1a677d52360866d28f8e247bffbf1ca7dd406e21
[dweather.git] / loop.pl
1 #!/usr/bin/perl
2 use strict;
3
4 use v5.10.1;
5
6 use Mojolicious::Lite;
7 use Serial;
8 use Mojo::IOLoop;
9 use Mojo::IOLoop::Stream;
10 use Mojo::Transaction::WebSocket;
11 #use Mojo::JSON  qw(decode_json encode_json);
12 use JSON;
13 use Debug;
14 use SMGLog;
15 use Math::Round qw(nearest);
16 use File::Copy;
17 use Data::Random qw(rand_chars);
18 use IO::File;
19
20 use constant pi => 3.14159265358979; 
21
22 my $devname = "/dev/davis";
23 my $datafn = ".loop_data";
24 my $dataf;
25
26 my $poll_interval = 2.5;
27 my $rain_mult = 0.2;                            # 0.1 or 0.2 mm or 0.01 inches
28 my $tid;
29 my $rid;
30 our $did;
31 my $nlcount;
32 my $state = "ready";
33 my $buf;
34 my $dbg;
35 my $ser;                                                        # the serial port Mojo::IOLoop::Stream
36 my $last_min_h;
37 my $last_hour_h;
38
39 our $json = JSON->new->canonical(1);
40 our $WS = {};                                   # websocket connections
41
42 our $ld = {};
43 our @last10minsr = ();
44 our @last5daysh = ();
45
46 our $loop_count;                                # how many LOOPs we have done, used as start indicator
47
48 our     @crc_table = (
49                                   0x0, 0x1021, 0x2042, 0x3063, 0x4084, 0x50a5, 0x60c6, 0x70e7,
50                                   0x8108, 0x9129, 0xa14a, 0xb16b, 0xc18c, 0xd1ad, 0xe1ce, 0xf1ef,
51                                   0x1231, 0x210, 0x3273, 0x2252, 0x52b5, 0x4294, 0x72f7, 0x62d6,
52                                   0x9339, 0x8318, 0xb37b, 0xa35a, 0xd3bd, 0xc39c, 0xf3ff, 0xe3de,
53                                   0x2462, 0x3443, 0x420, 0x1401, 0x64e6, 0x74c7, 0x44a4, 0x5485,
54                                   0xa56a, 0xb54b, 0x8528, 0x9509, 0xe5ee, 0xf5cf, 0xc5ac, 0xd58d,
55                                   0x3653, 0x2672, 0x1611, 0x630, 0x76d7, 0x66f6, 0x5695, 0x46b4,
56                                   0xb75b, 0xa77a, 0x9719, 0x8738, 0xf7df, 0xe7fe, 0xd79d, 0xc7bc,
57                                   0x48c4, 0x58e5, 0x6886, 0x78a7, 0x840, 0x1861, 0x2802, 0x3823,
58                                   0xc9cc, 0xd9ed, 0xe98e, 0xf9af, 0x8948, 0x9969, 0xa90a, 0xb92b,
59                                   0x5af5, 0x4ad4, 0x7ab7, 0x6a96, 0x1a71, 0xa50, 0x3a33, 0x2a12,
60                                   0xdbfd, 0xcbdc, 0xfbbf, 0xeb9e, 0x9b79, 0x8b58, 0xbb3b, 0xab1a,
61                                   0x6ca6, 0x7c87, 0x4ce4, 0x5cc5, 0x2c22, 0x3c03, 0xc60, 0x1c41,
62                                   0xedae, 0xfd8f, 0xcdec, 0xddcd, 0xad2a, 0xbd0b, 0x8d68, 0x9d49,
63                                   0x7e97, 0x6eb6, 0x5ed5, 0x4ef4, 0x3e13, 0x2e32, 0x1e51, 0xe70,
64                                   0xff9f, 0xefbe, 0xdfdd, 0xcffc, 0xbf1b, 0xaf3a, 0x9f59, 0x8f78,
65                                   0x9188, 0x81a9, 0xb1ca, 0xa1eb, 0xd10c, 0xc12d, 0xf14e, 0xe16f,
66                                   0x1080, 0xa1, 0x30c2, 0x20e3, 0x5004, 0x4025, 0x7046, 0x6067,
67                                   0x83b9, 0x9398, 0xa3fb, 0xb3da, 0xc33d, 0xd31c, 0xe37f, 0xf35e,
68                                   0x2b1, 0x1290, 0x22f3, 0x32d2, 0x4235, 0x5214, 0x6277, 0x7256,
69                                   0xb5ea, 0xa5cb, 0x95a8, 0x8589, 0xf56e, 0xe54f, 0xd52c, 0xc50d,
70                                   0x34e2, 0x24c3, 0x14a0, 0x481, 0x7466, 0x6447, 0x5424, 0x4405,
71                                   0xa7db, 0xb7fa, 0x8799, 0x97b8, 0xe75f, 0xf77e, 0xc71d, 0xd73c,
