diff options
| author | Jim Mussared <jim.mussared@gmail.com> | 2023-02-15 14:31:49 +1100 |
|---|---|---|
| committer | Damien George <damien@micropython.org> | 2023-02-17 12:17:28 +1100 |
| commit | b1cdb205ec42181434b2b3699dabd72dc8834e3c (patch) | |
| tree | f6a4ced7e8c7c13606802feaae3718deb2df6c4f /shared/runtime/softtimer.c | |
| parent | de1f1dd164958273c4ab62a46fdfe8a2f40ab1cf (diff) | |
shared/runtime/softtimer: Fix ticks range when computing ticks diff.
The previous computation incorrectly assumed that the uint32_t ticks
counter MICROPY_SOFT_TIMER_TICKS_MS was in the range [0,0x80000000) where
its actually [0,0xffffffff]. This means the diff calculation can be
simplified compared to the original implementation copied from
utime_mphal.c, which has to deal with a ticks range constrained by the
small int range.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>
Diffstat (limited to 'shared/runtime/softtimer.c')
| -rw-r--r-- | shared/runtime/softtimer.c | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/shared/runtime/softtimer.c b/shared/runtime/softtimer.c index 4d96301ea..68173ac33 100644 --- a/shared/runtime/softtimer.c +++ b/shared/runtime/softtimer.c @@ -30,9 +30,6 @@ #include "py/runtime.h" #include "softtimer.h" -#define TICKS_PERIOD 0x80000000 -#define TICKS_DIFF(t1, t0) ((int32_t)(((t1 - t0 + TICKS_PERIOD / 2) & (TICKS_PERIOD - 1)) - TICKS_PERIOD / 2)) - extern __IO uint32_t MICROPY_SOFT_TIMER_TICKS_MS; volatile uint32_t soft_timer_next; @@ -42,16 +39,23 @@ volatile uint32_t soft_timer_next; // and is explicitly GC traced by soft_timer_gc_mark_all(). STATIC soft_timer_entry_t *soft_timer_heap; +static inline int32_t ticks_diff(uint32_t t1, uint32_t t0) { + // t1 is after t0 (i.e. positive result) if there exists a uint32_t X <= INT_MAX + // such that t0 + X = t1. Otherwise t1 is interepreted to be earlier than + // t0 (negative result). + return t1 - t0; +} + STATIC int soft_timer_lt(mp_pairheap_t *n1, mp_pairheap_t *n2) { soft_timer_entry_t *e1 = (soft_timer_entry_t *)n1; soft_timer_entry_t *e2 = (soft_timer_entry_t *)n2; - return TICKS_DIFF(e1->expiry_ms, e2->expiry_ms) < 0; + return ticks_diff(e1->expiry_ms, e2->expiry_ms) < 0; } STATIC void soft_timer_schedule_systick(uint32_t ticks_ms) { uint32_t irq_state = disable_irq(); uint32_t uw_tick = MICROPY_SOFT_TIMER_TICKS_MS; - if (TICKS_DIFF(ticks_ms, uw_tick) <= 0) { + if (ticks_diff(ticks_ms, uw_tick) <= 0) { soft_timer_next = uw_tick + 1; } else { soft_timer_next = ticks_ms; @@ -79,7 +83,7 @@ void soft_timer_deinit(void) { void soft_timer_handler(void) { uint32_t ticks_ms = MICROPY_SOFT_TIMER_TICKS_MS; soft_timer_entry_t *heap = soft_timer_heap; - while (heap != NULL && TICKS_DIFF(heap->expiry_ms, ticks_ms) <= 0) { + while (heap != NULL && ticks_diff(heap->expiry_ms, ticks_ms) <= 0) { soft_timer_entry_t *entry = heap; heap = (soft_timer_entry_t *)mp_pairheap_pop(soft_timer_lt, &heap->pairheap); if (entry->flags & SOFT_TIMER_FLAG_PY_CALLBACK) { |