(*
s1 - Contains the current position in the source text.

- The compiler expects valid input, otherwise it will generate invalid
assembly or hang. There is no error checking, no semantic analysis, no
type checking.

- Imports with only a module name without package, e.g.
"import dummy", can be parsed, but are ignored.

- No loops. Only labels and goto.

- Only unsigned number literals are supported (in decimal or
hexadecimal format).

- Comments are accepted only at the end of a line.

- Return can be used only as the last statement of a procedure. It
doesn't actually return, but sets a0 to the appropriate value.
*)
program

import dummy

const
	SOURCE_BUFFER_SIZE := 81920

var
	source_code: [81920]Byte

(* Ignores the import. *)
proc _compile_import()
var loca0: Word
begin
	_advance(6)
	_skip_spaces()
	loca0 := _read_token()
	_advance(loca0) (* Skip the imported module name. *)
end

proc _build_binary_expression()
var loca0, loca4, loca8, loca20: Word
begin
	_build_expression(0)

	loca4 := 0x2c306120 (* _a0, *)
	loca8 := 0x0a316120 (* _a1\n *)

	_skip_spaces()
	loca20 := _read_token()

	li t0, 0x26 # &
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_and

	li t0, 0x726f # or
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_or

	li t0, 0x3d # =
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_equal

	li t0, 0x2b # +
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_plus

	li t0, 0x2d # -
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_minus

	li t0, 0x2a # *
	sw t0, 16(sp)
	mv a0, s1
	lw a1, 20(sp)
	addi a2, sp, 16
	call _token_compare
	beqz a0, .L_build_binary_expression_product

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_equal
	_advance(1) (* Skip =. *)
	_build_expression(1)
	_write_out(@loca0, 3)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	loca0 := 0x7a716573 (* seqz *)
	_write_out(@loca0, 4)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_and
	_advance(1) (* Skip &. *)
	_build_expression(1)
	loca0 := 0x646e61 (* and *)
	_write_out(@loca0, 3)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_or
	_advance(2) (* Skip or. *)
	_build_expression(1)
	loca0 := 0x726f (* or *)
	_write_out(@loca0, 2)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_plus
	_advance(1) (* Skip +. *)
	_build_expression(1)
	loca0 := 0x646461 (* add *)
	_write_out(@loca0, 3)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_minus
	_advance(1) (* Skip -. *)
	_build_expression(1)
	loca0 := 0x627573 (* sub *)
	_write_out(@loca0, 3)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	goto .Lbuild_binary_expression_end

	.L_build_binary_expression_product
	_advance(1) (* Skip *. *)
	_build_expression(1)
	loca0 := 0x6c756d (* mul *)
	_write_out(@loca0, 3)
	_write_out(@loca4, 4)
	_write_out(@loca4, 4)
	_write_out(@loca8, 4)

	goto .Lbuild_binary_expression_end

	.Lbuild_binary_expression_end
end

(*
Evalutes an expression and saves the result in a0.

a0 - X in aX, the register number to save the result.
*)
proc _build_expression()
var
	loca0, loca20, loca28, loca8: Word
	loca24, loca4: ^Byte
begin
	(* Make the register number to a character and save it. *)
	loca28 := loca84 + 0x30 (* 0 *)

	_skip_spaces()
	loca20 := _read_token()
	loca24 := _current()

	lbu a0, (s1)
	li t0, '-'
	beq a0, t0, .Lbuild_expression_negate

	lbu a0, (s1)
	li t0, '@'
	beq a0, t0, .Lbuild_expression_address

	loca0 := _front()
	if _is_digit(loca0) then
		goto .Lbuild_expression_literal
	end

	lbu a0, (s1)
	li t0, '_'
	beq a0, t0, .Lbuild_expression_call

	li t0, 0x61636f6c # loca
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 4
	call _memcmp
	beqz a0, .Lbuild_expression_identifier

	(* Named identifier. *)
	loca8 := 0x6120616c (* la a *)
	_write_out(@loca8, 4)
	loca8 := 0x00202c00 or loca28
	_write_out(@loca8, 3)

	_write_out(loca24, loca20)
	_put_char(0x0a)

	goto .Lbuild_expression_advance

	.Lbuild_expression_negate
	_advance(1) (* Skip the -. *)
	_build_expression(0)

	loca8 := 0x2067656e (* neg_ *)
	_write_out(@loca8, 4)
	loca8 := 0x202c3061 (* a0,_ *)
	_write_out(@loca8, 4)
	loca8 := 0x0a3061 (* a0,_ *)
	_write_out(@loca8, 3)

	goto .Lbuild_expression_advance

	.Lbuild_expression_address
	loca8 := 0x69646461 (* addi *)
	_write_out(@loca8, 4)
	loca8 := 0x6120 (* _a *)
	_write_out(@loca8, 2)
	_put_char(loca28)
	loca8 := 0x7073202c (* , sp *)
	_write_out(@loca8, 4)
	loca8 := 0x202c (* ,_ *)
	_write_out(@loca8, 2)