72                                   0x26d3, 0x36f2, 0x691, 0x16b0, 0x6657, 0x7676, 0x4615, 0x5634,
73                                   0xd94c, 0xc96d, 0xf90e, 0xe92f, 0x99c8, 0x89e9, 0xb98a, 0xa9ab,
74                                   0x5844, 0x4865, 0x7806, 0x6827, 0x18c0, 0x8e1, 0x3882, 0x28a3,
75                                   0xcb7d, 0xdb5c, 0xeb3f, 0xfb1e, 0x8bf9, 0x9bd8, 0xabbb, 0xbb9a,
76                                   0x4a75, 0x5a54, 0x6a37, 0x7a16, 0xaf1, 0x1ad0, 0x2ab3, 0x3a92,
77                                   0xfd2e, 0xed0f, 0xdd6c, 0xcd4d, 0xbdaa, 0xad8b, 0x9de8, 0x8dc9,
78                                   0x7c26, 0x6c07, 0x5c64, 0x4c45, 0x3ca2, 0x2c83, 0x1ce0, 0xcc1,
79                                   0xef1f, 0xff3e, 0xcf5d, 0xdf7c, 0xaf9b, 0xbfba, 0x8fd9, 0x9ff8,
80                                   0x6e17, 0x7e36, 0x4e55, 0x5e74, 0x2e93, 0x3eb2, 0xed1, 0x1ef0
81                                  );
82
83 our %bar_trend;
84
85 $bar_trend{-60} = "Falling Rapidly";
86 $bar_trend{196} = "Falling Rapidly";
87 $bar_trend{-20} = "Falling Slowly";
88 $bar_trend{236} = "Falling Slowly";
89 $bar_trend{0} = "Steady";
90 $bar_trend{20} = "Rising Slowly";
91 $bar_trend{60} = "Rising Rapidly";
92
93 our $ending = 0;
94
95 $SIG{TERM} = $SIG{INT} = sub {++$ending; Mojo::IOLoop->stop;};
96 $SIG{HUP} = 'IGNORE';
97
98
99 # WebSocket weather service
100 websocket '/weather' => sub {
101   my $c = shift;
102   my $msg = shift;
103   my $tx = $c->tx;
104
105   # Opened
106   app->log->debug('WebSocket opened.');
107   dbg 'WebSocket opened' if isdbg 'chan';
108   $WS->{$tx} = $tx; 
109
110   # send historical data
111   $c->send($ld->{lasthour_h}) if exists $ld->{lasthour_h};
112   $c->send($ld->{lastmin_h}) if exists $ld->{lastmin_h};
113
114   # disable timeout
115   $c->inactivity_timeout(3615);
116  
117   # Incoming message
118   $c->on(
119                  message => sub {
120                          my ($c, $msg) = @_;
121                          dbg "websocket: text $msg" if isdbg 'chan';
122                  },
123                  json => sub {
124                          my ($c, $msg) = @_;
125                          dbg "websocket: json $msg" if isdbg 'chan';
126                  }
127   );
128  
129   # Closed
130   $c->on(finish => sub {
131     my ($c, $code, $reason) = @_;
132     app->log->debug("WebSocket closed with status $code.");
133         dbg "websocket closed with status $code" if isdbg 'chan';
134         delete $WS->{$tx};
135   });
136 };
137
138 get '/' => {template => 'index'};
139
140
141 dbginit();
142 if (@ARGV) {
143         dbgadd(@ARGV);
144
145 dbgadd('chan');
146
147 dbg '***';
148 dbg "*** starting $0";
149 dbg '***';
150
151 read_ld();
152
153 my $tnow = time;
154 my $dayno = int ($tnow/86400);
155 @last5daysh = grab_history(SMGLog->new("day"), "h", $tnow-(86400*5), $_) for ($dayno-4, $dayno-3, $dayno-2, $dayno-1, $dayno);  
156 @last10minsr = map {my ($t, $js) = split(/\s/, $_, 2); $js} grab_history(SMGLog->new("debug"), "r", $tnow-(60*3), $dayno);
157
158 our $dlog = SMGLog->new("day");
159 dbg "before next tick";
160 Mojo::IOLoop->next_tick(sub { loop() });        
161 dbg "before app start";
162 app->start;
163 dbg "after app start";
164
165 write_ld();
166 $dataf->close if $dataf;
167 undef $dataf;
168
169
170 # move all the files along one 
171 cycle_loop_data_files();
172
173 dbg '***';
174 dbg "*** ending $0";
175 dbg '***';
176
177 exit 0;
178
