diff --git a/boot/common-boot.s b/boot/common-boot.s
index 2228a57..9c5ebc4 100644
--- a/boot/common-boot.s
+++ b/boot/common-boot.s
@@ -1,4 +1,4 @@
-.global is_alpha, is_digit, is_alnum, is_upper, is_lower, write_out, read_file, exit, memcmp, write_error
+.global _is_alpha, _is_digit, _is_alnum, _is_upper, _is_lower, _write_out, _read_file, exit, _memcmp, _write_error
 
 .section .rodata
 
@@ -16,8 +16,8 @@ new_line: .ascii "\n"
 # Write the current token to stderr.
 # a0 - String pointer.
 # a1 - String length.
-.type write_error, @function
-write_error:
+.type _write_error, @function
+_write_error:
 	mv t0, a0
 	mv t1, a1
 
@@ -40,8 +40,8 @@ write_error:
 # a2 - The length to compare.
 #
 # Returns 0 in a0 if memory regions are equal.
-.type memcmp, @function
-memcmp:
+.type _memcmp, @function
+_memcmp:
 	mv t0, a0
 	li a0, 0
 
@@ -64,7 +64,8 @@ memcmp:
 	ret
 
 # Detects if a0 is an uppercase character. Sets a0 to 1 if so, otherwise to 0.
-is_upper:
+.type _is_upper, @function
+_is_upper:
 	li t0, 'A' - 1
 	sltu t1, t0, a0 # t1 = a0 >= 'A'
 
@@ -74,8 +75,8 @@ is_upper:
 	ret
 
 # Detects if a0 is an lowercase character. Sets a0 to 1 if so, otherwise to 0.
-.type is_lower, @function
-is_lower:
+.type _is_lower, @function
+_is_lower:
 	li t0, 'a' - 1
 	sltu t2, t0, a0 # t2 = a0 >= 'a'
 
@@ -87,8 +88,8 @@ is_lower:
 # Detects if the passed character is a 7-bit alpha character or an underscore.
 # The character is passed in a0.
 # Sets a0 to 1 if the character is an alpha character or underscore, sets it to 0 otherwise.
-.type is_alpha, @function
-is_alpha:
+.type _is_alpha, @function
+_is_alpha:
 	# Prologue.
 	addi sp, sp, -16
 	sw ra, 12(sp)
@@ -97,11 +98,11 @@ is_alpha:
 
 	sw a0, 4(sp)
 
-	call is_upper
+	call _is_upper
 	sw a0, 0(sp)
 
 	lw a0, 4(sp)
-	call is_lower
+	call _is_lower
 
 	lw t0, 4(sp)
 	xori t1, t0, '_'
@@ -117,8 +118,8 @@ is_alpha:
 	addi sp, sp, 16
 	ret
 
-.type is_digit, @function
-is_digit:
+.type _is_digit, @function
+_is_digit:
 	li t0, '0' - 1
 	sltu t1, t0, a0 # t1 = a0 >= '0'
 
@@ -128,8 +129,8 @@ is_digit:
 
 	ret
 
-.type is_alnum, @function
-is_alnum:
+.type _is_alnum, @function
+_is_alnum:
 	# Prologue.
 	addi sp, sp, -16
 	sw ra, 12(sp)
@@ -138,11 +139,11 @@ is_alnum:
 
 	sw a0, 4(sp)
 
-	call is_alpha
+	call _is_alpha
 	sw a0, 0(sp)
 
 	lw a0, 4(sp)
-	call is_digit
+	call _is_digit
 
 	lw a1, 0(sp)
 	or a0, a0, a1
@@ -153,8 +154,8 @@ is_alnum:
 	addi sp, sp, 16
 	ret
 
-.type write, @function
-write_out:
+.type _write_out, @function
+_write_out:
 	# Prologue.
 	addi sp, sp, -8
 	sw ra, 4(sp)
@@ -178,8 +179,8 @@ write_out:
 # a1 - Buffer size.
 #
 # Returns the result in a0.
-.type read_file, @function
-read_file:
+.type _read_file, @function
+_read_file:
 	# Prologue.
 	addi sp, sp, -8
 	sw ra, 4(sp)
diff --git a/boot/echo-boot.s b/boot/echo-boot.s
index 22d59d0..8256bbd 100644
--- a/boot/echo-boot.s
+++ b/boot/echo-boot.s
@@ -11,6 +11,325 @@ source_code: .zero 20480
 
