1 files changed, 29 insertions, 0 deletions
diff --git a/subx/037heap.cc b/subx/037heap.cc
new file mode 100644
index 00000000..315fd0d5
--- /dev/null
+++ b/subx/037heap.cc
@@ -0,0 +1,29 @@
+//: Support for dynamic allocation.
+//:
+//: Just provide a special label marking the first unused address in the data
+//: segment. Then we'll write SubX helpers to make use of it.
+
+:(before "Begin rewrite_global_variables")
+insert_heap_global_variable(p);
+:(code)
+void insert_heap_global_variable(program& p) {
+  if (SIZE(p.segments) < 2)
+    return;  // no data segment defined
+  // Start-of-heap:
+  p.segments.at(1).lines.push_back(label("Start-of-heap"));
+}
+
+line label(string s) {
+  line result;
+  result.words.push_back(word());
+  result.words.back().data = (s+":");
+  return result;
+}
+
+line imm32(const string& s) {
+  line result;
+  result.words.push_back(word());
+  result.words.back().data = s;
+  result.words.back().metadata.push_back("imm32");
+  return result;
+}