py: Add micropython.schedule() function and associated runtime code.

1 files changed, 117 insertions, 0 deletions

diff --git a/py/scheduler.c b/py/scheduler.c
new file mode 100644
index 000000000..30851a4d2
--- /dev/null
+++ b/py/scheduler.c
@@ -0,0 +1,117 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2017 Damien P. George
+ *
+ * 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 <stdio.h>
+
+#include "py/runtime.h"
+
+#if MICROPY_ENABLE_SCHEDULER
+
+// A variant of this is inlined in the VM at the pending exception check
+void mp_handle_pending(void) {
+    if (MP_STATE_VM(sched_state) == MP_SCHED_PENDING) {
+        mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+        mp_obj_t obj = MP_STATE_VM(mp_pending_exception);
+        if (obj != MP_OBJ_NULL) {
+            MP_STATE_VM(mp_pending_exception) = MP_OBJ_NULL;
+            if (!mp_sched_num_pending()) {
+                MP_STATE_VM(sched_state) = MP_SCHED_IDLE;
+            }
+            MICROPY_END_ATOMIC_SECTION(atomic_state);
+            nlr_raise(obj);
+        }
+        mp_handle_pending_tail(atomic_state);
+    }
+}
+
+// This function should only be called be mp_sched_handle_pending,
+// or by the VM's inlined version of that function.
+void mp_handle_pending_tail(mp_uint_t atomic_state) {
+    MP_STATE_VM(sched_state) = MP_SCHED_LOCKED;
+    if (MP_STATE_VM(sched_sp) > 0) {
+        mp_sched_item_t item = MP_STATE_VM(sched_stack)[--MP_STATE_VM(sched_sp)];
+        MICROPY_END_ATOMIC_SECTION(atomic_state);
+        mp_call_function_1_protected(item.func, item.arg);
+    } else {
+        MICROPY_END_ATOMIC_SECTION(atomic_state);
+    }
+    mp_sched_unlock();
+}
+
+void mp_sched_lock(void) {
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+    if (MP_STATE_VM(sched_state) < 0) {
+        --MP_STATE_VM(sched_state);
+    } else {
+        MP_STATE_VM(sched_state) = MP_SCHED_LOCKED;
+    }
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+}
+
+void mp_sched_unlock(void) {
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+    if (++MP_STATE_VM(sched_state) == 0) {
+        // vm became unlocked
+        if (MP_STATE_VM(mp_pending_exception) != MP_OBJ_NULL || mp_sched_num_pending()) {
+            MP_STATE_VM(sched_state) = MP_SCHED_PENDING;
+        } else {
+            MP_STATE_VM(sched_state) = MP_SCHED_IDLE;
+        }
+    }
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+}
+
+bool mp_sched_schedule(mp_obj_t function, mp_obj_t arg) {
+    mp_uint_t atomic_state = MICROPY_BEGIN_ATOMIC_SECTION();
+    bool ret;
+    if (MP_STATE_VM(sched_sp) < MICROPY_SCHEDULER_DEPTH) {
+        if (MP_STATE_VM(sched_state) == MP_SCHED_IDLE) {
+            MP_STATE_VM(sched_state) = MP_SCHED_PENDING;
+        }
+        MP_STATE_VM(sched_stack)[MP_STATE_VM(sched_sp)].func = function;
+        MP_STATE_VM(sched_stack)[MP_STATE_VM(sched_sp)].arg = arg;
+        ++MP_STATE_VM(sched_sp);
+        ret = true;
+    } else {
+        // schedule stack is full
+        ret = false;
+    }
+    MICROPY_END_ATOMIC_SECTION(atomic_state);
+    return ret;
+}
+
+#else // MICROPY_ENABLE_SCHEDULER
+
+// A variant of this is inlined in the VM at the pending exception check
+void mp_handle_pending(void) {
+    if (MP_STATE_VM(mp_pending_exception) != MP_OBJ_NULL) {
+        mp_obj_t obj = MP_STATE_VM(mp_pending_exception);
+        MP_STATE_VM(mp_pending_exception) = MP_OBJ_NULL;
+        nlr_raise(obj);
+    }
+}
+
+#endif // MICROPY_ENABLE_SCHEDULER