179 ##################################################################################
180         
181 sub loop
182 {
183         dbg "last_min: " . scalar gmtime($ld->{last_min});
184         dbg "last_hour: " . scalar gmtime($ld->{last_hour});
185         
186         $did = Mojo::IOLoop->recurring(1 => sub {$dlog->flushall});
187         
188         do_reopen($devname);
189 }
190
191
192
193 sub on_read
194 {
195         my ($ser, $d) = @_;
196         $buf .= $d;
197         $d =~ s/([\%\x00-\x1f\x7f-\xff])/sprintf("%%%02X", ord($1))/eg; 
198         dbg "read added '$d' buf lth=" . length $buf if isdbg 'raw';
199         if ($state eq 'waitnl' && $buf =~ /[\cJ\cM]+/) {
200                 dbg "Got \\n" if isdbg 'state';
201                 Mojo::IOLoop->remove($tid) if $tid;
202                 undef $tid;
203                 undef $buf;
204                 $nlcount = 0;
205                 $ser->write("LPS 1 1\n");
206                 chgstate("waitloop");
207         } elsif ($state eq "waitloop") {
208                 if ($buf =~ /\x06/) {
209                         dbg "Got ACK 0x06" if isdbg 'state';
210                         chgstate('waitlooprec');
211                         undef $buf;
212                 }
213         } elsif ($state eq 'waitlooprec') {
214                 if (length $buf >= 99) {
215                         dbg "got loop record" if isdbg 'chan';
216                         chgstate('');
217                         process($buf);
218                         undef $buf;
219                 }
220         }
221 }
222
223 sub start_loop
224 {
225         $nlcount = 1;
226         dbg "start_loop writing $nlcount \\n" if isdbg 'state';
227         $ser->write("\n");
228         Mojo::IOLoop->remove($tid) if $tid;
229         undef $tid;
230         $tid = Mojo::IOLoop->recurring(0.6 => sub {
231                                                                            if (++$nlcount > 10) {
232                                                                                    dbg "\\n count > 10, closing connection" if isdbg 'chan';
233                                                                                    do_reopen($devname);
234                                                                                    return;
235                                                                            }
236                                                                            dbg "writing $nlcount \\n" if isdbg 'state'; 
237                                                                            $ser->write("\n");
238                                                                    });
239         chgstate("waitnl");
240 }
241
242 sub chgstate
243 {
244         dbg "state '$state' -> '$_[0]'" if isdbg 'state';
245         $state = $_[0];
246 }
247
248 sub do_reopen
249 {
250         my $name = shift;
251         dbg "do reopen on '$name' ending $ending";
252         unless ($ending) {
253                 $ser = do_open($name);
254                 start_loop();
255                 chgstate('');
256                 $nlcount = 0;
257                 Mojo::IOLoop->start unless Mojo::IOLoop->is_running;
258         }
259 }
260
261 sub do_open
262 {
263         my $name = shift;
264
265         $ser->close if $ser;
266         undef $ser;
267
268         my $ob = Serial->new($name, 19200) || die "$name $!\n";
269         dbg "streaming $name fileno(" . fileno($ob) . ")" if isdbg 'chan';
270         
271         my $ser = Mojo::IOLoop::Stream->new($ob);
