enhanced stix_divints() to handle modulo/remainder more clearly

stix/kernel/Stix.st

@@ -59,6 +59,19 @@
 		self primitiveFailed.
 	}
 
+
+	#method // aNumber
+	{
+		<primitive: #_integer_quo2>
+		self primitiveFailed.
+	}
+
+	#method \\ aNumber
+	{
+		<primitive: #_integer_rem2>
+		self primitiveFailed.
+	}
+
 	#method = aNumber
 	{
 		<primitive: #_integer_eq>

stix/kernel/test-005.st

@@ -270,8 +270,14 @@ PROCESS TESTING
 
 (2r111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111 * 128971234897128931) dump.
 
-(-10000 rem: -3) dump.
+"(-10000 rem: 3) dump.
-(-10000 quo: -3) dump.
+(-10000 quo: 3) dump.
+(-10000 \\ 3) dump.
+(-10000 // 3) dump."
+(7 rem: -3) dump.
+(7 quo: -3) dump.
+(7 \\ -3) dump.
+(7 // -3) dump.
 
 "
 		FFI isNil dump.

stix/lib/bigint.c

@@ -1034,7 +1034,7 @@ oops_einval:
 	return STIX_NULL;
 }
 
-stix_oop_t stix_divints (stix_t* stix, stix_oop_t x, stix_oop_t y, stix_oop_t* rem)
+stix_oop_t stix_divints (stix_t* stix, stix_oop_t x, stix_oop_t y, int modulo, stix_oop_t* rem)
 {
 	stix_oop_t t;
 
@@ -1054,9 +1054,50 @@ stix_oop_t stix_divints (stix_t* stix, stix_oop_t x, stix_oop_t y, stix_oop_t* r
 		q = xv / yv;
 		STIX_ASSERT (STIX_IN_SMOOI_RANGE(q));
 
+		r = xv - yv * q; /* xv % yv; */
+		if (modulo)
+		{
+			/* modulo */
+			/*
+				xv      yv      q       r
+				-------------------------
+				 7       3      2       1
+				-7       3     -3       2
+				 7      -3     -3      -2
+				-7      -3      2      -1
+			 */
+			if (r && ((yv ^ r) < 0))
+			{
+				/* if the divisor has a different sign from r,
+				 * change the sign of r to the divisor's sign */
+				r += yv;
+				--q;
+				STIX_ASSERT (r && ((yv ^ r) >= 0));
+			}
+		}
+		else
+		{
+			/* remainder */
+			/*
+				xv      yv      q       r
+				-------------------------
+				 7       3      2       1
+				-7       3     -2      -1
+				 7      -3     -2       1
+				-7      -3      2      -1
+			 */
+			if (xv && ((xv ^ r) < 0)) 
+			{
+				/* if the dividend has a different sign from r,
+				 * change the sign of r to the dividend's sign */
+				r -= yv;
+				++q;
+				STIX_ASSERT (xv && ((xv ^ r) >= 0));
+			}
+		}
+
 		if (rem)
 		{
-			r = xv - yv * q; /* r = xv % yv; */
 			STIX_ASSERT (STIX_IN_SMOOI_RANGE(r));
 			*rem = STIX_SMOOI_TO_OOP(r);
 		}

stix/lib/exec.c

@@ -1069,7 +1069,7 @@ static int prim_integer_quo (stix_t* stix, stix_ooi_t nargs)
 	rcv = ACTIVE_STACK_GET(stix, stix->sp - 1);
 	arg = ACTIVE_STACK_GET(stix, stix->sp);
 
-	quo = stix_divints (stix, rcv, arg, STIX_NULL);
+	quo = stix_divints (stix, rcv, arg, 0, STIX_NULL);
 	if (!quo) return (stix->errnum == STIX_EINVAL? 0: -1); /* soft or hard failure */
 
 	ACTIVE_STACK_POP (stix);
@@ -1086,7 +1086,41 @@ static int prim_integer_rem (stix_t* stix, stix_ooi_t nargs)
 	rcv = ACTIVE_STACK_GET(stix, stix->sp - 1);
 	arg = ACTIVE_STACK_GET(stix, stix->sp);
 
-	quo = stix_divints (stix, rcv, arg, &rem);
+	quo = stix_divints (stix, rcv, arg, 0, &rem);
+	if (!quo) return (stix->errnum == STIX_EINVAL? 0: -1); /* soft or hard failure */
+
+	ACTIVE_STACK_POP (stix);
+	ACTIVE_STACK_SETTOP (stix, rem);
+	return 1;
+}
+
+static int prim_integer_quo2 (stix_t* stix, stix_ooi_t nargs)
+{
+	stix_oop_t rcv, arg, quo;
+
+	STIX_ASSERT (nargs == 1);
+
+	rcv = ACTIVE_STACK_GET(stix, stix->sp - 1);
+	arg = ACTIVE_STACK_GET(stix, stix->sp);
+
+	quo = stix_divints (stix, rcv, arg, 1, STIX_NULL);
+	if (!quo) return (stix->errnum == STIX_EINVAL? 0: -1); /* soft or hard failure */
+
+	ACTIVE_STACK_POP (stix);
+	ACTIVE_STACK_SETTOP (stix, quo);
+	return 1;
+}
+
+static int prim_integer_rem2 (stix_t* stix, stix_ooi_t nargs)
+{
+	stix_oop_t rcv, arg, quo, rem;
+
+	STIX_ASSERT (nargs == 1);
+
+	rcv = ACTIVE_STACK_GET(stix, stix->sp - 1);
+	arg = ACTIVE_STACK_GET(stix, stix->sp);
+
+	quo = stix_divints (stix, rcv, arg, 1, &rem);
 	if (!quo) return (stix->errnum == STIX_EINVAL? 0: -1); /* soft or hard failure */
 
 	ACTIVE_STACK_POP (stix);
@@ -1601,6 +1635,8 @@ static prim_t primitives[] =
 	{   1,   prim_integer_mul,          "_integer_mul"         },
 	{   1,   prim_integer_quo,          "_integer_quo"         },
 	{   1,   prim_integer_rem,          "_integer_rem"         },
+	{   1,   prim_integer_quo2,         "_integer_quo2"        },
+	{   1,   prim_integer_rem2,         "_integer_rem2"        },
 	{   1,   prim_integer_eq,           "_integer_eq"          },
 	{   1,   prim_integer_ne,           "_integer_ne"          },
 	{   1,   prim_integer_lt,           "_integer_lt"          },

stix/lib/stix-prv.h

@@ -1093,6 +1093,7 @@ stix_oop_t stix_divints (
 	stix_t*     stix,
 	stix_oop_t  x,
 	stix_oop_t  y,
+	int         modulo,
 	stix_oop_t* rem
 );