under the terms of the GNU Library 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 Library General Public License for more details.
-
+
You should have received a copy of the GNU Library General Public License
along with this program; if not, write to the Free Software
Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
-
+
In other words, you are welcome to use, share and improve this program.
You are forbidden to forbid anyone else to use, share and improve
- what you give them. Help stamp out software-hoarding!
+ what you give them. Help stamp out software-hoarding!
-------------------------------------------------------------------------*/
-#define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
+/* Assembler-functions are provided for:
+ mcs51 small
+ mcs51 small stack-auto
+*/
+
+#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 _MODULONG_ASM_SMALL_AUTO
+# else
+# define _MODULONG_ASM_SMALL
+# endif
+# endif
+# endif
+#endif
+
+#if defined _MODULONG_ASM_SMALL
-unsigned long _modulong (unsigned long a ,unsigned long b)
+static void
+_modlong_dummy (void) __naked
{
- unsigned short count = 0;
-
-
- while (!MSB_SET(b)) {
- b <<= 1;
- if (b > a)
- {
- b >>=1;
- break;
- }
- count++;
- }
-
- do {
- if (b <= a) {
- a -= b;
- }
- b >>= 1;
- } while (count--);
-
- return a;
+ __asm
+
+ .globl __modulong
+
+ #define a0 dpl
+ #define a1 dph
+ #define a2 b
+ #define a3 r1
+ #define count r0
+
+__modulong:
+#if defined(SDCC_PARMS_IN_BANK1)
+ #define b0 (b1_0)
+ #define b1 (b1_1)
+ #define b2 (b1_2)
+ #define b3 (b1_3)
+#else
+#if defined(SDCC_NOOVERLAY)
+ .area DSEG (DATA)
+#else
+ .area OSEG (OVR,DATA)
+#endif
+
+ .globl __modulong_PARM_2
+ .globl __modslong_PARM_2
+
+__modulong_PARM_2:
+__modslong_PARM_2:
+ .ds 4
+
+ .area CSEG (CODE)
+
+ #define b0 (__modulong_PARM_2)
+ #define b1 (__modulong_PARM_2 + 1)
+ #define b2 (__modulong_PARM_2 + 2)
+ #define b3 (__modulong_PARM_2 + 3)
+#endif
+ ; parameter a comes in a, b, dph, dpl
+ mov a3,a ; save parameter a3
+
+ mov a,b0 ; b == 0? avoid endless loop
+ orl a,b1
+ orl a,b2
+ orl a,b3
+ jz div_by_0
+
+ mov count,#0
+ clr c ; when loop1 jumps immediately to loop2
+
+loop1: inc count
+
+ mov a,b3 ; if (!MSB_SET(b))
+ jb acc.7,loop2
+
+ mov a,b0 ; b <<= 1
+ add a,acc
+ mov b0,a
+ mov a,b1
+ rlc a
+ mov b1,a
+ mov a,b2
+ rlc a
+ mov b2,a
+ mov a,b3
+ rlc a
+ mov b3,a
+
+ mov a,a0 ; a - b
+ subb a,b0 ; here carry is always clear
+ mov a,a1
+ subb a,b1
+ mov a,a2
+ subb a,b2
+ mov a,a3
+ subb a,b3
+
+ jnc loop1
+
+
+ clr c
+ mov a,b3 ; b >>= 1;
+ rrc a
+ mov b3,a
+ mov a,b2
+ rrc a
+ mov b2,a
+ mov a,b1
+ rrc a
+ mov b1,a
+ mov a,b0
+ rrc a
+ mov b0,a
+
+loop2: ; clr c never set
+ mov a,a0 ; a - b
+ subb a,b0
+ mov r4,a
+ mov a,a1
+ subb a,b1
+ mov r5,a
+ mov a,a2
+ subb a,b2
+ mov r6,a
+ mov a,a3
+ subb a,b3
+
+ jc smaller ; a >= b?
