Add README.

README.md

@@ -1,22 +1,64 @@
 # chalk
 
-TODO: Write a description here
+Chalk is a basic compiler from a toy language into CHIP-8 bytecode.
+It supports some higher-level constructs like looks and if-statements,
+and has some higher-level functions for drawing numbers and sprites.
 
 ## Installation
 
-TODO: Write installation instructions here
+To compile chalk, simply run
+```Bash
+crystal build --release src/chalk.cr
+```
 
 ## Usage
+### Syntax
+Chalk has minimal syntax. All code goes into functions, which are declared as follows:
+```
+fun function(param, another_param): return_type {
 
-TODO: Write usage instructions here
+}
+```
+All parameters are assumed to be of type `u8`, an unsigned byte.
+The return type can be either `u8` or `u0`, the latter being the same as `void` in C.
+Users can declare variables using the `var` keyword:
+```
+var name = 5;
+```
+Assigning to existing variables is performed as such:
+```
+name = 6;
+```
+It's possible to call another function, which uses the CHIP-8 stack. This stack
+is used exclusively for function calls, and may not exceed 12, as per the specifications
+of the CHIP-8 virtual machine.
+```
+var result = double(name);
+```
+Additionally, to ensure that user-defined variables stored
+in registers are not modified, chalk uses its own custom stack, placed at the end of the program.
+This stack is accessed by modifying a stack pointer register, which holds the offset from the beginning of the stack. Because CHIP-8 registers can only hold up 8-bit unsinged numbers, the stack is therefore limited to 254 items.
 
-## Development
+If statements take "truthy" values to be those that have a nonzero value. As such,
+`if (0) {}` will never run, while `while(5) {}` will never terminate. Input can be awaited
+using the `get_key` function, which returns the number of the next key pressed.
 
-TODO: Write development instructions here
+Sprites can be declared using a quasi-visual syntax:
+```
+sprite dum [
+`  x  x  `
+`  x  x  `
+`  x  x  `
+`        `
+`x      x`
+` xxxxxx `
+]
+```
+These sprites can then be used in calls to `draw_sprite(sprite, x, y)`.
 
 ## Contributing
 
-1. Fork it (<https://github.com/your-github-user/chalk/fork>)
+1. Fork it (<https://github.com/DanilaFe/chalk/fork>)
 2. Create your feature branch (`git checkout -b my-new-feature`)
 3. Commit your changes (`git commit -am 'Add some feature'`)
 4. Push to the branch (`git push origin my-new-feature`)
@@ -24,4 +66,4 @@ TODO: Write development instructions here
 
 ## Contributors
 
-- [your-github-user](https://github.com/your-github-user) Danila Fedorin - creator, maintainer
+- [DanilaFe](https://github.com/DanilaFe) Danila Fedorin - creator, maintainer

programs/basic_arithmetic.chalk

@@ -0,0 +1,7 @@
+fun main(): u0 {
+    1+2+3;
+    var a = 5+5;
+    var b = a;
+    var a = a + b;
+    var c = a - b;
+}

programs/basic_call.chalk

@@ -0,0 +1,21 @@
+fun double(a): u8 {
+    return a + a;
+}
+
+fun quadruple(a): u8 {
+    return double(double(a));
+}
+
+fun reuse(): u0 {
+    var one = 2;
+    var two = 4;
+    var three = 6;
+}
+
+fun main(): u0 {
+    var a = quadruple(4);
+    var one = 1;
+    var two = 2;
+    var three = 3;
+    reuse();
+}

programs/basic_draw_number.chalk

@@ -0,0 +1,3 @@
+fun main(): u0 {
+    draw_number(69, 1, 1);
+}

programs/basic_empty.chalk

@@ -0,0 +1,3 @@
+fun main(): u0 {
+
+}

programs/basic_if.chalk

@@ -0,0 +1,17 @@
+fun main(): u0 {
+    var a = 3+3;
+    if(a) {
+        a = 0;
+    }
+
+    var b = 0;
+    if(b) {
+        b = 4;
+    }
+
+    if(b) {
+        b = 4;
+    } else {
+        b = 5;
+    }
+}

programs/basic_input.chalk

@@ -0,0 +1,4 @@
+fun main(): u0 {
+    var a = get_key();
+    var b = get_key();
+}

