From 998b08890fa56e07db1cdd4402e94f74da95e1fa Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 00:05:20 +0000
Subject: [PATCH 01/16] Impl Parser#has_more_commands?

---
 lib/parser.rb | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/lib/parser.rb b/lib/parser.rb
index 7311279..964b976 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -1,2 +1,9 @@
-module Parser
+class Parser
+    def initialize input
+        @remaining = input
+    end
+
+    def has_more_commands?
+        @remaining =~ /^\s*[^\s\/]+.*$/
+    end
 end

From 9ed6185efaf88470d225bd208fc73c8220fb513b Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 00:31:06 +0000
Subject: [PATCH 02/16] Impl Parser#advance

---
 lib/parser.rb | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/parser.rb b/lib/parser.rb
index 964b976..e6f3b03 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -6,4 +6,10 @@ def initialize input
     def has_more_commands?
         @remaining =~ /^\s*[^\s\/]+.*$/
     end
+
+    def advance
+        begin
+            @current, _, @remaining = @remaining.partition("\n")
+        end while @current =~ /^((\s*\/+.*)|\s*$)/
+    end
 end

From d39cd8731983db52ae8f38acf479be938ffcdff3 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 01:04:21 +0000
Subject: [PATCH 03/16] Impl Parser#command_type

---
 lib/parser.rb | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/lib/parser.rb b/lib/parser.rb
index e6f3b03..752f1db 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -1,4 +1,8 @@
 class Parser
+    A_COMMAND = 4
+    L_COMMAND = 1
+    C_COMMAND = 8
+
     def initialize input
         @remaining = input
     end
@@ -12,4 +16,12 @@ def advance
             @current, _, @remaining = @remaining.partition("\n")
         end while @current =~ /^((\s*\/+.*)|\s*$)/
     end
+
+    def command_type
+        case @current.lstrip[0]
+        when '@' then Parser::A_COMMAND
+        when '(' then Parser::L_COMMAND
+        else Parser::C_COMMAND
+        end
+    end
 end

From 48660f2292fa270fcb3089a036c6fe1b4248247d Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 01:26:07 +0000
Subject: [PATCH 04/16] Impl Parser#symbol

---
 lib/parser.rb | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/lib/parser.rb b/lib/parser.rb
index 752f1db..4518fbc 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -24,4 +24,12 @@ def command_type
         else Parser::C_COMMAND
         end
     end
+
+    def symbol
+        case command_type
+        when Parser::A_COMMAND then @current.strip[1..-1]
+        when Parser::L_COMMAND then @current.strip[1..-2]
+        else raise "Parser#symbol not defined for current command_type"
+        end
+    end
 end

From 53a0722f707d4f10fbda0e6834164db53cc709bc Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 02:26:15 +0000
Subject: [PATCH 05/16] Impl Parser#dest

---
 lib/parser.rb | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/parser.rb b/lib/parser.rb
index 4518fbc..81f0e88 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -29,7 +29,20 @@ def symbol
         case command_type
         when Parser::A_COMMAND then @current.strip[1..-1]
         when Parser::L_COMMAND then @current.strip[1..-2]
-        else raise "Parser#symbol not defined for current command_type"
+        else wrong_command_type
         end
     end
+
+    def dest
+        wrong_command_type unless command_type == Parser::C_COMMAND
+
+        dest, match, _ = @current.partition('=')
+        match.empty? ? "" : dest
+    end
+
+    private
+    def wrong_command_type
+        f = caller[0][/`.*'/][1..-2]
+        raise "#{self.class}##{f} not defined for current command_type"
+    end
 end

From c38b09757c2ff9ec9bbdfc6cf36f1ae22b6c2aad Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 02:31:11 +0000
Subject: [PATCH 06/16] Impl Parser#jump

---
 lib/parser.rb | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/parser.rb b/lib/parser.rb
index 81f0e88..4eb01bf 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -40,6 +40,13 @@ def dest
         match.empty? ? "" : dest
     end
 
