Implement if statements

1 files changed, 214 insertions, 136 deletions

diff --git a/boot/stage2.elna b/boot/stage2.elna
index 3ee1f32..0eb713c 100644
--- a/boot/stage2.elna
+++ b/boot/stage2.elna
@@ -14,6 +14,9 @@ type checking.
 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
 
@@ -36,7 +39,7 @@ begin
 end
 
 proc _build_binary_expression()
-var loca0, loca4, loca8: Word
+var loca0, loca4, loca8, loca20: Word
 begin
 	_build_expression(0)
 
@@ -44,8 +47,7 @@ begin
 	loca8 := 0x0a316120 (* _a1\n *)
 
 	_skip_spaces()
-	call _read_token
-	sw a0, 20(sp)
+	loca20 := _read_token()
 
 	li t0, 0x26 # &
 	sw t0, 16(sp)
@@ -87,6 +89,14 @@ begin
 	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
@@ -146,6 +156,19 @@ begin
 	_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
 
@@ -156,28 +179,30 @@ a0 - X in aX, the register number to save the result.
 *)
 proc _build_expression()
 var
-	loca20, loca28, loca8: Word
-	loca24: ^Byte
+	loca0, loca20, loca28, loca8: Word
+	loca24, loca4: ^Byte
 begin
-	addi a0, a0, '0' # Make the register number to a character.
-	sw a0, 28(sp) # And save it.
+	(* Make the register number to a character and save it. *)
+	loca28 := loca84 + 0x30 (* 0 *)
 
 	_skip_spaces()
 	loca20 := _read_token()
 	loca24 := _current()
 
-	addi a0, s1, 0
-	lbu a0, (a0)
+	lbu a0, (s1)
+	li t0, '-'
+	beq a0, t0, .Lbuild_expression_negate
+
+	lbu a0, (s1)
 	li t0, '@'
 	beq a0, t0, .Lbuild_expression_address
 
-	addi a0, s1, 0
-	lbu a0, (a0)
-	call _is_digit
-	bnez a0, .Lbuild_expression_literal
+	loca0 := _front()
+	if _is_digit(loca0) then
+		goto .Lbuild_expression_literal
+	end
 
-	addi a0, s1, 0
-	lbu a0, (a0)
+	lbu a0, (s1)
 	li t0, '_'
 	beq a0, t0, .Lbuild_expression_call
 
@@ -200,6 +225,19 @@ begin
 
 	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)
@@ -216,40 +254,28 @@ begin
 	loca24 := _current()
 	loca20 := _read_token()
 
-	lw a0, 24(sp)
-	lw a1, 20(sp)
-	addi a0, a0, 4 # Skip the "loca" variable prefix.
-	addi a1, a1, -4 # Skip the "loca" variable prefix.
-	call _write_out
+	(* 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
-	lw t1, 28(sp)
-	li t0, 0x00202c00 # \0,_
-	or t0, t0, t1
-	sw t0, 8(sp)
-	li t0, 0x6120776c # lw a
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 7
-	call _write_out
+	loca8 := 0x6120776c (* lw a *)
+	_write_out(@loca8, 4)
+	loca8 := 0x00202c00 or loca28 # \0,_
+	_write_out(@loca8, 3)
 
-	lw a0, 24(sp)
-	lw a1, 20(sp)
-	addi a0, a0, 4 # Skip the "loca" variable prefix.
-	addi a1, a1, -4 # Skip the "loca" variable prefix.
-	call _write_out
+	loca4 := loca24 + 4
+	loca0 := loca20 - 4
+	_write_out(loca4, loca0) (* Skip the "loca" variable prefix. *)
 
