Implement if-else

4 files changed, 1859 insertions, 84 deletions

diff --git a/Rakefile b/Rakefile
index 32157d0..a772900 100644
--- a/Rakefile
+++ b/Rakefile
@@ -6,7 +6,9 @@
 require 'open3'
 require 'rake/clean'
 
-STAGES = Dir.glob('boot/stage*.elna').collect { |stage| File.basename stage, '.elna' }.sort
+STAGES = Dir.glob('boot/stage*.elna')
+  .collect { |stage| File.basename stage, '.elna' }
+  .sort { |a, b| a.delete_prefix('stage').to_i <=> b.delete_prefix('stage').to_i }
 
 CLEAN.include 'build/boot', 'build/valid'
 
@@ -39,17 +41,9 @@ end
 
 desc 'Convert previous stage language into the current stage language'
 task :convert do
-  File.open('boot/stage9.elna', 'w') do |current_stage|
-    File.readlines('boot/stage8.elna').each do |line|
-      comment_match = /^(\s*)#(.*)/.match line
-
-      if comment_match.nil?
-        current_stage << line
-      elsif comment_match[2].empty?
-        current_stage << "\n"
-      else
-        current_stage << "#{comment_match[1]}(* #{comment_match[2].strip} *)\n"
-      end
+  File.open('boot/stage10.elna', 'w') do |current_stage|
+    File.readlines('boot/stage9.elna').each do |line|
+      current_stage << line
     end
   end
 end
diff --git a/boot/stage10.elna b/boot/stage10.elna
new file mode 100644
index 0000000..da96da7
--- /dev/null
+++ b/boot/stage10.elna
@@ -0,0 +1,1722 @@
+(* This Source Code Form is subject to the terms of the Mozilla Public License, *)
+(* v. 2.0. If a copy of the MPL was not distributed with this file, You can *)
+(* obtain one at https://mozilla.org/MPL/2.0/. *)
+
+(* Stage 10 compiler. *)
+
+const
+	symbol_builtin_name_int := "Int";
+	symbol_builtin_name_word := "Word";
+	symbol_builtin_name_pointer := "Pointer";
+	symbol_builtin_name_char := "Char";
+	symbol_builtin_name_bool := "Bool";
+
+	(* Every type info starts with a word describing what type it is. *)
+
+	(* PRIMITIVE_TYPE = 1 *)
+
+	(* Primitive types have only type size. *)
+	symbol_builtin_type_int := S(1, 4);
+	symbol_builtin_type_word := S(1, 4);
+	symbol_builtin_type_pointer := S(1, 4);
+	symbol_builtin_type_char := S(1, 1);
+	symbol_builtin_type_bool := S(1, 1);
+
+	(* Info objects start with a word describing its type. *)
+
+	(* INFO_TYPE = 1 *)
+
+	(* Type info has the type it belongs to. *)
+	symbol_type_info_int := S(1, @symbol_builtin_type_int);
+	symbol_type_info_word := S(1, @symbol_builtin_type_word);
+	symbol_type_info_pointer := S(1, @symbol_builtin_type_pointer);
+	symbol_type_info_char := S(1, @symbol_builtin_type_char);
+	symbol_type_info_bool := S(1, @symbol_builtin_type_bool);
+
+var
+	source_code: Array;
+	compiler_strings: Array;
+	symbol_table_global: Array;
+	symbol_table_local: Array;
+	classification: Array;
+
+	compiler_strings_position: Pointer := @compiler_strings;
+	compiler_strings_length: Word := 0;
+	label_counter: Word := 0;
+	source_code_position: Pointer := @source_code;
+
+(* Calculates and returns the string token length between quotes, including the *)
+(* escaping slash characters. *)
+
+(* Parameters: *)
+(* a0 - String token pointer. *)
+
+(* Returns the length in a0. *)
+proc _string_length();
+begin
+	(* Reset the counter. *)
+	v0 := 0;
+
+.string_length_loop:
+	v88 := v88 + 1;
+
+	if _load_byte(v88) <> '"' then
+		v0 := v0 + 1;
+		goto .string_length_loop;
+	end;
+
+	return v0
+end;
+
+(* Adds a string to the global, read-only string storage. *)
+
+(* Parameters: *)
+(* a0 - String token. *)
+
+(* Returns the offset from the beginning of the storage to the new string in a0. *)
+proc _add_string();
+begin
+	v0 := v88 + 1;
+	v4 := compiler_strings_length;
+
+.add_string_loop:
+	if _load_byte(v0) <> '"' then
+		v8 := _load_byte(v0);
+		_store_byte(v8, compiler_strings_position);
+		_store_word(compiler_strings_position + 1, @compiler_strings_position);
+		v0 := v0 + 1;
+
+		if v8 <> '\\' then
+			_store_word(compiler_strings_length + 1, @compiler_strings_length);
+		end;
+		goto .add_string_loop;
+	end;
+
+	return v4
+end;
+
+(* Reads standard input into a buffer. *)
+(* a0 - Buffer pointer. *)
+(* a1 - Buffer size. *)
+
+(* Returns the amount of bytes written in a0. *)
+proc _read_file();
+begin
+	_syscall(0, v88, v84, 0, 0, 0, 63);
+end;
+
+(* Writes to the standard output. *)
+
+(* Parameters: *)
+(* a0 - Buffer. *)
+(* a1 - Buffer length. *)
+proc _write_s();
+begin
+	_syscall(1, v88, v84, 0, 0, 0, 64);
+end;
+
+(* Writes a number to a string buffer. *)
+
+(* t0 - Local buffer. *)
+(* t1 - Constant 10. *)
+(* t2 - Current character. *)
+(* t3 - Whether the number is negative. *)
+
+(* Parameters: *)
+(* a0 - Whole number. *)
+(* a1 - Buffer pointer. *)
+
+(* Sets a0 to the length of the written number. *)
+proc _print_i();
+begin
+	li t1, 10
+	addi t0, s0, -9
+
+	li t3, 0
+	bgez a0, .print_i_digit10
+	li t3, 1
+	neg a0, a0
+
+.print_i_digit10:
+	rem t2, a0, t1
+	addi t2, t2, '0'
+	sb t2, 0(t0)
+	div a0, a0, t1
+	addi t0, t0, -1
+	bne zero, a0, .print_i_digit10
+
+	beq zero, t3, .print_i_write_call
+	addi t2, zero, '-'
+	sb t2, 0(t0)
+	addi t0, t0, -1
+
+.print_i_write_call:
+	mv a0, a1
+	addi a1, t0, 1
+	sub a2, s0, t0
+	addi a2, a2, -9
+	sw a2, 0(sp)
+
+	_memcpy();
+
+	return v0
+end;
+
+(* Writes a number to the standard output. *)
+
+(* Parameters: *)
+(* a0 - Whole number. *)
+proc _write_i();
+begin
+	v4 := _print_i(v88, @v0);
+	_write_s(@v0, v4);
+end;
+
+(* Writes a character from a0 into the standard output. *)
+proc _write_c();
+begin
+	_write_s(@v88, 1);
+end;
+
+(* Write null terminated string. *)
+
+(* Parameters: *)
+(* a0 - String. *)
+proc _write_z();
+begin
+	(* Check for 0 character. *)
+	v0 := _load_byte(v88);
+
+	if v0 <> 0 then
+		(* Print a character. *)
+		_write_c(v0);
+
+		(* Advance the input string by one byte. *)
+		_write_z(v88 + 1);
+	end;
+end;
+
+(* Detects if a0 is an uppercase character. Sets a0 to 1 if so, otherwise to 0. *)
+proc _is_upper();
+begin
+	v0 := v88 >= 'A';
+	v4 := v88 <= 'Z';
+
+	return v0 & v4
+
+end;
+
+(* Detects if a0 is an lowercase character. Sets a0 to 1 if so, otherwise to 0. *)
+proc _is_lower();
+begin
+	v0 := v88 >= 'a';
+	v4 := v88 <= 'z';
+
+	return v0 & v4
+
+end;
+
+(* Detects if the passed character is a 7-bit alpha character or an underscore. *)
+
+(* Paramters: *)
+(* a0 - Tested character. *)
+
+(* Sets a0 to 1 if the character is an alpha character or underscore, sets it to 0 otherwise. *)
+proc _is_alpha();
+begin
+	v0 := _is_upper(v88);
+	v4 := _is_lower(v88);
+	v8 := v88 = '_';
+
+	v12 := v0 or v4;
+	return v12 or v8
+end;
+
+(* Detects whether the passed character is a digit *)
+(* (a value between 0 and 9). *)
+
+(* Parameters: *)
+(* a0 - Exemined value. *)
+
+(* Sets a0 to 1 if it is a digit, to 0 otherwise. *)
+proc _is_digit();
+begin
+	v0 := v88 >= '0';
+	v4 := v88 <= '9';
+
+	return v0 & v4
+end;
+
+proc _is_alnum();
+begin
+	v0 := _is_alpha(v88);
+	v4 := _is_digit(v88);
+
+	return v0 or v4
+end;
+
+(* Reads the next token. *)
+
+(* Returns token length in a0. *)
+proc _read_token();
+begin
+	(* Current token position. *)
+	v0 := source_code_position;
