From 1e97b660bf54da4a6df5f28363447d33b6058884 Mon Sep 17 00:00:00 2001
From: Eugen Wissner <belka@caraus.de>
Date: Thu, 18 Sep 2025 13:01:00 +0200
Subject: [PATCH] Support named local variables and parameters

---
 boot/stage12.elna |  234 +++++-
 boot/stage13.elna | 2037 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 2238 insertions(+), 33 deletions(-)
 create mode 100644 boot/stage13.elna

diff --git a/boot/stage12.elna b/boot/stage12.elna
index 98751bb..68f5592 100644
--- a/boot/stage12.elna
+++ b/boot/stage12.elna
@@ -4,6 +4,9 @@
 
 (* Stage 12 compiler. *)
 
+(* - Local variables and parameters are saved in a local symbol table. *)
+(* - Local variables and parameters can be referenced by their name in the symbol table. *)
+
 const
 	symbol_builtin_name_int := "Int";
 	symbol_builtin_name_word := "Word";
@@ -26,6 +29,7 @@ const
 
 	(* INFO_TYPE = 1 *)
 	(* INFO_PARAMETER = 2 *)
+	(* INFO_TEMPORARY = 3 *)
 
 	(* Type info has the type it belongs to. *)
 	symbol_type_info_int := S(1, @symbol_builtin_type_int);
@@ -722,11 +726,25 @@ end;
 
 proc _compile_designator();
 begin
+	v0 := _read_token();
+	v4 := _symbol_table_lookup(@symbol_table_local, source_code_position, v0);
+
+	if v4 <> 0 then
+		_write_z("\taddi t0, sp, \0");
+		v8 := _parameter_info_get_offset(v4);
+		_write_i(v8);
+		_write_c('\n');
+		_advance_token(v0);
+
+		goto .compile_designator_end;
+	end;
 	if _load_byte(source_code_position) = 'v' then
 		_compile_local_designator();
-	else
-		_compile_global_designator();
+		goto .compile_designator_end;
 	end;
+	_compile_global_designator();
+
+.compile_designator_end:
 end;
 
 proc _compile_assignment();
@@ -834,15 +852,15 @@ begin
 		_compile_call();
 		goto .compile_statement_semicolon;
 	end;
-	if v0 = 'g' then
+	if _memcmp(source_code_position, "goto ", 5) = 0 then
 		_compile_goto();
 		goto .compile_statement_semicolon;
 	end;
-	if v0 = 'i' then
+	if _memcmp(source_code_position, "if ", 3) = 0 then
 		_compile_if();
 		goto .compile_statement_semicolon;
 	end;
-	if v0 = 'r' then
+	if _memcmp(source_code_position, "return ", 7) = 0 then
 		_compile_return_statement();
 		_write_c('\n');
 
@@ -891,6 +909,15 @@ begin
 	_write_c(v84);
 end;
 
+proc _skip_spaces();
+begin
+	v0 := _load_byte(source_code_position);
+	if v0 = '\t' then
+		_advance_token(1);
+		_skip_spaces();
+	end;
+end;
+
 proc _read_type_expression();
 begin
 	v0 := _read_token();
@@ -900,13 +927,58 @@ end;
 (* Parameters: *)
 
 (* a0 - Parameter index. *)
-proc _create_parameter_info(v88: Word);
+proc _parameter_info_create(v88: Word);
 begin
+	v8 := memory_free_pointer;
+	v4 := v8;
+	(* 2 is INFO_PARAMETER *)
+	_store_word(2, v4);
+
+	v4 := v4 + 4;
+
 	(* Calculate the stack offset: 88 - (4 * parameter_counter) *)
 	v0 := v88 * 4;
 	v0 := 88 + -v0;
+	_store_word(v0, v4);
 
-	return v0
+	v4 := v4 + 4;
+	_store_word(v4, @memory_free_pointer);
+
+	return v8
+end;
+
+proc _parameter_info_get_offset(v88: Word);
+begin
+	v88 := v88 + 4;
+	return _load_word(v88)
+end;
+
+(* Parameters: *)
+
+(* a0 - Parameter index. *)
+proc _temporary_info_create(v88: Word);
+begin
+	v8 := memory_free_pointer;
+	v4 := v8;
+	(* 3 is INFO_TEMPORARY *)
+	_store_word(3, v4);
+
+	v4 := v4 + 4;
+
+	(* Calculate the stack offset: 4 * variable_counter. *)
+	v0 := v88 * 4;
+	_store_word(v0, v4);
+
+	v4 := v4 + 4;
+	_store_word(v4, @memory_free_pointer);
+
+	return v8
+end;
+
+proc _temporary_info_get_offset(v88: Word);
+begin
+	v88 := v88 + 4;
+	return _load_word(v88)
 end;
 
 (* Parameters: *)
@@ -915,6 +987,7 @@ end;
 proc _read_procedure_parameter(v88: Word);
 begin
 	(* Read the parameter name. *)
+	v8 := source_code_position;
 	v0 := _read_token();
 	_advance_token(v0);
 
@@ -927,8 +1000,10 @@ begin
 	_write_i(v88);
 	_write_z(", \0");
 
-	(* Calculate the stack offset: 88 - (4 * parameter_counter) *)
-	v4 := _create_parameter_info(v88);
+	v4 := _parameter_info_create(v88);
+	_symbol_table_enter(@symbol_table_local, v8, v0, v4);
+
+	v4 := _parameter_info_get_offset(v4);
 	_write_i(v4);
 
 	_write_z("(sp)\n\0");
@@ -954,10 +1029,52 @@ begin
 	_advance_token(1);
 end;
 