 .section .text
 
+# Evalutes an expression and saves the result in a0.
+.type _build_expression, @function
+_build_expression:
+	# Prologue.
+	addi sp, sp, -32
+	sw ra, 28(sp)
+	sw s0, 24(sp)
+	addi s0, sp, 32
+
+	call _skip_spaces
+	call _read_token
+	sw s1, 20(sp)
+	sw a0, 16(sp)
+
+	# Integer literal.
+	addi a0, s1, 0
+	lb a0, (a0)
+	call _is_digit
+	bnez a0, .Lbuild_expression_number_literal
+
+	# Named identifier.
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x6120616c # la a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	addi a0, sp, 12
+	li a1, 1
+	call _write_out
+
+	j .Lbuild_expression_end
+
+.Lbuild_expression_number_literal:
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x6120696c # li a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	addi a0, sp, 12
+	li a1, 1
+	call _write_out
+
+	j .Lbuild_expression_end
+
+.Lbuild_expression_end:
+	lw a0, 16(sp)
+	add s1, s1, a0
+
+	# Epilogue.
+	lw ra, 28(sp)
+	lw s0, 24(sp)
+	addi sp, sp, 32
+	ret
+
+# Compiles a statement beginning with an identifier.
+#
+# Left values should be variables named "loca n", where n is the offset
+# of the variable on the stack, like loca8 or loca4.
+.type _compile_identifier, @function
+_compile_identifier:
+	# Prologue.
+	addi sp, sp, -32
+	sw ra, 28(sp)
+	sw s0, 24(sp)
+	addi s0, sp, 32
+
+	call _read_token
+
+	# Save the pointer to the identifier and its length on the stack.
+	sw s1, 20(sp)
+	sw a0, 16(sp)
+
+	add s1, s1, a0
+	call _skip_spaces
+	call _read_token
+
+	# Save the pointer and the length of the token following the identifier.
+	sw s1, 12(sp)
+	sw a0, 8(sp)
+
+	add s1, s1, a0 # Skip that token.
+	call _skip_spaces
+
+	li t0, 0x3d3a # :=
+	sw t0, 4(sp)
+	lw a0, 12(sp)
+	lw a1, 8(sp)
+	addi a2, sp, 4
+	call _token_compare
+	beqz a0, .Lcompile_identifier_assign
+
+	/* DEBUG
+	mv a0, s1
+	li a1, 4
+	call _write_error */
+
+	lw t0, 12(sp)
+	lbu t0, (t0)
+	li t1, 0x28 # (
+	beq t0, t1, .Lcompile_identifier_call
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_call:
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _compile_call
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_assign:
+	call _build_expression
+
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x61207773 # sw a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	addi a0, a0, 4 # Skip the "loca" variable prefix.
+	addi a1, a1, -4 # Skip the "loca" variable prefix.
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	li t0, 0x29707328 # (sp)
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 5
+	call _write_out
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_end:
+	# Epilogue.
+	lw ra, 28(sp)
+	lw s0, 24(sp)
+	addi sp, sp, 32
+	ret
+
+# Compiles a procedure call. Expects s1 to point to the first argument.
+# a0 - Pointer to the procedure name.
+# a1 - Length of the procedure name.
+#
+# Returns the procedure result in a0.
+.type _compile_call, @function
+_compile_call:
+	# Prologue.
+	addi sp, sp, -32
+	sw ra, 28(sp)
+	sw s0, 24(sp)
+	addi s0, sp, 32
+
+	sw a0, 20(sp)
+	sw a1, 16(sp)
+	sw zero, 12(sp) # Argument count for a procedure call.
+
+.Lcompile_call_paren:
+	call _skip_spaces
+	call _read_token
+	lbu t0, (s1)
+	li t1, 0x29 # )
+	beq t0, t1, .Lcompile_call_complete
+
+.Lcompile_call_argument:
+	call _build_expression
+
+	li t0, 0x202c30 # 0,_
+	sw t0, 8(sp)
+	li t0, 0x61207773 # sw a
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 7
+	call _write_out
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+
+	# Only 8 arguments are supported with a0-a7.
+	# Save all arguments on the stack so they aren't overriden afterwards.
+	# The offset on the stack always has two digits in this case.
+	li t1, -4
+	mul t1, t0, t1
+	addi t1, t1, 84
+	li t2, 10
+	div t3, t1, t2
+	rem t4, t1, t2
+	addi t3, t3, '0'
+	addi t4, t4, '0'
+
+	sw t3, 8(sp)
+	sw t4, 4(sp)
+
+	addi a0, sp, 8
+	li a1, 1
+	call _write_out
+
+	addi a0, sp, 4
+	li a1, 1
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 8(sp)
+	li t0, 0x29707328 # (sp)
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 5
+	call _write_out
+
+	call _skip_spaces
+	call _read_token
+	lbu t0, (s1)
+	li t1, ','
+	bne t0, t1, .Lcompile_call_paren
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+	addi t0, t0, 1
+	sw t0, 12(sp)
+
+	addi s1, s1, 1 # Skip the comma between the arguments.
+	j .Lcompile_call_argument
+
+.Lcompile_call_complete:
+	sw zero, 12(sp)
+
+.Lcompile_call_restore:
+	# Just go through all a0-a7 registers and read them from stack.
+	# If this stack value contains garbage, the procedure just shouldn't use it.
+	lw t0, 12(sp)
+	li t1, 7
+	bgt t0, t1, .Lcompile_call_perform
+
+	li t0, 0x6120776c # lw a
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 4
+	call _write_out
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+
+	li t1, -4
+	mul t1, t0, t1
+	addi t1, t1, 84
+	li t2, 10
+	div t3, t1, t2
+	rem t4, t1, t2
+	addi t3, t3, '0'
+	addi t4, t4, '0'
+	addi t0, t0, '0'
+
+	li t5, 0x0a # \n
+	sb t5, 11(sp)
+	li t5, 0x29707328 # (sp)
+	sw t5, 7(sp)
+	sb t4, 6(sp)
+	sb t3, 5(sp)
+	li t5, 0x202c # ,_
+	sh t5, 3(sp)
+	sb t0, 2(sp)
+
+	addi a0, sp, 2
+	li a1, 10
+	call _write_out
+
+	lw t0, 12(sp) # Increment.
+	addi t0, t0, 1
+	sw t0, 12(sp)
+
+	j .Lcompile_call_restore
+
+.Lcompile_call_perform:
+	li t0, 0x20
+	sw t0, 8(sp)
+	li t0, 0x6c6c6163
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 5
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 1
+	call _write_out
+
+	call _skip_spaces
+	addi s1, s1, 1 # Skip the close paren.
+
+	# Epilogue.
+	lw ra, 28(sp)
+	lw s0, 24(sp)
+	addi sp, sp, 32
+	ret
+
 # Reads a token and returns its length in a0.
 # _read_token doesn't change s1, it finds the length of the token s1 is pointing to.
 .type _read_token, @function
@@ -53,7 +372,7 @@ _read_token:
 	add t1, s1, t6
 	lbu a0, (t1) # a0 = Current character.
 