	_advance(1) (* Skip @. *)
	_skip_spaces()
	loca24 := _current()
	loca20 := _read_token()

	(* Skip the "loca" variable prefix. *)
	loca4 := loca24 + 4
	loca0 := loca20 - 4
	_write_out(loca4, loca0)

	_put_char(0xa)

	goto .Lbuild_expression_advance

	.Lbuild_expression_identifier
	loca8 := 0x6120776c (* lw a *)
	_write_out(@loca8, 4)
	loca8 := 0x00202c00 or loca28 # \0,_
	_write_out(@loca8, 3)

	loca4 := loca24 + 4
	loca0 := loca20 - 4
	_write_out(loca4, loca0) (* Skip the "loca" variable prefix. *)

	loca8 := 0x29707328 (* (sp) *)
	_write_out(@loca8, 4)
	_put_char(0x0a) (* \n *)

	goto .Lbuild_expression_advance

	.Lbuild_expression_call
	_advance(loca20)
	_advance(1)
	_compile_call(loca24, loca20)

	goto .Lbuild_expression_end

	.Lbuild_expression_literal
	loca8 := 0x6120696c (* li a *)
	_write_out(@loca8, 4)
	loca8 := 0x00202c00 or loca28 (* \0,_ *)
	_write_out(@loca8, 3)

	_write_out(loca24, loca20)
	_put_char(0x0a) (* \n *)

	goto .Lbuild_expression_advance

	.Lbuild_expression_advance
	_advance(loca20)

	.Lbuild_expression_end
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()
var
	loca0, loca16, loca8: Word
	loca20, loca12: ^Byte
begin
	(* Save the pointer to the identifier and its length on the stack. *)
	loca20 := _current()
	loca16 := _read_token()

	_advance(loca16)
	_skip_spaces()

	(* Save the pointer and the length of the token following the identifier. *)
	loca12 := _current()
	loca8 := _read_token()

	_advance(loca8) # 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

	lw t0, 12(sp)
	lbu t0, (t0)
	li t1, 0x28 # (
	beq t0, t1, .Lcompile_identifier_call

	goto .Lcompile_identifier_end

	.Lcompile_identifier_call
	_compile_call(loca20, loca16)

	goto .Lcompile_identifier_end

	.Lcompile_identifier_assign
	_build_binary_expression()

	loca0 := 0x61207773 (* sw a *)
	_write_out(@loca0, 4)
	loca0 := 0x202c30 (* 0,_ *)
	_write_out(@loca0, 3)

	loca20 := loca20 + 4
	loca16 := loca16 - 4
	_write_out(loca20, loca16)

	loca0 := 0x29707328 (* (sp) *)
	_write_out(@loca0, 4)
	_put_char(0x0a) (* \n *)

	goto .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(loca84: ^Byte, loca80: Word)
var
	loca0, loca4, loca12: Word
begin
	loca12 := 0 (* Argument count for a procedure call. *)

	.Lcompile_call_paren
	_skip_spaces()
	lbu t0, (s1)
	li t1, 0x29 # )
	beq t0, t1, .Lcompile_call_complete

	.Lcompile_call_argument
	_build_expression(0)

	loca0 := 0x61207773 (* sw a *)
	_write_out(@loca0, 4)
	loca0 := 0x202c30 (* 0,_ *)
	_write_out(@loca0, 3)

	(*
	Only 6 arguments are supported with a0-a5.
	Save all arguments on the stack so they aren't overriden afterwards.
	*)
	loca0 := -4 * loca12
	loca0 := loca0 + 60
	_printi(loca0)

	loca0 := 0x29707328 (* (sp) *)
	_write_out(@loca0, 4)
	_put_char(0x0a) (* \n *)

	_skip_spaces()
	lbu t0, (s1)
	li t1, ','
	bne t0, t1, .Lcompile_call_paren

	loca12 := loca12 + 1 (* Argument count for a procedure call. *)

	_advance(1) (* Skip the comma between the arguments. *)
	goto .Lcompile_call_argument

