added tests as prepared by oliver

test/ref/divmod.c

@@ -0,0 +1,38 @@
+/*
+  !!DESCRIPTION!! div/mod test
+  !!ORIGIN!!
+  !!LICENCE!!     public domain
+*/
+
+#include <stdio.h>
+
+void printc(signed char a,signed char b){
+signed char x=a/b,y=a%b,z=a*b;
+	printf("%3d,%3d is %3d,%3d,%3d\n",a,b,x,y,z);
+}
+void prints(short a,short b){
+short x=a/b,y=a%b,z=a*b;
+	printf("%3d,%3d is %3d,%3d,%3d\n",a,b,x,y,z);
+}
+void printl(long a,long b){
+long x=a/b,y=a%b,z=a*b;
+	printf("%3ld,%3ld is %3ld,%3ld,%3ld\n",a,b,x,y,z);
+}
+
+int main(void) {
+	printl( 3,-2);
+	printl(-3,-2);
+	printl(-3, 2);
+	printl( 3, 2);
+	printf("-\n");
+	prints( 3,-2);
+	prints(-3,-2);
+	prints(-3, 2);
+	prints( 3, 2);
+	printf("-\n");
+	printc( 3,-2);
+	printc(-3,-2);
+	printc(-3, 2);
+	printc( 3, 2);
+	return 0;
+}