programs/basic_sprite.chalk

@@ -0,0 +1,12 @@
+sprite dum [
+`  x  x  `
+`  x  x  `
+`  x  x  `
+`        `
+`x      x`
+` xxxxxx `
+]
+
+fun main(): u0 {
+  draw_sprite(dum, 0, 0);
+}

programs/basic_while.chalk

@@ -0,0 +1,8 @@
+fun main(): u0 {
+    var a = 5;
+    var b = 0;
+    while(a) {
+        b = b + 2;
+        a = a - 1;
+    }
+}

programs/comb_fib.chalk

@@ -0,0 +1,14 @@
+fun main(): u0 {
+    var a = 1;
+    var b = 1;
+    while(233 - a) {
+        draw_number(a, 24, 13);
+        set_delay(30);
+        var temp = a;
+        a = b;
+        b = b + temp;
+        while(get_delay()){}
+        draw_number(temp, 24, 13);
+    }
+    draw_number(a, 24, 13);
+}

programs/comb_input.chalk

@@ -0,0 +1,13 @@
+fun main(): u0 {
+    var a = 1;
+    var b = 0;
+    var previous = 0;
+    draw_number(0, 24, 13);
+
+    while(a) {
+        previous = b;
+        b = get_key();
+        draw_number(previous, 24, 13);
+        draw_number(b, 24, 13);
+    }
+}

programs/comb_sprite.chalk

@@ -0,0 +1,39 @@
+sprite dum [
+`  x  x  `
+`  x  x  `
+`  x  x  `
+`        `
+`x      x`
+` xxxxxx `
+]
+
+fun main(): u8 {
+  var x = 0;
+  var y = 5;
+  var vy = 0;
+  var ay = 1;
+  var mode = 0;
+  while(1) {
+    draw_sprite(dum, x, y);
+    set_delay(1);
+    while(get_delay()){}
+    draw_sprite(dum, x, y);
+    if(5 - y) {
+
+    } else {
+        mode = 0;
+    }
+    if(26 - y) {
+
+    } else {
+        mode = 1;
+    }
+    if(mode) {
+        vy = vy - ay;
+        y = y - vy;
+    } else {
+        y = y + vy;
+        vy = vy + ay;
+    }
+  }
+}

programs/comb_sprite_2.chalk

@@ -0,0 +1,34 @@
+sprite dum [
+`  x  x  `
+`  x  x  `
+`  x  x  `
+`        `
+`x      x`
+` xxxxxx `
+]
+
+fun main(): u8 {
+  var x = 0;
+  var y = 27;
+  var vx = 1;
+  var vy = 0;
+  var a = 1;
+  while(1) {
+    var draw_y = 32 - y;
+    draw_sprite(dum, x, draw_y);
+    set_delay(1);
+    while(get_delay()){}
+
+    vy = vy - a;
+    y = y + vy;
+    x = x + vx;
+    if(6-y) {
+
+    } else {
+      var vtemp = vy;
+      vy = 0 - vtemp;
+      vy = vy + 1;
+    }
+    clear();
+  }
+}

