added simple comp library

src/comp.c

+#include "comp.h"
+
+int cstack[128];
+int cstack_size;
+
+void cpush(int n)
+{
+    cstack[cstack_size]=n;
+    cstack_size++;
+}
+
+void cpop()
+{
+    if(cstack_size==0)
+	return;
+    cstack_size--;
+}
+
+int cpeek()
+{
+    return cstack[cstack_size-1];
+}
+
+void cadd()
+{
+    if(cstack_size<2)
+	return;
+    int a=cpeek();
+    cpop();
+    int b=cpeek();
+    cpop();
+    cpush(a+b);
+}
+
+void cmult()
+{
+    if(cstack_size<2)
+	return;
+    int a=cpeek();
+    cpop();
+    int b=cpeek();
+    cpop();
+    cpush(a*b);
+}
+
+void csub()
+{
+    if(cstack_size<2)
+	return;
+    int a=cpeek();
+    cpop();
+    int b=cpeek();
+    cpop();
+    cpush(a-b);
+}
+
+void cdiv()
+{
+    if(cstack_size<2)
+	return;
+    int a=cpeek();
+    cpop();
+    int b=cpeek();
+    cpop();
+    cpush(a/b);
+}

src/comp.h

+#ifndef _INC_COMP
+#define _INC_COMP
+
+void cpush(int n);
+void cpop();
+int cpeek();
+void cadd();
+void cmult();
+void csub();
+void cdiv();
+#endif