+	(* Token length. *)
+	v4 := 0;
+
+.read_token_loop:
+	(* Current character. *)
+	v8 := _load_byte(v0);
+
+	(* First we try to read a derictive. *)
+	(* A derictive can contain a dot and characters. *)
+	v12 := v8 = '.';
+	v16 := _is_alnum(v8);
+
+	if v12 or v16 then
+		(* Advance the source code position and token length. *)
+		v4 := v4 + 1;
+		v0 := v0 + 1;
+
+		goto .read_token_loop;
+	end;
+
+	return v4
+end;
+
+(* a0 - First pointer. *)
+(* a1 - Second pointer. *)
+(* a2 - The length to compare. *)
+
+(* Returns 0 in a0 if memory regions are equal. *)
+proc _memcmp();
+begin
+	v8 := 0;
+
+.memcmp_loop:
+	if v80 <> 0 then
+		v0 := _load_byte(v88);
+		v4 := _load_byte(v84);
+		v8 := v0 + -v4;
+
+		v88 := v88 + 1;
+		v84 := v84 + 1;
+		v80 := v80 + -1;
+
+		if v8 = 0 then
+			goto .memcmp_loop;
+		end;
+	end;
+
+	return v8
+end;
+
+(* Copies memory. *)
+
+(* Parameters: *)
+(* a0 - Destination. *)
+(* a1 - Source. *)
+(* a2 - Size. *)
+
+(* Preserves a0. *)
+proc _memcpy();
+begin
+.memcpy_loop:
+	if v80 <> 0 then
+		v0 := _load_byte(v84);
+		_store_byte(v0, v88);
+
+		v88 := v88 + 1;
+		v84 := v84 + 1;
+		v80 := v80 + -1;
+		goto .memcpy_loop;
+	end;
+
+	return v88
+end;
+
+(* Advances the token stream by a0 bytes. *)
+proc _advance_token();
+begin
+	_store_word(source_code_position + v88, @source_code_position);
+end;
+
+(* Prints the current token. *)
+
+(* Parameters: *)
+(* a0 - Token length. *)
+
+(* Returns a0 unchanged. *)
+proc _write_token();
+begin
+	_write_s(source_code_position, v88);
+	return v88
+end;
+
+(* Prints and skips a line. *)
+proc _compile_line();
+begin
+.compile_line_loop:
+	v0 := _load_byte(source_code_position);
+
+	if v0 <> '\n' then
+		(* Print a character. *)
+		_write_c(v0);
+
+		(* Advance the input string by one byte. *)
+		_advance_token(1);
+
+		goto .compile_line_loop;
+	end;
+
+.compile_line_end:
+	_write_c('\n');
+	_advance_token(1);
+end;
+
+proc _compile_integer_literal();
+begin
+	_write_z("\tli t0, \0");
+
+	v0 := _read_token();
+	_write_token(v0);
+	_advance_token(v0);
+
+	_write_c('\n');
+end;
+
+proc _compile_character_literal();
+begin
+	_write_z("\tli t0, \0");
+
+	_write_c('\'');
+	_advance_token(1);
+
+	v0 := _load_byte(source_code_position);
+	if v0 = '\\' then
+		_write_c('\\');
+		_advance_token(1);
+	end;
+
+	v0 := _load_byte(source_code_position);
+	_write_c(v0);
+
+	_write_c('\'');
+	_write_c('\n');
+
+	_advance_token(2);
+end;
+
+proc _compile_variable_expression();
+begin
+	_compile_designator();
+	_write_z("\tlw t0, (t0)\n\0");
+end;
+
+proc _compile_address_expression();
+begin
+	(* Skip the "@" sign. *)
+	_advance_token(1);
+	_compile_designator();
+end;
+
+proc _compile_negate_expression();
+begin
+	(* Skip the "-" sign. *)
+	_advance_token(1);
+	_compile_term();
+
+	_write_z("\tneg t0, t0\n\0");
+end;
+
+proc _compile_not_expression();
+begin
+	(* Skip the "~" sign. *)
+	_advance_token(1);
+	_compile_term();
+
+	_write_z("\tnot t0, t0\n\0");
+end;
+
+proc _compile_string_literal();
+begin
+	v0 := _string_length(source_code_position);
+	v4 := _add_string(source_code_position);
+
+	_advance_token(v0 + 2);
+	_write_z("\tla t0, strings\n\0");
+
+	_write_z("\tli t1, \0");
+	_write_i(v4);
+	_write_c('\n');
+
+	_write_z("\tadd t0, t0, t1\n\0");
+end;
+
+proc _compile_term();
+begin
+	v0 := _load_byte(source_code_position);
+
+	if v0 = '\'' then
+		_compile_character_literal();
+	end;
+	if v0 = '@' then
+		_compile_address_expression();
+	end;
+	if v0 = '-' then
+		_compile_negate_expression();
+	end;
+	if v0 = '~' then
+		_compile_not_expression();
+	end;
+	if v0 = '"' then
+		_compile_string_literal();
+	end;
+	if v0 = '_' then
+		_compile_call();
+		_write_z("\nmv t0, a0\n\0");
+	end;
+	if _is_digit(v0) = 1 then
+		_compile_integer_literal();
+	end;
+	if _is_lower(v0) = 1 then
+		_compile_variable_expression();
+	end;
+end;
+
+proc _compile_binary_rhs();
+begin
+	(* Skip the whitespace after the binary operator. *)
+	_advance_token(1);
+	_compile_term();
+
+	(* Load the left expression from the stack; *)
+	_write_z("\tlw t1, 24(sp)\n\0");
+end;
+
+proc _compile_expression();
+begin
+	_compile_term();
+	v0 := _load_byte(source_code_position);
+
+	if v0 <> ' ' then
+		goto .compile_expression_end;
+	end;
+	(* It is a binary expression. *)
+
+	(* Save the value of the left expression on the stack. *)
+	_write_z("sw t0, 24(sp)\n\0");
+
+	(* Skip surrounding whitespace in front of the operator. *)
+	_advance_token(1);
+	v0 := _load_byte(source_code_position);
+
+	if v0 = '+' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("add t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = '*' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("\tmul t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = '&' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("\tand t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = 'o' then
+		_advance_token(2);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("or t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = 'x' then
+		_advance_token(3);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("xor t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = '=' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("xor t0, t0, t1\nseqz t0, t0\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = '<' then
+		_advance_token(1);
+		v0 := _load_byte(source_code_position);
+
+		if v0 = '>' then
+			_advance_token(1);
+			_compile_binary_rhs();
+
+			(* Execute the operation. *)
+			_write_z("\txor t0, t0, t1\nsnez t0, t0\n\0");
+
+			goto .compile_expression_end;
+		end;
+		if v0 = '=' then
+			_advance_token(1);
+			_compile_binary_rhs();
+
+			(* Execute the operation. *)
+			_write_z("\tslt t0, t0, t1\nxori t0, t0, 1\n\0");
+
+			goto .compile_expression_end;
+		end;
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("slt t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if v0 = '>' then
+		_advance_token(1);
+		v0 := _load_byte(source_code_position);
+		if v0 = '=' then
+			li t1, '='
+			_advance_token(1);
+			_compile_binary_rhs();
+
+			(* Execute the operation. *)
+			_write_z("\tslt t0, t1, t0\nxori t0, t0, 1\n\0");
+
+			goto .compile_expression_end;
+		end;
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("\tslt t0, t1, t0\n\0");
+
+		goto .compile_expression_end;
+	end;
+
+.compile_expression_end:
+end;
+
+proc _compile_call();
+begin
+	(* Stack variables: *)
+	(* v0 - Procedure name length. *)
+	(* v4 - Procedure name pointer. *)
+	(* v8 - Argument count. *)
+
+	v0 := _read_token();
+	v4 := source_code_position;
+	v8 := 0;
+
+	(* Skip the identifier and left paren. *)
+	_advance_token(v0 + 1);
+	v12 := _load_byte(source_code_position);
+
+	if v12 = ')' then
+		goto .compile_call_finalize
+	end;
+.compile_call_loop:
+	_compile_expression();
+
+	(* Save the argument on the stack. *)
+	_write_z("\tsw t0, \0");
+
+	(* Calculate the stack offset: 116 - (4 * argument_counter) *)
+	v12 := v8 * 4;
+	v12 := 116 + -v12;
+	_write_i(v12);
+
+	_write_z("(sp)\n\0");
+
+	(* Add one to the argument counter. *)