src/chalk/codegen.cr

@@ -19,7 +19,7 @@ module Chalk
         @table = Table.new table
 
         @function.params.each do |param|
-          @table[param] = VarEntry.new @registers
+          @table.set_var param, VarEntry.new @registers
           @registers += 1
         end
       end
@@ -74,9 +74,8 @@ module Chalk
       def generate!(tree, table, target, free)
         case tree
         when Trees::TreeId
-          entry = table[tree.id]?
-          raise "Unknown variable" unless entry &&
-                                          entry.is_a?(VarEntry)
+          entry = table.get_var? tree.id
+          raise "Unknown variable" unless entry
           loadr target, entry.register
         when Trees::TreeLit
           load target, tree.lit
@@ -85,28 +84,26 @@ module Chalk
           generate! tree.right, table, free, free + 1
           opr tree.op, target, free
         when Trees::TreeCall
-          entry = table[tree.name]?.not_nil!
+          entry = table.get_function?(tree.name).not_nil!
           raise "Unknown function" unless entry.is_a?(FunctionEntry)
           generate! tree, entry.function, table, target, free
         when Trees::TreeBlock
           table = Table.new(table)
           tree.children.each do |child|
-            free += generate! child, table, free, free + 1
+            free += generate! child, table, THROWAWAY_REG, free
           end
         when Trees::TreeVar
-          entry = table[tree.name]?
+          entry = table.get_var? tree.name
           if entry == nil
             entry = VarEntry.new free
             free += 1
-            table[tree.name] = entry
+            table.set_var tree.name, entry
           end
-          raise "Unknown variable" unless entry.is_a?(VarEntry)
-          generate! tree.expr, table, entry.register, free
+          generate! tree.expr, table, entry.as(VarEntry).register, free
           return 1
         when Trees::TreeAssign
-          entry = table[tree.name]?
-          raise "Unknown variable" unless entry &&
-                                          entry.is_a?(VarEntry)
+          entry = table.get_var? tree.name
+          raise "Unknown variable" unless entry
           generate! tree.expr, table, entry.register, free
         when Trees::TreeIf
           generate! tree.condition, table, free, free + 1
@@ -134,7 +131,8 @@ module Chalk
           cond_jump.offset = @instructions.size - old_size + 1
           after_jump.offset = before_cond - instructions.size + 1
         when Trees::TreeReturn
-          generate! tree.rvalue, table, RETURN_REG, free
+          generate! tree.rvalue, table, free, free + 1
+          loadr RETURN_REG, free
           ret
         end
         return 0
@@ -142,7 +140,7 @@ module Chalk
 
       # Generates code for the function that was given to it.
       def generate!
-        generate!(@function.block, @table, -1, @registers)
+        generate!(@function.block, @table, 0, @registers)
         return @instructions
       end
     end

src/chalk/compiler.cr

@@ -12,7 +12,7 @@ module Chalk
       def initialize(@config : Ui::Config)
         @logger = Logger.new STDOUT
         @logger.debug("Initialized compiler")
-        @logger.level = Logger::DEBUG
+        @logger.level = @config.loglevel
       end
 
       # Reads a file an extracts instances of
@@ -33,8 +33,9 @@ module Chalk
           @logger.debug("Beginning constant folding")
           folder = Trees::ConstantFolder.new
           trees.map! do |tree|
+            next tree unless tree.is_a?(Trees::TreeFunction)
             @logger.debug("Constant folding #{tree.name}")
-            tree.apply(folder).as(Trees::TreeFunction)
+            tree.apply(folder)
           end
           @logger.debug("Done constant folding")
           return trees
@@ -48,16 +49,26 @@ module Chalk
         table = Table.new
         @logger.debug("Creating symbol table")
         trees.each do |tree|
-          @logger.debug("Storing #{tree.name} in symbol table")
-          table[tree.name] = FunctionEntry.new tree
+          case tree
+          when Trees::TreeSprite
+              @logger.debug("Storing sprite #{tree.name} in symbol table")
+              table.set_sprite tree.name, SpriteEntry.new tree.sprite
+          when Trees::TreeFunction
+              @logger.debug("Storing function #{tree.name} in symbol table")
+              table.set_function tree.name, FunctionEntry.new tree
+          else
+              @logger.debug("Unexpected tree type in input.")
+          end
         end
         @logger.debug("Done creating symbol table")
 
-        table["get_key"] = FunctionEntry.new Builtin::InlineAwaitKeyFunction.new
-        table["set_delay"] = FunctionEntry.new Builtin::InlineSetDelayFunction.new
-        table["get_delay"] = FunctionEntry.new Builtin::InlineGetDelayFunction.new
-        table["set_sound"] = FunctionEntry.new Builtin::InlineSetSoundFunction.new
-        table["draw_number"] = FunctionEntry.new Builtin::InlineDrawNumberFunction.new
+        table.set_function "get_key", FunctionEntry.new Builtin::InlineAwaitKeyFunction.new
+        table.set_function "set_delay", FunctionEntry.new Builtin::InlineSetDelayFunction.new
+        table.set_function "get_delay", FunctionEntry.new Builtin::InlineGetDelayFunction.new
+        table.set_function "set_sound", FunctionEntry.new Builtin::InlineSetSoundFunction.new
+        table.set_function "draw_number", FunctionEntry.new Builtin::InlineDrawNumberFunction.new
+        table.set_function "draw_sprite", FunctionEntry.new Builtin::InlineDrawSpriteFunction.new
+        table.set_function "clear", FunctionEntry.new Builtin::InlineClearFunction.new
         return table
       end
 