+    def jump
+        wrong_command_type unless command_type == Parser::C_COMMAND
+
+        _, match, jump = @current.rpartition(';')
+        match.empty? ? "": jump
+    end
+
     private
     def wrong_command_type
         f = caller[0][/`.*'/][1..-2]

From 736af77b6d0a8b4376c125b48123d468ea71b45e Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 02:41:23 +0000
Subject: [PATCH 07/16] Impl Parser#comp

---
 lib/parser.rb | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/parser.rb b/lib/parser.rb
index 4eb01bf..74eaaae 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -47,6 +47,13 @@ def jump
         match.empty? ? "": jump
     end
 
+    def comp
+        wrong_command_type unless command_type == Parser::C_COMMAND
+
+        comp, _, _ = @current.partition(';')
+        comp.rpartition('=')[2]
+    end
+
     private
     def wrong_command_type
         f = caller[0][/`.*'/][1..-2]

From 4cbde0bbb56639641da65f3a2e2ed49c7ef68c98 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 03:02:53 +0000
Subject: [PATCH 08/16] Impl Code#dest

---
 lib/code.rb | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/lib/code.rb b/lib/code.rb
index 646c2ea..1ef0dd1 100644
--- a/lib/code.rb
+++ b/lib/code.rb
@@ -1,2 +1,8 @@
 module Code
+    def self.dest mnemonic
+        d1 = mnemonic.index('A') ? '1' : '0'
+        d2 = mnemonic.index('D') ? '1' : '0'
+        d3 = mnemonic.index('M') ? '1' : '0'
+        d1 + d2 + d3
+    end
 end

From 01eb9e590973e7f98aefba5aa90d7ae1cef65cc8 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 03:07:01 +0000
Subject: [PATCH 09/16] Impl Code#jump

---
 lib/code.rb | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/lib/code.rb b/lib/code.rb
index 1ef0dd1..421752c 100644
--- a/lib/code.rb
+++ b/lib/code.rb
@@ -5,4 +5,13 @@ def self.dest mnemonic
         d3 = mnemonic.index('M') ? '1' : '0'
         d1 + d2 + d3
     end
+
+    def self.jump mnemonic
+        return "111" if mnemonic == "JMP"
+        return "101" if mnemonic == "JNE"
+        j1 = mnemonic.index('L') ? '1' : '0'
+        j2 = mnemonic.index('E') ? '1' : '0'
+        j3 = mnemonic.index('G') ? '1' : '0'
+        j1 + j2 + j3
+    end
 end

From c51d5b1e8f0aff098e8b4224ace1e010dfe8ee95 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 03:21:12 +0000
Subject: [PATCH 10/16] Impl Code#comp

---
 lib/code.rb | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/lib/code.rb b/lib/code.rb
index 421752c..9441659 100644
--- a/lib/code.rb
+++ b/lib/code.rb
@@ -14,4 +14,34 @@ def self.jump mnemonic
         j3 = mnemonic.index('G') ? '1' : '0'
         j1 + j2 + j3
     end
+
+    def self.comp mnemonic
+        address = mnemonic.index('M') ? '1' : '0'
+
+        # Swap M for A so the lookup table doesn't need to account for both
+        comp = case mnemonic.sub('M', 'A')
+        when "0"   then '101010'
+        when '0'   then '101010'
+        when '1'   then '111111'
+        when '-1'  then '111010'
+        when 'D'   then '001100'
+        when 'A'   then '110000'
+        when '!D'  then '001101'
+        when '!A'  then '110001'
+        when '-D'  then '001111'
+        when '-A'  then '110011'
+        when 'D+1' then '011111'
+        when 'A+1' then '110111'
+        when 'D-1' then '001110'
+        when 'A-1' then '110010'
+        when 'D+A' then '000010'
+        when 'D-A' then '010011'
+        when 'A-D' then '000111'
+        when 'D&A' then '000000'
+        when 'D|A' then '010101'
+        else raise "Unknown mnemonic"
+        end
+
+        address + comp
+    end
 end

