1 files changed, 97 insertions, 0 deletions
diff --git a/stmhal/pybthread.c b/stmhal/pybthread.c
new file mode 100644
index 0000000000..9f9f82a451
--- /dev/null
+++ b/stmhal/pybthread.c
@@ -0,0 +1,97 @@
+/*
+ * 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 <string.h>
+#include <stdio.h>
+
+#include "py/obj.h"
+#include "gccollect.h"
+#include "irq.h"
+#include "pybthread.h"
+
+#if MICROPY_PY_THREAD
+
+int pyb_thread_enabled;
+pyb_thread_t *pyb_thread_cur;
+
+void pyb_thread_init(pyb_thread_t *thread) {
+    pyb_thread_cur = thread;
+    pyb_thread_cur->sp = NULL; // will be set when this thread switches out
+    pyb_thread_cur->local_state = 0; // will be set by mp_thread_init
+    pyb_thread_cur->arg = NULL;
+    pyb_thread_cur->stack = &_heap_end;
+    pyb_thread_cur->stack_len = ((uint32_t)&_estack - (uint32_t)&_heap_end) / sizeof(uint32_t);
+    pyb_thread_cur->prev = thread;
+    pyb_thread_cur->next = thread;
+}
+
+STATIC void pyb_thread_terminate(void) {
+    uint32_t irq_state = raise_irq_pri(IRQ_PRI_PENDSV);
+    pyb_thread_cur->prev->next = pyb_thread_cur->next;
+    pyb_thread_cur->next->prev = pyb_thread_cur->prev;
+    if (pyb_thread_cur->next == pyb_thread_cur->prev) {
+        pyb_thread_enabled = 0;
+    }
+    restore_irq_pri(irq_state);
+    pyb_thread_yield(); // should not return
+}
+
+uint32_t pyb_thread_new(pyb_thread_t *thread, void *stack, size_t stack_len, void *entry, void *arg) {
+    uint32_t *stack_top = (uint32_t*)stack + stack_len; // stack is full descending
+    *--stack_top = 0x01000000; // xPSR (thumb bit set)
+    *--stack_top = (uint32_t)entry & 0xfffffffe; // pc (must have bit 0 cleared, even for thumb code)
+    *--stack_top = (uint32_t)pyb_thread_terminate; // lr
+    *--stack_top = 0; // r12
+    *--stack_top = 0; // r3
+    *--stack_top = 0; // r2
+    *--stack_top = 0; // r1
+    *--stack_top = (uint32_t)arg; // r0
+    *--stack_top = 0xfffffff9; // lr (return to thread mode, non-FP, use MSP)
+    stack_top -= 8; // r4-r11
+    stack_top -= 16; // s16-s31 (we assume all threads use FP registers)
+    thread->sp = stack_top;
+    thread->local_state = 0;
+    thread->arg = arg;
+    thread->stack = stack;
+    thread->stack_len = stack_len;
+    uint32_t irq_state = raise_irq_pri(IRQ_PRI_PENDSV);
+    pyb_thread_enabled = 1;
+    thread->next = pyb_thread_cur->next;
+    thread->prev = pyb_thread_cur;
+    pyb_thread_cur->next->prev = thread;
+    pyb_thread_cur->next = thread;
+    restore_irq_pri(irq_state);
+    return (uint32_t)thread; // success
+}
+
+// should only be called from pendsv_isr_handler
+void *pyb_thread_next(void *sp) {
+    pyb_thread_cur->sp = sp;
+    pyb_thread_cur = pyb_thread_cur->next;
+    return pyb_thread_cur->sp;
+}
+
+#endif // MICROPY_PY_THREAD