+
+#include <sdcc-lib.h>
+
+#if _SDCC_MANGLES_SUPPORT_FUNS
+unsigned long _modulong (unsigned long a, unsigned long b);
+#endif
+
+/* 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 _MODSLONG_ASM_SMALL_AUTO
+# else
+# define _MODSLONG_ASM_SMALL
+# endif
+# endif
+# endif
+#endif
+
+#if defined _MODSLONG_ASM_SMALL
+
+static void
+_modslong_dummy (void) _naked
+{
+ _asm
+
+ #define a0 dpl
+ #define a1 dph
+ #define a2 b
+ #define a3 r1
+
+ .globl __modslong
+#if defined(SDCC_PARMS_IN_BANK1)
+ #define b0 (b1_0)
+ #define b1 (b1_1)
+ #define b2 (b1_2)
+ #define b3 (b1_3)
+#else
+ // _modslong_PARM_2 shares the same memory with _modulong_PARM_2
+ // and is defined in _modulong.c
+ #define b0 (__modslong_PARM_2)
+ #define b1 (__modslong_PARM_2 + 1)
+ #define b2 (__modslong_PARM_2 + 2)
+ #define b3 (__modslong_PARM_2 + 3)
+#endif
+ __modslong:
+ ; a3 in acc
+ ; b3 in (__modslong_PARM_2 + 3)
+ mov a3,a ; save a3
+
+ clr F0 ; Flag 0 in PSW
+ ; available to user for general purpose
+ jnb acc.7,a_not_negative
+
+ setb F0
+
+ clr a ; a = -a;
+ clr c
+ subb a,a0
+ mov a0,a
+ clr a
+ subb a,a1
+ mov a1,a
+ clr a
+ subb a,a2
+ mov a2,a
+ clr a
+ subb a,a3
+ mov a3,a
+
+ a_not_negative:
+
+ mov a,b3
+ jnb acc.7,b_not_negative
+
+ clr a ; b = -b;
+ clr c
+ subb a,b0
+ mov b0,a
+ clr a
+ subb a,b1
+ mov b1,a
+ clr a
+ subb a,b2
+ mov b2,a
+ clr a
+ subb a,b3
+ mov b3,a
+
+ b_not_negative:
+
+ mov a,a3 ; restore a3 in acc
+
+ lcall __modulong
+
+ jnb F0,not_negative
+
+ ; result in (a == r1), b, dph, dpl
+ clr a
+ clr c
+ subb a,a0
+ mov a0,a
+ clr a
+ subb a,a1
+ mov a1,a
+ clr a
+ subb a,a2
+ mov a2,a
+ clr a
+ subb a,a3
+ ; result in a, b, dph, dpl
+ not_negative:
+ ret
+
+ _endasm ;
+}
+
+#elif defined _MODSLONG_ASM_SMALL_AUTO
+
+static void
+_modslong_dummy (void) _naked