	.Lcompile_call_complete
	loca12 := 0

	.Lcompile_call_restore
	(*
	Just go through all a0-a5 registers and read them from stack.
	If this stack value contains garbage, the procedure just shouldn't use it.
	*)
	loca0 := 0x6120776c (* lw a *)
	(* lw a0, 60(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x36202c30 (* 0, 6 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732830 (* 0(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	(* lw a1, 56(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x35202c31 (* 1, 5 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732836 (* 6(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	(* lw a2, 52(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x35202c32 (* 2, 5 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732832 (* 2(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	(* lw a3, 48(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x34202c33 (* 3, 4 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732838 (* 8(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	(* lw a4, 44(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x34202c34 (* 4, 4 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732834 (* 4(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	(* lw a5, 40(sp) *)
	_write_out(@loca0, 4)
	loca4 := 0x34202c35 (* 5, 4 *)
	_write_out(@loca4, 4)
	loca4 := 0x70732830 (* 0(sp *)
	_write_out(@loca4, 4)
	loca4 := 0x0a29 (* )\n *)
	_write_out(@loca4, 2)

	loca0 := 0x6c6c6163 (* call *)
	_write_out(@loca0, 4)
	_put_char(0x20) (* _ *)

	_write_out(loca84, loca80)
	_put_char(0x0a) (* \n *)

	_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()
var loca4: Word
begin
	lbu t0, (s1) # t0 = Current character.
	loca4 := 0

	li t1, '.'
	beq t0, t1, .Ltoken_character_single

	li t1, ','
	beq t0, t1, .Ltoken_character_single

	li t1, ':'
	beq t0, t1, .Ltoken_character_colon

	li t1, ';'
	beq t0, t1, .Ltoken_character_single

	li t1, '('
	beq t0, t1, .Ltoken_character_single

	li t1, ')'
	beq t0, t1, .Ltoken_character_single

	li t1, '['
	beq t0, t1, .Ltoken_character_single

	li t1, ']'
	beq t0, t1, .Ltoken_character_single

	li t1, '^'
	beq t0, t1, .Ltoken_character_single

	li t1, '&'
	beq t0, t1, .Ltoken_character_single

	li t1, '='
	beq t0, t1, .Ltoken_character_single

	li t1, '+'
	beq t0, t1, .Ltoken_character_single

	li t1, '-'
	beq t0, t1, .Ltoken_character_single

	li t1, '*'
	beq t0, t1, .Ltoken_character_single

	li t1, '@'
	beq t0, t1, .Ltoken_character_single
	(* Expect an identifier or a number. *)
	.Ltoken_character_loop_do
	lw t6, 4(sp)
	add t1, s1, t6
	lbu a0, (t1) # a0 = Current character.

	call _is_alnum

	beqz a0, .Ltoken_character_end
	loca4 := loca4 + 1
	goto .Ltoken_character_loop_do

	.Ltoken_character_single
	loca4 := loca4 + 1
	goto .Ltoken_character_end

	.Ltoken_character_colon
	lbu t0, 1(s1) # t0 = The character after the colon.
	loca4 := loca4 + 1

	li t1, '='
	beq t0, t1, .Ltoken_character_single
	goto .Ltoken_character_end

	.Ltoken_character_end
	lw a0, 4(sp)
end

(* Skips the spaces till the next non space character. *)
proc _skip_spaces()
begin
	.Lspace_loop_do
	lbu t0, (s1) # t0 = Current character.

	li t1, ' '
	beq t0, t1, .Lspace_loop_repeat
	li t1, '\t'
	beq t0, t1, .Lspace_loop_repeat
	li t1, '\n'
	beq t0, t1, .Lspace_loop_repeat
	li t1, '\r'
	beq t0, t1, .Lspace_loop_repeat

	goto .Lspace_loop_end
	.Lspace_loop_repeat
	_advance(1)
	goto .Lspace_loop_do

	.Lspace_loop_end
end

(* Skips tabs at the line beginning. *)
proc _skip_indentation()
begin
	.Lskip_indentation_do
	lbu t0, (s1)

	li t1, '\t'
	beq t0, t1, .Lskip_indentation_skip

	goto .Lskip_indentation_end

	.Lskip_indentation_skip
	_advance(1)
	goto .Lskip_indentation_do

	.Lskip_indentation_end
end

(*
Parameters:
	a0 - Line length.
*)
proc _skip_comment(loca84: Word)
begin
	(* Check whether this is a comment. *)
	li t0, 0x2a28 # (*
	sw t0, 4(sp)
	addi a0, sp, 4
	mv a1, s1
	li a2, 2
	call _memcmp
	bnez a0, .Lskip_comment_end

	_advance(2) (* Skip (*. *)

	li t0, 0x292a # *)
	sw t0, 4(sp)

	.Lskip_comment_loop
	addi a0, sp, 4
	mv a1, s1
	li a2, 2
	call _memcmp
	beqz a0, .Lskip_comment_close

	_advance(1)

	goto .Lskip_comment_loop

	.Lskip_comment_close
	_advance(2) (* Skip "*" and ")". *)

	.Lskip_comment_end
end

(*
Parameters:
	a0 - Line length.
*)
proc _compile_assembly(loca84: Word)
var loca0: ^Byte
begin
	(* Write the source to the standard output. *)
	loca0 := _current()

