diff options
Diffstat (limited to 'hw/arm_timer.c')
| -rw-r--r-- | hw/arm_timer.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/hw/arm_timer.c b/hw/arm_timer.c index a97d73e447..c8864f13ce 100644 --- a/hw/arm_timer.c +++ b/hw/arm_timer.c @@ -107,29 +107,29 @@ static void arm_timer_update(arm_timer_state *s, int64_t now) /* Return the current value of the timer. */ static uint32_t arm_timer_getcount(arm_timer_state *s, int64_t now) { - int64_t elapsed; + int64_t left; int64_t period; if (s->count == 0) return 0; if ((s->control & TIMER_CTRL_ENABLE) == 0) return s->count; - elapsed = now - s->loaded; + left = s->expires - now; period = s->expires - s->loaded; /* If the timer should have expired then return 0. This can happen when the host timer signal doesnt occur immediately. It's better to have a timer appear to sit at zero for a while than have it wrap around before the guest interrupt is raised. */ /* ??? Could we trigger the interrupt here? */ - if (elapsed > period) + if (left < 0) return 0; /* We need to calculate count * elapsed / period without overfowing. Scale both elapsed and period so they fit in a 32-bit int. */ while (period != (int32_t)period) { period >>= 1; - elapsed >>= 1; + left >>= 1; } - return ((uint64_t)s->count * (uint64_t)(int32_t)elapsed) + return ((uint64_t)s->count * (uint64_t)(int32_t)left) / (int32_t)period; } |