diff options
| author | Keith Packard <keithp@keithp.com> | 2009-05-23 21:16:22 -0700 |
|---|---|---|
| committer | Keith Packard <keithp@keithp.com> | 2009-05-23 21:16:22 -0700 |
| commit | d6f5a0689023546464a71561f53fa2c943077c88 (patch) | |
| tree | 48fd63d1c4c381b6ec574575eb147473ec2ad424 | |
| parent | aa6d87aeb616dd62f0debaded297232022b4f8bd (diff) | |
Avoid 16-bit overflow in velocity computation.
Adding two 16 bit integers together can wrap around to negative numbers,
this resulted in velocity values which never decreased, making the switch
from coast to apogee state not occur.
Signed-off-by: Keith Packard <keithp@keithp.com>
| -rw-r--r-- | ao_flight.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/ao_flight.c b/ao_flight.c index 3e747d06..51b2cd5e 100644 --- a/ao_flight.c +++ b/ao_flight.c @@ -170,7 +170,7 @@ ao_flight(void) * so subtract instead of add. */ ticks = ao_flight_tick - ao_flight_prev_tick; - ao_vel_change = (((ao_raw_accel + ao_raw_accel_prev) >> 1) - ao_ground_accel); + ao_vel_change = (((ao_raw_accel >> 1) + (ao_raw_accel_prev >> 1)) - ao_ground_accel); ao_raw_accel_prev = ao_raw_accel; /* one is a common interval */ |