+	v8 := v8 + 1;
+
+	v12 := _load_byte(source_code_position);
+
+	if v12 <> ',' then
+		goto .compile_call_finalize;
+	end;
+	_advance_token(2);
+	goto .compile_call_loop;
+
+.compile_call_finalize:
+	(* Load the argument from the stack. *)
+	if v8 <> 0 then
+		(* Decrement the argument counter. *)
+		v8 := v8 + -1;
+
+		_write_z("\tlw a\0");
+		_write_i(v8);
+
+		_write_z(", \0");
+
+		(* Calculate the stack offset: 116 - (4 * argument_counter) *)
+		v12 := v8 * 4;
+		v12 := 116 + -v12;
+		_write_i(v12);
+
+		_write_z("(sp)\n\0");
+
+		goto .compile_call_finalize;
+	end;
+
+.compile_call_end:
+	_write_z("\tcall \0");
+	_write_s(v4, v0);
+
+	(* Skip the right paren. *)
+	_advance_token(1);
+end;
+
+proc _compile_goto();
+begin
+	_advance_token(5);
+
+	v0 := _read_token();
+	_write_z("\tj \0");
+
+	_write_token(v0);
+	_advance_token();
+end;
+
+proc _compile_local_designator();
+begin
+	(* Skip "v" in the local variable name. *)
+	_advance_token(1);
+	_write_z("\t addi t0, sp, \0");
+
+	(* Read local variable stack offset and save it. *)
+	v0 := _read_token();
+	_write_token(v0);
+	_advance_token(v0);
+	_write_c('\n');
+end;
+
+proc _compile_global_designator();
+begin
+	_write_z("\tla t0, \0");
+
+	v0 := _read_token();
+	_write_token(v0);
+	_advance_token(v0);
+
+	_write_c('\n');
+end;
+
+proc _compile_designator();
+begin
+	if _load_byte(source_code_position) = 'v' then
+		_compile_local_designator();
+	else
+		_compile_global_designator();
+	end;
+end;
+
+proc _compile_assignment();
+begin
+	_compile_designator();
+
+	(* Save the assignee address on the stack. *)
+	_write_z("\tsw t0, 20(sp)\n\0");
+
+	(* Skip the assignment sign (:=) with surrounding whitespaces. *)
+	_advance_token(4);
+
+	(* Compile the assignment. *)
+	_compile_expression();
+
+	_write_z("\tlw t1, 20(sp)\nsw t0, (t1)\n\0");
+end;
+
+proc _compile_return_statement();
+begin
+	(* Skip "return" keyword and whitespace after it. *)
+	_advance_token(7);
+	_compile_expression();
+
+	_write_z("mv a0, t0\n\0");
+end;
+
+(* Writes a label, .Ln, where n is a unique number. *)
+
+(* Parameters: *)
+(* a0 - Label counter. *)
+proc _write_label();
+begin
+	_write_z(".L\0");
+	_write_i(v88);
+end;
+
+proc _compile_if();
+begin
+	(* Skip "if ". *)
+	_advance_token(3);
+	(* Compile condition. *)
+	_compile_expression();
+	(* Skip " then" with newline. *)
+	_advance_token(6);
+
+	(* v0 is the label after the if statement. *)
+	v0 := label_counter;
+	_store_word(label_counter + 1, @label_counter);
+	(* v4 is the label in front of the next elsif condition or end. *)
+	v4 := label_counter;
+	_store_word(label_counter + 1, @label_counter);
+
+	_write_z("\tbeqz t0, \0");
+	_write_label(v4);
+	_write_c('\n');
+
+	_compile_procedure_body();
+
+	_write_z("\tj \0");
+	_write_label(v0);
+	_write_c('\n');
+
+	_write_label(v4);
+	_write_z(":\n\0");
+
+	_memcmp(source_code_position, "end", 3);
+	beqz a0, .compile_if_end
+
+	_memcmp(source_code_position, "else", 3);
+	beqz a0, .compile_if_else
+
+.compile_if_else:
+	(* Skip "else" and newline. *)
+	_advance_token(5);
+	_compile_procedure_body();
+
+.compile_if_end:
+	(* Skip "end". *)
+	_advance_token(3);
+
+	_write_label(v0);
+	_write_z(":\n\0");
+end;
+
+proc _compile_statement();
+begin
+	_skip_spaces();
+	v0 := _load_byte(source_code_position);
+
+	(* This is a call if the statement starts with an underscore. *)
+	if v0 = '_' then
+		_compile_call();
+		goto .compile_statement_semicolon;
+	end;
+	if v0 = 'g' then
+		_compile_goto();
+		goto .compile_statement_semicolon;
+	end;
+	if v0 = 'v' then
+		_compile_assignment();
+		goto .compile_statement_semicolon;
+	end;
+	if v0 = 'i' then
+		_compile_if();
+		goto .compile_statement_semicolon;
+	end;
+	if _memcmp(source_code_position, "return", 6) = 0 then
+		_compile_return_statement();
+		_write_c('\n');
+
+		goto .compile_statement_end;
+	end;
+	_compile_line();
+	goto .compile_statement_end;
+
+.compile_statement_semicolon:
+	_advance_token(2);
+	_write_c('\n');
+
+.compile_statement_end:
+end;
+
+proc _compile_procedure_body();
+begin
+.compile_procedure_body_loop:
+	_skip_empty_lines();
+	_skip_spaces();
+
+	v0 := _memcmp(source_code_position, "end", 3) = 0;
+	v4 := _memcmp(source_code_position, "else", 4) = 0;
+	v4 := v0 or v4;
+
+	if v4 = 0 then
+		_compile_statement();
+		goto .compile_procedure_body_loop;
+	end;
+end;
+
+(* Writes a regster name to the standard output. *)
+
+(* Parameters: *)
+(* a0 - Register character. *)
+(* a1 - Register number. *)
+proc _write_register();
+begin
+	_write_c(v88);
+	v84 := v84 + '0';
+	_write_c(v84);
+end;
+
+proc _compile_procedure_prologue();
+begin
+	_write_z("\taddi sp, sp, -128\n\tsw ra, 124(sp)\n\tsw s0, 120(sp)\n\taddi s0, sp, 128\n\0");
+	v0 := 0;
+
+.compile_procedure_prologue_loop:
+	_write_z("\tsw a\0");
+	_write_i(v0);
+	_write_z(", \0");
+
+	(* Calculate the stack offset: 88 - (4 * parameter_counter) *)
+	v4 := v0 * 4;
+	v4 := 88 + -v4;
+	_write_i(v4);
+
+	_write_z("(sp)\n\0");
+
+	v0 := v0 + 1;
+	if v0 <> 8 then
+		goto .compile_procedure_prologue_loop;
+	end;
+end;
+
+proc _compile_procedure();
+begin
+	(* Skip "proc ". *)
+	_advance_token(5);
+
+	(* Save the procedure name length. *)
+	v0 := _read_token();
+
+	(* Write .type _procedure_name, @function. *)
+	_write_z(".type \0");
+
+	_write_token(v0);
+	_write_z(", @function\n\0");
+
+	(* Write procedure label, _procedure_name: *)
+	_write_token(v0);
+	_write_z(":\n\0");
+
+	(* Skip the function name and trailing parens, semicolon, "begin" and newline. *)
+	_advance_token(v0 + 10);
+
+	_compile_procedure_prologue();
+	_compile_procedure_body();
+
+	(* Write the epilogue. *)
+	_write_z("\tlw ra, 124(sp)\n\tlw s0, 120(sp)\n\taddi sp, sp, 128\n\tret\n\0");
+
+	(* Skip the "end" keyword, semicolon and newline. *)
+	_advance_token(5);
+end;
+
+proc _skip_spaces();
+begin
+	v0 := _load_byte(source_code_position);
+	if v0 = '\t' then
+		_advance_token(1);
+		_skip_spaces();
+	end;
+end;
+
+(* Prints and skips a line. *)
+proc _skip_comment();
+begin
+.skip_comment_loop:
+	v0 := _load_byte(source_code_position);
+
+	(* Check for newline character. *)
+	if v0 <> '\n' then
+		(* Advance the input string by one byte. *)
+		_advance_token(1);
+
+		goto .skip_comment_loop;
+	end;
+	(* Skip the newline. *)
+	_advance_token(1);
+end;
+
+(* Skip newlines and comments. *)
+proc _skip_empty_lines();
+begin
+.skip_empty_lines_rerun:
+	v0 := source_code_position;
+
+.skip_empty_lines_loop:
+	v4 := _load_byte(v0);
+
+	if v4 = '\n' then
+		goto .skip_empty_lines_newline;
+	end;
+	if v4 = '\t' then
+		goto .skip_empty_lines_tab;
+	end;
+	if v4 <> '(' then
+		goto .skip_empty_lines_end;
+	end;
+	v4 := v0 + 1;
+
+	if _load_byte(v4) = '*' then
+		goto .skip_empty_lines_comment
+	end;
+	goto .skip_empty_lines_end;
+
+.skip_empty_lines_comment:
+	_store_word(v0, @source_code_position);
+	_skip_comment();
+	goto .skip_empty_lines_rerun;
+
+.skip_empty_lines_newline:
+	_store_word(v0 + 1, @source_code_position);
+	goto .skip_empty_lines_rerun;
+
+.skip_empty_lines_tab:
+	v0 := v0 + 1;