-	call is_alnum
+	call _is_alnum
 
 	beqz a0, .Ltoken_character_end
 	lw t6, 4(sp)
@@ -150,7 +469,7 @@ _compile_assembly:
 	# Write the source to the standard output.
 	mv a0, s1
 	lw a1, 4(sp)
-	call write_out
+	call _write_out
 
 	lw t0, 4(sp)
 	add s1, s1, t0
@@ -159,7 +478,7 @@ _compile_assembly:
 	sb t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 1
-	call write_out
+	call _write_out
 
 	addi s1, s1, 1 # Skip the new line.
 
@@ -189,7 +508,7 @@ _compile_program:
 
 	addi a0, sp, 8
 	li a1, 15
-	call write_out
+	call _write_out
 
 	addi s1, s1, 8 # program\n.
 
@@ -221,14 +540,14 @@ _compile_constant_section:
 
 	addi a0, sp, 4
 	li a1, 17
-	call write_out
+	call _write_out
 
 	addi s1, s1, 6 # const\n.
 
 .Lcompile_constant_section_item:
 	call _skip_spaces
 	lbu a0, (s1)
-	call is_upper
+	call _is_upper
 	beqz a0, .Lcompile_constant_section_end
 
 	call _compile_constant
@@ -254,7 +573,7 @@ _compile_constant:
 	mv a1, a0 # The identifier length from _read_token should be in a1.
 	mv a0, s1 # Save the identifier pointer before advancing it.
 	add s1, s1, a1
-	call write_out
+	call _write_out
 
 	call _skip_spaces
 	call _read_token
@@ -267,7 +586,7 @@ _compile_constant:
 	sw t0, 0(sp)
 	mv a0, sp
 	li a1, 8
-	call write_out
+	call _write_out
 
 	call _skip_spaces
 	call _read_token
@@ -275,13 +594,13 @@ _compile_constant:
 	mv a1, a0 # The literal length from _read_token should be in a1.
 	mv a0, s1 # Save the literal pointer before advancing it.
 	add s1, s1, a1
-	call write_out
+	call _write_out
 
 	li t0, '\n'
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 1
-	call write_out
+	call _write_out
 
 	# Epilogue.
 	lw ra, 12(sp)
@@ -309,14 +628,14 @@ _compile_variable_section:
 
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	addi s1, s1, 4 # var\n.
 
