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/*
atmega88_coroutine.c
Copyright 2008-2013 Michel Pollet <buserror@gmail.com>
This file is part of simavr.
simavr is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
simavr is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with simavr. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef __AVR_CR_H__
#define __AVR_CR_H__
/*
* Smallest coroutine implementation for AVR. Takes
* 23 + (24 * tasks) bytes of SRAM to run.
*
* Use it like:
*
* AVR_TASK(mytask1, 32);
* AVR_TASK(mytask2, 48);
* ...
* void my_task_function() {
* do {
* AVR_YIELD(mytask1, 1);
* } while (1);
* }
* ...
* main() {
* AVR_TASK_START(mytask1, my_task_function);
* AVR_TASK_START(mytask2, my_other_task_function);
* do {
* AVR_RESUME(mytask1);
* AVR_RESUME(mytask2);
* } while (1);
* }
* NOTE: Do *not* use "static" on the function prototype, otherwise it
* will fail to link (compiler doesn't realize the "jmp" is referencing)
*/
#include <setjmp.h>
#include <stdint.h>
static inline void _set_stack(register void * stack)
{
asm volatile (
"in r0, __SREG__" "\n\t"
"cli" "\n\t"
"out __SP_H__, %B0" "\n\t"
"out __SREG__, r0" "\n\t"
"out __SP_L__, %A0" "\n\t"
: : "e" (stack) /* : */
);
}
jmp_buf g_caller;
#define AVR_TASK(_name, _stack_size) \
struct { \
jmp_buf jmp; \
uint8_t running : 1; \
uint8_t stack[_stack_size]; \
} _name
#define AVR_TASK_START(_name, _entry) \
if (!setjmp(g_caller)) { \
_set_stack(_name.stack+sizeof(_name.stack));\
asm volatile ("rjmp "#_entry); \
}
#define AVR_YIELD(_name, _sleep) \
_name.running = !_sleep; \
if (!setjmp(_name.jmp)) \
longjmp(g_caller, 1)
#define AVR_RESUME(_name) \
if (!setjmp(g_caller)) \
longjmp(_name.jmp, 1)
#endif /* __AVR_CR_H__ */
#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>
#include <stdio.h>
#include "avr_mcu_section.h"
AVR_MCU(F_CPU, "atmega88");
static int uart_putchar(char c, FILE *stream)
{
if (c == '\n')
uart_putchar('\r', stream);
loop_until_bit_is_set(UCSR0A, UDRE0);
UDR0 = c;
return 0;
}
static FILE mystdout = FDEV_SETUP_STREAM(uart_putchar, NULL,
_FDEV_SETUP_WRITE);
AVR_TASK(mytask1, 32);
AVR_TASK(mytask2, 48);
uint16_t t = 0;
void task1_function() {
uint16_t c = 0;
do {
c++;
if (c == 1000) {
c = 0;
printf("task1\n");
t++;
}
AVR_YIELD(mytask1, 1);
} while (1);
}
void task2_function() {
uint16_t c = 0;
do {
c++;
if (c == 2000) {
c = 0;
printf("task2\n");
}
AVR_YIELD(mytask2, 1);
} while (1);
}
int main(void)
{
stdout = &mystdout;
sei(); // Enable global interrupts
printf("Starting\n");
AVR_TASK_START(mytask1, task1_function);
AVR_TASK_START(mytask2, task2_function);
do {
AVR_RESUME(mytask1);
AVR_RESUME(mytask2);
} while (t < 500);
// exit simavr
cli();
sleep_mode();
}
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