From 1142c375ca72c70effee689e4a94b660d36f9d75 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 03:38:36 +0000
Subject: [PATCH 11/16] Impl assembler with no symbol table support

---
 bin/assembler | 15 ++++++++++++++-
 lib/parser.rb |  7 +++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/bin/assembler b/bin/assembler
index 836ed1f..65ce62e 100755
--- a/bin/assembler
+++ b/bin/assembler
@@ -4,4 +4,17 @@ require_relative '../lib/parser'
 require_relative '../lib/code'
 require_relative '../lib/symbol_table'
 
-input = ARGF.read
+parser = Parser.new(ARGF.read)
+
+parser.each_command do |command_type|
+    case command_type
+    when Parser::A_COMMAND then puts "0%015b" % parser.symbol
+    when Parser::C_COMMAND then
+        comp, dest, jump = [:comp, :dest, :jump].map do |sym|
+            Code.send(sym, parser.send(sym))
+        end
+
+        puts "111#{comp}#{dest}#{jump}"
+    else raise "Unimplemented"
+    end
+end
diff --git a/lib/parser.rb b/lib/parser.rb
index 74eaaae..e71051d 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -25,6 +25,13 @@ def command_type
         end
     end
 
+    def each_command
+        while has_more_commands?
+            advance
+            yield command_type
+        end
+    end
+
     def symbol
         case command_type
         when Parser::A_COMMAND then @current.strip[1..-1]

From 20f41d40c5bc191f4edaeb0b8c5184dbcd701473 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 03:42:40 +0000
Subject: [PATCH 12/16] Impl SymbolTable

---
 lib/symbol_table.rb | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/lib/symbol_table.rb b/lib/symbol_table.rb
index 9d0005c..1a11d27 100644
--- a/lib/symbol_table.rb
+++ b/lib/symbol_table.rb
@@ -1,2 +1,15 @@
-module SymbolTable
+class SymbolTable
+  def initialize
+    @table = {}
+  end
+
+  def add_entry symbol, value
+    @table[symbol] = value
+  end
+
+  def get_address symbol
+    @table[symbol]
+  end
+
+  alias contains? get_address
 end

From 8cda02e64b48056470f46f4bc513655d8943329f Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 04:06:09 +0000
Subject: [PATCH 13/16] Improve error message for bad mneumonics

---
 lib/code.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/code.rb b/lib/code.rb
index 9441659..30bb19d 100644
--- a/lib/code.rb
+++ b/lib/code.rb
@@ -39,7 +39,7 @@ def self.comp mnemonic
         when 'A-D' then '000111'
         when 'D&A' then '000000'
         when 'D|A' then '010101'
-        else raise "Unknown mnemonic"
+        else raise "Unknown mnemonic: '#{mnemonic}'"
         end
 
         address + comp

From 98ed0fe368573d4989bd1fe65df4d3e988b654f3 Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 04:06:33 +0000
Subject: [PATCH 14/16] Strip trailing linecomments

---
 lib/parser.rb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/parser.rb b/lib/parser.rb
index e71051d..6d48915 100644
--- a/lib/parser.rb
+++ b/lib/parser.rb
@@ -13,8 +13,10 @@ def has_more_commands?
 
     def advance
         begin
-            @current, _, @remaining = @remaining.partition("\n")
-        end while @current =~ /^((\s*\/+.*)|\s*$)/
+            line, _, @remaining = @remaining.partition("\n")
+            # Strip trailing comments
+            @current = line.partition('//').first.strip
+        end while @current.empty?
     end
 
     def command_type

From 9cf89da96a9a795d421eb5ff5dfe04e040b5987a Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 04:35:38 +0000
Subject: [PATCH 15/16] Implement assembler with symbol support

---
 bin/assembler       | 81 +++++++++++++++++++++++++++++++++++++++------
 lib/symbol_table.rb |  4 +--
 2 files changed, 73 insertions(+), 12 deletions(-)

diff --git a/bin/assembler b/bin/assembler
index 65ce62e..cd20ba9 100755
--- a/bin/assembler
+++ b/bin/assembler
@@ -4,17 +4,78 @@ require_relative '../lib/parser'
 require_relative '../lib/code'
 require_relative '../lib/symbol_table'
 