	_write_out(loca0, loca84)
	_advance(loca84)

	_put_char(0xa) (* \n *)

	_advance(1) (* Skip the new line. *)
end

proc _compile_program()
var loca0: Word
begin
	(* .global _start *)
	loca0 := 0x6f6c672e (* .glo *)
	_write_out(@loca0, 4)
	loca0 := 0x206c6162 (* bal_ *)
	_write_out(@loca0, 4)
	loca0 := 0x6174735f (* _sta *)
	_write_out(@loca0, 4)
	loca0 := 0x0a7472 (* rt\n *)
	_write_out(@loca0, 3)

	_advance(8) (* program\n. *)
end

proc _compile_constant_section()
var loca0: Word
begin
	(* .section .rodata *)
	loca0 := 0x6365732e (* .sec *)
	_write_out(@loca0, 4)
	loca0 := 0x6e6f6974 (* tion *)
	_write_out(@loca0, 4)
	loca0 := 0x6f722e20 (* _.ro *)
	_write_out(@loca0, 4)
	loca0 := 0x61746164 (* data *)
	_write_out(@loca0, 4)
	loca0 := 0x0a (* \n *)
	_write_out(@loca0, 1)

	_advance(6) (* const\n. *)

	.Lcompile_constant_section_item
	_skip_spaces()
	lbu a0, (s1)
	call _is_upper
	beqz a0, .Lcompile_constant_section_end

	_compile_constant()
	goto .Lcompile_constant_section_item

	.Lcompile_constant_section_end
end

proc _compile_constant()
var
	loca0, loca4: Word
	loca8: ^Byte
begin
	loca4 := _read_token()
	loca8 := _current() (* Save the identifier pointer before advancing it. *)

	_write_out(loca8, loca4)
	_advance(loca4)

	_skip_spaces()
	_advance(2) (* Skip the assignment sign. *)

	(* : .long *)
	loca0 := 0x6c2e203a (* : .l *)
	_write_out(@loca0, 4)
	loca0 := 0x20676e6f (* ong_ *)
	_write_out(@loca0, 4)

	_skip_spaces()
	loca4 := _read_token()
	loca8 := _current() (* Save the literal pointer before advancing it. *)

	_write_out(loca8, loca4)
	_advance(loca4)

	_put_char(0x0a) (* \n *)
end

proc _compile_variable_section()
var loca0: Word
begin
	(* .section .bss *)
	loca0 := 0x6365732e (* .sec *)
	_write_out(@loca0, 4)
	loca0 := 0x6e6f6974 (* tion *)
	_write_out(@loca0, 4)
	loca0 := 0x73622e20 (* _.bs *)
	_write_out(@loca0, 4)
	loca0 := 0x0a73 (* s\n *)
	_write_out(@loca0, 2)

	_advance(4) (* var\n. *)

	.Lcompile_variable_section_item
	_skip_spaces()
	lbu a0, (s1)
	call _is_lower
	beqz a0, .Lcompile_variable_section_end

	_compile_variable()
	goto .Lcompile_variable_section_item

	.Lcompile_variable_section_end
end

proc _compile_variable()
var
	loca28, loca16: ^Byte
	loca0, loca24, loca20: Word
begin
	(* Save the identifier on the stack since it should emitted multiple times. *)
	loca24 := _read_token()
	loca28 := _current()

	_advance(loca24)

	_skip_spaces()
	_advance(1) (* Skip the colon in front of the type. *)

	_skip_spaces()
	_advance(1) (* Skip the opening bracket. *)

	(* Save the array size on the stack since it has to be emitted multiple times. *)
	loca16 := _read_token()
	loca20 := _current()
	_advance(loca16)

	_skip_spaces()
	_advance(1) (* Skip the closing bracket. *)

	_skip_spaces()
	loca0 := _read_token()
	_advance(loca0) (* Skip the type. *)

	(* .type identifier, @object *)
	loca0 := 0x7079742e (* .typ *)
	_write_out(@loca0, 4)
	loca0 := 0x2065 (* e_ *)
	_write_out(@loca0, 2)

	_write_out(loca28, loca24)

	loca0 := 0x6f40202c (* , @o *)
	_write_out(@loca0, 4)
	loca0 := 0x63656a62 (* bjec *)
	_write_out(@loca0, 4)
	loca0 := 0x0a74 (* t\n *)
	_write_out(@loca0, 2)

	(* .size identifier, size *)
	loca0 := 0x7a69732e (* .siz *)
	_write_out(@loca0, 4)
	loca0 := 0x2065 (* e_ *)
	_write_out(@loca0, 2)

	_write_out(loca28, loca24)

	loca0 := 0x202c (* ,_ *)
	_write_out(@loca0, 2)

	_write_out(loca20, loca16)
	_put_char(0x0a) (* \n *)

