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      1 /*
      2  * Copyright (C) 2010 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include <stdint.h>
     18 #include <math.h>
     19 #include <sys/types.h>
     20 
     21 #include <utils/Errors.h>
     22 
     23 #include <hardware/sensors.h>
     24 
     25 #include "GravitySensor.h"
     26 #include "SensorDevice.h"
     27 #include "SensorFusion.h"
     28 
     29 namespace android {
     30 // ---------------------------------------------------------------------------
     31 
     32 GravitySensor::GravitySensor(sensor_t const* list, size_t count)
     33     : mSensorDevice(SensorDevice::getInstance()),
     34       mSensorFusion(SensorFusion::getInstance())
     35 {
     36     for (size_t i=0 ; i<count ; i++) {
     37         if (list[i].type == SENSOR_TYPE_ACCELEROMETER) {
     38             mAccelerometer = Sensor(list + i);
     39             break;
     40         }
     41     }
     42 }
     43 
     44 bool GravitySensor::process(sensors_event_t* outEvent,
     45         const sensors_event_t& event)
     46 {
     47     const static double NS2S = 1.0 / 1000000000.0;
     48     if (event.type == SENSOR_TYPE_ACCELEROMETER) {
     49         vec3_t g;
     50         if (!mSensorFusion.hasEstimate())
     51             return false;
     52         const mat33_t R(mSensorFusion.getRotationMatrix());
     53         // FIXME: we need to estimate the length of gravity because
     54         // the accelerometer may have a small scaling error. This
     55         // translates to an offset in the linear-acceleration sensor.
     56         g = R[2] * GRAVITY_EARTH;
     57 
     58         *outEvent = event;
     59         outEvent->data[0] = g.x;
     60         outEvent->data[1] = g.y;
     61         outEvent->data[2] = g.z;
     62         outEvent->sensor = '_grv';
     63         outEvent->type = SENSOR_TYPE_GRAVITY;
     64         return true;
     65     }
     66     return false;
     67 }
     68 
     69 status_t GravitySensor::activate(void* ident, bool enabled) {
     70     return mSensorFusion.activate(ident, enabled);
     71 }
     72 
     73 status_t GravitySensor::setDelay(void* ident, int handle, int64_t ns) {
     74     return mSensorFusion.setDelay(ident, ns);
     75 }
     76 
     77 Sensor GravitySensor::getSensor() const {
     78     sensor_t hwSensor;
     79     hwSensor.name       = "Gravity Sensor";
     80     hwSensor.vendor     = "AOSP";
     81     hwSensor.version    = 3;
     82     hwSensor.handle     = '_grv';
     83     hwSensor.type       = SENSOR_TYPE_GRAVITY;
     84     hwSensor.maxRange   = GRAVITY_EARTH * 2;
     85     hwSensor.resolution = mAccelerometer.getResolution();
     86     hwSensor.power      = mSensorFusion.getPowerUsage();
     87     hwSensor.minDelay   = mSensorFusion.getMinDelay();
     88     Sensor sensor(&hwSensor);
     89     return sensor;
     90 }
     91 
     92 // ---------------------------------------------------------------------------
     93 }; // namespace android
     94 
     95