+(* Parameters: *)
+(* a0 - Variable index. *)
+proc _read_procedure_temporary(v88: Word);
+begin
+	_skip_spaces();
+	v8 := source_code_position;
+
+	(* Read and skip variable name, colon and the space *)
+	v0 := _read_token();
+	_advance_token(v0 + 2);
+
+	_read_type_expression();
+
+	v4 := _temporary_info_create(v88);
+	_symbol_table_enter(@symbol_table_local, v8, v0, v4);
+
+	(* Skip semicolon and newline after the variable declaration *)
+	_advance_token(2);
+end;
+
+proc _read_procedure_temporaries();
+begin
+	if _memcmp(source_code_position, "var", 3) <> 0 then
+		goto .read_local_variables_end;
+	end;
+	_advance_token(4);
+	v0 := 0;
+
+.read_local_variables_loop:
+	if _memcmp(source_code_position, "begin", 5) = 0 then
+		goto .read_local_variables_end;
+	end;
+	_read_procedure_temporary(v0);
+
+	v0 := v0 + 1;
+	goto .read_local_variables_loop;
+
+.read_local_variables_end:
+end;
+
 proc _compile_procedure();
 begin
 	(* Skip "proc ". *)
 	_advance_token(5);
+	(* Clear local symbol table. *)
+	_store_word(0, @symbol_table_local);
 
 	(* Save the procedure name length. *)
 	v0 := _read_token();
@@ -977,8 +1094,12 @@ begin
 	_write_z("\taddi sp, sp, -128\n\tsw ra, 124(sp)\n\tsw s0, 120(sp)\n\taddi s0, sp, 128\n\0");
 	_read_procedure_parameters();
 
+	(* Skip semicolon and newline. *)
+	_advance_token(2);
+	_read_procedure_temporaries();
+
 	(* Skip semicolon, "begin" and newline. *)
-	_advance_token(8);
+	_advance_token(6);
 
 	_compile_procedure_body();
 
@@ -989,15 +1110,6 @@ begin
 	_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
@@ -1277,37 +1389,93 @@ begin
 	_syscall(0, 0, 0, 0, 0, 0, 93);
 end;
 
+(* Looks for a symbol in the given symbol table. *)
+
+(* Parameters: *)
+(* a0 - Symbol table. *)
+(* a1 - Symbol name pointer. *)
+(* a2 - Symbol name length. *)
+
+(* Returns the symbol pointer or 0 in a0. *)
+proc _symbol_table_lookup(v88: Word, v84: Word, v80: Word);
+begin
+	v0 := 0;
+
+	(* The first word in the symbol table is its length, get it. *)
+	v4 := _load_word(v88);
+
+	(* Go to the first symbol position. *)
+	v88 := v88 + 4;
+
+	.symbol_table_lookup_loop;
+	if v4 = 0 then
+		goto .symbol_table_lookup_end;
+	end;
+
+	(* Symbol name pointer and length. *)
+	v8 := _load_word(v88);
+	v12 := _load_word(v88 + 4);
+
+	(* If lengths don't match, exit and return nil. *)
+	if v80 <> v12 then
+		goto .symbol_table_lookup_repeat;
+	end;
+	(* If names don't match, exit and return nil. *)
+	if _memcmp(v84, v8, v80) <> 0 then
+		goto .symbol_table_lookup_repeat;
+	end;
+	(* Otherwise, the symbol is found. *)
+	v0 := _load_word(v88 + 8);
+	goto .symbol_table_lookup_end;
+
+	.symbol_table_lookup_repeat;
+	v88 := v88 + 12;
+	v4 := v4 + -1;
+	goto .symbol_table_lookup_loop;
+
+	.symbol_table_lookup_end;
+	return v0
+end;
+
 (* Inserts a symbol into the table. *)
 
 (* Parameters: *)
-(* a0 - Symbol pointer. *)
-(* a1 - Symbol name length. *)
-(* a2 - Symbol name pointer. *)
-(* a3 - Symbol table. *)
+(* a0 - Symbol table. *)
+(* a1 - Symbol name pointer. *)
+(* a2 - Symbol name length. *)
+(* a3 - Symbol pointer. *)
 proc _symbol_table_enter(v88: Word, v84: Word, v80: Word, v76: Word);
 begin
 	(* The first word in the symbol table is its length, get it. *)
-	v0 := _load_word(v76);
+	v0 := _load_word(v88);
 
 	(* Calculate the offset for the new symbol. *)
-	v4 := v0 * 4;
+	v4 := v0 * 12;
 	v4 := v4 + 4;
-	v4 := v76 + 4;
+	v4 := v88 + v4;
 
-	_memcpy(v4, @v80, 12);
+	_store_word(v84, v4);
+	v4 := v4 + 4;
+	_store_word(v80, v4);
+	v4 := v4 + 4;
+	_store_word(v76, v4);
 
 	(* Increment the symbol table length. *)
 	v0 := v0 + 1;
-	_store_word(v0, v76);
+	_store_word(v0, v88);
 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);
+	(* Set the table length to 0. *)
+	_store_word(0, @symbol_table_global);
+
+	(* Enter built-in symbols. *)
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_int, 3, @symbol_type_info_int);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_word, 4, @symbol_type_info_word);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_pointer, 7, @symbol_type_info_pointer);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_char, 4, @symbol_type_info_char);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_bool, 4, @symbol_type_info_bool);
 end;
 