-parser = Parser.new(ARGF.read)
-
-parser.each_command do |command_type|
-    case command_type
-    when Parser::A_COMMAND then puts "0%015b" % parser.symbol
-    when Parser::C_COMMAND then
-        comp, dest, jump = [:comp, :dest, :jump].map do |sym|
-            Code.send(sym, parser.send(sym))
+HARDCODED_ADDRESSES = {
+    'SP' => 0,
+    'LCL' => 1,
+    'ARG' => 2,
+    'THIS' => 3,
+    'THAT' => 4,
+    'R0' => 0,
+    'R1' => 1,
+    'R2' => 2,
+    'R3' => 3,
+    'R4' => 4,
+    'R5' => 5,
+    'R6' => 6,
+    'R7' => 7,
+    'R8' => 8,
+    'R9' => 9,
+    'R10' => 10,
+    'R11' => 11,
+    'R12' => 12,
+    'R13' => 13,
+    'R14' => 14,
+    'R15' => 15,
+    'SCREEN' => 0x4000,
+    'KBD' => 0x6000
+}
+
+def parse_labels(input)
+    parser = Parser.new(input)
+    table = SymbolTable.new HARDCODED_ADDRESSES
+    icount = 0
+
+    parser.each_command do |command_type|
+        if command_type == Parser::L_COMMAND
+            table.add_entry parser.symbol, icount
+        else
+            icount += 1
+        end
+    end
+
+    table
+end
+
+def generate_code(input, table)
+    parser = Parser.new(input)
+    # Start placing variables from address 16 onwards
+    next_address = 16
+
+    get_address = ->(sym) do
+        if sym =~ /^\d+$/
+            sym
+        elsif table.contains? sym
+            table.get_address sym
+        else
+            table.add_entry sym, next_address
+            address, next_address = next_address, next_address + 1
         end
+    end
 
-        puts "111#{comp}#{dest}#{jump}"
-    else raise "Unimplemented"
+    parser.each_command do |command_type|
+        case command_type
+        when Parser::A_COMMAND then
+            puts "0%015b" % get_address.(parser.symbol)
+        when Parser::C_COMMAND then
+            comp, dest, jump = [:comp, :dest, :jump].map do |sym|
+                Code.send(sym, parser.send(sym))
+            end
+
+            puts "111#{comp}#{dest}#{jump}"
+        end
     end
 end
+
+input = ARGF.read
+table = parse_labels(input)
+generate_code(input, table)
diff --git a/lib/symbol_table.rb b/lib/symbol_table.rb
index 1a11d27..374d221 100644
--- a/lib/symbol_table.rb
+++ b/lib/symbol_table.rb
@@ -1,6 +1,6 @@
 class SymbolTable
-  def initialize
-    @table = {}
+  def initialize table = {}
+    @table = table
   end
 
   def add_entry symbol, value

From 611ce4f6b18ddb938c4736bc4b0a0822076fc40e Mon Sep 17 00:00:00 2001
From: Kevin Butler <haqkrs@gmail.com>
Date: Thu, 5 Mar 2015 17:01:10 +0000
Subject: [PATCH 16/16] Remove fancypants code

---
 bin/assembler | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/bin/assembler b/bin/assembler
index cd20ba9..3b553c7 100755
--- a/bin/assembler
+++ b/bin/assembler
@@ -67,9 +67,9 @@ def generate_code(input, table)
         when Parser::A_COMMAND then
             puts "0%015b" % get_address.(parser.symbol)
         when Parser::C_COMMAND then
-            comp, dest, jump = [:comp, :dest, :jump].map do |sym|
-                Code.send(sym, parser.send(sym))
-            end
+            comp = Code.comp(parser.comp)
+            dest = Code.dest(parser.dest)
+            jump = Code.jump(parser.jump)
 
             puts "111#{comp}#{dest}#{jump}"
         end