Add return statements

boot/stage1.s

@@ -1,7 +1,7 @@
 .global _start # Program entry point.
 # s1 - Contains the current position in the source text.
 
-.equ SOURCE_BUFFER_SIZE, 40960
+.equ SOURCE_BUFFER_SIZE, 81920
 
 .section .rodata
 section_rodata: .ascii ".section .rodata\n"
@@ -16,6 +16,7 @@ prologue: .ascii "addi sp, sp, -96\nsw ra, 92(sp)\nsw s0, 88(sp)\naddi s0, sp, 9
 .equ PROLOGUE_SIZE, . - prologue
 epilogue: .ascii "lw ra, 92(sp)\nlw s0, 88(sp)\naddi sp, sp, 96\nret\n"
 .equ EPILOGUE_SIZE, . - epilogue
+
 asm_exit: .ascii "li a0, 0\nli a7, 93\necall\n"
 .equ ASM_EXIT_SIZE, . - asm_exit
 asm_start: .ascii ".type _start, @function\n_start:\n"
@@ -24,6 +25,14 @@ asm_and_a0_a1: .ascii "and a0, a0, a1\n"
 .equ ASM_AND_A0_A1_SIZE, . - asm_and_a0_a1
 asm_or_a0_a1: .ascii "or a0, a0, a1\n"
 .equ ASM_OR_A0_A1_SIZE, . - asm_or_a0_a1
+asm_add_a0_a1: .ascii "add a0, a0, a1\n"
+.equ ASM_ADD_A0_A1_SIZE, . - asm_add_a0_a1
+asm_sub_a0_a1: .ascii "sub a0, a0, a1\n"
+.equ ASM_SUB_A0_A1_SIZE, . - asm_sub_a0_a1
+asm_seqz_a0: .ascii "seqz a0, a0\n"
+.equ ASM_SEQZ_A0_SIZE, . - asm_seqz_a0
+asm_type: .ascii ".type "
+.equ ASM_TYPE_SIZE, . - asm_type
 
 .section .bss
 .type source_code, @object
@@ -67,7 +76,7 @@ _build_binary_expression:
 	call _read_token
 	sw a0, 20(sp)
 
-	li t0, 0x26 # &
+	li t0, '&'
 	sw t0, 16(sp)
 	mv a0, s1
 	lw a1, 20(sp)
@@ -83,7 +92,7 @@ _build_binary_expression:
 	call _token_compare
 	beqz a0, .L_build_binary_expression_or
 
-	li t0, 0x3d # =
+	li t0, '='
 	sw t0, 16(sp)
 	mv a0, s1
 	lw a1, 20(sp)
@@ -91,32 +100,34 @@ _build_binary_expression:
 	call _token_compare
 	beqz a0, .L_build_binary_expression_equal
 
+	li t0, '+'
+	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, '-'
+	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
+
 	j .Lbuild_binary_expression_end
 
 .L_build_binary_expression_equal:
 	addi s1, s1, 1 # Skip =.
 	li a0, 1
 	call _build_expression
-	li t0, 0x0a3161 # a1\n
-	sw t0, 16(sp)
-	li t0, 0x202c3061 # a0,_
-	sw t0, 12(sp)
-	li t0, 0x202c3061 # a0,_
-	sw t0, 8(sp)
-	li t0, 0x20627573 # sub_
-	sw t0, 4(sp)
-	addi a0, sp, 4
-	li a1, 15
+	la a0, asm_sub_a0_a1
+	li a1, ASM_SUB_A0_A1_SIZE
 	call _write_out
 
-	li t0, 0x0a306120 # _a0\n
-	sw t0, 16(sp)
-	li t0, 0x2c306120 # _a0,
-	sw t0, 12(sp)
-	li t0, 0x7a716573 # seqz
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 12
+	la a0, asm_seqz_a0
+	li a1, ASM_SEQZ_A0_SIZE
 	call _write_out
 
 	j .Lbuild_binary_expression_end
@@ -141,6 +152,26 @@ _build_binary_expression:
 
 	j .Lbuild_binary_expression_end
 
+.L_build_binary_expression_plus:
+	addi s1, s1, 1 # Skip +.
+	li a0, 1
+	call _build_expression
+	la a0, asm_add_a0_a1
+	li a1, ASM_ADD_A0_A1_SIZE
+	call _write_out
+
+	j .Lbuild_binary_expression_end
+
+.L_build_binary_expression_minus:
+	addi s1, s1, 1 # Skip -.
+	li a0, 1
+	call _build_expression
+	la a0, asm_sub_a0_a1
+	li a1, ASM_SUB_A0_A1_SIZE
+	call _write_out
+
+	j .Lbuild_binary_expression_end
+
 .Lbuild_binary_expression_end:
 	# Epilogue.
 	lw ra, 28(sp)
@@ -237,11 +268,8 @@ _build_expression:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
-	sw t0, 16(sp)
-	addi a0, sp, 16
-	li a1, 1
-	call _write_out
+	li a0, '\n'
+	call _put_char
 
 	j .Lbuild_expression_advance
 
@@ -262,7 +290,7 @@ _build_expression:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 16(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 12(sp)
@@ -380,7 +408,7 @@ _compile_identifier:
 	addi a1, a1, -4 # Skip the "loca" variable prefix.
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 12(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 8(sp)
@@ -416,7 +444,6 @@ _compile_call:
 
