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-rw-r--r--lib/st-decode.cc121
1 files changed, 121 insertions, 0 deletions
diff --git a/lib/st-decode.cc b/lib/st-decode.cc
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1#include <stdexcept>
2#include <numeric>
3#include <napkin/exception.h>
4#include <napkin/st/decode.h>
5
6namespace napkin {
7 namespace sleeptracker {
8 using std::invalid_argument;
9 using std::runtime_error;
10
11 struct st_time_t {
12 uint8_t hour;
13 uint8_t min;
14 };
15 struct st_date_t {
16 uint8_t month;
17 uint8_t day;
18 };
19 struct st_fulltime_t {
20 uint8_t hour;
21 uint8_t min;
22 uint8_t sec;
23 };
24 struct st_data_header_t {
25 char magic;
26 st_date_t today;
27 uint8_t unknown;
28 uint8_t window;
29 st_time_t to_bed;
30 st_time_t alarm;
31 uint8_t nawakes;
32 };
33 struct st_data_footer_t {
34 uint16_t data_a;
35 uint8_t checksum;
36 uint8_t eof_mark;
37 };
38
39 static void back_a_day(struct tm& t) {
40 time_t ts = mktime(&t);
41 if(ts==(time_t)-1)
42 throw exception_st_data("failed to make up time to step back a day");
43 ts -= 60*60*24;
44 if(!localtime_r(&ts,&t))
45 throw exception_st_data("failed to localtime_r() while stepping back a day");
46 }
47
48 hypnodata_t& decode(hypnodata_t& rv,const void *data,size_t data_length) {
49 if(data_length < (sizeof(st_data_header_t)+sizeof(st_data_footer_t)))
50 throw exception_st_data_envelope("not enough sleeptracker data to decode");
51 st_data_header_t *h = (st_data_header_t*)data;
52 if(h->magic != 'V')
53 throw exception_st_data_envelope("invalid magic in the data");
54 st_data_footer_t *f = (st_data_footer_t*)(static_cast<const char *>(data)+data_length-sizeof(st_data_footer_t));
55 if( (std::accumulate((uint8_t*)&h->today,(uint8_t*)&f->checksum,0)&0xFF) != f->checksum )
56 throw exception_st_data_integrity("checksum mismatch");
57 st_fulltime_t *aawake = (st_fulltime_t*)&h[1];
58 if((void*)&aawake[h->nawakes] != (void*)f)
59 throw exception_st_data_envelope("unbelievably screwed up data");
60 rv.clear();
61 time_t now = time(0);
62 struct tm t;
63 if(!localtime_r(&now,&t))
64 throw exception_st_data("failed to localtime_r()");
65 t.tm_mon = h->today.month-1;
66 t.tm_mday = h->today.day;
67 time_t mkt = mktime(&t);
68 if(mkt == (time_t)-1)
69 throw exception_st_data("failed to mktime() for a timestamp");
70 if(mkt > now) {
71 --t.tm_year;
72 }
73 struct tm ta;
74 memmove(&ta,&t,sizeof(ta));
75 ta.tm_sec = 0;
76 ta.tm_hour = h->alarm.hour; ta.tm_min = h->alarm.min;
77 rv.alarm = mktime(&ta);
78 if(rv.alarm == (time_t)-1)
79 throw exception_st_data("failed to mktime() for alarm");
80 struct tm tb;
81 memmove(&tb,&ta,sizeof(tb));
82 tb.tm_hour = h->to_bed.hour; tb.tm_min = h->to_bed.min;
83 rv.to_bed = mktime(&tb);
84 if(rv.to_bed == (time_t)-1)
85 throw exception_st_data("failed to mktime() for 'to bed'");
86 if(rv.to_bed > rv.alarm) {
87 back_a_day(tb);
88 rv.to_bed -= 24*60*60;
89 }
90 struct tm taaw;
91 memmove(&taaw,&tb,sizeof(taaw));
92 for(int rest=h->nawakes;rest;--rest,++aawake) {
93 if(
94 taaw.tm_mday!=ta.tm_mday
95 && (
96 aawake->hour < tb.tm_hour
97 || (
98 aawake->hour==tb.tm_hour
99 && aawake->min < tb.tm_min )
100 ) )
101 memmove(&taaw,&ta,sizeof(taaw));
102 taaw.tm_hour = aawake->hour;
103 taaw.tm_min = aawake->min;
104 taaw.tm_sec = aawake->sec;
105 rv.almost_awakes.push_back( mktime(&taaw) );
106 if(rv.almost_awakes.back() == (time_t)-1)
107 throw exception_st_data("failed to mktime() for almost awake moment");
108 }
109 rv.window = h->window;
110 rv.data_a = f->data_a;
111 return rv;
112 }
113
114 hypnodata_ptr_t decode(const void *data,size_t data_length) {
115 hypnodata_ptr_t rv( new hypnodata_t );
116 decode(*rv,data,data_length);
117 return rv;
118 }
119
120 }
121}