/* $Id$ */ /* * Copyright (c) 2010 Dimitri Sokolyuk * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */ /* * inspired by TinyRealTime by Dan Henriksson and Anton Cervin * http://www.control.lth.se/Publication/hen+04t.html */ #include #include #include #include #include #include #include #include "kernel.h" #include "stack.h" #include "queue.h" #define LO8(x) ((uint8_t)((uint16_t)(x))) #define HI8(x) ((uint8_t)((uint16_t)(x) >> 8)) #define NOW(hi, lo) (((uint32_t)(hi) << 0x10) | (lo)) #define SPAN(from, to) ((int32_t)((to) - (from))) #define SLICE USEC(200) #define TIMEOUT WDTO_500MS #define SWITCH TIMER1_COMPA_vect struct task { uint32_t release; /* release time */ uint16_t sp; /* stack pointer */ uint8_t *stack; /* stack area */ TAILQ_ENTRY(task) r_link; TAILQ_ENTRY(task) t_link; TAILQ_ENTRY(task) w_link; }; TAILQ_HEAD(queue, task); struct kern { struct queue rq; /* run queue */ struct queue tq; /* time queue */ struct queue *wq; /* wait queues */ struct task *idle; struct task *cur; /* current task */ uint16_t cycles; /* clock high byte */ uint8_t semaphore; /* bitmap */ uint8_t reboot; } kern; ISR(TIMER1_OVF_vect) { if (!kern.reboot) wdt_reset(); ++kern.cycles; } ISR(TIMER1_COMPA_vect, ISR_NAKED) { struct task *tp; pusha(); /* pick the first RTR task and move it to tail of RQ */ if ((tp = TAILQ_FIRST(&kern.rq))) { TAILQ_REMOVE(&kern.rq, tp, r_link); TAILQ_INSERT_TAIL(&kern.rq, tp, r_link); } else tp = kern.idle; /* switch context */ kern.cur->sp = SP; kern.cur = tp; SP = kern.cur->sp; /* set next task switch timeout */ OCR1A = TCNT1 + SLICE; popa(); reti(); } ISR(TIMER1_COMPB_vect) { struct task *tp, *rq; uint32_t now = NOW(kern.cycles, TCNT1); /* release waiting tasks */ rq = TAILQ_FIRST(&kern.rq); while ((tp = TAILQ_FIRST(&kern.tq)) && SPAN(tp->release, now) >= 0) { TAILQ_REMOVE(&kern.tq, tp, t_link); if (rq) TAILQ_INSERT_BEFORE(rq, tp, r_link); else TAILQ_INSERT_TAIL(&kern.rq, tp, r_link); } /* set next wakeup timer */ if (tp) OCR1B = TCNT1 + SPAN(now, tp->release); } void init(uint8_t sema) { uint8_t i; cli(); /* disable watchdog */ MCUSR = 0; wdt_disable(); /* turn all on */ power_all_enable(); /* set clock prescale to 1 in case CKDIV8 fuse is on */ clock_prescale_set(clock_div_1); /* Set up timer 1 */ TCNT1 = 0; /* reset timer */ TCCR1A = 0; /* normal operation */ TCCR1B = TIMER1_FLAGS; /* prescale */ TIMSK1 = _BV(OCIE1A) | _BV(OCIE1B) | _BV(TOIE1); OCR1A = 0; OCR1B = 0; /* init queues */ TAILQ_INIT(&kern.rq); TAILQ_INIT(&kern.tq); kern.wq = calloc(sema, sizeof(struct queue)); for (i = 0; i < sema; i++) TAILQ_INIT(&kern.wq[i]); /* init idle task */ kern.idle = calloc(1, sizeof(struct task)); kern.idle->release = 0; kern.idle->sp = SP; /* not really needed */ kern.cur = kern.idle; kern.cycles = 0; kern.semaphore = 0; kern.reboot = 0; wdt_enable(TIMEOUT); SWITCH(); } void exec(void (*fun)(void *), void *args, uint8_t stack) { struct task *tp; uint8_t *sp; cli(); /* allocate task memory */ tp = calloc(1, sizeof(struct task)); tp->stack = calloc(stack, sizeof(uint8_t)); sp = &tp->stack[stack - 1]; /* initialize stack */ *sp-- = LO8(fun); /* PC(lo) */ *sp-- = HI8(fun); /* PC(hi) */ *sp-- = 0; /* r1 */ *sp-- = 0; /* r0 */ *sp-- = SREG | _BV(SREG_I); /* SREG with interrupts enabled */ sp -= 22; memset(sp, 0, 22); /* r2-r23 */ *sp-- = LO8(args); /* r24 */ *sp-- = HI8(args); /* r25 */ sp -= 6; memset(sp, 0, 6); /* r26-r31 */ tp->release = 0; tp->sp = (uint16_t)sp; /* SP */ TAILQ_INSERT_TAIL(&kern.rq, tp, r_link); sei(); } void lock(uint8_t chan) { cli(); if (kern.semaphore & _BV(chan)) { /* semaphore busy, go into wait queue */ TAILQ_REMOVE(&kern.rq, kern.cur, r_link); TAILQ_INSERT_TAIL(&kern.wq[chan], kern.cur, w_link); } else { /* occupy semaphore and continue */ kern.semaphore |= _BV(chan); } SWITCH(); } void unlock(uint8_t chan) { struct task *tp; cli(); if ((tp = TAILQ_FIRST(&kern.wq[chan]))) { /* release first waiting task from wait queue */ TAILQ_REMOVE(&kern.wq[chan], tp, w_link); TAILQ_INSERT_HEAD(&kern.rq, tp, r_link); } else { /* clear semaphore and continue */ kern.semaphore &= ~_BV(chan); } sei(); } void sleep(uint32_t sec, uint32_t usec) { struct task *tp; cli(); /* remove current task from RTR queue */ TAILQ_REMOVE(&kern.rq, kern.cur, r_link); /* set next wakeup time and put it on Wait queue */ kern.cur->release = NOW(kern.cycles, TCNT1) + SEC(sec) + USEC(usec); /* find right place */ TAILQ_FOREACH(tp, &kern.tq, t_link) if (SPAN(tp->release, kern.cur->release) < 0) break; if (tp) TAILQ_INSERT_BEFORE(tp, kern.cur, t_link); else TAILQ_INSERT_TAIL(&kern.tq, kern.cur, t_link); SWITCH(); } void terminate(void) { cli(); /* TODO: free memory */ TAILQ_REMOVE(&kern.rq, kern.cur, r_link); SWITCH(); } uint32_t now(void) { return NOW(kern.cycles, TCNT1); } void reboot(void) { kern.reboot = 1; }