 
diff --git a/boot/stage13.elna b/boot/stage13.elna
new file mode 100644
index 0000000..6bdb58d
--- /dev/null
+++ b/boot/stage13.elna
@@ -0,0 +1,2037 @@
+(* 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 13 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 *)
+	(* INFO_PARAMETER = 2 *)
+	(* INFO_TEMPORARY = 3 *)
+
+	(* 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;
+	memory: Array;
+
+	compiler_strings_position: Pointer := @compiler_strings;
+	compiler_strings_length: Word := 0;
+	label_counter: Word := 0;
+	source_code_position: Pointer := @source_code;
+	memory_free_pointer: Word := @memory;
+
+(* Calculates and returns the string token length between quotes, including the *)
+(* escaping slash characters. *)
+
+(* Parameters: *)
+(* string - String token pointer. *)
+
+(* Returns the length in a0. *)
+proc _string_length(string: Word);
+var
+	counter: Word;
+begin
+	(* Reset the counter. *)
+	counter := 0;
+
+	.string_length_loop;
+	string := string + 1;
+
+	if _load_byte(string) <> '"' then
+		counter := counter + 1;
+		goto .string_length_loop;
+	end;
+
+	return counter
+end;
+
+(* Adds a string to the global, read-only string storage. *)
+
+(* Parameters: *)
+(* string - String token. *)
+
+(* Returns the offset from the beginning of the storage to the new string in a0. *)
+proc _add_string(string: Word);
+var
+	contents: Word;
+	result: Word;
+	current_byte: Word;
+begin
+	contents := string + 1;
+	result := compiler_strings_length;
+
+	.add_string_loop;
+	if _load_byte(contents) <> '"' then
+		current_byte := _load_byte(contents);
+		_store_byte(current_byte, compiler_strings_position);
+		compiler_strings_position := compiler_strings_position + 1;
+		contents := contents + 1;
+
+		if current_byte <> '\\' then
+			compiler_strings_length := compiler_strings_length + 1;
+		end;
+		goto .add_string_loop;
+	end;
+
+	return result
+end;
+
+(* Reads standard input into a buffer. *)
+(* buffer - Buffer pointer. *)
+(* size - Buffer size. *)
+
+(* Returns the amount of bytes written in a0. *)
+proc _read_file(buffer: Word, size: Word);
+begin
+	_syscall(0, buffer, size, 0, 0, 0, 63);
+end;
+
+(* Writes to the standard output. *)
+
+(* Parameters: *)
+(* buffer - Buffer. *)
+(* size - Buffer length. *)
+proc _write_s(buffer: Word, size: Word);
+begin
+	_syscall(1, buffer, size, 0, 0, 0, 64);
+end;
+
+(* Writes a number to a string buffer. *)
+
+(* Parameters: *)
+(* number - Whole number. *)
+(* output_buffer - Buffer pointer. *)
+
+(* Sets a0 to the length of the written number. *)
+proc _print_i(number: Word, output_buffer: Word);
+var
+	local_buffer: Word;
+	is_negative: Word;
+	current_character: Word;
+	result: Word;
+begin
+	local_buffer := @result + 11;
+
+	if number >= 0 then
+		is_negative := 0;
+	else
+		number = -number;
+		is_negative := 1;
+	end;
+
+	.print_i_digit10;
+	current_character := number % 10;
+	_store_byte(current_character + '0', local_buffer);
+
+	number := number / 10;
+	local_buffer := local_buffer + -1;
+
+	if number <> 0 then
+		goto .print_i_digit10;
+	end;
+	if is_negative = 1 then
+		_store_byte('-', local_buffer);
+		local_buffer := local_buffer + -1;
+	end;
+	result := @result + 11;
+	result := result + -local_buffer;
+	_memcpy(output_buffer, local_buffer + 1, result);
+
+	return result
+end;
+
+(* Writes a number to the standard output. *)
+
+(* Parameters: *)
+(* number - Whole number. *)
+proc _write_i(number: Word);
+var
+	local_buffer: Word;
+	length: Word;
+begin
+	length := _print_i(number, @local_buffer);
+	_write_s(@local_buffer, length);
+end;
+
+(* Writes a character from a0 into the standard output. *)
+
+(* Parameters: *)
+(* character - Character to write. *)
+proc _write_c(character: Word);
+begin
+	_write_s(@character, 1);
+end;
+
+(* Write null terminated string. *)
+
+(* Parameters: *)
+(* string - String. *)
+proc _write_z(string: Word);
+var
+	next_byte: Word;
+begin
+	(* Check for 0 character. *)
+	next_byte := _load_byte(string);
+
+	if next_byte <> 0 then
+		(* Print a character. *)
+		_write_c(next_byte);
+
+		(* Advance the input string by one byte. *)
+		_write_z(string + 1);
+	end;
+end;
+
+(* Detects if a0 is an uppercase character. Sets a0 to 1 if so, otherwise to 0. *)
+proc _is_upper(character: Word);
+var
+	lhs: Word;
+	rhs: Word;
+begin
+	lhs := character >= 'A';
+	rhs := character <= 'Z';
+
+	return lhs & rhs
+
+end;
+
+(* Detects if a0 is an lowercase character. Sets a0 to 1 if so, otherwise to 0. *)
+proc _is_lower(character: Word);
+var
+	lhs: Word;
+	rhs: Word;
+begin
+	lhs := character >= 'a';
+	rhs := character <= 'z';
+
+	return lhs & rhs
+end;
+
+(* Detects if the passed character is a 7-bit alpha character or an underscore. *)
+
+(* Paramters: *)
+(* character - Tested character. *)
+
+(* Sets a0 to 1 if the character is an alpha character or underscore, sets it to 0 otherwise. *)
+proc _is_alpha(character: Word);
+var
+	is_upper_result: Word;
+	is_lower_result: Word;
+	is_alpha_result: Word;
+	is_underscore: Word;
+begin
+	is_upper_result := _is_upper(character);
+	is_lower_result := _is_lower(character);
+	is_underscore := character = '_';
+
+	is_alpha_result := is_lower_result or is_upper_result;
+	return is_alpha_result or is_underscore
+end;
+
+(* Detects whether the passed character is a digit *)
+(* (a value between 0 and 9). *)
+
+(* Parameters: *)
+(* character - Exemined value. *)
+
+(* Sets a0 to 1 if it is a digit, to 0 otherwise. *)
+proc _is_digit(character: Word);
+var
+	lhs: Word;
+	rhs: Word;
+begin
+	lhs := character >= '0';
