1 # https://adventofcode.com/2020/day/4
 2 #
 3 # To run (on Linux):
 4 #   $ git clone https://github.com/akkartik/mu
 5 #   $ cd mu
 6 #   $ ./translate advent2020/4a.mu
 7 #   $ ./a.elf < input
 8 #
 9 # You'll need to register to download the 'input' file for yourself.
10 
11 fn main -> _/ebx: int {
12   var curr-passport-field-count/esi: int <- copy 0
13   var valid-passport-count/edi: int <- copy 0
14   var line-storage: (stream byte 0x100)  # 256 bytes
15   var line/ecx: (addr stream byte) <- address line-storage
16   var slice-storage: slice
17   var slice/edx: (addr slice) <- address slice-storage
18   $main:line-loop: {
19     # read line from stdin
20     clear-stream line
21     read-line-from-real-keyboard line
22     # if line is empty (not even a newline), quit
23     var done?/eax: boolean <- stream-empty? line
24     compare done?, 0/false
25     break-if-!=
26     print-stream-to-real-screen line
27     # if line has just a newline, process passport
28     skip-chars-matching-whitespace line
29     var new-passport?/eax: boolean <- stream-empty? line
30     {
31       compare new-passport?, 0/false
32       break-if-=
33       compare curr-passport-field-count, 7
34       {
35         break-if-!=
36         valid-passport-count <- increment
37         print-string 0, "=> "
38         print-int32-decimal 0, valid-passport-count
39         print-string 0, "\n"
40       }
41       curr-passport-field-count <- copy 0
42       loop $main:line-loop
43     }
44     $main:word-loop: {
45       next-word line, slice
46       var done?/eax: boolean <- slice-empty? slice
47       compare done?, 0/false
48       break-if-!=
49       print-string 0, "  "
50       print-slice-to-real-screen slice
51       # treat cid as optional
52       var optional?/eax: boolean <- slice-starts-with? slice, "cid:"
53       compare optional?, 0/false
54       {
55         break-if-!=
56         # otherwise assume there are no invalid fields and no duplicate fields
57         curr-passport-field-count <- increment
58         print-string 0, " => "
59         print-int32-decimal 0, curr-passport-field-count
60       }
61       print-string 0, "\n"
62       loop
63     }
64     loop
65   }
66   # process final passport
67   compare curr-passport-field-count, 7
68   {
69     break-if-!=
70     valid-passport-count <- increment
71   }
72   print-int32-decimal 0, valid-passport-count
73   print-string 0, "\n"
74   return 0
75 }