 .Lcompile_call_paren:
 	call _skip_spaces
-	call _read_token
 	lbu t0, (s1)
 	li t1, 0x29 # )
 	beq t0, t1, .Lcompile_call_complete
@@ -458,7 +485,7 @@ _compile_call:
 	li a1, 1
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 8(sp)
 	li t0, 0x29707328 # (sp)
 	sw t0, 4(sp)
@@ -467,7 +494,6 @@ _compile_call:
 	call _write_out
 
 	call _skip_spaces
-	call _read_token
 	lbu t0, (s1)
 	li t1, ','
 	bne t0, t1, .Lcompile_call_paren
@@ -507,7 +533,7 @@ _compile_call:
 	addi t4, t4, '0'
 	addi t0, t0, '0'
 
-	li t5, 0x0a # \n
+	li t5, '\n'
 	sb t5, 11(sp)
 	li t5, 0x29707328 # (sp)
 	sw t5, 7(sp)
@@ -540,7 +566,7 @@ _compile_call:
 	lw a1, 16(sp)
 	call _write_out
 
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 8(sp)
 	addi a0, sp, 8
 	li a1, 1
@@ -601,6 +627,12 @@ _read_token:
 	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.
@@ -693,11 +725,6 @@ _skip_comment:
 	sw s0, 8(sp)
 	addi s0, sp, 16
 
-	/* DEBUG
-	mv a0, s1
-	li a1, 8
-	call _write_error */
-
 	# Check whether this is a comment.
 	li t0, 0x2a28 # (*
 	sw t0, 4(sp)
@@ -924,12 +951,8 @@ _compile_variable:
 	add s1, s1, a0 # Skip the type.
 
 	# .type identifier, @object
-	li t0, 0x2065 # e_
-	sw t0, 12(sp)
-	li t0, 0x7079742e # .typ
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 6
+	la a0, asm_type
+	li a1, ASM_TYPE_SIZE
 	call _write_out
 
 	lw a0, 28(sp)
@@ -959,7 +982,7 @@ _compile_variable:
 	lw a1, 24(sp)
 	call _write_out
 
-	li t0, 0x202c # ,
+	li t0, 0x202c # ,_
 	sw t0, 12(sp)
 	addi a0, sp, 12
 	li a1, 2
@@ -969,11 +992,8 @@ _compile_variable:
 	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
+	li a0, '\n'
+	call _put_char
 
 	# identifier: .zero size
 	lw a0, 28(sp)
@@ -992,11 +1012,8 @@ _compile_variable:
 	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
+	li a0, '\n'
+	call _put_char
 
 	# Epilogue.
 	lw ra, 36(sp)
@@ -1019,12 +1036,8 @@ _compile_procedure:
 	add s1, s1, a0
 
 	# .type identifier, @function
-	li t0, 0x2065 # e_
-	sw t0, 12(sp)
-	li t0, 0x7079742e # .typ
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 6
+	la a0, asm_type
+	li a1, ASM_TYPE_SIZE
 	call _write_out
 
 	lw a0, 20(sp)
@@ -1235,11 +1248,8 @@ _compile_goto:
 
 	addi s1, s1, 1 # Skip the new line.
 
-	li t0, 0x0a # \n
-	sw t0, 8(sp)
-	addi a0, sp, 8
-	li a1, 1
-	call _write_out
+	li a0, '\n'
+	call _put_char
 
 	# Epilogue.
 	lw ra, 12(sp)
@@ -1280,7 +1290,7 @@ _compile_label:
 	call _write_out
 
 .Lcompile_label_colon:
-	li t0, 0x0a # \n
+	li t0, '\n'
 	sw t0, 4(sp)
 	addi a0, sp, 4
 	li a1, 1
@@ -1296,6 +1306,25 @@ _compile_label:
 	addi sp, sp, 16
 	ret
 
+.type _compile_return, @function
+_compile_return:
+	# Prologue.
+	addi sp, sp, -16
+	sw ra, 12(sp)
+	sw s0, 8(sp)
+	addi s0, sp, 16
+
+	addi s1, s1, 6 # Skip return.
+	call _skip_spaces
+
+	call _build_binary_expression
+
+	# Epilogue.
+	lw ra, 12(sp)
+	lw s0, 8(sp)
+	addi sp, sp, 16
+	ret
+
 # Parameters:
 # a0 - Line length.
 # a1 - Whether the section header was already emitted. If not it should be
@@ -1403,6 +1432,16 @@ _compile_line:
 	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
+
 	lbu t0, (s1)
 	li t1, '.'
 	beq t0, t1, .Lcompile_line_label
@@ -1416,6 +1455,14 @@ _compile_line:
 	call _compile_label
 	j .Lcompile_line_section
 
+.Lcompile_line_return:
+	/* DEBUG
+	mv a0, s1
+	li a1, 6
+	call _write_error */
+	call _compile_return
+	j .Lcompile_line_section
+
 .Lcompile_line_goto:
 	call _compile_goto
 	j .Lcompile_line_section