Line data    Source code

       1             : /**
       2             :  * @copyright Copyright (c) 2021 Sagetech, Inc. All rights reserved.
       3             :  *
       4             :  * @file   sgDecodeAck.c
       5             :  * @author jimb
       6             :  *
       7             :  * @date   Feb 10, 2021
       8             :  *
       9             :  * This file receives a raw Acknowledge message buffer and
      10             :  * parses the payload into a data struct.
      11             :  */
      12             : 
      13             : #include <string.h>
      14             : #include <stdbool.h>
      15             : #include <math.h>
      16             : 
      17             : #include "sg.h"
      18             : #include "sgUtil.h"
      19             : 
      20             : #define SG_ACK_XPNDR_FAIL 0x01
      21             : #define SG_ACK_SYSTEM_FAIL 0x02
      22             : #define SG_ACK_CRYPTO_FAIL 0x04
      23             : #define SG_ACK_WOW 0x08
      24             : #define SG_ACK_MAINT 0x10
      25             : #define SG_ACK_ALT_SOURCE 0x20
      26             : #define SG_ACK_OP_MODE 0xC0
      27             : 
      28             : typedef struct __attribute__((packed))
      29             : {
      30             :     uint8_t start;
      31             :     uint8_t type;
      32             :     uint8_t id;
      33             :     uint8_t payloadLen;
      34             :     uint8_t ackType;
      35             :     uint8_t ackId;
      36             :     uint8_t state;
      37             :     uint8_t alt[3];
      38             :     uint8_t checksum;
      39             : } ack_t;
      40             : 
      41             : /*
      42             :  * Documented in the header file.
      43             :  */
      44           3 : bool sgDecodeAck(uint8_t *buffer, sg_ack_t *ack)
      45             : {
      46             :     ack_t sgAck;
      47           3 :     memcpy(&sgAck, buffer, sizeof(ack_t));
      48             : 
      49           3 :     ack->ackType = sgAck.ackType;
      50           3 :     ack->ackId = sgAck.ackId;
      51           3 :     ack->failXpdr = (sgAck.state & SG_ACK_XPNDR_FAIL) > 0;
      52           3 :     ack->failSystem = (sgAck.state & SG_ACK_SYSTEM_FAIL) > 0;
      53           3 :     ack->failCrypto = (sgAck.state & SG_ACK_CRYPTO_FAIL) > 0;
      54           3 :     ack->wow = (sgAck.state & SG_ACK_WOW) > 0;
      55           3 :     ack->maint = (sgAck.state & SG_ACK_MAINT) > 0;
      56           3 :     ack->isHostAlt = (sgAck.state & SG_ACK_ALT_SOURCE) > 0;
      57           3 :     ack->opMode = (sgAck.state & SG_ACK_OP_MODE) >> 6;
      58             : 
      59           3 :     int32_t int24 = toInt32(sgAck.alt);
      60             : 
      61             :     // Bitmask altitude field to determine if alt = invalid
      62           3 :     if ((int24 & 0x00FFFFFF) == 0x00800000)
      63             :     {
      64           0 :         ack->alt = 0;
      65           0 :         ack->altValid = false;
      66             :     }
      67             :     else
      68             :     {
      69           3 :         ack->alt = int24;
      70           3 :         ack->altValid = true;
      71             :     }
      72             : 
      73           3 :     return true;
      74             : }