add circuitpython code

1 files changed, 99 insertions, 0 deletions

diff --git a/circuitpython/py/stackctrl.c b/circuitpython/py/stackctrl.c
new file mode 100644
index 0000000..d699d6d
--- /dev/null
+++ b/circuitpython/py/stackctrl.c
@@ -0,0 +1,99 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2014 Paul Sokolovsky
+ *
+ * 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 "py/runtime.h"
+#include "py/stackctrl.h"
+
+void mp_stack_ctrl_init(void) {
+    // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
+    __asm volatile ("");
+    volatile int stack_dummy;
+    MP_STATE_THREAD(stack_top) = (char *)&stack_dummy;
+}
+
+void mp_stack_set_top(void *top) {
+    MP_STATE_THREAD(stack_top) = top;
+}
+
+mp_uint_t mp_stack_usage(void) {
+    // Assumes descending stack
+    // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
+    __asm volatile ("");
+    volatile int stack_dummy;
+    return MP_STATE_THREAD(stack_top) - (char *)&stack_dummy;
+}
+
+#if MICROPY_STACK_CHECK
+
+void mp_stack_set_limit(mp_uint_t limit) {
+    MP_STATE_THREAD(stack_limit) = limit;
+}
+
+void mp_stack_check(void) {
+    if (mp_stack_usage() >= MP_STATE_THREAD(stack_limit)) {
+        mp_raise_recursion_depth();
+    }
+}
+
+#endif // MICROPY_STACK_CHECK
+
+#if MICROPY_MAX_STACK_USAGE
+
+// Fill stack space with this unusual value.
+const char MP_MAX_STACK_USAGE_SENTINEL_BYTE = 0xEE;
+
+// Record absolute bottom (logical limit) of stack.
+void mp_stack_set_bottom(void *stack_bottom) {
+    MP_STATE_THREAD(stack_bottom) = stack_bottom;
+}
+
+// Return the current frame pointer. This can be used as an
+// approximation for the stack pointer of the _calling_ function.
+// This routine must not be inlined.  This method is
+// architecture-independent, as opposed to using asm("sp") or similar.
+//
+// The stack_dummy approach used elsewhere in this file is not safe in
+// all cases. That value may be below the actual top of the stack.
+static void *approx_stack_pointer(void) {
+    __asm volatile ("");
+    return __builtin_frame_address(0);
+}
+
+// Fill stack space down toward the stack limit with a known unusual value.
+void mp_stack_fill_with_sentinel(void) {
+    // Force routine to not be inlined. Better guarantee than MP_NOINLINE for -flto.
+    __asm volatile ("");
+    // Start filling stack just below the current stack frame.
+    // Continue until we've hit the bottom of the stack (lowest address,
+    // logical "ceiling" of stack).
+    char *p = (char *)approx_stack_pointer() - 1;
+
+    while (p >= MP_STATE_THREAD(stack_bottom)) {
+        *p-- = MP_MAX_STACK_USAGE_SENTINEL_BYTE;
+    }
+}
+
+#endif // MICROPY_MAX_STACK_USAGE