@@ -71,7 +82,7 @@ module Chalk
         @logger.debug("Generating code for #{tree.name}")
         code = generator.generate!
         code << instruction
-        return optimizer.optimize(code)
+        return code # optimizer.optimize(code)
       end
 
       # Generate code for a builtin function. Neither the *table* nor the *instruction*
@@ -93,6 +104,11 @@ module Chalk
         return code
       end
 
+      private def create_code(trees : Array(Trees::Tree), table)
+        functions = trees.select &.is_a?(Trees::TreeFunction)
+        return create_code(functions.map &.as(Trees::TreeFunction), table)
+      end
+
       # Runs in the tree `Ui::OutputMode`. The file is
       # tokenized and parsed, and the result is printed
       # to the standard output.
@@ -126,9 +142,9 @@ module Chalk
         binary = instructions.map_with_index { |it, i| it.to_bin(table, instructions.size, i).to_u16 }
         binary.each do |inst|
           first = (inst >> 8).to_u8
-          dest.write_byte(first)
+          dest << first
           second = (inst & 0xff).to_u8
-          dest.write_byte(second)
+          dest << second
         end
       end
 
@@ -143,8 +159,8 @@ module Chalk
           first = open.first
           open.delete first
 
-          entry = table[first]?
-          raise "Unknown function" unless entry && entry.is_a?(FunctionEntry)
+          entry = table.get_function? first
+          raise "Unknown function" unless entry
           function = entry.function
           next if function.is_a?(Builtin::InlineFunction)
           done << first
@@ -166,13 +182,13 @@ module Chalk
         names = collect_calls(table)
         names.delete "main"
 
-        main_entry = table["main"]?.as(FunctionEntry)
+        main_entry = table.get_function?("main").not_nil!
         all_instructions.concat create_code(main_entry.function.as(Trees::TreeFunction),
           table, Ir::JumpRelativeInstruction.new 0)
         main_entry.addr = 0
 
         names.each do |name|
-          entry = table[name]?.as(FunctionEntry)
+          entry = table.get_function?(name).not_nil!
           entry.addr = all_instructions.size
           function = entry.function
           raise "Trying to compile inlined function" if function.is_a?(Builtin::InlineFunction)
@@ -180,8 +196,22 @@ module Chalk
           all_instructions << Ir::ReturnInstruction.new
         end
 
-        file = File.open("out.ch8", "w")
-        generate_binary(table, all_instructions, file)
+        sprite_bytes = [] of UInt8
+        offset = 0
+        table.sprites.each do |k, v|
+          data = v.sprite.encode
+          v.addr = offset + all_instructions.size * 2
+          offset += data.size
+          sprite_bytes.concat data
+        end
+
+        binary = [] of UInt8
+        file = File.open(@config.output, "w")
+        generate_binary(table, all_instructions, binary)
+        binary.concat sprite_bytes
+        binary.each do |byte|
+          file.write_byte byte
+        end
         file.close
       end
 

src/chalk/config.cr

@@ -22,10 +22,20 @@ module Chalk
       getter mode : OutputMode
       # Sets the mode in which the compiler should operate.
       setter mode : OutputMode
+      # Gets the log level.
+      getter loglevel : Logger::Severity
+      # Sets the log level.
+      setter loglevel : Logger::Severity
+      # Gets the output file destination.
+      getter output : String
+      # Sets the output file destination.
+      setter output : String
 
       # Creates a new configuration.
       def initialize(@file = "",
-                     @mode = OutputMode::Tree)
+                     @mode = OutputMode::Tree,
+                     @loglevel = Logger::Severity::DEBUG,
+                     @output : String = "out.ch8")
       end
 
