1 files changed, 40 insertions, 0 deletions
diff --git a/stack.c b/stack.c
new file mode 100644
index 0000000..80b8ed2
--- /dev/null
+++ b/stack.c
@@ -0,0 +1,40 @@
+#include "stack.h"
+
+stack* newstack() {
+    stack* s = (stack*)malloc(sizeof(stack));
+    s->size = 0;
+    s->maxsize = 1024;
+    s->start = (stackitem*)malloc(sizeof(stackitem) * s->maxsize);
+    return s;
+}
+
+stackitem pop(stack* s) {
+    if (s->size > 0) {
+        s->size = s->size - 1;
+        stackitem si = s->start[s->size];
+        return si;
+    } else {
+        // tried to pop empty stack
+        return 0;
+    }
+}
+
+stackitem peek(stack* s) {
+    if (s->size > 0) {
+        return s->start[s->size - 1];
+    } else {
+        // tried to pop empty stack
+        return 0;
+    }
+}
+
+void push(stack *s, stackitem si) {
+//        fprintf(stderr, "pushing %d", si);
+    if (s->size >= s->maxsize) {
+        fprintf(stderr, "Error Stack Overflow");
+        exit(1);
+    } else {
+        s->start[s->size] = si;
+        s->size = s->size + 1;
+    }
+}