Implement datum support and add make for ex-5.52

shared/scm2c/datum.h

@@ -0,0 +1,60 @@
+enum datum_type {
+    datum_type_i32,
+    datum_type_bool,
+    datum_type_primitive_proc,
+    datum_type_compiled_proc,
+};
+
+typedef struct datum {
+    enum datum_type type;
+    int32_t value;
+    void* (*primitive_procedure) (void**);
+    void* compiled_pr;
+} datum;
+
+typedef struct procedure {
+} procedure;
+
+
+datum* const_int(int32_t value) {
+    datum* r = malloc(sizeof(datum));
+    if (!r) exit(-1);
+    r->type = datum_type_i32;
+    r->value = value;
+}
+
+int primitive_procedure(datum* d) {
+    if (d->type == datum_type_primitive_proc) {
+        return 1;
+    }
+    return 0;
+}
+
+datum* add(datum** args) {
+    size_t i = 0;
+    int32_t result = 0;
+
+    while (args[i] != NULL) {
+        if (args[i]->type != datum_type_i32) {
+            printf("ADD - invalid type\n");
+            exit(-1);
+        }
+        result += args[i]->value;
+        i += 1;
+    }
+
+    return const_int(result);
+}
+
+void* compiled_procedure_entry(void* p) {
+    return compiled_procedure_entry;
+}
+
+datum* lookup_variable_value(char* c, void* e) {
+    datum* r = malloc(sizeof(datum));
+    if (!r) exit(-1);
+    r->type = datum_type_primitive_proc;
+    r->primitive_procedure = (void*) &add;
+    return r;
+}
+