	(* identifier: .zero size *)
	_write_out(loca28, loca24)

	loca0 := 0x7a2e203a (* : .z *)
	_write_out(@loca0, 4)
	loca0 := 0x206f7265 (* ero_ *)
	_write_out(@loca0, 4)

	_write_out(loca20, loca16)

	_put_char(0x0a) (* \n *)
end

proc _compile_procedure()
var
	loca0, loca4, loca8, loca12, loca16: Word
	loca20: ^Char
begin
	_advance(5) (* Skip proc_ *)
	loca16 := _read_token()
	loca20 := _current()
	_advance(loca16)

	(* .type identifier, @function *)
	loca0 := 0x7079742e (* .typ *)
	_write_out(@loca0, 4)
	loca0 := 0x2065 (* e_ *)
	_write_out(@loca0, 2)

	_write_out(loca20, loca16)

	loca0 := 0x6640202c (* , @f *)
	_write_out(@loca0, 4)
	loca0 := 0x74636e75 (* unct *)
	_write_out(@loca0, 4)
	loca0 := 0x0a6e6f69 (* ion\n *)
	_write_out(@loca0, 4)

	_write_out(loca20, loca16)

	loca0 := 0x0a3a (* :\n *)
	_write_out(@loca0, 2)

	_skip_spaces()
	_advance(1) (* Skip opening argument paren. *)
	_skip_spaces()
	_advance(1) (* Skip closing argument paren. *)

	loca12 := 0x6e (* n *)
	loca8 := 0x69676562 (* begi *)

	(*
	Skip all declarations until we find the "begin" keyword, denoting the
	beginning of the procedure body.
	*)
	.Lcompile_procedure_begin
	_skip_spaces()
	call _read_token

	mv a1, a0
	mv a0, s1
	addi a2, sp, 8
	add s1, s1, a1
	call _token_compare

	bnez a0, .Lcompile_procedure_begin

	(* Generate the procedure prologue with a predefined stack size. *)
	loca0 := 0x69646461 (* addi *)
	_write_out(@loca0, 4)

	loca0 := 0x2c707320 (* _sp, *)
	_write_out(@loca0, 4)
	_write_out(@loca0, 4)

	loca0 := 0x0a36392d (* -96\n *)
	_write_out(@loca0, 4)

	loca0 := 0x72207773 (* sw r *)
	_write_out(@loca0, 4)
	loca0 := 0x39202c61 (* a, 9 *)
	_write_out(@loca0, 4)
	loca0 := 0x70732832 (* 2(sp *)
	_write_out(@loca0, 4)
	loca0 := 0x0a29 (* )\n *)
	_write_out(@loca0, 2)

	loca0 := 0x73207773 (* sw s *)
	_write_out(@loca0, 4)
	loca0 := 0x38202c30 (* 0, 8 *)
	_write_out(@loca0, 4)
	loca0 := 0x70732838 (* 8(sp *)
	_write_out(@loca0, 4)
	loca0 := 0x0a29 (* )\n *)
	_write_out(@loca0, 2)

	loca0 := 0x69646461 (* addi *)
	_write_out(@loca0, 4)
	loca0 := 0x2c307320 (* _s0, *)
	_write_out(@loca0, 4)
	loca0 := 0x2c707320 (* _sp, *)
	_write_out(@loca0, 4)
	loca0 := 0x0a363920 (* _96\n *)
	_write_out(@loca0, 4)

	(* Save passed arguments on the stack. *)
	loca0 := 0x61207773 (* sw a *)
	_write_out(@loca0, 4)
	loca4 := 0x38202c30 (* 0, 8 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732834 (* 4(sp *)
	_write_out(@loca8, 4)
	loca12 := 0x0a29 (* )\n *)
	_write_out(@loca12, 2)

	_write_out(@loca0, 4)
	loca4 := 0x38202c31 (* 1, 8 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732830 (* 0(sp *)
	_write_out(@loca8, 4)
	_write_out(@loca12, 2)

	_write_out(@loca0, 4)
	loca4 := 0x37202c32 (* 2, 7 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732836 (* 6(sp *)
	_write_out(@loca8, 4)
	_write_out(@loca12, 2)

	_write_out(@loca0, 4)
	loca4 := 0x37202c33 (* 3, 7 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732832 (* 2(sp *)
	_write_out(@loca8, 4)
	_write_out(@loca12, 2)

	_write_out(@loca0, 4)
	loca4 := 0x36202c34 (* 4, 6 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732838 (* 8(sp *)
	_write_out(@loca8, 4)
	_write_out(@loca12, 2)

	_write_out(@loca0, 4)
	loca4 := 0x36202c35 (* 5, 6 *)
	_write_out(@loca4, 4)
	loca8 := 0x70732838 (* 4(sp *)
	_write_out(@loca8, 4)
	_write_out(@loca12, 2)