272         $ser->on(error=>sub {dbg "serial $_[1]"; do_reopen($name) unless $ending});
273         $ser->on(close=>sub {dbg "serial closing"; do_reopen($name) unless $ending});
274         $ser->on(timeout=>sub {dbg "serial timeout";});
275         $ser->on(read=>sub {on_read(@_)});
276         $ser->start;
277
278         Mojo::IOLoop->remove($tid) if $tid;
279         undef $tid;
280         Mojo::IOLoop->remove($rid) if $rid;
281         undef $rid;
282         $rid = Mojo::IOLoop->recurring($poll_interval => sub {
283                                                                            start_loop() if !$state;
284                                                                    });
285         chgstate('');
286         $nlcount = 0;
287         
288         return $ser;
289 }
290
291 my @min;
292 my @hour;
293
294 sub process
295 {
296         my $blk = shift;
297         my $loo =  substr $blk,0,3;
298         unless ( $loo eq 'LOO') {
299                 dbg "Block invalid loo -> $loo" if isdbg 'chan'; return;
300         }
301
302         my $tmp;
303         my $temp;
304         my $rain;
305         my %h;
306
307         my $crc_calc = CRC_CCITT($blk);
308
309         if ($crc_calc==0) {
310
311                 # Common ones
312                 $tmp = unpack("s", substr $blk,7,2) / 1000;
313                 $h{Pressure} = nearest(1, in2mb($tmp));
314
315                 $tmp = unpack("s", substr $blk,9,2) / 10;
316                 $h{Temp_In} = nearest(0.1, f2c($tmp));
317
318                 $temp  = nearest(0.1, f2c(unpack("s", substr $blk,12,2) / 10));
319                 $h{Temp_Out}  = $temp;
320                 if ($temp > 75 || $temp < -75) {
321                         dbg "LOOP Temperature out of range ($temp), record ignored";
322                         return;
323                 }
324
325                 $tmp = unpack("C", substr $blk,14,1);
326                 $h{Wind} = nearest(0.1, mph2mps($tmp));
327                 $h{Dir}     = unpack("s", substr $blk,16,2)+0;
328
329                 my $wind = {w => $h{Wind}, d => $h{Dir}};
330                 $wind = 0 if $wind == 255;
331                 push @{$ld->{wind_min}}, $wind;
332
333                 $tmp = int(unpack("C", substr $blk,33,1)+0);
334                 if ($tmp > 100) {
335                         dbg "LOOP Outside Humidity out of range ($tmp), record ignored";
336                         return;
337                 }
338                 $h{Humidity_Out} = $tmp;
339                 $tmp = int(unpack("C", substr $blk,11,1)+0);
340                 if ($tmp > 100) {
341                         dbg "LOOP Inside Humidity out of range ($tmp), record ignored";
342                         return;
343                 }
344                 $h{Humidity_In}  = $tmp;
345                 
346
347                 $tmp = unpack("C", substr $blk,43,1)+0;
348                 $h{UV} = $tmp unless $tmp >= 255;
349                 $tmp = unpack("s", substr $blk,44,2)+0; # watt/m**2
350                 $h{Solar} = $tmp unless $tmp >= 32767;
351
352                 #       $h{Rain_Rate}  = nearest(0.1,unpack("s", substr $blk,41,2) * $rain_mult);
353                 $rain = $h{Rain_Day}   = nearest(0.1, unpack("s", substr $blk,50,2) * $rain_mult);
354                 my $delta_rain = $h{Rain} = nearest(0.1, ($rain >= $ld->{last_rain} ? $rain - $ld->{last_rain} : $rain)) if $loop_count;
355                 $ld->{last_rain} = $rain;
356
357                 # what sort of packet is it?