+	goto .skip_empty_lines_loop
+
+.skip_empty_lines_end:
+end;
+
+proc _compile_global_initializer();
+begin
+	v0 := _load_byte(source_code_position);
+
+	if v0 = '"' then
+		_write_z("\n\t.word strings + \0");
+		v4 := _string_length(source_code_position);
+
+		_add_string(source_code_position);
+		_write_i();
+
+		(* Skip the quoted string. *)
+		_advance_token(v4 + 2);
+
+		goto .compile_global_initializer_end;
+	end;
+	if v0 = 'S' then
+		(* Skip "S(". *)
+		_advance_token(2);
+
+		if _load_byte(source_code_position) = ')' then
+			goto .compile_global_initializer_closing;
+		end;
+		goto .compile_global_initializer_loop;
+	end;
+	if v0 = '@' then
+		(* Skip @. *)
+		_advance_token(1);
+		_write_z("\n\t.word \0");
+		v0 := _read_token();
+		_write_token(v0);
+		_advance_token(v0);
+
+		goto .compile_global_initializer_end;
+	end;
+	if _is_digit(v0) = 1 then
+		_write_z("\n\t.word \0");
+		v0 := _read_token();
+		_write_token(v0);
+		_advance_token(1);
+
+		goto .compile_global_initializer_end;
+	end;
+	unimp
+
+.compile_global_initializer_loop:
+	_compile_global_initializer();
+
+	if _load_byte(source_code_position) <> ')' then
+		(* Skip comma and whitespace after it. *)
+		_advance_token(2);
+
+		goto .compile_global_initializer_loop;
+	end;
+
+.compile_global_initializer_closing:
+	(* Skip ")" *)
+	_advance_token(1);
+
+	goto .compile_global_initializer_end;
+
+.compile_global_initializer_end:
+end;
+
+proc _compile_constant_declaration();
+begin
+	v0 := _read_token();
+
+	_write_z(".type \0");
+	_write_token(v0);
+	_write_z(", @object\n\0");
+
+	_write_token(v0);
+	_write_c(':');
+
+	(* Skip the constant name with assignment sign and surrounding whitespaces. *)
+	_advance_token(v0 + 4);
+	_compile_global_initializer();
+	(* Skip semicolon and newline. *)
+	_advance_token(2);
+	_write_c('\n');
+end;
+
+proc _compile_const_part();
+begin
+	_skip_empty_lines();
+
+	if _memcmp(source_code_position, "const\0", 5) <> 0 then
+		goto .compile_const_part_end;
+	end;
+	(* Skip "const" with the newline after it. *)
+	_advance_token(6);
+	_write_z(".section .rodata # Compiled from const section.\n\n\0");
+
+.compile_const_part_loop:
+	_skip_empty_lines();
+
+	(* If the character at the line beginning is not indentation, *)
+	(* it is probably the next code section. *)
+	if _load_byte(source_code_position) = '\t' then
+		_advance_token(1);
+
+		_compile_constant_declaration();
+		goto .compile_const_part_loop;
+	end;
+
+.compile_const_part_end:
+end;
+
+proc _compile_variable_declaration();
+begin
+	v0 := _read_token();
+
+	_write_z(".type \0");
+	_write_token(v0);
+	_write_z(", @object\n\0");
+
+	_write_token(v0);
+	_write_c(':');
+
+	(* Skip the variable name and colon with space before the type. *)
+	_advance_token(v0 + 2);
+
+	(* Skip the type name. *)
+	v4 := _read_token();
+	_advance_token(v4);
+
+	if _load_byte(source_code_position) <> ' ' then
+		(* Else we assume this is a zeroed 81920 bytes big array. *)
+		_write_z(" .zero 81920\0");
+	else
+		(* Skip the assignment sign with surrounding whitespaces. *)
+		_advance_token(4);
+		_compile_global_initializer();
+	end;
+
+	(* Skip semicolon and newline. *)
+	_advance_token(2);
+	_write_c('\n');
+end;
+
+proc _compile_var_part();
+begin
+	if _memcmp(source_code_position, "var\0", 3) <> 0 then
+		goto .compile_var_part_end;
+	end;
+	(* Skip "var" and newline. *)
+	_advance_token(4);
+	_write_z(".section .data\n\0");
+
+.compile_var_part_loop:
+	_skip_empty_lines();
+	v0 := _load_byte(source_code_position);
+
+	if v0 = '\t' then
+		_advance_token(1);
+		_compile_variable_declaration();
+		goto .compile_var_part_loop;
+	end;
+
+.compile_var_part_end:
+end;
+
+(* Process the source code and print the generated code. *)
+proc _compile_module();
+begin
+	_compile_const_part();
+	_skip_empty_lines();
+	_compile_var_part();
+
+	_write_z(".section .text\n\n\0");
+	_write_z(".type _syscall, @function\n_syscall:\n\tmv a7, a6\n\tecall\n\tret\n\n\0");
+	_write_z(".type _load_byte, @function\n_load_byte:\n\tlb a0, (a0)\nret\n\n\0");
+	_write_z(".type _load_word, @function\n_load_word:\n\tlw a0, (a0)\nret\n\n\0");
+	_write_z(".type _store_byte, @function\n_store_byte:\n\tsb a0, (a1)\nret\n\n\0");
+	_write_z(".type _store_word, @function\n_store_word:\n\tsw a0, (a1)\nret\n\n\0");
+
+.compile_module_loop:
+	_skip_empty_lines();
+
+	if _load_byte(source_code_position) <> 0 then
+		(* 5 is "proc " length. Space is needed to distinguish from "procedure". *)
+		if _memcmp(source_code_position, "proc ", 5) = 0 then
+			_compile_procedure();
+			goto .compile_module_loop;
+		end;
+	end;
+.compile_module_end:
+end;
+
+proc _compile();
+begin
+	_write_z(".globl _start\n\n\0");
+	_compile_module();
+
+	_write_z(".section .rodata\n.type strings, @object\nstrings: .ascii \0");
+	_write_c('"');
+
+	v0 := @compiler_strings;
+	v4 := compiler_strings_position;
+
+.compile_loop:
+	lw t0, 0(sp)
+	lw t1, 4(sp)
+	bge t0, t1, .compile_end
+
+	v8 := _load_byte(v0);
+	v0 := v0 + 1;
+	_write_c(v8);
+
+	j .compile_loop
+
+.compile_end:
+	_write_c('"');
+	_write_c('\n');
+end;
+
+(* Terminates the program. a0 contains the return code. *)
+
+(* Parameters: *)
+(* a0 - Status code. *)
+proc _exit();
+begin
+	_syscall(0, 0, 0, 0, 0, 0, 93);
+end;
+
+(* Inserts a symbol into the table. *)
+
+(* Parameters: *)
+(* a0 - Symbol pointer. *)
+(* a1 - Symbol name length. *)
+(* a2 - Symbol name pointer. *)
+(* a3 - Symbol table. *)
+proc _symbol_table_enter();
+begin
+	(* The first word in the symbol table is its length, get it. *)
+	v0 := _load_word(v76);
+
+	(* Calculate the offset for the new symbol. *)
+	v4 := v0 * 4;
+	v4 := v4 + 4;
+	v4 := v76 + 4;
+
+	_memcpy(v4, @v80, 12);
+
+	(* Increment the symbol table length. *)
+	v0 := v0 + 1;
+	_store_word(v0, v76);
+end;
+
+proc _symbol_table_build();
+begin
+	_symbol_table_enter(@symbol_type_info_int, 3, symbol_builtin_name_int, @symbol_table_global);
+	_symbol_table_enter(@symbol_type_info_word, 4, symbol_builtin_name_word, @symbol_table_global);
+	_symbol_table_enter(@symbol_type_info_pointer, 7, symbol_builtin_name_pointer, @symbol_table_global);
+	_symbol_table_enter(@symbol_type_info_char, 4, symbol_builtin_name_char, @symbol_table_global);
+	_symbol_table_enter(@symbol_type_info_bool, 4, symbol_builtin_name_bool, @symbol_table_global);
+end;
+
+
+(* Classification table assigns each possible character to a group (class). All *)
+(* characters of the same group a handled equivalently. *)
+
+(* Classification: *)
+
+(* TransitionClass = ( *)
+(* transitionClassInvalid = 1, *)
+(* transitionClassDigit = 2, *)
+(* transitionClassAlpha = 3, *)
+(* transitionClassSpace = 4, *)
+(* transitionClassColon = 5, *)
+(* transitionClassEquals = 6, *)
+(* transitionClassLeftParen = 7, *)
+(* transitionClassRightParen = 8, *)
+(* transitionClassAsterisk = 9, *)
+(* transitionClassUnderscore = 10, *)
+(* transitionClassSingle = 11, *)
+(* transitionClassHex = 12, *)
+(* transitionClassZero = 13, *)
+(* transitionClassX = 14, *)
+(* transitionClassEof = 15, *)
+(* transitionClassDot = 16, *)