+	rhs := character <= '9';
+
+	return lhs & rhs
+end;
+
+proc _is_alnum(character: Word);
+var
+	lhs: Word;
+	rhs: Word;
+begin
+	lhs := _is_alpha(character);
+	rhs := _is_digit(character);
+
+	return lhs or rhs
+end;
+
+(* Reads the next token. *)
+
+(* Returns token length in a0. *)
+proc _read_token();
+var
+	current_token_position: Word;
+	token_length: Word;
+	current_character: Word;
+	is_dot: Word;
+	is_alnum_result: Word;
+begin
+	current_token_position := source_code_position;
+	token_length := 0;
+
+	.read_token_loop;
+	(* Current character. *)
+	current_character := _load_byte(current_token_position);
+
+	(* First we try to read a derictive. *)
+	(* A derictive can contain a dot and characters. *)
+	is_dot := current_character = '.';
+	is_alnum_result := _is_alnum(current_character);
+
+	if is_dot or is_alnum_result then
+		(* Advance the source code position and token length. *)
+		token_length := token_length + 1;
+		current_token_position := current_token_position + 1;
+
+		goto .read_token_loop;
+	end;
+
+	return token_length
+end;
+
+(* Parameters: *)
+(* lhs - First pointer. *)
+(* rhs - Second pointer. *)
+(* count - The length to compare. *)
+
+(* Returns 0 if memory regions are equal. *)
+proc _memcmp(lhs: Word, rhs: Word, count: Word);
+var
+	lhs_byte: Word;
+	rhs_byte: Word;
+	result: Word;
+begin
+	result := 0;
+
+	.memcmp_loop;
+	if count <> 0 then
+		lhs_byte := _load_byte(lhs);
+		rhs_byte := _load_byte(rhs);
+		result := lhs_byte + -rhs_byte;
+
+		lhs := lhs + 1;
+		rhs := rhs + 1;
+		count := count + -1;
+
+		if result = 0 then
+			goto .memcmp_loop;
+		end;
+	end;
+
+	return result
+end;
+
+(* Copies memory. *)
+
+(* Parameters: *)
+(* destination - Destination. *)
+(* source - Source. *)
+(* count - Size. *)
+
+(* Returns the destination. *)
+proc _memcpy(destination: Word, source: Word, count: Word);
+var
+	current_byte: Word;
+begin
+	.memcpy_loop;
+	if count <> 0 then
+		current_byte := _load_byte(source);
+		_store_byte(current_byte, destination);
+
+		destination := destination + 1;
+		source := source + 1;
+		count := count + -1;
+		goto .memcpy_loop;
+	end;
+
+	return destination
+end;
+
+(* Advances the token stream by a0 bytes. *)
+proc _advance_token(count: Word);
+begin
+	source_code_position := source_code_position + count;
+end;
+
+(* Prints the current token. *)
+
+(* Parameters: *)
+(* length - Token length. *)
+
+(* Returns a0 unchanged. *)
+proc _write_token(length: Word);
+begin
+	_write_s(source_code_position, length);
+	return length
+end;
+
+proc _compile_integer_literal();
+var
+	integer_token: Word;
+begin
+	_write_z("\tli t0, \0");
+
+	integer_token := _read_token();
+	_write_token(integer_token);
+	_advance_token(integer_token);
+
+	_write_c('\n');
+end;
+
+proc _compile_character_literal();
+var
+	character: Word;
+begin
+	_write_z("\tli t0, '\0");
+	_advance_token(1);
+
+	character := _load_byte(source_code_position);
+	if character = '\\' then
+		_write_c('\\');
+		_advance_token(1);
+	end;
+	_write_s(source_code_position, 1);
+	_write_s("'\n", 2);
+	_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();
+var
+	length: Word;
+	offset: Word;
+begin
+	length := _string_length(source_code_position);
+	offset := _add_string(source_code_position);
+
+	_advance_token(length + 2);
+	_write_z("\tla t0, strings\n\0");
+
+	_write_z("\tli t1, \0");
+	_write_i(offset);
+	_write_c('\n');
+
+	_write_z("\tadd t0, t0, t1\n\0");
+end;
+
+proc _compile_term();
+var
+	current_character: Word;
+begin
+	current_character := _load_byte(source_code_position);
+
+	if current_character = '\'' then
+		_compile_character_literal();
+	end;
+	if current_character = '@' then
+		_compile_address_expression();
+	end;
+	if current_character = '-' then
+		_compile_negate_expression();
+	end;
+	if current_character = '~' then
+		_compile_not_expression();
+	end;
+	if current_character = '"' then
+		_compile_string_literal();
+	end;
+	if current_character = '_' then
+		_compile_call();
+		_write_z("\nmv t0, a0\n\0");
+	end;
+	if _is_digit(current_character) = 1 then
+		_compile_integer_literal();
+	end;
+	if _is_lower(current_character) = 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();
+var
+	current_character: Word;
+begin
+	_compile_term();
+	current_character := _load_byte(source_code_position);
+
+	if current_character <> ' ' 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);
+	current_character := _load_byte(source_code_position);
+
+	if current_character = '+' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("add t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '*' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("\tmul t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '&' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("\tand t0, t0, t1\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '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 current_character = '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 current_character = '=' 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 current_character = '%' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("rem t0, t1, t0\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '/' then
+		_advance_token(1);
+		_compile_binary_rhs();
+
+		(* Execute the operation. *)
+		_write_z("div t0, t1, t0\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '<' then
+		_advance_token(1);
+		current_character := _load_byte(source_code_position);
+