358                 my $sort =  unpack("C", substr $blk,4,1);
359                 if ($sort) {
360
361                         # Newer LOOP2 packet
362                         $tmp = unpack("C", substr $blk,18,2);
363                         #               $h{Wind_Avg_10} = nearest(0.1,mph2mps($tmp/10));
364                         $tmp = unpack("C", substr $blk,20,2);
365                         #               $h{Wind_Avg_2} = nearest(0.1,mph2mps($tmp/10));
366                         $tmp = unpack("C", substr $blk,22,2);
367                         #               $h{Wind_Gust_10} = nearest(0.1,mph2mps($tmp/10));
368
369                         #               $h{Dir_Avg_10} = unpack("C", substr $blk,24,2)+0;
370                         $tmp = unpack("C", substr $blk,30,2);
371                         $h{Dew_Point} = nearest(0.1, f2c($tmp));
372
373                 } else {
374
375                         # Older LOOP packet
376                         $tmp = unpack("C", substr $blk,15,1);
377                         #               $h{Wind_Avg_10} = nearest(0.1,mph2mps($tmp));
378                         $h{Dew_Point}  = nearest(0.1, dew_point($h{Temp_Out}, $h{Humidity_Out}));
379                         $h{Rain_Month}  = nearest(0.1, unpack("s", substr $blk,52,2) * $rain_mult);
380                         $h{Rain_Year}  = nearest(0.1, unpack("s", substr $blk,54,2) * $rain_mult);
381                 }
382
383                 my $ts = time;
384                 my $s;
385                 my $dayno = int($ts/86400);
386                 if ($dayno > $ld->{last_day}) {
387                         $ld->{Temp_Out_Max} = $ld->{Temp_Out_Min} = $temp;
388                         $ld->{Temp_Out_Max_T} = $ld->{Temp_Out_Min_T} = clocktime($ts, 0);
389                         $ld->{last_day} = $dayno;
390                         write_ld();
391                         cycle_loop_data_files();
392                 }
393                 if ($temp > $ld->{Temp_Out_Max}) {
394                         $ld->{Temp_Out_Max} = $temp;
395                         $ld->{Temp_Out_Max_T} = clocktime($ts, 0);
396                         write_ld();
397                 }
398                 if ($temp < $ld->{Temp_Out_Min}) {
399                         $ld->{Temp_Out_Min} = $temp;
400                         $ld->{Temp_Out_Min_T} = clocktime($ts, 0);
401                         write_ld();
402                 }
403
404                 if ($ts >= $ld->{last_hour} + 1800) {
405                         $h{Pressure_Trend}    = unpack("C", substr $blk,3,1);
406                         $h{Pressure_Trend_txt} = $bar_trend{$h{Pressure_Trend}};
407                         $h{Batt_TX_OK}  = (unpack("C", substr $blk,86,1)+0) ^ 1;
408                         $h{Batt_Console}  = nearest(0.01, unpack("s", substr $blk,87,2) * 0.005859375);
409                         $h{Forecast_Icon}  = unpack("C", substr $blk,89,1);
410                         $h{Forecast_Rule}  = unpack("C", substr $blk,90,1);
411                         $h{Sunrise}  = sprintf( "%04d", unpack("S", substr $blk,91,2) );
412                         $h{Sunrise}  =~ s/(\d{2})(\d{2})/$1:$2/;
413                         $h{Sunset}   = sprintf( "%04d", unpack("S", substr $blk,93,2) );
414                         $h{Sunset}  =~ s/(\d{2})(\d{2})/$1:$2/;
415                         $h{Temp_Out_Max} = $ld->{Temp_Out_Max};
416                         $h{Temp_Out_Min} = $ld->{Temp_Out_Min};
417                         $h{Temp_Out_Max_T} = $ld->{Temp_Out_Max_T};