 .Lcompile_variable_section_item:
 	call _skip_spaces
 	lbu a0, (s1)
-	call is_lower
+	call _is_lower
 	beqz a0, .Lcompile_variable_section_end
 
 	call _compile_variable
@@ -371,11 +690,11 @@ _compile_variable:
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a74 # t\n
 	sw t0, 12(sp)
@@ -385,7 +704,7 @@ _compile_variable:
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 10
-	call write_out
+	call _write_out
 
 	# .size identifier, size
 	li t0, 0x2065 # e_
@@ -394,32 +713,32 @@ _compile_variable:
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x202c # ,
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a # \n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 1
-	call write_out
+	call _write_out
 
 	# identifier: .zero size
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x206f7265 # ero_
 	sw t0, 12(sp)
@@ -427,17 +746,17 @@ _compile_variable:
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 8
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a # \n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 1
-	call write_out
+	call _write_out
 
 	# Epilogue.
 	lw ra, 36(sp)
@@ -466,11 +785,11 @@ _compile_procedure:
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a6e6f69 # ion\n
 	sw t0, 12(sp)
@@ -480,17 +799,17 @@ _compile_procedure:
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 12
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a3a # :\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
-	call write_out
+	call _write_out
 
 	call _skip_spaces
 	addi s1, s1, 1 # Skip opening argument paren.
@@ -521,24 +840,24 @@ _compile_procedure:
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x2c707320 # _sp,
 	sw t0, 12(sp)
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a36392d # -96\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -550,7 +869,7 @@ _compile_procedure:
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -562,7 +881,7 @@ _compile_procedure:
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a363920 # _96\n
 	sw t0, 12(sp)
@@ -574,7 +893,7 @@ _compile_procedure:
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 16
-	call write_out
+	call _write_out
 
 	# Generate the body of the procedure.
 .Lcompile_procedure_body:
@@ -586,7 +905,7 @@ _compile_procedure:
 	mv a0, s1
 	addi a1, sp, 8
 	li a2, 4
-	call memcmp
+	call _memcmp
 
 	beqz a0, .Lcompile_procedure_end
 
@@ -608,7 +927,7 @@ _compile_procedure:
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -620,36 +939,36 @@ _compile_procedure:
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x69646461 # addi
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x2c707320 # _sp,
 	sw t0, 12(sp)
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a3639 # 96\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 3
-	call write_out
+	call _write_out
 
 	li t0, 0x0a746572 # ret\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	# Epilogue.
 	lw ra, 28(sp)
@@ -726,7 +1045,7 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 8
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_program
 
 	li t0, 0x0a74 # t\n
@@ -736,7 +1055,7 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 6
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_const
 
 	li t0, 0x0a726176 # var\n
@@ -744,7 +1063,7 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 16
 	li a2, 4
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_var
 
 	li t0, 0x20 # _
@@ -754,7 +1073,7 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 5
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_procedure
 
 	li t0, 0x0a6e # n\n
@@ -764,7 +1083,7 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 6
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_begin
 
 	li t0, 0x2e646e65 # end.
@@ -772,11 +1091,27 @@ _compile_line:
 	mv a0, s1
 	addi a1, sp, 16
 	li a2, 4
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_exit
 
+	li t0, 0x61636f6c # loca
+	sw t0, 16(sp)
+	mv a0, s1
+	addi a1, sp, 16
+	li a2, 4
+	call _memcmp
+	beqz a0, .Lcompile_line_identifier
+
+	lbu t0, (s1)
+	li t1, '_'
+	beq t0, t1, .Lcompile_line_identifier
+
 	j .Lcompile_line_unchanged # Else.
 
+.Lcompile_line_identifier:
+	call _compile_identifier
+	j .Lcompile_line_section
+
 .Lcompile_line_exit:
 	call _compile_exit
 	j .Lcompile_line_section
@@ -796,12 +1131,6 @@ _compile_line:
 	j .Lcompile_line_end
 
 .Lcompile_line_var:
-
-	/* DEBUG
-	mv a0, s1
-	li a1, 20
-	call write_error */
-
 	call _compile_variable_section
 	j .Lcompile_line_section
 
@@ -853,7 +1182,7 @@ _compile_text_section:
 
 	addi a0, sp, 0
 	li a1, 15
-	call write_out
+	call _write_out
 
 	# Epilogue.
 	lw ra, 20(sp)
@@ -888,7 +1217,7 @@ _compile_entry_point:
 	sw t0, 24(sp)
 	addi a0, sp, 24
 	li a1, 32
-	call write_out
+	call _write_out
 
 	addi s1, s1, 6 # Skip begin\n.
 
@@ -925,7 +1254,7 @@ _compile_exit:
 	sw t0, 28(sp)
 	addi a0, sp, 28
 	li a1, 25
-	call write_out
+	call _write_out
 
 	addi s1, s1, 4 # Skip end.
 	call _skip_spaces # Read the possible new line at the end of the file.
@@ -986,7 +1315,7 @@ _start:
 	la a0, source_code
 	la a1, SOURCE_BUFFER_SIZE # Buffer size.
 	lw a1, (a1)
-	call read_file
+	call _read_file
 
 	la s1, source_code # s1 = Source code position.
 	call _compile
diff --git a/boot/goto-boot.elna b/boot/goto-boot.elna
deleted file mode 100644
index c2fd69b..0000000
--- a/boot/goto-boot.elna
+++ /dev/null
@@ -1,12 +0,0 @@
-program
-
-import dummy
-
-var source_code: [2048]Byte
-
-begin
-  read_file(source_code, 2048);
-
-  s1 := source_code;
-
-end.
diff --git a/boot/stage2.elna b/boot/stage2.elna
index e954762..e37b3e6 100644
--- a/boot/stage2.elna
+++ b/boot/stage2.elna
@@ -9,6 +9,293 @@ var
 