+		if current_character = '>' 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 current_character = '=' 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, t1, t0\n\0");
+
+		goto .compile_expression_end;
+	end;
+	if current_character = '>' then
+		_advance_token(1);
+		current_character := _load_byte(source_code_position);
+		if current_character = '=' then
+			_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();
+var
+	name_length: Word;
+	name: Word;
+	argument_count: Word;
+	stack_offset: Word;
+begin
+	name_length := _read_token();
+	name := source_code_position;
+	argument_count := 0;
+
+	(* Skip the identifier and left paren. *)
+	_advance_token(name_length + 1);
+
+	if _load_byte(source_code_position) = ')' 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) *)
+	stack_offset := argument_count * 4;
+	_write_i(116 + -stack_offset);
+
+	_write_z("(sp)\n\0");
+
+	(* Add one to the argument counter. *)
+	argument_count := argument_count + 1;
+
+	if _load_byte(source_code_position) <> ',' then
+		goto .compile_call_finalize;
+	end;
+	_advance_token(2);
+	goto .compile_call_loop;
+
+	.compile_call_finalize;
+	(* Load the argument from the stack. *)
+	if argument_count <> 0 then
+		(* Decrement the argument counter. *)
+		argument_count := argument_count + -1;
+
+		_write_z("\tlw a\0");
+		_write_i(argument_count);
+
+		_write_z(", \0");
+
+		(* Calculate the stack offset: 116 - (4 * argument_counter) *)
+		stack_offset := argument_count * 4;
+		_write_i(116 + -stack_offset);
+
+		_write_z("(sp)\n\0");
+
+		goto .compile_call_finalize;
+	end;
+
+	.compile_call_end;
+	_write_z("\tcall \0");
+	_write_s(name, name_length);
+
+	(* Skip the right paren. *)
+	_advance_token(1);
+end;
+
+proc _compile_goto();
+var
+	next_token: Word;
+begin
+	_advance_token(5);
+
+	next_token := _read_token();
+	_write_z("\tj \0");
+
+	_write_token(next_token);
+	_advance_token(next_token);
+end;
+
+proc _compile_local_designator(symbol: Word, name_length: Word);
+var
+	variable_offset: Word;
+begin
+
+	_write_z("\taddi t0, sp, \0");
+	variable_offset := _parameter_info_get_offset(symbol);
+	_write_i(variable_offset);
+	_write_c('\n');
+	_advance_token(name_length);
+end;
+
+proc _compile_global_designator();
+var
+	name: Word;
+begin
+	_write_z("\tla t0, \0");
+
+	name := _read_token();
+	_write_token(name);
+	_advance_token(name);
+
+	_write_c('\n');
+end;
+
+proc _compile_designator();
+var
+	name_token: Word;
+	lookup_result: Word;
+begin
+	name_token := _read_token();
+	lookup_result := _symbol_table_lookup(@symbol_table_local, source_code_position, name_token);
+
+	if lookup_result <> 0 then
+		_compile_local_designator(lookup_result, name_token);
+		goto .compile_designator_end;
+	end;
+	_compile_global_designator();
+
+	.compile_designator_end;
+end;
+
+proc _compile_assignment();
+begin
+	_compile_designator();
+
+	(* Save the assignee address on the stack. *)
+	_write_z("\tsw t0, 60(sp)\n\0");
+
+	(* Skip the assignment sign (:=) with surrounding whitespaces. *)
+	_advance_token(4);
+
+	(* Compile the assignment. *)
+	_compile_expression();
+
+	_write_z("\tlw t1, 60(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: *)
+(* counter - Label counter. *)
+proc _write_label(counter: Word);
+begin
+	_write_z(".L\0");
+	_write_i(counter);
+end;
+
+proc _compile_if();
+var
+	after_end_label: Word;
+	condition_label: Word;
+begin
+	(* Skip "if ". *)
+	_advance_token(3);
+	(* Compile condition. *)
+	_compile_expression();
+	(* Skip " then" with newline. *)
+	_advance_token(6);
+
+	after_end_label := label_counter;
+	label_counter := label_counter + 1;
+
+	(* condition_label is the label in front of the next elsif condition or end. *)
+	condition_label := label_counter;
+	label_counter := label_counter + 1;
+
+	_write_z("\tbeqz t0, \0");
+	_write_label(condition_label);
+	_write_c('\n');
+
+	_compile_procedure_body();
+
+	_write_z("\tj \0");
+	_write_label(after_end_label);
+	_write_c('\n');
+
+	_write_label(condition_label);
+	_write_z(":\n\0");
+
+	if _memcmp(source_code_position, "end", 3) = 0 then
+		goto .compile_if_end;
+	end;
+	if _memcmp(source_code_position, "else", 3) = 0 then
+		goto .compile_if_else
+	end;
+	.compile_if_else;
+	(* Skip "else" and newline. *)
+	_advance_token(5);
+	_compile_procedure_body();
+
+	.compile_if_end;
+	(* Skip "end". *)
+	_advance_token(3);
+
+	_write_label(after_end_label);
+	_write_z(":\n\0");
+end;
+
+proc _compile_label_declaration();
+var
+	label_token: Word;
+begin
+	(* Skip the dot. *)
+	_advance_token(1);
+	label_token := _read_token();
+	_write_c('.');
+	_write_s(source_code_position, label_token);
+	_write_z(":\n\0");
+	_advance_token(label_token);
+end;
+
+proc _compile_statement();
+var
+	current_byte: Word;
+begin
+	_skip_spaces();
+	current_byte := _load_byte(source_code_position);
+
+	(* This is a call if the statement starts with an underscore. *)
+	if current_byte = '_' then
+		_compile_call();
+		goto .compile_statement_semicolon;
+	end;
+	if _memcmp(source_code_position, "goto ", 5) = 0 then
+		_compile_goto();
+		goto .compile_statement_semicolon;
+	end;
+	if _memcmp(source_code_position, "if ", 3) = 0 then
+		_compile_if();
+		goto .compile_statement_semicolon;
+	end;
+	if _memcmp(source_code_position, "return ", 7) = 0 then
+		_compile_return_statement();
+		_write_c('\n');
+
+		goto .compile_statement_end;
+	end;
+	if current_byte = '.' then
+		_compile_label_declaration();
+
+		goto .compile_statement_semicolon;
+	end;
+	_compile_assignment();
+	goto .compile_statement_semicolon;
+
+	.compile_statement_semicolon;
+	_advance_token(2);
+	_write_c('\n');
+
