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/*

* 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

#define PYB_MUTEX_UNLOCKED ((void*)0)

#define PYB_MUTEX_LOCKED ((void*)1)

// These macros are used when we only need to protect against a thread

// switch; other interrupts are still allowed to proceed.

#define RAISE_IRQ_PRI() raise_irq_pri(IRQ_PRI_PENDSV)

#define RESTORE_IRQ_PRI(state) restore_irq_pri(state)

extern void __fatal_error(const char*);

volatile int pyb_thread_enabled;

pyb_thread_t *volatile pyb_thread_all;

pyb_thread_t *volatile pyb_thread_cur;

static inline void pyb_thread_add_to_runable(pyb_thread_t *thread) {

thread->run_prev = pyb_thread_cur->run_prev;

thread->run_next = pyb_thread_cur;

pyb_thread_cur->run_prev->run_next = thread;

pyb_thread_cur->run_prev = thread;

}

static inline void pyb_thread_remove_from_runable(pyb_thread_t *thread) {

if (thread->run_next == thread) {

__fatal_error("deadlock");

}

thread->run_prev->run_next = thread->run_next;

thread->run_next->run_prev = thread->run_prev;

}

void pyb_thread_init(pyb_thread_t *thread) {

pyb_thread_enabled = 0;

pyb_thread_all = thread;

pyb_thread_cur = thread;

thread->sp = NULL; // will be set when this thread switches out

thread->local_state = 0; // will be set by mp_thread_init

thread->arg = NULL;

thread->stack = &_heap_end;

thread->stack_len = ((uint32_t)&_estack - (uint32_t)&_heap_end) / sizeof(uint32_t);

thread->all_next = NULL;

thread->run_prev = thread;

thread->run_next = thread;

thread->queue_next = NULL;

}

void pyb_thread_deinit() {

uint32_t irq_state = disable_irq();

pyb_thread_enabled = 0;

pyb_thread_all = pyb_thread_cur;

pyb_thread_cur->all_next = NULL;

pyb_thread_cur->run_prev = pyb_thread_cur;

pyb_thread_cur->run_next = pyb_thread_cur;

enable_irq(irq_state);

}

STATIC void pyb_thread_terminate(void) {

uint32_t irq_state = disable_irq();

pyb_thread_t *thread = pyb_thread_cur;

// take current thread off the run list

pyb_thread_remove_from_runable(thread);

// take current thread off the list of all threads

for (pyb_thread_t **n = (pyb_thread_t**)&pyb_thread_all;; n = &(*n)->all_next) {

if (*n == thread) {

*n = thread->all_next;

break;

}

}

// clean pointers as much as possible to help GC

thread->all_next = NULL;

thread->queue_next = NULL;

thread->stack = NULL;

if (pyb_thread_all->all_next == NULL) {

// only 1 thread left

pyb_thread_enabled = 0;

}

// thread switch will occur after we enable irqs

SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;

enable_irq(irq_state);

// should not return

__fatal_error("could not terminate");

}

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;

thread->queue_next = NULL;

uint32_t irq_state = disable_irq();

pyb_thread_enabled = 1;

thread->all_next = pyb_thread_all;

pyb_thread_all = thread;

pyb_thread_add_to_runable(thread);

enable_irq(irq_state);

return (uint32_t)thread; // success

}

void pyb_thread_dump(void) {

if (!pyb_thread_enabled) {

printf("THREAD: only main thread\n");

} else {

printf("THREAD:\n");

for (pyb_thread_t *th = pyb_thread_all; th != NULL; th = th->all_next) {

bool runable = false;

for (pyb_thread_t *th2 = pyb_thread_cur;; th2 = th2->run_next) {

if (th == th2) {

runable = true;

break;

}

if (th2->run_next == pyb_thread_cur) {

break;

}

}

printf(" id=%p sp=%p sz=%u", th, th->stack, th->stack_len);

if (runable) {

printf(" (runable)");

}

printf("\n");

}

}

}

// 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->run_next;

pyb_thread_cur->timeslice = 4; // in milliseconds

return pyb_thread_cur->sp;

}

void pyb_mutex_init(pyb_mutex_t *m) {

*m = PYB_MUTEX_UNLOCKED;

}

int pyb_mutex_lock(pyb_mutex_t *m, int wait) {

uint32_t irq_state = RAISE_IRQ_PRI();

if (*m == PYB_MUTEX_UNLOCKED) {

// mutex is available

*m = PYB_MUTEX_LOCKED;

RESTORE_IRQ_PRI(irq_state);

} else {

// mutex is locked

if (!wait) {

RESTORE_IRQ_PRI(irq_state);

return 0; // failed to lock mutex

}

if (*m == PYB_MUTEX_LOCKED) {

*m = pyb_thread_cur;

} else {

for (pyb_thread_t *n = *m;; n = n->queue_next) {

if (n->queue_next == NULL) {

n->queue_next = pyb_thread_cur;

break;

}

}

}

pyb_thread_cur->queue_next = NULL;

// take current thread off the run list

pyb_thread_remove_from_runable(pyb_thread_cur);

// thread switch will occur after we enable irqs

SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;

RESTORE_IRQ_PRI(irq_state);

// when we come back we have the mutex

}

return 1; // have mutex

}

void pyb_mutex_unlock(pyb_mutex_t *m) {

uint32_t irq_state = RAISE_IRQ_PRI();

if (*m == PYB_MUTEX_LOCKED) {

// no threads are blocked on the mutex

*m = PYB_MUTEX_UNLOCKED;

} else {

// at least one thread is blocked on this mutex

pyb_thread_t *th = *m;

if (th->queue_next == NULL) {

// no other threads are blocked

*m = PYB_MUTEX_LOCKED;

} else {

// at least one other thread is still blocked

*m = th->queue_next;

}

// put unblocked thread on runable list

pyb_thread_add_to_runable(th);

}

RESTORE_IRQ_PRI(irq_state);

}

#endif // MICROPY_PY_THREAD