+
+ mov a3,a ; -> yes; a = a - b;
+ mov a2,r6
+ mov a1,r5
+ mov a0,r4
+smaller: ; -> no
+ clr c
+ mov a,b3 ; b >>= 1;
+ rrc a
+ mov b3,a
+ mov a,b2
+ rrc a
+ mov b2,a
+ mov a,b1
+ rrc a
+ mov b1,a
+ mov a,b0
+ rrc a
+ mov b0,a
+
+ djnz count,loop2
+
+ mov a,a3 ; prepare the return value
+div_by_0:
+ ret
+
+ __endasm;
}
+
+#elif defined _MODULONG_ASM_SMALL_AUTO
+
+static void
+_modlong_dummy (void) __naked
+{
+ __asm
+
+ .globl __modulong
+
+__modulong:
+
+ #define count r0
+
+ #define a0 dpl
+ #define a1 dph
+ #define a2 b
+ #define a3 r1
+
+ #define b0 r2
+ #define b1 r3
+ #define b2 r4
+ #define b3 r5
+
+ ar2 = 2 ; BUG register set is not considered
+ ar3 = 3
+ ar4 = 4
+ ar5 = 5
+
+ .globl __modlong ; entry point for __modslong
+
+ ; parameter a comes in a, b, dph, dpl
+ mov a3,a ; save parameter a3
+
+ mov a,sp
+ add a,#-2-3 ; 2 bytes return address, 3 bytes param b
+ mov r0,a ; r1 points to b0
+
+ mov ar2,@r0 ; load b0
+ inc r0 ; r0 points to b1
+ mov ar3,@r0 ; b1
+ inc r0
+ mov ar4,@r0 ; b2
+ inc r0
+ mov ar5,@r0 ; b3
+
+__modlong: ; entry point for __modslong
+ ; a in r1, b, dph, dpl
+ ; b in r5, r4, r3, r2
+
+ mov count,#0
+
+ mov a,b0 ; b == 0? avoid endless loop
+ orl a,b1
+ orl a,b2
+ orl a,b3
+ jz div_by_0
+
+ mov count,#0
+ clr c ; when loop1 jumps immediately to loop2
+
+loop1: inc count
+
+ mov a,b3 ; if (!MSB_SET(b))
+ jb acc.7,loop2
+
+ mov a,b0 ; b <<= 1
+ add a,acc
+ mov b0,a
+ mov a,b1
+ rlc a
+ mov b1,a
+ mov a,b2
+ rlc a
+ mov b2,a
+ mov a,b3
+ rlc a
+ mov b3,a
+
+ mov a,a0 ; a - b
+ subb a,b0 ; here carry is always clear
+ mov a,a1
+ subb a,b1
+ mov a,a2
+ subb a,b2
+ mov a,a3
+ subb a,b3
+
+ jnc loop1
+
+ clr c
+ mov a,b3 ; b >>= 1;
+ rrc a
+ mov b3,a
+ mov a,b2
+ rrc a
+ mov b2,a
+ mov a,b1
+ rrc a
+ mov b1,a
+ mov a,b0
+ rrc a
+ mov b0,a
+
+loop2: ; clr c never set
+ mov a,a0 ; a - b
+ subb a,b0
+ mov a,a1
+ subb a,b1
+ mov r6,a ; d1
+ mov a,a2
+ subb a,b2
+ mov r7,a ; d2
+ mov a,a3
+ subb a,b3
+
+ jc smaller ; a >= b?
+
+ mov a3,a ; -> yes; a = a - b;
+ mov a2,r7
+ mov a1,r6
+ mov a,a0
+ subb a,b0
+ mov a0,a
+smaller: ; -> no
+ clr c
+ mov a,b3 ; b >>= 1;
+ rrc a
+ mov b3,a
+ mov a,b2
+ rrc a
+ mov b2,a
+ mov a,b1
+ rrc a
+ mov b1,a
+ mov a,b0
+ rrc a
+ mov b0,a
+
+ djnz count,loop2
+
+ mov a,a3 ; prepare the return value
+div_by_0:
+ ret
+
+ __endasm;
+}
+
+#else // _MODULONG_ASM
+
+#define MSB_SET(x) ((x >> (8*sizeof(x)-1)) & 1)
+
+unsigned long
+_modulong (unsigned long a, unsigned long b)
+{
+ unsigned char count = 0;
+
+ while (!MSB_SET(b))
+ {
+ b <<= 1;
+ if (b > a)
+ {
+ b >>=1;
+ break;
+ }
+ count++;
+ }
+ do
+ {
+ if (a >= b)
+ a -= b;
+ b >>= 1;
+ }
+ while (count--);
+
+ return a;
+}
+
+#endif // _MODULONG_ASM
projects / fw / sdcc / blobdiff