+(* transitionClassMinus = 17, *)
+(* transitionClassSingleQuote = 18, *)
+(* transitionClassDoubleQuote = 19, *)
+(* transitionClassGreater = 20, *)
+(* transitionClassLess = 21, *)
+(* transitionClassOther = 22 *)
+(* ); *)
+(* TransitionState = ( *)
+(* transitionStateStart = 1, *)
+(* transitionStateColon = 2, *)
+(* transitionStateIdentifier = 3, *)
+(* transitionStateDecimal = 4, *)
+(* transitionStateGreater = 5, *)
+(* transitionStateMinus = 6, *)
+(* transitionStateLeftParen = 7, *)
+(* transitionStateLess = 8, *)
+(* transitionStateDot = 9, *)
+(* transitionStateComment = 10, *)
+(* transitionStateClosingComment = 11, *)
+(* transitionStateCharacter = 12, *)
+(* transitionStateString = 13, *)
+(* transitionStateLeadingZero = 14, *)
+(* transitionStateDecimalSuffix = 15, *)
+(* transitionStateEnd = 16 *)
+(* ); *)
+(* Transition = record *)
+(* action: TransitionAction; *)
+(* next_state: TransitionState *)
+(* end; *)
+(* TransitionAction = ( *)
+(* none = 1, *)
+(* accumulate = 2, *)
+(* skip = 3, *)
+(* single = 4, *)
+(* eof = 5, *)
+(* finalize = 6, *)
+(* composite = 7, *)
+(* key_id = 8, *)
+(* integer = 9, *)
+(* delimited = 10 *)
+(* ); *)
+
+(* Assigns some value to at array index. *)
+
+(* Parameters: *)
+(* a0 - Array pointer. *)
+(* a1 - Index (word offset into the array). *)
+(* a2 - Data to assign. *)
+proc _assign_at();
+begin
+	v0 := v84 + -1;
+	v0 := v0 * 4;
+	v0 := v88 + v0;
+
+	_store_word(v80, v0);
+end;
+
+proc _create_classification();
+begin
+	_assign_at(@classification, 1, 15);
+	_assign_at(@classification, 2, 1);
+	_assign_at(@classification, 3, 1);
+	_assign_at(@classification, 4, 1);
+	_assign_at(@classification, 5, 1);
+	_assign_at(@classification, 6, 1);
+	_assign_at(@classification, 7, 1);
+	_assign_at(@classification, 8, 1);
+	_assign_at(@classification, 9, 1);
+	_assign_at(@classification, 10, 4);
+	_assign_at(@classification, 11, 4);
+	_assign_at(@classification, 12, 1);
+	_assign_at(@classification, 13, 1);
+	_assign_at(@classification, 14, 4);
+	_assign_at(@classification, 15, 1);
+	_assign_at(@classification, 16, 1);
+	_assign_at(@classification, 17, 1);
+	_assign_at(@classification, 18, 1);
+	_assign_at(@classification, 19, 1);
+	_assign_at(@classification, 20, 1);
+	_assign_at(@classification, 21, 1);
+	_assign_at(@classification, 22, 1);
+	_assign_at(@classification, 23, 1);
+	_assign_at(@classification, 24, 1);
+	_assign_at(@classification, 25, 1);
+	_assign_at(@classification, 26, 1);
+	_assign_at(@classification, 27, 1);
+	_assign_at(@classification, 28, 1);
+	_assign_at(@classification, 29, 1);
+	_assign_at(@classification, 30, 1);
+	_assign_at(@classification, 31, 1);
+	_assign_at(@classification, 32, 1);
+	_assign_at(@classification, 33, 4);
+	_assign_at(@classification, 34, 11);
+	_assign_at(@classification, 35, 19);
+	_assign_at(@classification, 36, 22);
+	_assign_at(@classification, 37, 22);
+	_assign_at(@classification, 38, 11);
+	_assign_at(@classification, 39, 11);
+	_assign_at(@classification, 40, 18);
+	_assign_at(@classification, 41, 7);
+	_assign_at(@classification, 42, 8);
+	_assign_at(@classification, 43, 9);
+	_assign_at(@classification, 44, 11);
+	_assign_at(@classification, 45, 11);
+	_assign_at(@classification, 46, 17);
+	_assign_at(@classification, 47, 16);
+	_assign_at(@classification, 48, 11);
+	_assign_at(@classification, 49, 13);
+	_assign_at(@classification, 50, 2);
+	_assign_at(@classification, 51, 2);
+	_assign_at(@classification, 52, 2);
+	_assign_at(@classification, 53, 2);
+	_assign_at(@classification, 54, 2);
+	_assign_at(@classification, 55, 2);
+	_assign_at(@classification, 56, 2);
+	_assign_at(@classification, 57, 2);
+	_assign_at(@classification, 58, 2);
+	_assign_at(@classification, 59, 5);
+	_assign_at(@classification, 60, 11);
+	_assign_at(@classification, 61, 21);
+	_assign_at(@classification, 62, 6);
+	_assign_at(@classification, 63, 20);
+	_assign_at(@classification, 64, 22);
+	_assign_at(@classification, 65, 11);
+	_assign_at(@classification, 66, 3);
+	_assign_at(@classification, 67, 3);
+	_assign_at(@classification, 68, 3);
+	_assign_at(@classification, 69, 3);
+	_assign_at(@classification, 70, 3);
+	_assign_at(@classification, 71, 3);
+	_assign_at(@classification, 72, 3);
+	_assign_at(@classification, 73, 3);
+	_assign_at(@classification, 74, 3);
+	_assign_at(@classification, 75, 3);
+	_assign_at(@classification, 76, 3);
+	_assign_at(@classification, 77, 3);
+	_assign_at(@classification, 78, 3);
+	_assign_at(@classification, 79, 3);
+	_assign_at(@classification, 80, 3);
+	_assign_at(@classification, 81, 3);
+	_assign_at(@classification, 82, 3);
+	_assign_at(@classification, 83, 3);
+	_assign_at(@classification, 84, 3);
+	_assign_at(@classification, 85, 3);
+	_assign_at(@classification, 86, 3);
+	_assign_at(@classification, 87, 3);
+	_assign_at(@classification, 88, 3);
+	_assign_at(@classification, 89, 3);
+	_assign_at(@classification, 90, 3);
+	_assign_at(@classification, 91, 3);
+	_assign_at(@classification, 92, 11);
+	_assign_at(@classification, 93, 22);
+	_assign_at(@classification, 94, 11);
+	_assign_at(@classification, 95, 11);
+	_assign_at(@classification, 96, 10);
+	_assign_at(@classification, 97, 22);
+	_assign_at(@classification, 98, 12);
+	_assign_at(@classification, 99, 12);
+	_assign_at(@classification, 100, 12);
+	_assign_at(@classification, 101, 12);
+	_assign_at(@classification, 102, 12);
+	_assign_at(@classification, 103, 12);
+	_assign_at(@classification, 104, 3);
+	_assign_at(@classification, 105, 3);
+	_assign_at(@classification, 106, 3);
+	_assign_at(@classification, 107, 3);
+	_assign_at(@classification, 108, 3);
+	_assign_at(@classification, 109, 3);
+	_assign_at(@classification, 110, 3);
+	_assign_at(@classification, 111, 3);
+	_assign_at(@classification, 112, 3);
+	_assign_at(@classification, 113, 3);
+	_assign_at(@classification, 114, 3);
+	_assign_at(@classification, 115, 3);
+	_assign_at(@classification, 116, 3);
+	_assign_at(@classification, 117, 3);
+	_assign_at(@classification, 118, 3);
+	_assign_at(@classification, 119, 3);
+	_assign_at(@classification, 120, 3);
+	_assign_at(@classification, 121, 14);
+	_assign_at(@classification, 122, 3);
+	_assign_at(@classification, 123, 3);
+	_assign_at(@classification, 124, 22);
+	_assign_at(@classification, 125, 11);
+	_assign_at(@classification, 126, 22);
+	_assign_at(@classification, 127, 11);
+	_assign_at(@classification, 128, 1);
+
+	v0 := 129;
+
+(* Set the remaining 129 - 256 bytes to transitionClassOther. *)
+.create_classification_loop:
+	_assign_at(@classification, v0, 22);
+	v0 := v0 + 1;
+
+	if v0 < 257 then
+		goto .create_classification_loop;
+	end;
+end;
+
+(* Parameters: *)
+(* a0 - Current state (first index into transitions table). *)
+(* a1 - Transition (second index into transitions table).. *)
+(* a2 - Action to assign. *)
+(* a3 - Next state to assign. *)
+proc _set_transition();
+begin
+	(* Transitions start at offset in classification array. Save the transitions start in v0. *)
+	v0 := @classification + 256
+