+	.compile_statement_end;
+end;
+
+proc _compile_procedure_body();
+var
+	lhs: Word;
+	rhs: Word;
+begin
+	.compile_procedure_body_loop;
+	_skip_empty_lines();
+	_skip_spaces();
+
+	lhs := _memcmp(source_code_position, "end", 3) = 0;
+	rhs := _memcmp(source_code_position, "else", 4) = 0;
+	lhs := lhs or rhs;
+
+	if lhs = 0 then
+		_compile_statement();
+		goto .compile_procedure_body_loop;
+	end;
+end;
+
+(* Writes a regster name to the standard output. *)
+
+(* Parameters: *)
+(* register_character - Register character. *)
+(* register_number - Register number. *)
+proc _write_register(register_character: Word, register_number: Word);
+begin
+	_write_c(register_character);
+	register_number := register_number + '0';
+	_write_c(register_number);
+end;
+
+proc _skip_spaces();
+var
+	current_byte: Word;
+begin
+	current_byte := _load_byte(source_code_position);
+	if current_byte = '\t' then
+		_advance_token(1);
+		_skip_spaces();
+	end;
+end;
+
+proc _read_type_expression();
+var
+	type_name: Word;
+begin
+	type_name := _read_token();
+	_advance_token(type_name);
+end;
+
+(* Parameters: *)
+
+(* parameter_index - Parameter index. *)
+proc _parameter_info_create(parameter_index: Word);
+var
+	offset: Word;
+	current_word: Word;
+	result: Word;
+begin
+	result := memory_free_pointer;
+	current_word := result;
+	(* 2 is INFO_PARAMETER *)
+	_store_word(2, current_word);
+
+	current_word := current_word + 4;
+
+	(* Calculate the stack offset: 88 - (4 * parameter_counter) *)
+	offset := parameter_index * 4;
+	_store_word(88 + -offset, current_word);
+
+	memory_free_pointer := current_word + 4;
+
+	return result
+end;
+
+proc _parameter_info_get_offset(info: Word);
+begin
+	info := info + 4;
+	return _load_word(info)
+end;
+
+(* Parameters: *)
+
+(* temporary_index - Parameter index. *)
+proc _temporary_info_create(temporary_index: Word);
+var
+	offset: Word;
+	current_word: Word;
+	result: Word;
+begin
+	result := memory_free_pointer;
+	current_word := result;
+	(* 3 is INFO_TEMPORARY *)
+	_store_word(3, current_word);
+
+	current_word := current_word + 4;
+
+	(* Calculate the stack offset: 4 * variable_counter. *)
+	_store_word(temporary_index * 4, current_word);
+
+	memory_free_pointer := current_word + 4;
+
+	return result
+end;
+
+proc _temporary_info_get_offset(info: Word);
+begin
+	info := info + 4;
+	return _load_word(info)
+end;
+
+(* Parameters: *)
+
+(* parameter_index - Parameter index. *)
+proc _read_procedure_parameter(parameter_index: Word);
+var
+	name_length: Word;
+	info: Word;
+	name_position: Word;
+begin
+	(* Read the parameter name. *)
+	name_position := source_code_position;
+	name_length := _read_token();
+	_advance_token(name_length);
+
+	(* Skip colon and space in front of the type expression. *)
+	_advance_token(2);
+
+	_read_type_expression();
+
+	_write_z("\tsw a\0");
+	_write_i(parameter_index);
+	_write_z(", \0");
+
+	info := _parameter_info_create(parameter_index);
+	_symbol_table_enter(@symbol_table_local, name_position, name_length, info);
+
+	info := _parameter_info_get_offset(info);
+	_write_i(info);
+
+	_write_z("(sp)\n\0");
+end;
+
+proc _read_procedure_parameters();
+var
+	parameter_counter: Word;
+begin
+	(* Skip open paren. *)
+	_advance_token(1);
+	parameter_counter := 0;
+
+	.compile_procedure_prologue_skip;
+	if _load_byte(source_code_position) <> ')' then
+		_read_procedure_parameter(parameter_counter);
+		parameter_counter := parameter_counter + 1;
+
+		if _load_byte(source_code_position) = ',' then
+			_advance_token(2);
+			goto .compile_procedure_prologue_skip;
+		end;
+	end;
+	(* Skip close paren. *)
+	_advance_token(1);
+end;
+
+(* Parameters: *)
+(* variable_index - Variable index. *)
+proc _read_procedure_temporary(variable_index: Word);
+var
+	name_length: Word;
+	info: Word;
+	name_position: Word;
+begin
+	_skip_spaces();
+	name_position := source_code_position;
+
+	(* Read and skip variable name, colon and the space *)
+	name_length := _read_token();
+	_advance_token(name_length + 2);
+
+	_read_type_expression();
+
+	info := _temporary_info_create(variable_index);
+	_symbol_table_enter(@symbol_table_local, name_position, name_length, info);
+
+	(* Skip semicolon and newline after the variable declaration *)
+	_advance_token(2);
+end;
+
+proc _read_procedure_temporaries();
+var
+	temporary_counter: Word;
+begin
+	if _memcmp(source_code_position, "var", 3) <> 0 then
+		goto .read_local_variables_end;
+	end;
+	_advance_token(4);
+	temporary_counter := 0;
+
+	.read_local_variables_loop;
+	if _memcmp(source_code_position, "begin", 5) = 0 then
+		goto .read_local_variables_end;
+	end;
+	_read_procedure_temporary(temporary_counter);
+
+	temporary_counter := temporary_counter + 1;
+	goto .read_local_variables_loop;
+
+	.read_local_variables_end;
+end;
+
+proc _compile_procedure();
+var
+	name_length: Word;
+begin
+	(* Skip "proc ". *)
+	_advance_token(5);
+	(* Clear local symbol table. *)
+	_store_word(0, @symbol_table_local);
+
+	name_length := _read_token();
+
+	(* Write .type _procedure_name, @function. *)
+	_write_z(".type \0");
+
+	_write_token(name_length);
+	_write_z(", @function\n\0");
+
+	(* Write procedure label, _procedure_name: *)
+	_write_token(name_length);
+	_write_z(":\n\0");
+
+	(* Skip procedure name. *)
+	_advance_token(name_length);
+	_write_z("\taddi sp, sp, -128\n\tsw ra, 124(sp)\n\tsw s0, 120(sp)\n\taddi s0, sp, 128\n\0");
+	_read_procedure_parameters();
+
+	(* Skip semicolon and newline. *)
+	_advance_token(2);
+	_read_procedure_temporaries();
+
+	(* Skip semicolon, "begin" and newline. *)
