char)b;
t.s.hi += ((unsigned char)a * y->s.hi) + (x->s.hi * (unsigned char)b);
return t.t;
}
#endif
#undef _MULINT_ASM
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