418                         $h{Temp_Out_Min_T} = $ld->{Temp_Out_Min_T};
419                         
420
421                         if ($loop_count) {      # i.e not the first
422                                 my $a = wind_average(scalar @{$ld->{wind_hour}} ? @{$ld->{wind_hour}} : {w => $h{Wind}, d => $h{Dir}});
423
424                                 $h{Wind_1h} = nearest(0.1, $a->{w});
425                                 $h{Dir_1h} = nearest(0.1, $a->{d});
426
427                                 $a = wind_average(@{$ld->{wind_min}});
428                                 $h{Wind_1m} = nearest(0.1, $a->{w});
429                                 $h{Dir_1m} = nearest(1, $a->{d});
430
431                                 ($h{Rain_1m}, $h{Rain_1h}, $h{Rain_24h}) = calc_rain($rain);
432                         }
433                         $ld->{last_rain_min} = $ld->{last_rain_hour} = $rain;
434
435                         $last_hour_h = {%h};
436                         $s = genstr($ts, 'h', \%h);
437                         $ld->{lasthour_h} = $s;
438                         
439                         $ld->{last_hour} = int($ts/1800)*1800;
440                         $ld->{last_min} = int($ts/60)*60;
441                         @{$ld->{wind_hour}} = ();
442                         @{$ld->{wind_min}} = ();
443
444                         if ($s) {
445                                 output_str($s, 1);
446                                 push @last5daysh, $s;
447                                 shift @last5daysh if @last5daysh > 5*24;
448                         }
449                         write_ld();
450                         
451                 } elsif ($ts >= $ld->{last_min} + 60) {
452                         my $a = wind_average(@{$ld->{wind_min}});
453                         my %save;
454
455                         push @{$ld->{wind_hour}}, $a;
456
457                         if ($loop_count) {      # i.e not the first
458                                 my $rm;
459                                 
460                                 $h{Wind_1m} = nearest(0.1, $a->{w});
461                                 $h{Dir_1m} = nearest(1, $a->{d});
462                                 ($h{Rain_1m}, $h{Rain_1h}, $h{Rain_24h}) = calc_rain($rain);
463                         }
464                         $ld->{last_rain_min} = $rain;
465
466                         $h{Temp_Out_Max} = $ld->{Temp_Out_Max};
467                         $h{Temp_Out_Min} = $ld->{Temp_Out_Min};
468                         $h{Temp_Out_Max_T} = $ld->{Temp_Out_Max_T};
469                         $h{Temp_Out_Min_T} = $ld->{Temp_Out_Min_T};
470
471                         $last_min_h = {%h};
472                         $s = genstr($ts, 'm', \%h);
473                         $ld->{lastmin_h} = $s;
474                         
475                         $ld->{last_min} = int($ts/60)*60;
476                         @{$ld->{wind_min}} = ();
477                         
478                         output_str($s, 1) if $s;
479                         write_ld();
480
481                 } else {
482                         my $o = gen_hash_diff($ld->{last_h}, \%h);
483                         if ($o) {
484                                 $s = genstr($ts, 'r', $o);
485                                 push @last10minsr, $s;
486                                 shift @last10minsr if @last10minsr > 240;
487                         }
488                         else {
489                                 dbg "loop rec not changed" if isdbg 'chan';