+	(* Each state is 8 bytes long (2 words: action and next state). *)
+	(* There are 16 transition classes, so a transition 8 * 16 = 128 bytes long. *)
+
+	v4 := v88 + -1;
+	v4 := v4 * 128;
+
+	v8 := v84 + -1;
+	v8 := v8 * 8;
+
+	v12 := v0 + v4;
+	v12 := v12 + v8;
+
+	_store_word(v80, v12);
+	v12 := v12 + 4;
+	_store_word(v76, v12);
+end;
+
+(* Parameters: *)
+(* a0 - Current state (Transition state enumeration). *)
+(* a1 - Default action (Callback). *)
+(* a2 - Next state (Transition state enumeration). *)
+proc _set_default_transition();
+begin
+	_set_transition(v88, 1, v84, v80);
+	_set_transition(v88, 2, v84, v80);
+	_set_transition(v88, 3, v84, v80);
+	_set_transition(v88, 4, v84, v80);
+	_set_transition(v88, 5, v84, v80);
+	_set_transition(v88, 6, v84, v80);
+	_set_transition(v88, 7, v84, v80);
+	_set_transition(v88, 8, v84, v80);
+	_set_transition(v88, 9, v84, v80);
+	_set_transition(v88, 10, v84, v80);
+	_set_transition(v88, 11, v84, v80);
+	_set_transition(v88, 12, v84, v80);
+	_set_transition(v88, 13, v84, v80);
+	_set_transition(v88, 14, v84, v80);
+	_set_transition(v88, 15, v84, v80);
+	_set_transition(v88, 16, v84, v80);
+	_set_transition(v88, 17, v84, v80);
+	_set_transition(v88, 18, v84, v80);
+	_set_transition(v88, 19, v84, v80);
+	_set_transition(v88, 20, v84, v80);
+	_set_transition(v88, 21, v84, v80);
+	_set_transition(v88, 22, v84, v80);
+end;
+
+
+(* The transition table describes transitions from one state to another, given *)
+(* a symbol (character class). *)
+
+(* The table has m rows and n columns, where m is the amount of states and n is *)
+(* the amount of classes. So given the current state and a classified character *)
+(* the table can be used to look up the next state. *)
+
+(* Each cell is a word long. *)
+(* - The least significant byte of the word is a row number (beginning with 0). *)
+(* It specifies the target state. "ff" means that this is an end state and no *)
+(* transition is possible. *)
+(* - The next byte is the action that should be performed when transitioning. *)
+(* For the meaning of actions see labels in the lex_next function, which *)
+(* handles each action. *)
+proc _create_transitions();
+begin
+	(* Start state. *)
+	_set_transition(1, 1, 1, 16);
+	_set_transition(1, 2, 2, 4);
+	_set_transition(1, 3, 2, 3);
+	_set_transition(1, 4, 3, 1);
+	_set_transition(1, 5, 2, 5);
+	_set_transition(1, 6, 4, 16);
+	_set_transition(1, 7, 2, 7);
+	_set_transition(1, 8, 4, 16);
+	_set_transition(1, 9, 4, 16);
+	_set_transition(1, 10, 2, 3);
+	_set_transition(1, 11, 4, 16);
+	_set_transition(1, 12, 2, 3);
+	_set_transition(1, 13, 2, 14);
+	_set_transition(1, 14, 2, 3);
+	_set_transition(1, 15, 5, 16);
+	_set_transition(1, 16, 2, 9);
+	_set_transition(1, 17, 2, 6);
+	_set_transition(1, 18, 2, 12);
+	_set_transition(1, 19, 2, 13);
+	_set_transition(1, 20, 2, 5);
+	_set_transition(1, 21, 2, 8);
+	_set_transition(1, 22, 1, 16);
+
+	(* Colon state. *)
+	_set_default_transition(2, 6, 16);
+	_set_transition(2, 6, 7, 16);
+
+	(* Identifier state. *)
+	_set_default_transition(3, 8, 16);
+	_set_transition(3, 2, 2, 3);
+	_set_transition(3, 3, 2, 3);
+	_set_transition(3, 10, 2, 3);
+	_set_transition(3, 12, 2, 3);
+	_set_transition(3, 13, 2, 3);
+	_set_transition(3, 14, 2, 3);
+
+	(* Decimal state. *)
+	_set_default_transition(4, 9, 16);
+	_set_transition(4, 2, 2, 4);
+	_set_transition(4, 3, 2, 15);
+	_set_transition(4, 10, 1, 16);
+	_set_transition(4, 12, 2, 15);
+	_set_transition(4, 13, 2, 4);
+	_set_transition(4, 14, 2, 15);
+
+	(* Greater state. *)
+	_set_default_transition(5, 6, 16);
+	_set_transition(5, 6, 7, 16);
+
+	(* Minus state. *)
+	_set_default_transition(6, 6, 16);
+	_set_transition(6, 20, 7, 16);
+
+	(* Left paren state. *)
+	_set_default_transition(7, 6, 16);
+	_set_transition(7, 9, 2, 10);
+
+	(* Less state. *)
+	_set_default_transition(8, 6, 16);
+	_set_transition(8, 6, 7, 16);
+	_set_transition(8, 20, 7, 16);
+
+	(* Hexadecimal after 0x. *)
+	_set_default_transition(9, 6, 16);
+	_set_transition(9, 16, 7, 16);
+
+	(* Comment. *)
+	_set_default_transition(10, 2, 10);
+	_set_transition(10, 9, 2, 11);
+	_set_transition(10, 15, 1, 16);
+
+	(* Closing comment. *)
+	_set_default_transition(11, 2, 10);
+	_set_transition(11, 1, 1, 16);
+	_set_transition(11, 8, 10, 16);
+	_set_transition(11, 9, 2, 11);
+	_set_transition(11, 15, 1, 16);
+
+	(* Character. *)
+	_set_default_transition(12, 2, 12);
+	_set_transition(12, 1, 1, 16);
+	_set_transition(12, 15, 1, 16);
+	_set_transition(12, 18, 10, 16);
+
+	(* String. *)
+	_set_default_transition(13, 2, 13);
+	_set_transition(13, 1, 1, 16);
+	_set_transition(13, 15, 1, 16);
+	_set_transition(13, 19, 10, 16);
+
+	(* Leading zero. *)
+	_set_default_transition(14, 9, 16);
+	_set_transition(14, 2, 1, 16);
+	_set_transition(14, 3, 1, 16);
+	_set_transition(14, 10, 1, 16);
+	_set_transition(14, 12, 1, 16);
+	_set_transition(14, 13, 1, 16);
+	_set_transition(14, 14, 1, 16);
+
+	(* Digit with a character suffix. *)
+	_set_default_transition(15, 9, 16);
+	_set_transition(15, 3, 1, 16);
+	_set_transition(15, 2, 1, 16);
+	_set_transition(15, 12, 1, 16);
+	_set_transition(15, 13, 1, 16);
+	_set_transition(15, 14, 1, 16);
+end;
+
+proc _lexer_get_state();
+begin
+	(* Lexer state is saved after the transition tables. The offset is 256 + 16 * 22. *)
+	v0 := @classification;
+	v4 := 16 * 22;
+	v0 := v0 + 256;
+
+	return v0 + v4
+end;
+
+(* Gets pointer to the current source text. *)
+proc _lexer_get_current();
+begin
+	return _lexer_get_state() + 4;
+end;
+
+(* Resets the lexer state for reading the next token. *)
+proc _lexer_reset();
+begin
+	(* Transition start state is 1. *)
+	v0 := _lexer_get_state();
+	_store_word(1, v4);
+
+	(* Text pointer to the beginning of the currently read token. *)
+	v4 := _lexer_get_current();
+	_store_word(source_code_position, v4);
+
+	(* Initial length of the token is 0. *)
+	_store_word(0, source_code_position + 4);
+end;
+
+(* One time lexer initialization. *)
+proc _lexer_initialize();
+begin
+	_create_classification();
+	_create_transitions();
+end;
+
+(* Entry point. *)
+proc _start();
+begin
+	_lexer_initialize();
+	_symbol_table_build();
+
+	(* Read the source from the standard input. *)
+	(* Second argument is buffer size. Modifying update the source_code definition. *)
+	_read_file(@source_code, 81920);
+	_compile();
+
+	_exit(0);
+end;
diff --git a/boot/stage8.elna b/boot/stage8.elna
index 6243634..75c24d7 100644
--- a/boot/stage8.elna
+++ b/boot/stage8.elna
@@ -7,6 +7,10 @@
 # - Procedure calls in expressions.
 # - Comments between (* and *) are supported. These are still single line
 #   comments and they should be on a separate line.
+# - _syscall builtin. _syscall takes 7 arguments,
+#   the 7th argument gets stored in a7 before invoking ecall.
+#   Other arguments are saved in a0 through a5.
+# - New intrinsics: _load_byte, _load_word, _store_byte, _store_word.
 const
 	symbol_builtin_name_int := "Int";
 	symbol_builtin_name_word := "Word";
@@ -1403,7 +1407,13 @@ begin
 	_skip_empty_lines();
 	_compile_var_part();
 
