Add mmap module to bank various memory in and out.

src/mmap.c

@@ -0,0 +1,11 @@
+#include "mmap.h"
+
+#include "io.h"
+
+#define MMAP_VALID_BITS 0x81
+#define MMAP_PORT_ADDR  0x81
+
+void mmap_set(enum mmap_mode_t mode) {
+    io_out(MMAP_PORT_ADDR, (io_in(MMAP_PORT_ADDR) & ~MMAP_VALID_BITS) |
+                               (mode & MMAP_VALID_BITS));
+}

src/mmap.h

@@ -0,0 +1,12 @@
+#ifndef CEDA_DEMO_MMAP
+#define CEDA_DEMO_MMAP
+
+enum mmap_mode_t {
+    MMAP_MODE_LINEAR = 0x01,
+    MMAP_MODE_CEDA_VIDEO = 0x00,
+    MMAP_MODE_CEDA_ATTR = 0x80,
+};
+
+void mmap_set(enum mmap_mode_t mode);
+
+#endif // CEDA_DEMO_MMAP