       # Reads a configuration from the command line options.
@@ -34,20 +44,35 @@ module Chalk
         OptionParser.parse! do |parser|
           parser.banner = "Usage: chalk [arguments]"
           parser.on("-m", "--mode=MODE", "Set the mode of the compiler.") do |mode|
-            case mode.downcase
-            when "tree", "t"
-              config.mode = OutputMode::Tree
-            when "intermediate", "i"
-              config.mode = OutputMode::Intermediate
-            when "binary", "b"
-              config.mode = OutputMode::Binary
-            else
-              puts "Invalid mode type. Using default."
-            end
+            hash = { 
+                "tree" => OutputMode::Tree,
+                "t" => OutputMode::Tree,
+                "intermediate" => OutputMode::Intermediate,
+                "i" => OutputMode::Intermediate,
+                "binary" => OutputMode::Binary,
+                "b" => OutputMode::Binary
+            }
+            puts "Invalid mode type. Using default." if !hash.has_key?(mode)
+            config.mode = hash[mode]? || OutputMode::Tree
           end
           parser.on("-f", "--file=FILE", "Set the input file to compile.") do |file|
             config.file = file
           end
+          parser.on("-o", "--output=OUT", "Sets the output file.") do |out|
+            config.output = out
+          end
+          parser.on("-l", "--log=LOG", "Set the log level of the compiler.") do |log|
+            hash = {
+                "debug" => Logger::Severity::DEBUG,
+                "fatal" => Logger::Severity::FATAL,
+                "error" => Logger::Severity::ERROR,
+                "info" => Logger::Severity::INFO,
+                "unknown" => Logger::Severity::UNKNOWN,
+                "warn" => Logger::Severity::WARN
+            }
+            puts "Invalid log level. Using default." if !hash.has_key?(log)
+            config.loglevel = hash[log]? || Logger::Severity::DEBUG
+          end
           parser.on("-h", "--help", "Show this message.") { puts parser }
         end
         return config

src/chalk/emitter.cr

@@ -4,6 +4,8 @@ module Chalk
     RETURN_REG = 14
     # The register into which the "stack pointer" is stored.
     STACK_REG  = 13
+    # Register used for throwing away values.
+    THROWAWAY_REG = 12
 
     # Module to emit instructions and store
     # them into an existing array.

src/chalk/inline.cr

@@ -81,5 +81,31 @@ module Chalk
           return Compiler::FunctionType.new([Compiler::Type::U8] * 3, Compiler::Type::U0)
       end
     end
+
+    class InlineDrawSpriteFunction < InlineFunction
+      def generate!(emitter, params, table, target, free)
+        raise "First parameter should be a sprite name." if !params[0].is_a?(Trees::TreeId)
+        sprite_name = params[0].as(Trees::TreeId).id
+        sprite = table.get_sprite?(sprite_name).not_nil!.sprite
+        emitter.generate! params[1], table, free, free + 1
+        emitter.generate! params[2], table, free + 1, free + 2
+        emitter.instructions << Ir::SetISpriteInstruction.new params[0].as(Trees::TreeId).id
+        emitter.instructions << Ir::DrawInstruction.new free, free + 1, sprite.height.to_i32
+      end
+
+      def type
+          return Compiler::FunctionType.new([Compiler::Type::U8] * 3, Compiler::Type::U0)
+      end
+    end
+
+    class InlineClearFunction < InlineFunction
+      def generate!(emitter, params, table, target, free)
+        emitter.instructions << Ir::ClearInstruction.new
+      end
+
+      def type
+          return Compiler::FunctionType.new(([] of Compiler::Type), Compiler::Type::U0)
+      end
+    end
   end
 end

src/chalk/ir.cr

@@ -282,7 +282,7 @@ module Chalk
       end
 
       def to_bin(table, stack, index)
-        return 0x2000 | (table[name]?.as(Compiler::FunctionEntry).addr * 2 + 0x200)
+          return 0x2000 | (table.get_function?(name).as(Compiler::FunctionEntry).addr * 2 + 0x200)
       end
     end
 
@@ -297,6 +297,21 @@ module Chalk
       end
     end
 
+    class SetISpriteInstruction < Instruction
+      getter name
+
+      def initialize(@name : String)
+      end
+
+      def to_s(io)
+        io << "setispr " << @name
+      end
+      
+      def to_bin(table, stack, index)
+        return 0xa000 | (table.get_sprite?(@name).not_nil!.addr + 0x200)
+      end
+    end
+
     # Instruction to add a register to I.
     class AddIRegInstruction < Instruction
       def initialize(@reg : Int32)

src/chalk/lexer.cr

@@ -7,6 +7,7 @@ module Chalk
       Any,
       Str,
       Id,
+      SpriteRow,
       LitDec,
       LitBin,
       LitHex,
@@ -54,6 +55,8 @@ module Chalk
           TokenType::Str.value)
         @lexer.add_pattern("[a-zA-Z_][a-zA-Z_0-9]*",
           TokenType::Id.value)
+        @lexer.add_pattern("`[ x]*`",
+          TokenType::SpriteRow.value)
         @lexer.add_pattern("[0-9]+",
           TokenType::LitDec.value)
         @lexer.add_pattern("0b[0-1]+",