-	_write_z(".section .text\n\0");
+	_write_z(".section .text\n\n\0");
+	_write_z(".type _syscall, @function\n_syscall:\n\tmv a7, a6\n\tecall\n\tret\n\n\0");
+	_write_z(".type _load_byte, @function\n_load_byte:\n\tlb a0, (a0)\nret\n\n\0");
+	_write_z(".type _load_word, @function\n_load_word:\n\tlw a0, (a0)\nret\n\n\0");
+	_write_z(".type _store_byte, @function\n_store_byte:\n\tsb a0, (a1)\nret\n\n\0");
+	_write_z(".type _store_word, @function\n_store_word:\n\tsw a0, (a1)\nret\n\n\0");
+
 .compile_module_loop:
 	_skip_empty_lines();
 
diff --git a/boot/stage9.elna b/boot/stage9.elna
index ebeb467..9f5e4d5 100644
--- a/boot/stage9.elna
+++ b/boot/stage9.elna
@@ -2,11 +2,12 @@
 (* v. 2.0. If a copy of the MPL was not distributed with this file, You can *)
 (* obtain one at https://mozilla.org/MPL/2.0/. *)
 
-(* Stage 8 compiler. *)
+(* Stage 9 compiler. *)
 
 (* - Procedure calls in expressions. *)
 (* - Comments between (* and *) are supported. These are still single line *)
 (* comments and they should be on a separate line. *)
+(* - if-else statements. *)
 const
 	symbol_builtin_name_int := "Int";
 	symbol_builtin_name_word := "Word";
@@ -45,6 +46,7 @@ var
 
 	compiler_strings_position: Pointer := @compiler_strings;
 	compiler_strings_length: Word := 0;
+	label_counter: Word := 0;
 	source_code_position: Pointer := @source_code;
 
 (* Calculates and returns the string token length between quotes, including the *)
@@ -93,16 +95,12 @@ begin
 
 	beq t1, t2, .add_string_end
 
-	la t2, compiler_strings_position
-	lw t3, (t2)
-	sb t1, (t3)
-
-	addi t3, t3, 1
-	sw t3, (t2)
-
-	addi t0, t0, 1
-	sw t0, 0(sp)
+	v8 := _load_byte(v0);
+	_store_byte(v8, compiler_strings_position);
+	_store_word(compiler_strings_position + 1, @compiler_strings_position);
+	v0 := v0 + 1;
 
+	lb t1, 8(sp)
 	li t2, '\\'
 	bne t1, t2, .add_string_increment
 
@@ -127,13 +125,7 @@ end;
 (* Returns the amount of bytes written in a0. *)
 proc _read_file();
 begin
-	mv a2, a1
-	mv a1, a0
-	(* STDIN. *)
-	li a0, 0
-	(* SYS_READ. *)
-	li a7, 63
-	ecall
+	_syscall(0, v88, v84, 0, 0, 0, 63);
 end;
 
 (* Writes to the standard output. *)
@@ -143,13 +135,7 @@ end;
 (* a1 - Buffer length. *)
 proc _write_s();
 begin
-	mv a2, a1
-	mv a1, a0
-	(* STDOUT. *)
-	li a0, 1
-	(* SYS_WRITE. *)
-	li a7, 64
-	ecall
+	_syscall(1, v88, v84, 0, 0, 0, 64);
 end;
 
 (* Writes a number to a string buffer. *)
@@ -317,9 +303,8 @@ begin
 	li t1, '.'
 	beq t0, t1, .read_token_next
 
-	lw a0, 0(sp)
-	lb a0, (a0)
-	_is_alnum();
+	v8 := _load_byte(v0);
+	_is_alnum(v8);
 	bnez a0, .read_token_next
 
 	goto .read_token_end;
@@ -464,10 +449,8 @@ begin
 	_advance_token(1);
 
 .compile_character_literal_end:
-	la t0, source_code_position
-	lw t0, (t0)
-	lb a0, (t0)
-	_write_c();
+	v0 := _load_byte(source_code_position);
+	_write_c(v0);
 
 	_write_c('\'');
 	_write_c('\n');
@@ -523,10 +506,8 @@ end;
 
 proc _compile_term();
 begin
-	la t0, source_code_position
-	lw t0, (t0)
-	lb a0, (t0)
-	sw a0, 0(sp)
+	v0 := _load_byte(source_code_position);
+	lb a0, 0(sp)
 
 	li t1, '\''
 	beq a0, t1, .compile_term_character_literal
@@ -925,13 +906,72 @@ begin
 	_write_z("mv a0, t0\n\0");
 end;
 
