1 files changed, 111 insertions, 0 deletions
diff --git a/lib/AdventOfCode.pm6 b/lib/AdventOfCode.pm6
new file mode 100644
index 0000000..cac317a
--- /dev/null
+++ b/lib/AdventOfCode.pm6
@@ -0,0 +1,111 @@
+use v6.d;
+enum opcode (
+    halt => 99,
+    add => 1,
+    multiply => 2
+);
+class X::Halt is Exception {}
+
+class IntcodeVM is export {
+    has @.program;
+    has @.memory;
+    # Program counter
+    has $!pc = 0;
+
+    submethod new(Str $program) {
+        my @program = $program.split(',').map(*.Int);
+        self.bless(:@program, :memory(@program));
+    }
+
+    method run {
+        loop {
+            CATCH {
+                when X::Halt { last }
+            }
+            self!run-next-command;
+        }
+    }
+
+    method reset-memory {
+        @!memory = @.program;
+        $!pc = 0;
+    }
+
+    method !run-next-command {
+        given self!peek-opcode {
+            when halt {
+                die X::Halt.new;
+            }
+            when add {
+                self!add();
+                $!pc += 4;
+            }
+            when multiply {
+                self!multiply();
+                $!pc += 4;
+            }
+            default { die "Unknwon opcode {self!peek-opcode()}"; }
+        }
+    }
+
+    method !peek-opcode(--> Int) {
+        die "$!pc exceeds memory {@!memory.elems}" if $!pc >= @!memory.elems;
+        @!memory[$!pc]
+    }
+
+    method !program-chunk(Range $r) {
+        @!memory[$r + $!pc]
+    }
+
+    method !add {
+        my ($opcode, $mem1, $mem2, $memresult) = self!program-chunk(^4);
+        @!memory[$memresult] =  @!memory[$mem1] + @!memory[$mem2];
+    }
+
+    method !multiply {
+        my ($opcode, $mem1, $mem2, $memresult) = self!program-chunk(^4);
+        @!memory[$memresult] =  @!memory[$mem1] * @!memory[$mem2];
+    }
+
+    method output {
+        @!memory[0]
+    }
+}
+
+sub try-inputs(IntcodeVM $vm, $noun, $verb) {
+    $vm.reset-memory();
+    $vm.memory[1] = $noun;
+    $vm.memory[2] = $verb;
+    $vm.run;
+    say $vm.memory[^3];
+    return $vm.memory[0];
+}
+
+#| First problem of day 2
+sub day2a($input-filename) is export {
+    my $program = slurp($input-filename);
+    my $vm = IntcodeVM.new($program);
+    # Replace bits
+    $vm.memory[1] = 12;
+    $vm.memory[2] = 2;
+    $vm.run;
+
+    say "Value at position 0: {$vm.output}"
+}
+
+sub day2b($input-filename) is export {
+    my $program = slurp($input-filename);
+    my $vm = IntcodeVM.new($program);
+
+    for ((^100) X (^100)) -> $p {
+        $vm.memory[1] = $p[0];
+        $vm.memory[2] = $p[1];
+        $vm.run;
+        my $output = $vm.output;
+        if $output == 19690720 {
+            say "100 * noun + verb: {100 * $p[0] + $p[1]}";
+            last;
+        }
+        $vm.reset-memory;
+    }
+}