src/chalk/parser.cr

@@ -6,6 +6,20 @@ module Chalk
     class Parser
       include ParserBuilder
 
+      private def create_sprite
+        type(Compiler::TokenType::KwSprite)
+            .then(type(Compiler::TokenType::Id))
+            .then(char('['))
+            .then(many(type(Compiler::TokenType::SpriteRow)))
+            .then(char(']'))
+            .transform do |array|
+            array = array.flatten
+            name = array[1].string
+            sprite = Compiler::Sprite.new(array[3..array.size - 2].map &.string)
+            Trees::TreeSprite.new(name, sprite).as(Trees::Tree)
+        end
+      end
+
       # Creates a parser for a type.
       private def create_type
         either(type(Compiler::TokenType::KwU0),
@@ -185,14 +199,14 @@ module Chalk
                 Compiler::TokenType::KwU8 => Compiler::Type::U8,
                 Compiler::TokenType::KwU12 => Compiler::Type::U12
             }
-            Trees::TreeFunction.new(name, params, table[type], code)
+            Trees::TreeFunction.new(name, params, table[type], code).as(Trees::Tree)
           end
         return func
       end
 
       def initialize
         _, block = create_statement_block
-        @parser = many(create_func(block, create_type)).as(BasicParser(Array(Trees::TreeFunction)))
+        @parser = many(either(create_func(block, create_type), create_sprite)).as(BasicParser(Array(Trees::Tree)))
       end
 
       # Parses the given tokens into a tree.

src/chalk/sprite.cr

@@ -0,0 +1,97 @@
+module Chalk
+  module Compiler
+    class Sprite
+      def initialize
+        @pixels = Hash(UInt8, UInt8).new(default_value: 0_u8)
+      end
+
+      def height
+        return (@pixels.keys.max || 0_u8) + 1
+      end
+
+      def initialize(string, blank_char = ' ')
+        @pixels = Hash(UInt8, UInt8).new(default_value: 0_u8)
+        string.split("\n").each_with_index do |s, i|
+          break if i > 15
+          index = 0
+          byte = 0_u8
+          s.each_char do |char|
+            break if index > 7
+            bit = (char == blank_char) ? 0_u8 : 1_u8
+            byte |= (bit << (7 - index))
+            index += 1
+          end
+          @pixels[i.to_u8] = byte
+        end
+      end
+      
+      def initialize(tokens)
+          raise "Invalid sprite" if tokens.size > 15
+          @pixels = Hash(UInt8, UInt8).new(default_value: 0_u8)
+          tokens.each_with_index do |token, i|
+            byte = 0_u8
+            substring = token[1..token.size - 2]
+            raise "Invalid sprite" if substring.size > 8
+            bit = 0b10000000
+            substring.each_char do |char|
+                byte |= bit if char == 'x'
+                bit >>= 1
+            end
+            @pixels[i.to_u8] = byte
+          end
+      end
+
+      def set_pixel(x, y)
+        raise "Invalid x-coordinate" if x > 7
+        raise "Invalid y-coordinate" if y > 15
+        x = x.to_u8
+        y = y.to_u8
+        char = @pixels.fetch y, 0_u8
+        char |= (1 << (7 - x))
+        @pixels[y] = char
+      end
+
+      def unset_pixel(x, y)
+        raise "Invalid x-coordinate" if x > 7
+        raise "Invalid y-coordinate" if y > 15
+        x = x.to_u8
+        y = y.to_u8
+        char = @pixels.fetch y, 0_u8
+        char &= ~(1 << (7 - x))
+        @pixels[y] = char
+      end
+
+      def toggle_pixel(x, y)
+        raise "Invalid x-coordinate" if x > 7
+        raise "Invalid y-coordinate" if y > 15
+        x = x.to_u8
+        y = y.to_u8
+        char = @pixels.fetch y, 0_u8
+        char ^= (1 << (7 - x))
+        @pixels[y] = char
+      end
+
+      def draw(io = STDOUT, blank_char = ' ', ink_char = 'x')
+        until_y = @pixels.keys.max?
+        return unless until_y
+        (0..until_y).each do |y|
+          row = @pixels.fetch y, 0_u8
+          pointer = 0b10000000
+          while pointer != 0
+            draw_pixel = (row & pointer) != 0
+            io << (draw_pixel ? ink_char : blank_char)
+            pointer = pointer >> 1
+          end
+          io << '\n'
+        end
+      end
+
+      def encode
+        if until_y = @pixels.keys.max?
+          return (0..until_y).map { |it| @pixels.fetch it, 0_u8 }
+        end
+        return [0_u8]
+      end
+    end
+  end
+end