 .section .text
 
+# Evalutes an expression and saves the result in a0.
+proc _build_expression()
+begin
+	_skip_spaces()
+	call _read_token
+	sw s1, 20(sp)
+	sw a0, 16(sp)
+
+	# Integer literal.
+	addi a0, s1, 0
+	lb a0, (a0)
+	call _is_digit
+	bnez a0, .Lbuild_expression_number_literal
+
+	# Named identifier.
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x6120616c # la a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	addi a0, sp, 12
+	li a1, 1
+	call _write_out
+
+	j .Lbuild_expression_end
+
+.Lbuild_expression_number_literal:
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x6120696c # li a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	addi a0, sp, 12
+	li a1, 1
+	call _write_out
+
+	j .Lbuild_expression_end
+
+.Lbuild_expression_end:
+	lw a0, 16(sp)
+	add s1, s1, a0
+end
+
+# Compiles a statement beginning with an identifier.
+#
+# Left values should be variables named "loca n", where n is the offset
+# of the variable on the stack, like loca8 or loca4.
+proc _compile_identifier()
+begin
+	call _read_token
+
+	# Save the pointer to the identifier and its length on the stack.
+	sw s1, 20(sp)
+	sw a0, 16(sp)
+
+	add s1, s1, a0
+	_skip_spaces()
+	call _read_token
+
+	# Save the pointer and the length of the token following the identifier.
+	sw s1, 12(sp)
+	sw a0, 8(sp)
+
+	add s1, s1, a0 # Skip that token.
+	_skip_spaces()
+
+	li t0, 0x3d3a # :=
+	sw t0, 4(sp)
+	lw a0, 12(sp)
+	lw a1, 8(sp)
+	addi a2, sp, 4
+	call _token_compare
+	beqz a0, .Lcompile_identifier_assign
+
+	/* DEBUG
+	mv a0, s1
+	li a1, 4
+	call _write_error */
+
+	lw t0, 12(sp)
+	lbu t0, (t0)
+	li t1, 0x28 # (
+	beq t0, t1, .Lcompile_identifier_call
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_call:
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _compile_call
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_assign:
+	call _build_expression
+
+	li t0, 0x202c30 # 0,_
+	sw t0, 12(sp)
+	li t0, 0x61207773 # sw a
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 7
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	addi a0, a0, 4 # Skip the "loca" variable prefix.
+	addi a1, a1, -4 # Skip the "loca" variable prefix.
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 12(sp)
+	li t0, 0x29707328 # (sp)
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 5
+	call _write_out
+
+	j .Lcompile_identifier_end
+
+.Lcompile_identifier_end:
+end
+
+# Compiles a procedure call. Expects s1 to point to the first argument.
+# a0 - Pointer to the procedure name.
+# a1 - Length of the procedure name.
+#
+# Returns the procedure result in a0.
+proc _compile_call()
+begin
+	sw a0, 20(sp)
+	sw a1, 16(sp)
+	sw zero, 12(sp) # Argument count for a procedure call.
+
+.Lcompile_call_paren:
+	_skip_spaces()
+	call _read_token
+	lbu t0, (s1)
+	li t1, 0x29 # )
+	beq t0, t1, .Lcompile_call_complete
+
+.Lcompile_call_argument:
+	call _build_expression
+
+	li t0, 0x202c30 # 0,_
+	sw t0, 8(sp)
+	li t0, 0x61207773 # sw a
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 7
+	call _write_out
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+
+	# Only 8 arguments are supported with a0-a7.
+	# Save all arguments on the stack so they aren't overriden afterwards.
+	# The offset on the stack always has two digits in this case.
+	li t1, -4
+	mul t1, t0, t1
+	addi t1, t1, 84
+	li t2, 10
+	div t3, t1, t2
+	rem t4, t1, t2
+	addi t3, t3, '0'
+	addi t4, t4, '0'
+
+	sw t3, 8(sp)
+	sw t4, 4(sp)
+
+	addi a0, sp, 8
+	li a1, 1
+	call _write_out
+
+	addi a0, sp, 4
+	li a1, 1
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 8(sp)
+	li t0, 0x29707328 # (sp)
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 5
+	call _write_out
+
+	_skip_spaces()
+	call _read_token
+	lbu t0, (s1)
+	li t1, ','
+	bne t0, t1, .Lcompile_call_paren
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+	addi t0, t0, 1
+	sw t0, 12(sp)
+
+	_advance(1) # Skip the comma between the arguments.
+	j .Lcompile_call_argument
+
+.Lcompile_call_complete:
+	sw zero, 12(sp)
+
+.Lcompile_call_restore:
+	# Just go through all a0-a7 registers and read them from stack.
+	# If this stack value contains garbage, the procedure just shouldn't use it.
+	lw t0, 12(sp)
+	li t1, 7
+	bgt t0, t1, .Lcompile_call_perform
+
+	li t0, 0x6120776c # lw a
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 4
+	call _write_out
+
+	lw t0, 12(sp) # Argument count for a procedure call.
+
+	li t1, -4
+	mul t1, t0, t1
+	addi t1, t1, 84
+	li t2, 10
+	div t3, t1, t2
+	rem t4, t1, t2
+	addi t3, t3, '0'
+	addi t4, t4, '0'
+	addi t0, t0, '0'
+
+	li t5, 0x0a # \n
+	sb t5, 11(sp)
+	li t5, 0x29707328 # (sp)
+	sw t5, 7(sp)
+	sb t4, 6(sp)
+	sb t3, 5(sp)
+	li t5, 0x202c # ,_
+	sh t5, 3(sp)
+	sb t0, 2(sp)
+
+	addi a0, sp, 2
+	li a1, 10
+	call _write_out
+
+	lw t0, 12(sp) # Increment.
+	addi t0, t0, 1
+	sw t0, 12(sp)
+
+	j .Lcompile_call_restore
+
+.Lcompile_call_perform:
+	li t0, 0x20
+	sw t0, 8(sp)
+	li t0, 0x6c6c6163
+	sw t0, 4(sp)
+	addi a0, sp, 4
+	li a1, 5
+	call _write_out
+
+	lw a0, 20(sp)
+	lw a1, 16(sp)
+	call _write_out
+
+	li t0, 0x0a # \n
+	sw t0, 8(sp)
+	addi a0, sp, 8
+	li a1, 1
+	call _write_out
+
+	_skip_spaces()
+	_advance(1) # Skip the close paren.
+end
+
 # Reads a token and returns its length in a0.
 # _read_token doesn't change s1, it finds the length of the token s1 is pointing to.
 proc _read_token()
@@ -45,7 +332,7 @@ begin
 	add t1, s1, t6
 	lbu a0, (t1) # a0 = Current character.
 
