+/* 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
+
+static void
+_modlong_dummy (void) _naked
+{
+ _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