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      1 /*
      2  * Copyright (C) 2017 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 // This file contains frequently used constants and helper macros.
     18 
     19 #include <stdint.h>
     20 
     21 #ifndef LOCATION_LBS_CONTEXTHUB_NANOAPPS_COMMON_MATH_MACROS_H_
     22 #define LOCATION_LBS_CONTEXTHUB_NANOAPPS_COMMON_MATH_MACROS_H_
     23 
     24 // Constants.
     25 #define NANO_PI                     (3.14159265359f)
     26 #define INVALID_TEMPERATURE_CELSIUS (-274.0f)
     27 
     28 // Common math operations.
     29 #define NANO_ABS(x) ((x) > 0 ? (x) : -(x))
     30 #define NANO_MAX(a, b) ((a) > (b)) ? (a) : (b)
     31 #define NANO_MIN(a, b) ((a) < (b)) ? (a) : (b)
     32 #define SIGMOID(x) (1 / (1 + expf(-x)))
     33 
     34 // Timestamp conversion macros.
     35 #ifdef __cplusplus
     36 #define MSEC_TO_NANOS(x) (static_cast<uint64_t>(x * UINT64_C(1000000)))
     37 #else
     38 #define MSEC_TO_NANOS(x) ((uint64_t)(x * UINT64_C(1000000)))  // NOLINT
     39 #endif
     40 
     41 #define SEC_TO_NANOS(x)  MSEC_TO_NANOS(x * UINT64_C(1000))
     42 #define MIN_TO_NANOS(x)  SEC_TO_NANOS (x * UINT64_C(60))
     43 #define HRS_TO_NANOS(x)  MIN_TO_NANOS (x * UINT64_C(60))
     44 #define DAYS_TO_NANOS(x) HRS_TO_NANOS (x * UINT64_C(24))
     45 
     46 // Sample rate to period conversion.
     47 #ifdef __cplusplus
     48 #define HZ_TO_PERIOD_NANOS(hz) \
     49   (SEC_TO_NANOS(1024) / (static_cast<uint64_t>(hz * 1024)))
     50 #else
     51 #define HZ_TO_PERIOD_NANOS(hz) \
     52   (SEC_TO_NANOS(1024) / ((uint64_t)(hz * 1024)))  // NOLINT
     53 #endif
     54 
     55 // Unit conversion: nanoseconds to seconds.
     56 #define NANOS_TO_SEC (1.0e-9f)
     57 
     58 // Unit conversion: milli-degrees to radians.
     59 #define MDEG_TO_RAD (NANO_PI / 180.0e3f)
     60 
     61 // Unit conversion: radians to milli-degrees.
     62 #define RAD_TO_MDEG (180.0e3f / NANO_PI)
     63 
     64 // Time check helper macro that returns true if:
     65 //    i.  't1' is equal to or exceeds 't2' plus 't_delta'.
     66 //    ii. Or, a negative timestamp delta occurred since,
     67 //        't1' should always >= 't2'. This prevents potential lockout conditions
     68 //        if the timer count 't1' rolls over or an erroneously large
     69 //        timestamp is passed through.
     70 #define NANO_TIMER_CHECK_T1_GEQUAL_T2_PLUS_DELTA(t1, t2, t_delta) \
     71   (((t1) >= (t2) + (t_delta)) || ((t1) < (t2)))
     72 
     73 #ifdef __cplusplus
     74 extern "C" {
     75 #endif
     76 
     77 // This conversion function may be necessary for embedded hardware that can't
     78 // cast a uint64_t to a float directly. This conversion function was taken from:
     79 // [android]//device/google/contexthub/firmware/os/core/floatRt.c
     80 static inline float floatFromUint64(uint64_t v) {
     81   uint32_t hi = v >> 32;
     82   uint32_t lo = (uint32_t) v;
     83 
     84   if (!hi) {  // This is very fast for cases where 'v' fits into a uint32_t.
     85     return (float)lo;
     86   } else {
     87     return ((float)hi) * 4294967296.0f + (float)lo;
     88   }
     89 }
     90 
     91 #ifdef __cplusplus
     92 }
     93 #endif
     94 
     95 #endif  // LOCATION_LBS_CONTEXTHUB_NANOAPPS_COMMON_MATH_MACROS_H_
     96