490                         }
491                         output_str($s, 0) if $s;
492                 }
493                 $ld->{last_h} = \%h;
494                 ++$loop_count;
495         } else {
496                 dbg "CRC check failed for LOOP data!";
497         }
498         return;
499 }
500
501 sub genstr
502 {
503         my $ts = shift;
504         my $let = shift;
505         my $h = shift;
506         
507         my $j =  $json->encode($h);
508         my $tm = clocktime($ts, 1);
509         return qq|{"tm":"$tm","t":$ts,"$let":$j}|;
510 }
511
512 sub clocktime
513 {
514         my $ts = shift;
515         my $secsreq = shift;
516         my ($sec,$min,$hr) = (gmtime $ts)[0,1,2];
517         my $s;
518         if ($secsreq) {
519                 $s = sprintf "%02d:%02d:%02d", $hr, $min, $sec;
520         } else {
521                 $s = sprintf "%02d:%02d", $hr, $min;
522         }
523         return $s;
524 }
525
526 sub output_str
527 {
528         my $s = shift;
529         my $logit = shift;
530         
531         dbg $s;
532 #       say $s;
533         $dlog->writenow($s) if $logit;
534         foreach my $ws (keys $WS) {
535                 my $tx = $WS->{$ws};
536                 if ($tx) {
537                         $tx->send($s);
538                 } else {
539                         delete $WS->{$tx};
540                 }
541         }
542 }
543
544 sub gen_hash_diff
545 {
546         my $last = shift;
547         my $now = shift;
548         my %o;
549         my $count;
550
551         while (my ($k, $v) = each %$now) {
552                 if (!exists $last->{$k} || $last->{$k} ne $now->{$k}) {
553                         $o{$k} = $v;
554                         ++$count;
555                 }
556         }
557         return $count ? \%o : undef;
558 }
559
560 sub dew_point
561 {
562         my $temp = shift @_;
563         my $rh   = shift @_;
564
565         #  Using the simplified approximation for dew point
566         #  Accurate to 1 degree C for humidities > 50 %
567         #  http://en.wikipedia.org/wiki/Dew_point
568
569         my $dewpoint = $temp - ((100 - $rh) / 5);
570
571         # this is the more complete one (which doesn't work)
572         #my $a = 6.1121;
573         #my $b = 18.678;
574         #my $c = 257.14;
575         #my $ytrh = log(($rh/100) + ($b * $temp) / ($c + $temp));
576         #my $dewpoint = ($c * $ytrh) / ($b - $ytrh); 
577
578         return $dewpoint;
579 }
580
581 sub CRC_CCITT
582 {
583     # Expects packed data...
584     my $data_str = shift @_;
585
586         my $crc = 0;
587         my @lst = split //, $data_str;
588         foreach my $data (@lst) {
589                 my $data = unpack("c",$data);
590
591                 my $crc_prev = $crc;
592                 my $index = $crc >> 8 ^ $data;
593                 my $lhs = $crc_table[$index];
594                 #print "lhs=$lhs, crc=$crc\n";
595                 my $rhs = ($crc << 8) & 0xFFFF;
596                 $crc = $lhs ^ $rhs;
597
598
599         }
600
601         return $crc;
602 }
603
604 sub f2c
605 {
606         return ($_[0] - 32) * 5/9;
607 }
608
609 sub mph2mps
610 {
611         return $_[0] * 0.44704;
612 }
613
614 sub in2mb
615 {
616         return $_[0] * 33.8637526;
617 }
618
619 sub wind_average
620 {
621         my ($sindir, $cosdir, $wind);
622         my $count;
623         
624         foreach my $r (@_) {
625                 $wind += $r->{w};
626                 $sindir += sin(d2r($r->{d})) * $r->{w};
627                 $cosdir += cos(d2r($r->{d})) * $r->{w};
