From b60c9a9a638f9bda12246373ced60216bf18185b Mon Sep 17 00:00:00 2001
From: Shadowfacts <me@shadowfacts.net>
Date: Thu, 5 Dec 2019 22:48:17 -0500
Subject: [PATCH] Add simple Intcode assembler

---
 lib/day5/day5.ex         |  10 ++-
 lib/intcode/assembler.ex | 155 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 162 insertions(+), 3 deletions(-)
 create mode 100644 lib/intcode/assembler.ex

diff --git a/lib/day5/day5.ex b/lib/day5/day5.ex
index d5e1e41..4bbaeee 100644
--- a/lib/day5/day5.ex
+++ b/lib/day5/day5.ex
@@ -66,11 +66,12 @@ defmodule Day5 do
   def run(memory, ip \\ 0)
 
   def run(memory, ip) when ip < length(memory) do
+    IO.puts("IP: #{ip}")
     IO.inspect(memory)
 
     case eval(Enum.drop(memory, ip), memory) do
-      {memory, :halt} ->
-        memory
+      {_memory, :halt} ->
+        :halt
 
       {memory, :cont, offset} ->
         run(memory, ip + offset)
@@ -78,6 +79,8 @@ defmodule Day5 do
       {memory, :jump, ip} ->
         run(memory, ip)
     end
+
+    :ok
   end
 
   def run(memory, _ip), do: memory
@@ -146,7 +149,8 @@ defmodule Day5 do
 
   # output
   def eval([op, param | _], memory) when opcode(op, 4) do
-    get_param(op, 0, param, memory) |> IO.inspect()
+    out = get_param(op, 0, param, memory)
+    IO.puts("Output: #{out}")
 
     {memory, :cont, 2}
   end
diff --git a/lib/intcode/assembler.ex b/lib/intcode/assembler.ex
new file mode 100644
index 0000000..b01e3cc
--- /dev/null
+++ b/lib/intcode/assembler.ex
@@ -0,0 +1,155 @@
+defmodule Assembler do
+  @asm """
+    in #30
+    clt 30 #8 #31
+    jnz 31 #lessThan
+    ceq 30 #8 #31
+    jnz 31 #equal
+    out #1001
+    hlt
+
+  lessThan:
+    out #999
+    hlt
+
+  equal:
+    out #1000
+    hlt
+  """
+  def test do
+    @asm
+    |> IO.inspect()
+    |> assemble(32)
+  end
+
+  def assemble(asm, pad_length \\ 0) do
+    {memory, labels} =
+      asm
+      |> String.split("\n")
+      |> Enum.reject(&(String.length(&1) == 0))
+      |> Enum.reduce({[], %{}}, fn line, {memory, labels} ->
+        cond do
+          Regex.match?(~r/^\s+$/, line) ->
+            {memory, labels}
+
+          String.starts_with?(line, "  ") ->
+            {
+              assemble_instruction(String.slice(line, 2..-1), memory),
+              labels
+            }
+
+          String.ends_with?(line, ":") ->
+            {
+              memory,
+              Map.put(labels, String.slice(line, 0..-2), length(memory))
+            }
+
+          true ->
+            IO.inspect("Ignoring line: #{line}")
+        end
+      end)
+
+    memory =
+      Enum.map(memory, fn
+        {:label, name} -> Map.fetch!(labels, name)
+        it -> it
+      end)
+
+    memory =
+      if pad_length > length(memory) do
+        repeat(0, pad_length - length(memory)) ++ memory
+      else
+        memory
+      end
+
+    IO.inspect(labels)
+    Enum.reverse(memory)
+  end
+
+  def repeat(_, 0), do: []
+  def repeat(n, count), do: [n | repeat(n, count - 1)]
+
+  def pow(base, 1), do: base
+  def pow(base, exp), do: base * pow(base, exp - 1)
+
+  def parse_params(params, param_types) do
+    params
+    |> String.split(" ")
+    |> Enum.zip(param_types)
+    |> Enum.with_index()
+    |> Enum.map_reduce(0, fn {{param, type}, index}, modes ->
+      val =
+        case Regex.run(~r/^#?(\d+)$/, param) do
+          [_, digits] ->
+            String.to_integer(digits)
+
+          _ ->
+            [_, name] = Regex.run(~r/^#(\w+)$/, param)
+            {:label, name}
+        end
+
+      modes =
+        if type == :read && String.starts_with?(param, "#") do
+          modes + pow(10, index + 2)
+        else
+          modes
+        end
+
+      {val, modes}
+    end)
+  end
+
+  def assemble_instruction(insn, memory \\ [])
+
+  def assemble_instruction("add " <> params, memory) do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+
+    [dest, b, a, 1 + modes | memory]
+  end
+
+  def assemble_instruction("mul " <> params, memory) do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+
+    [dest, b, a, 2 + modes | memory]
+  end
+
+  def assemble_instruction("hlt", memory) do
+    [99 | memory]
+  end
+
+  def assemble_instruction("in " <> params, memory) do
+    {[dest], modes} = parse_params(params, [:write])
+
+    [dest, 3 + modes | memory]
+  end
+
+  def assemble_instruction("out " <> params, memory) do
+    {[val], modes} = parse_params(params, [:read])
+
+    [val, 4 + modes | memory]
+  end
+
+  def assemble_instruction("jnz " <> params, memory) do
+    {[target, dest], modes} = parse_params(params, [:read, :read])
+
+    [dest, target, 5 + modes | memory]
+  end
+
+  def assemble_instruction("jez " <> params, memory) do
+    {[target, dest], modes} = parse_params(params, [:read, :read])
+
+    [dest, target, 6 + modes | memory]
+  end
+
+  def assemble_instruction("clt " <> params, memory) do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+
+    [dest, b, a, 7 + modes | memory]
+  end
+
+  def assemble_instruction("ceq " <> params, memory) do
+    {[a, b, dest], modes} = parse_params(params, [:read, :read, :write])
+
+    [dest, b, a, 8 + modes | memory]
+  end
+end