Initial step towards factoring out command line configuration

This commit defines a "cfg_t" structure, which currently just holds
the initrd address range. It will be augmented in future commits to
hold other configuration arguments as well.

To represent a configuration argument, we define an arg_t base class.
This holds a current value, together with a flag that tells us whether
the value has been updated from the default. The idea is that in
future we're going to use that flag when reading a DTB file: if an
argument has actually been specified on the command line, we need to
take it into account; if not, we can ignore the default and use the
DTB file's supplied value.

1 files changed, 38 insertions, 0 deletions

diff --git a/riscv/cfg.h b/riscv/cfg.h
new file mode 100644
index 0000000..bee5051
--- /dev/null
+++ b/riscv/cfg.h
@@ -0,0 +1,38 @@
+// See LICENSE for license details.
+#ifndef _RISCV_CFG_H
+#define _RISCV_CFG_H
+
+#include "decode.h"
+
+template <typename T>
+class cfg_arg_t {
+public:
+  cfg_arg_t(T default_val)
+    : value(default_val), was_set(false) {}
+
+  bool overridden() const { return was_set; }
+
+  T operator()() const { return value; }
+
+  T operator=(const T v) {
+    value = v;
+    was_set = true;
+    return value;
+  }
+
+private:
+  T value;
+  bool was_set;
+};
+
+class cfg_t
+{
+public:
+  cfg_t(std::pair<reg_t, reg_t> default_initrd_bounds)
+    : initrd_bounds(default_initrd_bounds)
+  {}
+
+  cfg_arg_t<std::pair<reg_t, reg_t>> initrd_bounds;
+};
+
+#endif