diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/avr/timer.c | 25 | ||||
| -rw-r--r-- | src/sched.c | 6 |
2 files changed, 22 insertions, 9 deletions
diff --git a/src/avr/timer.c b/src/avr/timer.c index e96b88bf..f1fbd284 100644 --- a/src/avr/timer.c +++ b/src/avr/timer.c @@ -25,13 +25,29 @@ timer_from_us(uint32_t us) return us * (F_CPU / 1000000); } +union u32_u { + struct { uint8_t b0, b1, b2, b3; }; + struct { uint16_t lo, hi; }; + uint32_t val; +}; + // Return true if time1 is before time2. Always use this function to // compare times as regular C comparisons can fail if the counter // rolls over. -uint8_t +uint8_t __always_inline timer_is_before(uint32_t time1, uint32_t time2) { - return (int32_t)(time1 - time2) < 0; + // This asm is equivalent to: + // return (int32_t)(time1 - time2) < 0; + // But gcc doesn't do a good job with the above, so it's hand coded. + union u32_u utime1 = { .val = time1 }; + uint8_t f = utime1.b3; + asm(" cp %A1, %A2\n" + " cpc %B1, %B2\n" + " cpc %C1, %C2\n" + " sbc %0, %D2" + : "+r"(f) : "r"(time1), "r"(time2)); + return (int8_t)f < 0; } static inline uint16_t @@ -99,11 +115,8 @@ static uint16_t timer_high; uint32_t timer_read_time(void) { - union u32_u16_u { - struct { uint16_t lo, hi; }; - uint32_t val; - } calc; irqstatus_t flag = irq_save(); + union u32_u calc; calc.val = timer_get(); calc.hi = timer_high; if (!(TIFR1 & (1<<TOV1))) { diff --git a/src/sched.c b/src/sched.c index 7a68db86..cae2f819 100644 --- a/src/sched.c +++ b/src/sched.c @@ -127,9 +127,9 @@ sched_del_timer(struct timer *del) static struct timer * reschedule_timer(struct timer *t) { + uint32_t waketime = t->waketime; struct timer *pos = t->next; - uint32_t minwaketime = t->waketime + 1; - if (!timer_is_before(pos->waketime, minwaketime)) + if (timer_is_before(waketime, pos->waketime)) // Timer is still the first - no insertion needed return t; @@ -142,7 +142,7 @@ reschedule_timer(struct timer *t) // micro optimization for AVR - reduces register pressure asm("" : "+r"(prev) : : "memory"); pos = pos->next; - if (!timer_is_before(pos->waketime, minwaketime)) + if (timer_is_before(waketime, pos->waketime)) break; } t->next = pos; |