-	call is_alnum
+	call _is_alnum
 
 	beqz a0, .Ltoken_character_end
 	lw t6, 4(sp)
@@ -90,7 +377,7 @@ begin
 
 	j .Lspace_loop_end
 .Lspace_loop_repeat:
-	addi s1, s1, 1
+	_advance(1)
 	j .Lspace_loop_do
 
 .Lspace_loop_end:
@@ -108,7 +395,7 @@ begin
 	j .Lskip_indentation_end
 
 .Lskip_indentation_skip:
-	addi s1, s1, 1
+	_advance(1)
 	j .Lskip_indentation_do
 
 .Lskip_indentation_end:
@@ -119,7 +406,7 @@ end
 proc _skip_comment()
 begin
 	add s1, s1, a0
-	addi s1, s1, 1 # Skip the new line.
+	_advance(1) # Skip the new line.
 end
 
 # Parameters:
@@ -131,7 +418,7 @@ begin
 	# Write the source to the standard output.
 	mv a0, s1
 	lw a1, 4(sp)
-	call write_out
+	call _write_out
 
 	lw t0, 4(sp)
 	add s1, s1, t0
@@ -140,9 +427,9 @@ begin
 	sb t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 1
-	call write_out
+	call _write_out
 
-	addi s1, s1, 1 # Skip the new line.
+	_advance(1) # Skip the new line.
 end
 
 proc _compile_program()
@@ -159,9 +446,9 @@ begin
 
 	addi a0, sp, 8
 	li a1, 15
-	call write_out
+	call _write_out
 
-	addi s1, s1, 8 # program\n.
+	_advance(8) # program\n.
 end
 
 proc _compile_constant_section()
@@ -180,14 +467,14 @@ begin
 
 	addi a0, sp, 4
 	li a1, 17
-	call write_out
+	call _write_out
 
-	addi s1, s1, 6 # const\n.
+	_advance(6) # const\n.
 
 .Lcompile_constant_section_item:
-	call _skip_spaces
+	_skip_spaces()
 	lbu a0, (s1)
-	call is_upper
+	call _is_upper
 	beqz a0, .Lcompile_constant_section_end
 
 	call _compile_constant
@@ -203,11 +490,11 @@ begin
 	mv a1, a0 # The identifier length from _read_token should be in a1.
 	mv a0, s1 # Save the identifier pointer before advancing it.
 	add s1, s1, a1
-	call write_out
+	call _write_out
 
-	call _skip_spaces
+	_skip_spaces()
 	call _read_token
-	addi s1, s1, 2 # Skip the assignment sign.
+	_advance(2) # Skip the assignment sign.
 
