osd-contiki/cpu/pico-rv32/mtarch.c

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