175 lines
5.5 KiB
C
175 lines
5.5 KiB
C
/*
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* Copyright (c) 2016, Dr. Ralf Schlatterbeck Open Source Consulting
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the Institute nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This file is part of the Contiki operating system.
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*
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* \file PicoRV32 specific implementation of multithreading architecture
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*
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* \author Ralf Schlatterbeck <rsc@runtux.com>
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*
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*/
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#include <stdio.h>
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#include "sys/mt.h"
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/*--------------------------------------------------------------------------*/
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void
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mtarch_init(void)
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{
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_start(struct mtarch_thread *t,
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void (*function)(void *), void *data)
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{
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/* Initialize stack with number sequence (used for
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* measuring stack usage */
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uint8_t i;
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printf ("mtarch_start called\n");
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for(i = 0; i < MTARCH_STACKSIZE; ++i) {
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t->stack[i] = i;
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}
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/*
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* Push pointer to mt_exit and the thread onto our stack:
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* Caveats:
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* - The stack is defined as an array of bytes, but pointers are 32 bit wide
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* - Function pointers are 32-bit addresses
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*/
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/* Initialize stack. This is done in reverse order ("pushing") the
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* pre-allocated array */
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/* mt_exit function that is to be invoked if the thread dies
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* function is the thread handler. Invoked when RET is called in mtarch_exec
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*/
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*((uint32_t *)(t->stack + MTARCH_STACKSIZE - 4)) = (uint32_t)mt_exit;
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*((uint32_t *)(t->stack + MTARCH_STACKSIZE - 8)) = (uint32_t)function;
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/* FIXME: Push args to function and saved registers, check calling
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* conventions
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*/
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/* Initialize stack pointer: Space for 2 2-byte-addresses and 32 registers,
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* post-decrement POP / pre-increment PUSH scheme
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* FIXME: Need to calculate correct address here
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*/
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t->sp = &t->stack[MTARCH_STACKSIZE - 1 - 4 - 32];
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}
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/*--------------------------------------------------------------------------*/
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static struct mtarch_thread *running;
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static void
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sw(void)
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{
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printf ("sw called\n");
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/* FIXME: Disable interrupts while we perform the context switch */
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/* Needs to be in separate asm statement, we don't want to be
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* interrupted while the C-Compiler-generated wrapper-code pushes
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* registers on the stack.
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*/
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/*
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* Need to save ra, s0/fp, s1-s11, we make the C-compiler do it by
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* specifying these registers as clobber.
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* For now we leave MT threads alone -- the stack management is too
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* unstable in the currently-used gcc port, in our example for storing
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* 13 4-byte variables on the stack the compiler allocates 64 bytes on
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* the stack (52 would be ok, 64 is not even explained if the stack is
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* kept 8-byte aligned (maybe 16?)). Also the normal function wrapper
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* code is not called if we have a single asm statement in a function
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* (the normal wrapper code already saves ra, s0/fp on the stack).
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*/
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/* Switch stack pointer */
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asm (
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"mv t0, sp\n"
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"mv sp, %0\n"
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"mv %0, t0\n"
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: "+r" (running->sp)
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:
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: "t0","ra","s0","s1","s2","s3","s4","s5","s6","s7","s8","s9","s10","s11"
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);
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_exec(struct mtarch_thread *t)
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{
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printf ("mtarch_exec called\n");
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running = t;
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sw();
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running = NULL;
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_remove(void)
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{
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_yield(void)
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{
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sw();
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_pstop(void)
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{
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_pstart(void)
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{
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}
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/*--------------------------------------------------------------------------*/
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void
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mtarch_stop(struct mtarch_thread *t)
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{
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}
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/*--------------------------------------------------------------------------*/
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int
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mtarch_stack_usage(struct mt_thread *t)
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{
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uint8_t i;
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for(i = 0; i < MTARCH_STACKSIZE; ++i) {
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if(t->thread.stack[i] != i) {
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break;
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}
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}
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return MTARCH_STACKSIZE - i;
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}
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/*--------------------------------------------------------------------------*/
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