Initial commit

1 files changed, 68 insertions, 0 deletions

diff --git a/stack.c b/stack.c
new file mode 100644
index 0000000..8aee3d7
--- /dev/null
+++ b/stack.c
@@ -0,0 +1,68 @@
+#include "stack.h"
+#include "calls.h"
+
+#define QUANTITY_ADDRESSES 5
+
+enum address_control { get_address, set_address };
+void* heap_base;
+
+void init_stack(stack *st)
+{
+    *st = 0;
+}
+
+static void* address_management(void* address, enum address_control state)
+{
+    enum { null = 0 };
+    static void* available_addresses[QUANTITY_ADDRESSES];
+    int i;
+    if(state == set_address) {
+        for(i = 0; i < QUANTITY_ADDRESSES; ++i) {
+            if(!available_addresses[i]) {
+                available_addresses[i] = address;
+                return null;
+            }
+        }
+        return null;
+    }
+    for(i = 0; i < QUANTITY_ADDRESSES; ++i) {
+        if(available_addresses[i]) {
+            address = available_addresses[i];
+            available_addresses[i] = 0;
+            return address;
+        }
+    }
+    return null;
+}
+
+
+void push_stack(stack *st, long num)
+{
+    struct item *tmp;
+    tmp = address_management(0, get_address);
+    if(!tmp)
+        tmp = sys_alloc(sizeof(struct item));
+    if(!heap_base)
+        heap_base = tmp;
+    tmp->data = num;
+    tmp->next = *st;
+    *st = tmp;
+}
+
+long pop_stack(stack *st)
+{
+    long num = (*st)->data;
+    address_management(*st, set_address);
+    *st = (*st)->next;
+    return num;
+}
+
+int is_empty_stack(const stack *st)
+{
+    return *st ? 0 : 1;
+}
+
+long top_stack(const stack *st)
+{
+    return (*st)->data;
+}