	(* Generate the body of the procedure. *)
	.Lcompile_procedure_body
	_skip_indentation()
	call _read_line
	sw a0, 12(sp)
	li t0, 0x0a646e65 # end\n
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 4
	call _memcmp

	beqz a0, .Lcompile_procedure_end

	lw a0, 12(sp)
	call _compile_line
	goto .Lcompile_procedure_body

	.Lcompile_procedure_end
	_advance(4) (* Skip end\n. *)

	(* Generate the procedure epilogue with a predefined stack size. *)
	loca0 := 0x7220776c # lw r
	_write_out(@loca0, 4)
	loca0 := 0x39202c61 # a, 9
	_write_out(@loca0, 4)
	loca0 := 0x70732832 # 2(sp
	_write_out(@loca0, 4)
	loca0 := 0x0a29 # )\n
	_write_out(@loca0, 2)

	loca0 := 0x7320776c (* lw s *)
	_write_out(@loca0, 4)
	loca0 := 0x38202c30 (* 0, 8 *)
	_write_out(@loca0, 4)
	loca0 := 0x70732838 (* 8(sp *)
	_write_out(@loca0, 4)
	loca0 := 0x0a29 (* )\n *)
	_write_out(@loca0, 2)

	loca0 := 0x69646461 (* addi *)
	_write_out(@loca0, 4)

	loca0 := 0x2c707320 (* _sp, *)
	_write_out(@loca0, 4)
	_write_out(@loca0, 4)

	loca0 := 0x0a3639 (* 96\n *)
	_write_out(@loca0, 4)

	loca0 := 0x0a746572 (* ret\n *)
	_write_out(@loca0, 4)
end

(*
Compares two string, which of one has a length, the other one is null-terminated.

	a0 - The address of the token string.
	a1 - The length of the string in a0.
	a2 - The address of the null-terminated string.

If the strings match sets a0 to 0, otherwise sets it to 1.
*)
proc _token_compare()
begin
	addi t0, a0, 0
	addi t1, a1, 0
	addi t2, a2, 0

	.Ltoken_compare_loop
	lbu t3, (t2)

	(*
	Will only be 0 if the current character in the null terminated string is \0 and the remaining length of the
	another string is 0.
	*)
	or t4, t3, t1
	beqz t4, .Ltoken_compare_equal

	beqz t1, .Ltoken_compare_not_equal
	beqz t3, .Ltoken_compare_not_equal

	lbu t4, (t0)
	bne t3, t4, .Ltoken_compare_not_equal

	addi t0, t0, 1
	addi t1, t1, -1
	addi t2, t2, 1
	goto .Ltoken_compare_loop

	.Ltoken_compare_not_equal
	li a0, 1
	goto .Ltoken_compare_end

	.Ltoken_compare_equal
	li a0, 0

	.Ltoken_compare_end
end

proc _compile_goto()
var
	loca0: Word
	loca8: ^Byte
begin
	_advance(4) (* Skip the goto keyword. *)

	loca0 := 0x206a (* j_ *)
	_write_out(@loca0, 2)

	_skip_spaces()
	loca8 := _current() (* We should be on dot the label is beginning with. *)
	_advance(1)

	loca0 := _read_token()
	_advance(loca0)
	loca0 := loca0 + 1 (* Label length and the dot. *)
	_write_out(loca8, loca0)

	_advance(1) (* Skip the new line. *)
	_put_char(0x0a) (* \n *)
end

(* a0 - Line length. *)
proc _compile_label(loca84: Word)
var
	loca0: Word
begin
	(* Write the whole line as is. *)
	loca0 := _current()
	_write_out(loca0, loca84)

	lw t0, 84(sp) # Line length.
	mv t1, s1 # Line start.

	add t1, t1, t0
	addi t1, t1, -1 # Last character on the line.

	lbu t1, (t1)
	li t2, ':'
	beq t1, t2, .Lcompile_label_colon

	_put_char(0x3a) (* : *)

	.Lcompile_label_colon
	_put_char(0x0a) (* \n *)

	_advance(loca84)
end

proc _compile_return()
begin
	_advance(6) (* Skip return. *)
	_skip_spaces()
	_build_binary_expression()
end

proc _compile_if()
var
	loca8, loca12, loca16, loca20: Word
	loca4: ^Byte
begin
	_advance(2) (* Skip the if. *)
	_skip_spaces()

	_build_binary_expression()

	_skip_spaces()
	_advance(4) (* Skip the then. *)

	loca20 := 0x00646e65 (* if end marker and newline. *)
	loca16 := 0x66694c2e (* Label prefix ".Lif". *)

	loca12 := 0x7a716562 (* beqz *)
	_write_out(@loca12, 4)
	loca12 := 0x2c306120 (* _a0, *)
	_write_out(@loca12, 4)
	_put_char(0x20) (* _ *)