 	# : .long
 	li t0, 0x20676e6f # ong_
@@ -216,21 +503,21 @@ begin
 	sw t0, 0(sp)
 	mv a0, sp
 	li a1, 8
-	call write_out
+	call _write_out
 
-	call _skip_spaces
+	_skip_spaces()
 	call _read_token
 
 	mv a1, a0 # The literal length from _read_token should be in a1.
 	mv a0, s1 # Save the literal pointer before advancing it.
 	add s1, s1, a1
-	call write_out
+	call _write_out
 
 	li t0, '\n'
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 1
-	call write_out
+	call _write_out
 end
 
 proc _compile_variable_section()
@@ -247,14 +534,14 @@ begin
 
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
-	addi s1, s1, 4 # var\n.
+	_advance(4) # var\n.
 
 .Lcompile_variable_section_item:
-	call _skip_spaces
+	_skip_spaces()
 	lbu a0, (s1)
-	call is_lower
+	call _is_lower
 	beqz a0, .Lcompile_variable_section_end
 
 	call _compile_variable
@@ -272,11 +559,11 @@ begin
 	sw a0, 24(sp)
 	add s1, s1, a0
 
-	call _skip_spaces
-	addi s1, s1, 1 # Skip the colon in front of the type.
+	_skip_spaces()
+	_advance(1) # Skip the colon in front of the type.
 
-	call _skip_spaces
-	addi s1, s1, 1 # Skip the opening bracket.
+	_skip_spaces()
+	_advance(1) # Skip the opening bracket.
 
 	call _read_token
 
@@ -285,10 +572,10 @@ begin
 	sw a0, 16(sp)
 	add s1, s1, a0
 
-	call _skip_spaces
-	addi s1, s1, 1 # Skip the closing bracket.
+	_skip_spaces()
+	_advance(1) # Skip the closing bracket.
 
-	call _skip_spaces
+	_skip_spaces()
 	call _read_token
 	add s1, s1, a0 # Skip the type.
 
@@ -299,11 +586,11 @@ begin
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a74 # t\n
 	sw t0, 12(sp)
@@ -313,7 +600,7 @@ begin
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 10
-	call write_out
+	call _write_out
 
 	# .size identifier, size
 	li t0, 0x2065 # e_
@@ -322,32 +609,32 @@ begin
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x202c # ,
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a # \n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 1
-	call write_out
+	call _write_out
 
 	# identifier: .zero size
 	lw a0, 28(sp)
 	lw a1, 24(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x206f7265 # ero_
 	sw t0, 12(sp)
@@ -355,22 +642,22 @@ begin
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 8
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a # \n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 1
-	call write_out
+	call _write_out
 end
 
 proc _compile_procedure()
 begin
-	addi s1, s1, 5 # Skip proc_
+	_advance(5) # Skip proc_
 	call _read_token
 	sw s1, 20(sp)
 	sw a0, 16(sp)
@@ -383,11 +670,11 @@ begin
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 6
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a6e6f69 # ion\n
 	sw t0, 12(sp)
@@ -397,22 +684,22 @@ begin
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 12
-	call write_out
+	call _write_out
 
 	lw a0, 20(sp)
 	lw a1, 16(sp)
-	call write_out
+	call _write_out
 
 	li t0, 0x0a3a # :\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
-	call write_out
+	call _write_out
 
-	call _skip_spaces
-	addi s1, s1, 1 # Skip opening argument paren.
-	call _skip_spaces
-	addi s1, s1, 1 # Skip closing argument paren.
+	_skip_spaces()
+	_advance(1) # Skip opening argument paren.
+	_skip_spaces()
+	_advance(1) # Skip closing argument paren.
 
 	li t0, 0x6e # n
 	sw t0, 12(sp)
@@ -422,7 +709,7 @@ begin
 	# Skip all declarations until we find the "begin" keyword, denoting the
 	# beginning of the procedure body.
 .Lcompile_procedure_begin:
-	call _skip_spaces
+	_skip_spaces()
 	call _read_token
 
 	mv a1, a0
@@ -438,24 +725,24 @@ begin
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x2c707320 # _sp,
 	sw t0, 12(sp)
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a36392d # -96\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -467,7 +754,7 @@ begin
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -479,7 +766,7 @@ begin
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a363920 # _96\n
 	sw t0, 12(sp)
@@ -491,11 +778,11 @@ begin
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 16
-	call write_out
+	call _write_out
 