628                 ++$count;
629         }
630
631         my $avhdg = r2d(atan2($sindir, $cosdir));
632         $avhdg += 360 if $avhdg < 0; 
633         return {w => nearest(0.1,$wind / $count), d => nearest(0.1,$avhdg)};
634 }
635
636 # radians to degrees
637 sub r2d
638 {
639     my $n = shift;
640     return ($n / pi) * 180;
641 }
642
643 # degrees to radians
644 sub d2r 
645 {
646     my $n = shift;
647     return ($n / 180) * pi;
648 }
649
650 sub calc_rain
651 {
652         my $rain = shift;
653         
654         $ld->{rain24} ||= [];
655         
656         my $Rain_1h = nearest(0.1, $rain >= $ld->{last_rain_hour} ? $rain - $ld->{last_rain_hour} : $rain); # this is the rate for this hour, so far
657         my $rm = nearest(0.1, $rain >= $ld->{last_rain_min} ? $rain - $ld->{last_rain_min} : $rain);
658         my $Rain_1m = nearest(0.1, $rm);
659         push @{$ld->{rain24}}, $Rain_1m;
660         $ld->{rain_24} += $rm;
661         while (@{$ld->{rain24}} > 24*60) {
662                 $ld->{rain_24} -= shift @{$ld->{rain24}};
663         }
664         my $Rain_24h = nearest(0.1, $ld->{rain_24});
665         return ($Rain_1m, $Rain_1h, $Rain_24h);
666 }
667
668 sub read_ld
669 {
670         unless ($dataf) {
671                 $dataf = IO::File->new("+>> $datafn") or die "cannot open $datafn $!";
672                 $dataf->autoflush(1);
673         }
674
675         seek $dataf, 0, 0;
676         my $s = <$dataf>;
677         chomp $s;
678         dbg "read loop data: $s" if isdbg 'json';
679         $ld = $json->decode($s) if length $s;
680         
681         # sort out rain stats
682         my $c;
683         if ($ld->{rain24} && ($c = @{$ld->{rain24}}) < 24*60) {
684                 my $diff = 24*60 - $c;
685                 unshift @{$ld->{rain24}}, 0 for 0 .. $diff;  
686         }
687         my $rain;
688         
689         if ($ld->{rain24}) {
690                 $rain += $_ for @{$ld->{rain24}};
691         }
692         
693         $ld->{rain_24} = nearest(0.1, $rain);
694         delete $ld->{hour};
695         delete $ld->{min};
696 }
697
698 sub write_ld
699 {
700         unless ($dataf) {
701                 $dataf = IO::File->new("+>> $datafn") or die "cannot open $datafn $!";
702                 $dataf->autoflush(1);
703         }
704
705         seek $dataf, 0, 0;
706         truncate $dataf, 0;
707         $ld->{ts} = time;
708         my $s = $json->encode($ld);
709         dbg "write loop data: $s" if isdbg 'json';
710         print $dataf "$s\n";
711 }
712
713 sub cycle_loop_data_files
714 {
715         $dataf->close if $dataf;
716         undef $dataf;
717         
718         rename "$datafn.oooo", "$datafn.ooooo";
719         rename "$datafn.ooo", "$datafn.oooo";
720         rename "$datafn.oo", "$datafn.ooo";
721         rename "$datafn.o", "$datafn.oo";
722         copy $datafn, "$datafn.o";
723 }
724
725 sub grab_history
726 {
727         my $lg = shift;
728         my $let = shift;
729         my $start = shift || time - 86400;
730         my $dayno = shift;
731         my @out;
732         
733         if ($lg->open($dayno, 'r+')) {
734                 while (my $l = $lg->read) {
735                         next unless $l =~ /,"$let":/;
736                         my ($t) = $l =~ /"t":(\d+)/;
737                         if ($t && $t >= $start) {
738                                 push @out, $l;
739                         }
740                 }
741                 $lg->close;
742         }
743         return @out;
744 }