Measure and report maximum stack usage. (#175)

Add max stack usage tracking, visible via debug module ustack.
Add separate cpp flag for enabling modules: MICROPY_DEBUG_MODULES

1 files changed, 52 insertions, 0 deletions

diff --git a/shared-module/ustack/__init__.c b/shared-module/ustack/__init__.c
new file mode 100644
index 000000000..947f81f8e
--- /dev/null
+++ b/shared-module/ustack/__init__.c
@@ -0,0 +1,52 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Dan Halbert
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include <stdint.h>
+
+#include "py/mpstate.h"
+#include "py/stackctrl.h"
+
+#include "shared-bindings/ustack/__init__.h"
+
+#if MICROPY_MAX_STACK_USAGE
+uint32_t shared_module_ustack_max_stack_usage(void) {
+    // Start at stack limit and move up.
+    // Untouched stack was filled with a sentinel value.
+    // Stop at first non-sentinel byte.
+    char* p = MP_STATE_THREAD(stack_bottom);
+    while (*p++ == MP_MAX_STACK_USAGE_SENTINEL_BYTE) { }
+    return MP_STATE_THREAD(stack_top) - p;
+}
+#endif
+
+uint32_t shared_module_ustack_stack_size() {
+    return MP_STATE_THREAD(stack_limit);
+}
+
+uint32_t shared_module_ustack_stack_usage() {
+  return mp_stack_usage();
+}
+