 	# Generate the body of the procedure.
 .Lcompile_procedure_body:
-	call _skip_indentation
+	_skip_indentation()
 	call _read_line
 	sw a0, 12(sp)
 	li t0, 0x0a646e65 # end\n
@@ -503,7 +790,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 8
 	li a2, 4
-	call memcmp
+	call _memcmp
 
 	beqz a0, .Lcompile_procedure_end
 
@@ -525,7 +812,7 @@ begin
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x0a29 # )\n
 	sw t0, 12(sp)
@@ -537,36 +824,36 @@ begin
 	sw t0, 0(sp)
 	addi a0, sp, 0
 	li a1, 14
-	call write_out
+	call _write_out
 
 	li t0, 0x69646461 # addi
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x2c707320 # _sp,
 	sw t0, 12(sp)
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 
 	li t0, 0x0a3639 # 96\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 3
-	call write_out
+	call _write_out
 
 	li t0, 0x0a746572 # ret\n
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 4
-	call write_out
+	call _write_out
 end
 
 # Compares two string, which of one has a length, the other one is null-terminated.
@@ -632,7 +919,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 8
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_program
 
 	li t0, 0x0a74 # t\n
@@ -642,7 +929,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 6
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_const
 
 	li t0, 0x0a726176 # var\n
@@ -650,7 +937,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 16
 	li a2, 4
-	call memcmp
+	call _memcmp;
 	beqz a0, .Lcompile_line_var
 
 	li t0, 0x20 # _
@@ -660,7 +947,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 5
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_procedure
 
 	li t0, 0x0a6e # n\n
@@ -670,7 +957,7 @@ begin
 	mv a0, s1
 	addi a1, sp, 12
 	li a2, 6
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_begin
 
 	li t0, 0x2e646e65 # end.
@@ -678,11 +965,27 @@ begin
 	mv a0, s1
 	addi a1, sp, 16
 	li a2, 4
-	call memcmp
+	call _memcmp
 	beqz a0, .Lcompile_line_exit
 
+	li t0, 0x61636f6c # loca
+	sw t0, 16(sp)
+	mv a0, s1
+	addi a1, sp, 16
+	li a2, 4
+	call _memcmp
+	beqz a0, .Lcompile_line_identifier
+
+	lbu t0, (s1)
+	li t1, '_'
+	beq t0, t1, .Lcompile_line_identifier
+
 	j .Lcompile_line_unchanged # Else.
 
+.Lcompile_line_identifier:
+	call _compile_identifier
+	j .Lcompile_line_section
+
 .Lcompile_line_exit:
 	call _compile_exit
 	j .Lcompile_line_section
@@ -702,12 +1005,6 @@ begin
 	j .Lcompile_line_end
 
 .Lcompile_line_var:
-
-	/* DEBUG
-	mv a0, s1
-	li a1, 20
-	call write_error */
-
 	call _compile_variable_section
 	j .Lcompile_line_section
 
@@ -721,7 +1018,7 @@ begin
 	j .Lcompile_line_section
 
 .Lcompile_line_empty:
-	addi s1, s1, 1
+	_advance(1)
 	j .Lcompile_line_section
 
 .Lcompile_line_unchanged:
@@ -749,7 +1046,7 @@ begin
 
 	addi a0, sp, 0
 	li a1, 15
-	call write_out
+	call _write_out
 end
 
 proc _compile_entry_point()
@@ -773,9 +1070,9 @@ begin
 	sw t0, 24(sp)
 	addi a0, sp, 24
 	li a1, 32
-	call write_out
+	call _write_out
 
-	addi s1, s1, 6 # Skip begin\n.
+	_advance(6) # Skip begin\n.
 end
 
 proc _compile_exit()
@@ -799,10 +1096,10 @@ begin
 	sw t0, 28(sp)
 	addi a0, sp, 28
 	li a1, 25
-	call write_out
+	call _write_out
 
-	addi s1, s1, 4 # Skip end.
-	call _skip_spaces # Read the possible new line at the end of the file.
+	_advance(4) # Skip end.
+	_skip_spaces() # Read the possible new line at the end of the file.
 end
 
 # Finds the end of the line and returns its length in a0.
@@ -829,7 +1126,7 @@ begin
 	lbu t0, (s1) # t0 = Current character.
 	beqz t0, .Lcompile_end # Exit the loop on the NUL character.
 
-	call _skip_indentation
+	_skip_indentation()
 	call _read_line
 	call _compile_line
 
@@ -837,13 +1134,25 @@ begin
 .Lcompile_end:
 end
 
+# Returns the pointer to the current position in the source text in a0.
+proc _current()
+begin
+	mv a0, s1
+end
+
+# a0 is the number of bytes to advance in the source text.
+proc _advance()
+begin
+	add s1, s1, a0
+end
+
 # Entry point.
 begin
 	# Read the source from the standard input.
 	la a0, source_code
 	la a1, SOURCE_BUFFER_SIZE # Buffer size.
 	lw a1, (a1)
-	call read_file
+	call _read_file
 
 	la s1, source_code # s1 = Source code position.
 	call _compile