185 lines
6.7 KiB
C
185 lines
6.7 KiB
C
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/*
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* This file is part of the MicroPython project, http://micropython.org/
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*
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* The MIT License (MIT)
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*
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* Copyright (c) 2013, 2014 Damien P. George
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stdlib.h>
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#include "py/runtime.h"
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#include "shared/runtime/interrupt_char.h"
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#include "pendsv.h"
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#include "irq.h"
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// This variable is used to save the exception object between a ctrl-C and the
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// PENDSV call that actually raises the exception. It must be non-static
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// otherwise gcc-5 optimises it away. It can point to the heap but is not
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// traced by GC. This is okay because we only ever set it to
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// mp_kbd_exception which is in the root-pointer set.
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void *pendsv_object;
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#if defined(PENDSV_DISPATCH_NUM_SLOTS)
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uint32_t pendsv_dispatch_active;
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pendsv_dispatch_t pendsv_dispatch_table[PENDSV_DISPATCH_NUM_SLOTS];
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#endif
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void pendsv_init(void) {
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#if defined(PENDSV_DISPATCH_NUM_SLOTS)
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pendsv_dispatch_active = false;
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#endif
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// set PendSV interrupt at lowest priority
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NVIC_SetPriority(PendSV_IRQn, IRQ_PRI_PENDSV);
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}
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// Call this function to raise a pending exception during an interrupt.
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// It will first try to raise the exception "softly" by setting the
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// mp_pending_exception variable and hoping that the VM will notice it.
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// If this function is called a second time (ie with the mp_pending_exception
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// variable already set) then it will force the exception by using the hardware
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// PENDSV feature. This will wait until all interrupts are finished then raise
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// the given exception object using nlr_jump in the context of the top-level
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// thread.
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void pendsv_kbd_intr(void) {
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if (MP_STATE_MAIN_THREAD(mp_pending_exception) == MP_OBJ_NULL) {
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mp_sched_keyboard_interrupt();
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} else {
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MP_STATE_MAIN_THREAD(mp_pending_exception) = MP_OBJ_NULL;
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pendsv_object = &MP_STATE_VM(mp_kbd_exception);
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SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
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}
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}
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#if defined(PENDSV_DISPATCH_NUM_SLOTS)
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void pendsv_schedule_dispatch(size_t slot, pendsv_dispatch_t f) {
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pendsv_dispatch_table[slot] = f;
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pendsv_dispatch_active = true;
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SCB->ICSR = SCB_ICSR_PENDSVSET_Msk;
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}
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void pendsv_dispatch_handler(void) {
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for (size_t i = 0; i < PENDSV_DISPATCH_NUM_SLOTS; ++i) {
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if (pendsv_dispatch_table[i] != NULL) {
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pendsv_dispatch_t f = pendsv_dispatch_table[i];
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pendsv_dispatch_table[i] = NULL;
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f();
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}
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}
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}
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#endif
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__attribute__((naked)) void PendSV_Handler(void) {
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// Handle a PendSV interrupt
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//
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// For the case of an asynchronous exception, re-jig the
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// stack so that when we return from this interrupt handler
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// it returns instead to nlr_jump with argument pendsv_object
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// note that stack has a different layout if DEBUG is enabled
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//
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// For the case of a thread switch, swap stacks.
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//
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// on entry to this (naked) function, stack has the following layout:
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//
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// stack layout with DEBUG disabled:
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// sp[6]: pc=r15
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// sp[5]: lr=r14
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// sp[4]: r12
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// sp[3]: r3
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// sp[2]: r2
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// sp[1]: r1
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// sp[0]: r0
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//
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// stack layout with DEBUG enabled:
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// sp[8]: pc=r15
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// sp[7]: lr=r14
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// sp[6]: r12
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// sp[5]: r3
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// sp[4]: r2
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// sp[3]: r1
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// sp[2]: r0
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// sp[1]: 0xfffffff9
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// sp[0]: ?
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__asm volatile (
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#if defined(PENDSV_DISPATCH_NUM_SLOTS)
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// Check if there are any pending calls to dispatch to
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"ldr r1, pendsv_dispatch_active_ptr\n"
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"ldr r0, [r1]\n"
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"cmp r0, #0\n"
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"beq .no_dispatch\n"
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"mov r2, #0\n"
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"str r2, [r1]\n" // clear pendsv_dispatch_active
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"b pendsv_dispatch_handler\n" // jump to the handler
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".no_dispatch:\n"
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#endif
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// Check if there is an active object to throw via nlr_jump
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"ldr r1, pendsv_object_ptr\n"
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"ldr r0, [r1]\n"
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"cmp r0, #0\n"
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"beq .no_obj\n"
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#if defined(PENDSV_DEBUG)
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"str r0, [sp, #8]\n" // store to r0 on stack
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#else
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"str r0, [sp, #0]\n" // store to r0 on stack
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#endif
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"mov r0, #0\n"
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"str r0, [r1]\n" // clear pendsv_object
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"ldr r0, nlr_jump_ptr\n"
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#if defined(PENDSV_DEBUG)
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"str r0, [sp, #32]\n" // store to pc on stack
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#else
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"str r0, [sp, #24]\n" // store to pc on stack
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#endif
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"bx lr\n" // return from interrupt; will return to nlr_jump
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".no_obj:\n" // pendsv_object==NULL
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#if MICROPY_PY_THREAD
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// Do a thread context switch
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"push {r4-r11, lr}\n"
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"vpush {s16-s31}\n"
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"mrs r5, primask\n" // save PRIMASK in r5
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"cpsid i\n" // disable interrupts while we change stacks
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"mov r0, sp\n" // pass sp to save
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"mov r4, lr\n" // save lr because we are making a call
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"bl pyb_thread_next\n" // get next thread to execute
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"mov lr, r4\n" // restore lr
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"mov sp, r0\n" // switch stacks
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"msr primask, r5\n" // reenable interrupts
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"vpop {s16-s31}\n"
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"pop {r4-r11, lr}\n"
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"bx lr\n" // return from interrupt; will return to new thread
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#else
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// Spurious pendsv, just return
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"bx lr\n"
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#endif
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// Data
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".align 2\n"
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#if defined(PENDSV_DISPATCH_NUM_SLOTS)
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"pendsv_dispatch_active_ptr: .word pendsv_dispatch_active\n"
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#endif
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"pendsv_object_ptr: .word pendsv_object\n"
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"nlr_jump_ptr: .word nlr_jump\n"
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);
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}
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