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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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index 0000000..f8459ac
--- a/dev/null
+++ b/lib/st-decode.cc
@@ -0,0 +1,121 @@
+#include <stdexcept>
+#include <numeric>
+#include <napkin/exception.h>
+#include <napkin/st/decode.h>
+
+namespace napkin {
+ namespace sleeptracker {
+ using std::invalid_argument;
+ using std::runtime_error;
+
+ struct st_time_t {
+ uint8_t hour;
+ uint8_t min;
+ };
+ struct st_date_t {
+ uint8_t month;
+ uint8_t day;
+ };
+ struct st_fulltime_t {
+ uint8_t hour;
+ uint8_t min;
+ uint8_t sec;
+ };
+ struct st_data_header_t {
+ char magic;
+ st_date_t today;
+ uint8_t unknown;
+ uint8_t window;
+ st_time_t to_bed;
+ st_time_t alarm;
+ uint8_t nawakes;
+ };
+ struct st_data_footer_t {
+ uint16_t data_a;
+ uint8_t checksum;
+ uint8_t eof_mark;
+ };
+
+ static void back_a_day(struct tm& t) {
+ time_t ts = mktime(&t);
+ if(ts==(time_t)-1)
+ throw exception_st_data("failed to make up time to step back a day");
+ ts -= 60*60*24;
+ if(!localtime_r(&ts,&t))
+ throw exception_st_data("failed to localtime_r() while stepping back a day");
+ }
+
+ hypnodata_t& decode(hypnodata_t& rv,const void *data,size_t data_length) {
+ if(data_length < (sizeof(st_data_header_t)+sizeof(st_data_footer_t)))
+ throw exception_st_data_envelope("not enough sleeptracker data to decode");
+ st_data_header_t *h = (st_data_header_t*)data;
+ if(h->magic != 'V')
+ throw exception_st_data_envelope("invalid magic in the data");
+ st_data_footer_t *f = (st_data_footer_t*)(static_cast<const char *>(data)+data_length-sizeof(st_data_footer_t));
+ if( (std::accumulate((uint8_t*)&h->today,(uint8_t*)&f->checksum,0)&0xFF) != f->checksum )
+ throw exception_st_data_integrity("checksum mismatch");
+ st_fulltime_t *aawake = (st_fulltime_t*)&h[1];
+ if((void*)&aawake[h->nawakes] != (void*)f)
+ throw exception_st_data_envelope("unbelievably screwed up data");
+ rv.clear();
+ time_t now = time(0);
+ struct tm t;
+ if(!localtime_r(&now,&t))
+ throw exception_st_data("failed to localtime_r()");
+ t.tm_mon = h->today.month-1;
+ t.tm_mday = h->today.day;
+ time_t mkt = mktime(&t);
+ if(mkt == (time_t)-1)
+ throw exception_st_data("failed to mktime() for a timestamp");
+ if(mkt > now) {
+ --t.tm_year;
+ }
+ struct tm ta;
+ memmove(&ta,&t,sizeof(ta));
+ ta.tm_sec = 0;
+ ta.tm_hour = h->alarm.hour; ta.tm_min = h->alarm.min;
+ rv.alarm = mktime(&ta);
+ if(rv.alarm == (time_t)-1)
+ throw exception_st_data("failed to mktime() for alarm");
+ struct tm tb;
+ memmove(&tb,&ta,sizeof(tb));
+ tb.tm_hour = h->to_bed.hour; tb.tm_min = h->to_bed.min;
+ rv.to_bed = mktime(&tb);
+ if(rv.to_bed == (time_t)-1)
+ throw exception_st_data("failed to mktime() for 'to bed'");
+ if(rv.to_bed > rv.alarm) {
+ back_a_day(tb);
+ rv.to_bed -= 24*60*60;
+ }
+ struct tm taaw;
+ memmove(&taaw,&tb,sizeof(taaw));
+ for(int rest=h->nawakes;rest;--rest,++aawake) {
+ if(
+ taaw.tm_mday!=ta.tm_mday
+ && (
+ aawake->hour < tb.tm_hour
+ || (
+ aawake->hour==tb.tm_hour
+ && aawake->min < tb.tm_min )
+ ) )
+ memmove(&taaw,&ta,sizeof(taaw));
+ taaw.tm_hour = aawake->hour;
+ taaw.tm_min = aawake->min;
+ taaw.tm_sec = aawake->sec;
+ rv.almost_awakes.push_back( mktime(&taaw) );
+ if(rv.almost_awakes.back() == (time_t)-1)
+ throw exception_st_data("failed to mktime() for almost awake moment");
+ }
+ rv.window = h->window;
+ rv.data_a = f->data_a;
+ return rv;
+ }
+
+ hypnodata_ptr_t decode(const void *data,size_t data_length) {
+ hypnodata_ptr_t rv( new hypnodata_t );
+ decode(*rv,data,data_length);
+ return rv;
+ }
+
+ }
+}