+	_advance_token(6);
+
+	_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;
+
+(* Prints and skips a line. *)
+proc _skip_comment();
+begin
+	.skip_comment_loop;
+
+	(* Check for newline character. *)
+	if _load_byte(source_code_position) <> '\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();
+var
+	current_position: Word;
+	current_byte: Word;
+begin
+	.skip_empty_lines_rerun;
+	current_position := source_code_position;
+
+	.skip_empty_lines_loop;
+	current_byte := _load_byte(current_position);
+
+	if current_byte = '\n' then
+		goto .skip_empty_lines_newline;
+	end;
+	if current_byte = '\t' then
+		goto .skip_empty_lines_tab;
+	end;
+	if current_byte <> '(' then
+		goto .skip_empty_lines_end;
+	end;
+	current_byte := _load_byte(current_position + 1);
+
+	if current_byte = '*' then
+		goto .skip_empty_lines_comment
+	end;
+	goto .skip_empty_lines_end;
+
+	.skip_empty_lines_comment;
+	source_code_position := current_position;
+	_skip_comment();
+	goto .skip_empty_lines_rerun;
+
+	.skip_empty_lines_newline;
+	source_code_position := current_position + 1;
+	goto .skip_empty_lines_rerun;
+
+	.skip_empty_lines_tab;
+	current_position := current_position + 1;
+	goto .skip_empty_lines_loop
+
+	.skip_empty_lines_end;
+end;
+
+proc _compile_global_initializer();
+var
+	current_byte: Word;
+	length: Word;
+begin
+	current_byte := _load_byte(source_code_position);
+
+	if current_byte = '"' then
+		_write_z("\n\t.word strings + \0");
+		length := _string_length(source_code_position);
+
+		_add_string(source_code_position);
+		_write_i();
+
+		(* Skip the quoted string. *)
+		_advance_token(length + 2);
+
+		goto .compile_global_initializer_end;
+	end;
+	if current_byte = '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 current_byte = '@' then
+		(* Skip @. *)
+		_advance_token(1);
+		_write_z("\n\t.word \0");
+		current_byte := _read_token();
+		_write_token(current_byte);
+		_advance_token(current_byte);
+
+		goto .compile_global_initializer_end;
+	end;
+	if _is_digit(current_byte) = 1 then
+		_write_z("\n\t.word \0");
+		current_byte := _read_token();
+		_write_token(current_byte);
+		_advance_token(1);
+
+		goto .compile_global_initializer_end;
+	end;
+
+	.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();
+var
+	name_length: Word;
+begin
+	name_length := _read_token();
+
+	_write_z(".type \0");
+	_write_token(name_length);
+	_write_z(", @object\n\0");
+
+	_write_token(name_length);
+	_write_c(':');
+
+	(* Skip the constant name with assignment sign and surrounding whitespaces. *)
+	_advance_token(name_length + 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();
+var
+	name_length: Word;
+begin
+	name_length := _read_token();
+
+	_write_z(".type \0");
+	_write_token(name_length);
+	_write_z(", @object\n\0");
+
+	_write_token(name_length);
+	_write_c(':');
+
+	(* Skip the variable name and colon with space before the type. *)
+	_advance_token(name_length + 2);
+	_read_type_expression();
+
+	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();
+var
+	current_character: Word;
+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();
+	current_character := _load_byte(source_code_position);
+
+	if current_character = '\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();
+var
+	compiler_strings_copy: Word;
+	compiler_strings_end: Word;
+	current_byte: Word;
+begin
+	_write_z(".globl _start\n\n\0");
+	_compile_module();
+
+	_write_z(".section .rodata\n.type strings, @object\nstrings: .ascii \0");
+	_write_c('"');
+
+	compiler_strings_copy := @compiler_strings;
+	compiler_strings_end := compiler_strings_position;
+
+	.compile_loop;
+	if compiler_strings_copy < compiler_strings_end then
+		current_byte := _load_byte(compiler_strings_copy);
+		compiler_strings_copy := compiler_strings_copy + 1;
+		_write_c(current_byte);
+
+		goto .compile_loop;
+	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;
+
+(* Looks for a symbol in the given symbol table. *)
+
+(* Parameters: *)
+(* symbol_table - Symbol table. *)
+(* symbol_name - Symbol name pointer. *)
+(* name_length - Symbol name length. *)
+
+(* Returns the symbol pointer or 0 in a0. *)
+proc _symbol_table_lookup(symbol_table: Word, symbol_name: Word, name_length: Word);
+var
+	result: Word;
+	symbol_table_length: Word;
+	current_name: Word;
+	current_length: Word;
+begin
+	result := 0;
+
+	(* The first word in the symbol table is its length, get it. *)
+	symbol_table_length := _load_word(symbol_table);
+
+	(* Go to the first symbol position. *)
+	symbol_table := symbol_table + 4;
+
+	.symbol_table_lookup_loop;
+	if symbol_table_length = 0 then
+		goto .symbol_table_lookup_end;
+	end;
+
+	(* Symbol name pointer and length. *)
+	current_name := _load_word(symbol_table);
+	current_length := _load_word(symbol_table + 4);
+
+	(* If lengths don't match, exit and return nil. *)
+	if name_length <> current_length then
+		goto .symbol_table_lookup_repeat;
+	end;
+	(* If names don't match, exit and return nil. *)
+	if _memcmp(symbol_name, current_name, name_length) <> 0 then
+		goto .symbol_table_lookup_repeat;
+	end;
+	(* Otherwise, the symbol is found. *)
+	result := _load_word(symbol_table + 8);
+	goto .symbol_table_lookup_end;
+
+	.symbol_table_lookup_repeat;
+	symbol_table := symbol_table + 12;
+	symbol_table_length := symbol_table_length + -1;
+	goto .symbol_table_lookup_loop;
+
+	.symbol_table_lookup_end;
+	return result
+end;
+
+(* Inserts a symbol into the table. *)
+
+(* Parameters: *)
+(* symbol_table - Symbol table. *)
+(* symbol_name - Symbol name pointer. *)