	(* Write the label *)
	_write_out(@loca16, 4)
	mv a0, s2
	call _printi

	_put_char(0x0a) (* \n *)

	.Lcompile_if_loop
	_skip_spaces()
	loca12 := _read_token()

	loca4 := _current()
	loca8 := _token_compare(loca4, loca12, @loca20)

	if loca8 then
		loca12 := _read_line()
		_compile_line(loca12, 1)

		goto .Lcompile_if_loop
	end

	(* Write the label *)
	_write_out(@loca16, 4)
	mv a0, s2
	call _printi

	loca12 := 0x0a3a0a3a (* :\n:\n *)
	_write_out(@loca12, 2)

	addi s2, s2, 1 # Increment the label counter.
	_advance(4) (* Skip the end with newline. *)
end

(*
Parameters:
	a0 - Line length.
	a1 - Whether the section header was already emitted. If not it should be
	emitted before any code is written.

Returns 1 in a0 if the parsed line contained a text section element such a
procedure or the program entry point. Otherwise sets a0 to 0.
*)
proc _compile_line(loca84: Word, loca80: Bool)
begin
	beqz a0, .Lcompile_line_empty # Skip an empty line.

	lbu t0, (s1)
	li t1, '('
	beq t0, t1, .Lcompile_line_comment

	li t0, 0x0a6d6172 # ram\n
	sw t0, 12(sp)
	li t0, 0x676f7270 # prog
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 8
	call _memcmp
	beqz a0, .Lcompile_line_program

	li t0, 0x0a74 # t\n
	sw t0, 12(sp)
	li t0, 0x736e6f63 # cons
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 6
	call _memcmp
	beqz a0, .Lcompile_line_const

	li t0, 0x0a726176 # var\n
	sw t0, 12(sp)
	mv a0, s1
	addi a1, sp, 12
	li a2, 4
	call _memcmp
	beqz a0, .Lcompile_line_var

	li t0, 0x20 # _
	sw t0, 12(sp)
	li t0, 0x636f7270 # proc
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 5
	call _memcmp
	beqz a0, .Lcompile_line_procedure

	li t0, 0x0a6e # n\n
	sw t0, 12(sp)
	li t0, 0x69676562 # begi
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 6
	call _memcmp
	beqz a0, .Lcompile_line_begin

	li t0, 0x2e646e65 # end.
	sw t0, 12(sp)
	mv a0, s1
	addi a1, sp, 12
	li a2, 4
	call _memcmp
	beqz a0, .Lcompile_line_exit

	li t0, 0x61636f6c # loca
	sw t0, 12(sp)
	mv a0, s1
	addi a1, sp, 12
	li a2, 4
	call _memcmp
	beqz a0, .Lcompile_line_identifier

	li t0, 0x7472 # rt
	sw t0, 12(sp)
	li t0, 0x6f706d69 # impo
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 6
	call _memcmp
	beqz a0, .Lcompile_line_import

	li t0, 0x6f746f67 # goto
	sw t0, 12(sp)
	mv a0, s1
	addi a1, sp, 12
	li a2, 4
	call _memcmp
	beqz a0, .Lcompile_line_goto

	li t0, 0x6e72 # rn
	sw t0, 12(sp)
	li t0, 0x75746572 # retu
	sw t0, 8(sp)
	mv a0, s1
	addi a1, sp, 8
	li a2, 6
	call _memcmp
	beqz a0, .Lcompile_line_return

	li t0, 0x6669 # if
	sw t0, 12(sp)
	mv a0, s1
	addi a1, sp, 12
	li a2, 2
	call _memcmp
	beqz a0, .Lcompile_line_if

	lbu t0, (s1)
	li t1, '.'
	beq t0, t1, .Lcompile_line_label
	li t1, '_'
	beq t0, t1, .Lcompile_line_identifier

	goto .Lcompile_line_unchanged (* Else. *)

	.Lcompile_line_if:
	_compile_if()
	goto .Lcompile_line_section

	.Lcompile_line_label
	_compile_label(loca84)
	goto .Lcompile_line_section

	.Lcompile_line_return
	(* DEBUG
	mv a0, s1
	li a1, 8
	call _write_error *)
	_compile_return()
	goto .Lcompile_line_section

	.Lcompile_line_goto
	_compile_goto()
	goto .Lcompile_line_section

	.Lcompile_line_import
	_compile_import()
	goto .Lcompile_line_section

	.Lcompile_line_identifier
	_compile_identifier()
	goto .Lcompile_line_section

	.Lcompile_line_exit
	_compile_exit()
	goto .Lcompile_line_section

	.Lcompile_line_begin
	lw a1, 80(sp)
	bnez a1, .Lcompile_line_compile_entry
	_compile_text_section()
	.Lcompile_line_compile_entry
	_compile_entry_point()
	li a0, 1
	goto .Lcompile_line_end