-	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
+	loca8 := 0x29707328 (* (sp) *)
+	_write_out(@loca8, 4)
+	_put_char(0x0a) (* \n *)
 
 	goto .Lbuild_expression_advance
 
@@ -261,18 +287,13 @@ begin
 	goto .Lbuild_expression_end
 
 	.Lbuild_expression_literal
-	lw t1, 28(sp)
-	li t0, 0x00202c00 # \0,_
-	or t0, t0, t1
-	sw t0, 8(sp)
-	li t0, 0x6120696c # li a
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 7
-	call _write_out
+	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
+	_put_char(0x0a) (* \n *)
 
 	goto .Lbuild_expression_advance
 
@@ -335,11 +356,9 @@ begin
 	loca0 := 0x202c30 (* 0,_ *)
 	_write_out(@loca0, 3)
 
-	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
+	loca20 := loca20 + 4
+	loca16 := loca16 - 4
+	_write_out(loca20, loca16)
 
 	loca0 := 0x29707328 (* (sp) *)
 	_write_out(@loca0, 4)
@@ -359,7 +378,7 @@ Returns the procedure result in a0.
 *)
 proc _compile_call(loca84: ^Byte, loca80: Word)
 var
-	loca0, loca12: Word
+	loca0, loca4, loca12: Word
 begin
 	loca12 := 0 (* Argument count for a procedure call. *)
 
@@ -377,49 +396,24 @@ begin
 	loca0 := 0x202c30 (* 0,_ *)
 	_write_out(@loca0, 3)
 
-	lw t0, 12(sp) # Argument count for a procedure call.
-
 	(*
 	Only 6 arguments are supported with a0-a5.
 	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, 60
-	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
+	loca0 := -4 * loca12
+	loca0 := loca0 + 60
+	_printi(loca0)
 
-	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
+	loca0 := 0x29707328 (* (sp) *)
+	_write_out(@loca0, 4)
+	_put_char(0x0a) (* \n *)
 
 	_skip_spaces()
 	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)
+	loca12 := loca12 + 1 (* Argument count for a procedure call. *)
 
 	_advance(1) (* Skip the comma between the arguments. *)
 	goto .Lcompile_call_argument
@@ -432,47 +426,62 @@ begin
 	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.
 	*)
-	lw t0, 12(sp)
-	li t1, 5
-	bgt t0, t1, .Lcompile_call_perform
+	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)
 
-	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, 60
-	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
-
-	loca12 := loca12 + 1
-	goto .Lcompile_call_restore
-
-	.Lcompile_call_perform
-	loca0 := 0x6c6c6163
+	(* 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) (* _ *)
 
@@ -532,6 +541,9 @@ begin
 	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. *)
@@ -1125,6 +1137,61 @@ begin
 	_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.
@@ -1234,6 +1301,14 @@ begin
 	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
@@ -1242,6 +1317,10 @@ begin
 
 	goto .Lcompile_line_unchanged (* Else. *)
 
+	.Lcompile_line_if:
+	_compile_if()
+	goto .Lcompile_line_section
+
 	.Lcompile_line_label
 	_compile_label(loca84)
 	goto .Lcompile_line_section
@@ -1409,7 +1488,9 @@ begin
 end
 
 proc _compile()
-var loca0, loca4: Word
+var
+	loca0, loca4: Word
+	loca8: Bool
 begin
 	loca4 := 0 (* Whether the text section header was already emitted. *)
 
@@ -1419,15 +1500,11 @@ begin
 
 	_skip_indentation()
 	loca0 := _read_line()
-	lw a0, 0(sp)
-	lw a1, 4(sp)
-	call _compile_line
+	loca8 := _compile_line(loca0, loca4)
 
 	beqz a0, .Lcompile_do
 	(* Update whether the text section header was already emitted. *)
-	lw t0, 4(sp)
-	or t0, t0, a0
-	sw t0, 4(sp)
+	loca4 := loca4 or loca8
 
 	goto .Lcompile_do
 	.Lcompile_end
@@ -1460,5 +1537,6 @@ begin
 	call _read_file
 
 	la s1, source_code # s1 = Source code position.
+	li s2, 1
 	_compile()
 end.