+(* name_length - Symbol name length. *)
+(* symbol - Symbol pointer. *)
+proc _symbol_table_enter(symbol_table: Word, symbol_name: Word, name_length: Word, symbol: Word);
+var
+	table_length: Word;
+	symbol_pointer: Word;
+begin
+	(* The first word in the symbol table is its length, get it. *)
+	table_length := _load_word(symbol_table);
+
+	(* Calculate the offset for the new symbol. *)
+	symbol_pointer := table_length * 12;
+	symbol_pointer := symbol_pointer + 4;
+	symbol_pointer := symbol_table + symbol_pointer;
+
+	_store_word(symbol_name, symbol_pointer);
+	symbol_pointer := symbol_pointer + 4;
+	_store_word(name_length, symbol_pointer);
+	symbol_pointer := symbol_pointer + 4;
+	_store_word(symbol, symbol_pointer);
+
+	(* Increment the symbol table length. *)
+	table_length := table_length + 1;
+	_store_word(table_length, symbol_table);
+end;
+
+proc _symbol_table_build();
+begin
+	(* Set the table length to 0. *)
+	_store_word(0, @symbol_table_global);
+
+	(* Enter built-in symbols. *)
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_int, 3, @symbol_type_info_int);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_word, 4, @symbol_type_info_word);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_pointer, 7, @symbol_type_info_pointer);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_char, 4, @symbol_type_info_char);
+	_symbol_table_enter(@symbol_table_global, symbol_builtin_name_bool, 4, @symbol_type_info_bool);
+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: *)
+(* array - Array pointer. *)
+(* index - Index (word offset into the array). *)
+(* data - Data to assign. *)
+proc _assign_at(array: Word, index: Word, data: Word);
+var
+	target: Word;
+begin
+	target := index + -1;
+	target := target * 4;
+	target := array + target;
+
+	_store_word(data, target);
+end;
+
+proc _create_classification();
+var
+	code: Word;
+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);
+
+	code := 129;
+
+	(* Set the remaining 129 - 256 bytes to transitionClassOther. *)
+	.create_classification_loop;
+	_assign_at(@classification, code, 22);
+	code := code + 1;
+
+	if code < 257 then
+		goto .create_classification_loop;
+	end;
+end;
+
+(* Parameters: *)
+(* current_state - Current state (first index into transitions table). *)
+(* transition - Transition (second index into transitions table). *)
+(* action - Action to assign. *)
+(* next_state - Next state to assign. *)
+proc _set_transition(current_state: Word, transition: Word, action: Word, next_state: Word);
+var
+	transition_table: Word;
+	row_position: Word;
+	state_position: Word;
+	target: Word;
+begin
+	(* Transitions start at offset in classification array. *)
+	transition_table := @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. *)
+
+	row_position := current_state + -1;
+	row_position := row_position * 128;
+
+	state_position := transition + -1;
+	state_position := state_position * 8;
+
+	target := transition_table + row_position;
+	target := target + state_position;
+
+	_store_word(action, target);
+	target := target + 4;
+	_store_word(next_state, target);
+end;
+
+(* Parameters: *)
+(* current_state - Current state (Transition state enumeration). *)
+(* default_action - Default action (Callback). *)
+(* next_state - Next state (Transition state enumeration). *)
+proc _set_default_transition(current_state: Word, default_action: Word, next_state: Word);
+begin
+	_set_transition(current_state, 1, default_action, next_state);
+	_set_transition(current_state, 2, default_action, next_state);
+	_set_transition(current_state, 3, default_action, next_state);
+	_set_transition(current_state, 4, default_action, next_state);
+	_set_transition(current_state, 5, default_action, next_state);
+	_set_transition(current_state, 6, default_action, next_state);
+	_set_transition(current_state, 7, default_action, next_state);
+	_set_transition(current_state, 8, default_action, next_state);
+	_set_transition(current_state, 9, default_action, next_state);
+	_set_transition(current_state, 10, default_action, next_state);
+	_set_transition(current_state, 11, default_action, next_state);
+	_set_transition(current_state, 12, default_action, next_state);
+	_set_transition(current_state, 13, default_action, next_state);
+	_set_transition(current_state, 14, default_action, next_state);
+	_set_transition(current_state, 15, default_action, next_state);
+	_set_transition(current_state, 16, default_action, next_state);
+	_set_transition(current_state, 17, default_action, next_state);
+	_set_transition(current_state, 18, default_action, next_state);
+	_set_transition(current_state, 19, default_action, next_state);
+	_set_transition(current_state, 20, default_action, next_state);
+	_set_transition(current_state, 21, default_action, next_state);
+	_set_transition(current_state, 22, default_action, next_state);
+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();
+var
+	offset: Word;
+	size: Word;
+begin
+	(* Lexer state is saved after the transition tables. The offset is 256 + 16 * 22. *)
+	offset := @classification;
+	size := 16 * 22;
+	offset := offset + 256;
+
+	return offset + size
+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();
+var
+	state: Word;
+	current: Word;
+begin
+	(* Transition start state is 1. *)
+	state := _lexer_get_state();
+	_store_word(1, state);
+
+	(* Text pointer to the beginning of the currently read token. *)
+	current := _lexer_get_current();
+	_store_word(source_code_position, current);
+
+	(* 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;