+(* Writes a label, .Ln, where n is a unique number. *)
+
+(* Parameters: *)
+(* a0 - Label counter. *)
+proc _write_label();
+begin
+	_write_z(".L\0");
+	_write_i(v88);
+end;
+
+proc _compile_if();
+begin
+	(* Skip "if ". *)
+	_advance_token(3);
+	(* Compile condition. *)
+	_compile_expression();
+	(* Skip " then" with newline. *)
+	_advance_token(6);
+
+	(* v0 is the label after the if statement. *)
+	v0 := label_counter;
+	_store_word(label_counter + 1, @label_counter);
+	(* v4 is the label in front of the next elsif condition or end. *)
+	v4 := label_counter;
+	_store_word(label_counter + 1, @label_counter);
+
+	_write_z("\tbeqz t0, \0");
+	_write_label(v4);
+	_write_c('\n');
+
+	_compile_procedure_body();
+
+	_write_z("\tj \0");
+	_write_label(v0);
+	_write_c('\n');
+
+	_write_label(v4);
+	_write_z(":\n\0");
+
+	_memcmp(source_code_position, "end", 3);
+	beqz a0, .compile_if_end
+
+	_memcmp(source_code_position, "else", 3);
+	beqz a0, .compile_if_else
+
+.compile_if_else:
+	(* Skip "else" and newline. *)
+	_advance_token(5);
+	_compile_procedure_body();
+
+.compile_if_end:
+	(* Skip "end". *)
+	_advance_token(3);
+
+	_write_label(v0);
+	_write_z(":\n\0");
+end;
+
 proc _compile_statement();
 begin
+	_skip_spaces();
 	(* This is a call if the statement starts with an underscore. *)
 	la t0, source_code_position
 	lw t0, (t0)
 	(* First character after alignment tab. *)
-	addi t0, t0, 1
+	(* addi t0, t0, 1 *)
 	lb t0, (t0)
 	
 	li t1, '_'
@@ -943,33 +983,42 @@ begin
 	li t1, 'v'
 	beq t0, t1, .compile_statement_assignment
 
+	li t1, 'i'
+	beq t0, t1, .compile_statement_if
+
 	(* keyword_ret contains "\tret", so it's 4 bytes long. *)
-	_memcmp(source_code_position, "\treturn", 7);
+	_memcmp(source_code_position, "return", 6);
 	beqz a0, .compile_statement_return
 
 	_compile_line();
 	goto .compile_statement_end;
 
 .compile_statement_call:
-	_advance_token(1);
+	(* _advance_token(1); *)
 	_compile_call();
 
 	goto .compile_statement_semicolon;
 
 .compile_statement_goto:
-	_advance_token(1);
+	(* _advance_token(1); *)
 	_compile_goto();
 
 	goto .compile_statement_semicolon;
 
 .compile_statement_assignment:
-	_advance_token(1);
+	(* _advance_token(1); *)
 	_compile_assignment();
 
 	goto .compile_statement_semicolon;
 
+.compile_statement_if:
+	(* _advance_token(1); *)
+	_compile_if();
+
+	goto .compile_statement_semicolon;
+
 .compile_statement_return:
-	_advance_token(1);
+	(* _advance_token(1); *)
 	_compile_return_statement();
 	_write_c('\n');
 
@@ -986,10 +1035,12 @@ proc _compile_procedure_body();
 begin
 .compile_procedure_body_loop:
 	_skip_empty_lines();
+	_skip_spaces();
 
-	(* 3 is "end" length. *)
 	_memcmp(source_code_position, "end", 3);
+	beqz a0, .compile_procedure_body_epilogue
 
+	_memcmp(source_code_position, "else", 4);
 	beqz a0, .compile_procedure_body_epilogue
 
 	_compile_statement();
@@ -1065,24 +1116,24 @@ begin
 	_advance_token(5);
 end;
 
-proc _skip_newlines();
+proc _skip_spaces();
 begin
 	(* Skip newlines. *)
 	la t0, source_code_position
 	lw t1, (t0)
 
-.skip_newlines_loop:
+.skip_spaces_loop:
 	lb t2, (t1)
-	li t3, '\n'
-	bne t2, t3, .skip_newlines_end
-	beqz t2, .skip_newlines_end
+	li t3, '\t'
+	bne t2, t3, .skip_spaces_end
+	beqz t2, .skip_spaces_end
 
 	addi t1, t1, 1
 	sw t1, (t0)
 
-	goto .skip_newlines_loop;
+	goto .skip_spaces_loop;
 
-.skip_newlines_end:
+.skip_spaces_end:
 end;
 
 (* Prints and skips a line. *)
@@ -1121,9 +1172,6 @@ begin
 	lw t2, 0(sp)
 	lb t0, (t2)
 
-	li t1, '#'
-	beq t0, t1, .skip_empty_lines_comment
-
 	li t1, '\n'
 	beq t0, t1, .skip_empty_lines_newline
 
@@ -1175,10 +1223,8 @@ begin
 	li t1, '@'
 	beq t0, t1, .compile_global_initializer_pointer
 
-	la a0, source_code_position
-	lw a0, (a0)
-	lb a0, (a0)
-	_is_digit();
+	v0 := _load_byte(source_code_position);
+	_is_digit(v0);
 	bnez a0, .compile_global_initializer_number
 
 	unimp
@@ -1373,7 +1419,13 @@ begin
 	_skip_empty_lines();
 	_compile_var_part();
 
-	_write_z(".section .text\n\0");
+	_write_z(".section .text\n\n\0");
+	_write_z(".type _syscall, @function\n_syscall:\n\tmv a7, a6\n\tecall\n\tret\n\n\0");
+	_write_z(".type _load_byte, @function\n_load_byte:\n\tlb a0, (a0)\nret\n\n\0");
+	_write_z(".type _load_word, @function\n_load_word:\n\tlw a0, (a0)\nret\n\n\0");
+	_write_z(".type _store_byte, @function\n_store_byte:\n\tsb a0, (a1)\nret\n\n\0");
+	_write_z(".type _store_word, @function\n_store_word:\n\tsw a0, (a1)\nret\n\n\0");
+
 .compile_module_loop:
 	_skip_empty_lines();
 
@@ -1413,10 +1465,9 @@ begin
 	lw t1, 4(sp)
 	bge t0, t1, .compile_end
 
-	lb a0, (t0)
-	addi t0, t0, 1
-	sw t0, 0(sp)
-	_write_c();
+	v8 := _load_byte(v0);
+	v0 := v0 + 1;
+	_write_c(v8);
 
 	j .compile_loop
 
@@ -1431,8 +1482,7 @@ end;
 (* a0 - Status code. *)
 proc _exit();
 begin
-	li a7, 93 # SYS_EXIT
-	ecall
+	_syscall(0, 0, 0, 0, 0, 0, 93);
 end;
 
 (* Inserts a symbol into the table. *)
@@ -1554,7 +1604,7 @@ begin
 	sw t1, (t0)
 end;
 
-proc _initialize_classification();
+proc _create_classification();
 begin
 	_assign_at(@classification, 1, 15);
 	_assign_at(@classification, 2, 1);
@@ -1688,13 +1738,13 @@ begin
 	v0 := 129;
 
 (* Set the remaining 129 - 256 bytes to transitionClassOther. *)
-.initialize_classification_loop:
+.create_classification_loop:
 	_assign_at(@classification, v0, 22);
 	v0 := v0 + 1;
 
 	lw t0, 0(sp)
 	li t1, 257
-	blt t0, t1, .initialize_classification_loop
+	blt t0, t1, .create_classification_loop
 end;
 
 (* Parameters: *)
@@ -1772,7 +1822,7 @@ end;
 (* - The next byte is the action that should be performed when transitioning. *)
 (* For the meaning of actions see labels in the lex_next function, which *)
 (* handles each action. *)
-proc _initialize_transitions();
+proc _create_transitions();
 begin
 	(* Start state. *)
 	_set_transition(1, 1, 1, 16);
@@ -1896,8 +1946,7 @@ end;
 (* Gets pointer to the current source text. *)
 proc _lexer_get_current();
 begin
-	_lexer_get_state();
-	sw a0, 0(sp)
+	v0 := _lexer_get_state();
 
 	return v0 + 4
 end;
@@ -1925,8 +1974,8 @@ end;
 (* One time lexer initialization. *)
 proc _lexer_initialize();
 begin
-	_initialize_classification();
-	_initialize_transitions();
+	_create_classification();
+	_create_transitions();
 end;
 
 (* Entry point. *)