src/chalk/table.cr

@@ -1,11 +1,9 @@
+require "./sprite.cr"
+
 module Chalk
   module Compiler
-    # An entry in the symbol table.
-    class Entry
-    end
-
     # An entry that represents a function in the symbol table.
-    class FunctionEntry < Entry
+    class FunctionEntry
       # Gets the function stored in this entry.
       getter function
       # Gets the address in code of this function.
@@ -23,7 +21,7 @@ module Chalk
     end
 
     # An entry that represents a variable in the symbol table.
-    class VarEntry < Entry
+    class VarEntry
       # Gets the register occupied by the variable
       # in this entry.
       getter register
@@ -36,32 +34,47 @@ module Chalk
       end
     end
 
+    class SpriteEntry
+      property sprite : Sprite
+      property addr : Int32
+
+      def initialize(@sprite, @addr = -1)
+      end
+    end
+
     # A symbol table.
     class Table
       # Gets the parent of this table.
       getter parent
+      # Gets the functions hash.
+      getter functions
+      # Gets the variables hash.
+      getter vars
+      # Gets the sprites hash.
+      getter sprites
 
       def initialize(@parent : Table? = nil)
-        @data = {} of String => Entry
+        @functions = {} of String => FunctionEntry
+        @vars = {} of String => VarEntry
+        @sprites = {} of String => SpriteEntry
       end
 
-      # Looks up the given *key* first in this table,
-      # then in its parent, continuing recursively.
-      def []?(key)
-        if entry = @data[key]?
-          return entry
-        end
-        return @parent.try &.[key]?
+      macro table_functions(name)
+          def get_{{name}}?(key)
+             @{{name}}s[key]? || @parent.try &.get_{{name}}?(key)
+          end
+
+          def set_{{name}}(key, value)
+             @{{name}}s[key] = value
+          end
       end
 
-      # Stores an *entry* under the given *key* into this table.
-      def []=(key, entry)
-        @data[key] = entry
-      end
+      table_functions function
+      table_functions var
+      table_functions sprite
 
       def to_s(io)
         @parent.try &.to_s(io)
-        io << @data.map { |k, v| k + ": " + v.to_s }.join("\n")
       end
     end
   end

src/chalk/tree.cr

@@ -296,5 +296,13 @@ module Chalk
         r.reduce(self, [@rvalue.reduce(r)])
       end
     end
+
+    class TreeSprite < Tree
+        property name : String
+        property sprite : Compiler::Sprite
+
+        def initialize(@name, @sprite)
+        end
+    end
   end
 end

src/chalk/typecheck.cr

@@ -12,8 +12,8 @@ module Chalk
             end
 
             def reduce(t : TreeCall, children)
-                entry = @table[t.name]?
-                raise "Unknwon function" unless entry && entry.is_a?(Compiler::FunctionEntry)
+                entry = @table.get_function? t.name
+                raise "Unknwon function" unless entry
                 type = entry.function.type
                 raise "Invalid parameters" if type.param_types.size != children.size
                 children.each_with_index do |child, i|

src/test.cr

@@ -0,0 +1,25 @@
+require "./chalk/*"
+
+module Chalk
+    regex = /([^.]+)\.chalk/
+    source_dir = "programs"
+    dest_dir = "out"
+
+    Dir.mkdir_p dest_dir
+    exit if !File.directory? source_dir
+    Dir.new(source_dir)
+        .children
+        .compact_map { |it| regex.match(it) }
+        .each do |match|
+        config = Ui::Config.new file: (source_dir + File::SEPARATOR + match[0]),
+                                output:  (dest_dir + File::SEPARATOR + match[1] + ".ch8"),
+                                loglevel: Logger::Severity::ERROR,
+                                mode: Ui::OutputMode::Binary
+        compiler = Compiler::Compiler.new config
+        begin
+            compiler.run
+        rescue e
+            puts "Exception compiling #{match[0]}"
+        end
+    end
+end