	.Lcompile_line_const
	_compile_constant_section()
	goto .Lcompile_line_section

	.Lcompile_line_procedure
	lw a1, 80(sp)
	bnez a1, .Lcompile_line_compile_procedure
	_compile_text_section()
	.Lcompile_line_compile_procedure
	_compile_procedure()
	li a0, 1
	goto .Lcompile_line_end

	.Lcompile_line_var
	_compile_variable_section()
	goto .Lcompile_line_section

	.Lcompile_line_program
	_compile_program()
	goto .Lcompile_line_section

	.Lcompile_line_comment
	_skip_comment(loca84)
	goto .Lcompile_line_section

	.Lcompile_line_empty
	_advance(1)
	goto .Lcompile_line_section

	.Lcompile_line_unchanged
	_compile_assembly(loca84)
	goto .Lcompile_line_section

	.Lcompile_line_section
	mv a0, zero

	.Lcompile_line_end
	sw a0, 12(sp)
	_skip_spaces()
	_skip_comment()
	lw a0, 12(sp)
end

(* Prints ".section .text" and exits. *)
proc _compile_text_section()
var loca0: Word
begin
	(* .section .text *)
	loca0 := 0x6365732e (* .sec *)
	_write_out(@loca0, 4)
	loca0 := 0x6e6f6974 (* tion *)
	_write_out(@loca0, 4)
	loca0 := 0x65742e20 (* _.te *)
	_write_out(@loca0, 4)
	loca0 := 0x0a7478 (* xt\n *)
	_write_out(@loca0, 3)
end

proc _compile_entry_point()
var loca0: Word
begin
	(* .type _start, @function *)
	loca0 := 0x7079742e (* .typ *)
	_write_out(@loca0, 4)
	loca0 := 0x735f2065 (* e _s *)
	_write_out(@loca0, 4)
	loca0 := 0x74726174 (* tart *)
	_write_out(@loca0, 4)
	loca0 := 0x6640202c (* , @f *)
	_write_out(@loca0, 4)
	loca0 := 0x74636e75 (* unct *)
	_write_out(@loca0, 4)
	loca0 := 0x0a6e6f69 (* ion\n *)
	_write_out(@loca0, 4)
	loca0 := 0x6174735f (* _sta *)
	_write_out(@loca0, 4)
	loca0 := 0x0a3a7472 (* rt:\n *)
	_write_out(@loca0, 4)

	_advance(6) (* Skip begin\n. *)
end

proc _compile_exit()
var loca0: Word
begin
	(*
	li a0, 0
	li a7, SYS_EXIT
	ecall
	*)
	loca0 := 0x6120696c (* li a *)
	_write_out(@loca0, 4)
	loca0 := 0x30202c30 (* 0, 0 *)
	_write_out(@loca0, 4)
	loca0 := 0x20696c0a (* \nli_ *)
	_write_out(@loca0, 4)
	loca0 := 0x202c3761 (* a7,_ *)
	_write_out(@loca0, 4)
	loca0 := 0x650a3339 (* 93\ne *)
	_write_out(@loca0, 4)
	loca0 := 0x6c6c6163 (* call *)
	_write_out(@loca0, 4)
	loca0 := 0x0a (* \n *)
	_write_out(@loca0, 1)

	_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. *)
proc _read_line()
begin
	loca0 := _current() (* Local position in the source text. *)

	.Lread_line_do
	lw t0, 0(sp)
	lbu t1, (t0) # t1 = Current character.
	beqz t1, .Lread_line_end # Exit the loop on the NUL character.
	li t2, '\n'
	beq t1, t2, .Lread_line_end # Exit the loop on the new line.

	loca0 := loca0 + 1
	goto .Lread_line_do

	.Lread_line_end
	loca4 := _current()
	return loca0 - loca4 (* Return the line length. *)
end

proc _compile()
var
	loca0, loca4: Word
	loca8: Bool
begin
	loca4 := 0 (* Whether the text section header was already emitted. *)

	.Lcompile_do
	lbu t0, (s1) # t0 = Current character.
	beqz t0, .Lcompile_end # Exit the loop on the NUL character.

	_skip_indentation()
	loca0 := _read_line()
	loca8 := _compile_line(loca0, loca4)

	beqz a0, .Lcompile_do
	(* Update whether the text section header was already emitted. *)
	loca4 := loca4 or loca8

	goto .Lcompile_do
	.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

(* Returns the first character in the remaining source text. *)
proc _front()
begin
	lbu a0, (s1)
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

	la s1, source_code # s1 = Source code position.
	li s2, 1
	_compile()
end.