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Change label and jump (now goto) syntax

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This commit is contained in:
Eugen Wissner
2025-04-25 23:12:36 +02:00
parent 2e0c958aa3
commit fee1781a5b
5 changed files with 1020 additions and 1377 deletions
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37
Rakefile
View File

@@ -22,31 +22,44 @@ def assemble_stage(output, compiler, source)
end
desc 'Final stage'
task default: ['build/stage2', 'boot/stage2.elna'] do |t|
assembler, exe = t.prerequisites.partition { |prerequisite| prerequisite.end_with? '.elna' }
task default: ['build/stage2b', 'build/stage2b.s', 'boot/stage2.elna'] do |t|
exe, previous_output, source = t.prerequisites
File.open File::NULL, 'w' do |output|
assemble_stage output, exe, assembler
end
cat_arguments = ['cat', source]
compiler_arguments = [QEMU, '-L', SYSROOT, exe]
diff_arguments = ['diff', '-Nur', previous_output, '-']
Open3.pipeline(cat_arguments, compiler_arguments, diff_arguments)
end
directory 'build'
desc 'Initial stage'
file 'build/stage1' => ['boot/echo-boot.s', 'boot/common-boot.s', 'build'] do |t|
assembler = t.prerequisites.filter { |prerequisite| prerequisite.end_with? '.s' }
file 'build/stage1' => ['boot/stage1.s', 'boot/common-boot.s', 'build'] do |t|
source = t.prerequisites.filter { |prerequisite| prerequisite.end_with? '.s' }
sh CROSS_GCC, '-nostdlib', '-o', t.name, *assembler
sh CROSS_GCC, '-nostdlib', '-o', t.name, *source
end
file 'build/stage2.s' => ['build/stage1', 'boot/stage2.elna'] do |t|
assembler, exe = t.prerequisites.partition { |prerequisite| prerequisite.end_with? '.elna' }
file 'build/stage2a.s' => ['build/stage1', 'boot/stage2.elna'] do |t|
source, exe = t.prerequisites.partition { |prerequisite| prerequisite.end_with? '.elna' }
File.open t.name, 'w' do |output|
assemble_stage output, exe, assembler
assemble_stage output, exe, source
end
end
file 'build/stage2' => ['build/stage2.s', 'boot/common-boot.s'] do |t|
file 'build/stage2a' => ['build/stage2a.s', 'boot/common-boot.s'] do |t|
sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end
file 'build/stage2b.s' => ['build/stage2a', 'boot/stage2.elna'] do |t|
source, exe = t.prerequisites.partition { |prerequisite| prerequisite.end_with? '.elna' }
File.open t.name, 'w' do |output|
assemble_stage output, exe, source
end
end
file 'build/stage2b' => ['build/stage2b.s', 'boot/common-boot.s'] do |t|
sh CROSS_GCC, '-nostdlib', '-o', t.name, *t.prerequisites
end

894
boot/asm-boot.s
View File

@@ -1,894 +0,0 @@
# s1 - Contains the current position in the source text.
.global _start # Program entry point.
.section .rodata
.equ SOURCE_BUFFER_SIZE, 2048
asm_begin: .ascii ".text\n.global _start\n_start:\naddi sp, sp, -64\nsw ra, 60(sp)\nsw s0, 56(sp)\naddi s0, sp, 64\n"
.equ ASM_BEGIN_SIZE, . - asm_begin
asm_end: .ascii "addi a0, zero, 0\naddi a7, zero, 93\necall\nlw ra, 60(sp)\nlw s0, 56(sp)\naddi sp, sp, 64\nret\n"
.equ ASM_END_SIZE, . - asm_end
asm_program: .ascii ".bss\n"
.equ ASM_PROGRAM_SIZE, . - asm_program
asm_type: .ascii ".type "
.equ ASM_TYPE_SIZE, . - asm_type
asm_object: .ascii ", @object\n"
.equ ASM_OBJECT_SIZE, . - asm_object
asm_size: .ascii ".size "
.equ ASM_SIZE_SIZE, . - asm_size
asm_zero: .ascii ".zero "
.equ ASM_ZERO_SIZE, . - asm_zero
asm_global: .ascii ".global "
.equ ASM_GLOBAL_SIZE, . - asm_global
token_begin: .string "begin"
token_end: .string "end"
token_import: .string "import"
token_open_paren: .string "("
token_close_paren: .string ")"
token_open_square: .string "["
token_assign: .string ":="
token_var: .string "var"
token_comma: .string ","
space: .ascii " "
comma: .ascii ","
new_line: .ascii "\n"
colon: .ascii ":"
digit_zero: .ascii "0"
instruction_la: .ascii "la"
instruction_call: .ascii "call"
instruction_addi: .ascii "addi"
instruction_li: .ascii "li"
instruction_sw: .ascii "sw"
instruction_lw: .ascii "lw"
register_a0: .ascii "a0"
register_sp: .ascii "sp"
register_a: .ascii "a"
.section .bss
.global source_code
.type source_code, @object
.size source_code, SOURCE_BUFFER_SIZE
source_code: .zero SOURCE_BUFFER_SIZE
.section .text
.type _skip_spaces, @function
_skip_spaces:
.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
j .Lspace_loop_end
.Lspace_loop_repeat:
addi s1, s1, 1
j .Lspace_loop_do
.Lspace_loop_end:
ret
# 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.
.type _token_compare, @function
_token_compare:
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
j .Ltoken_compare_loop
.Ltoken_compare_not_equal:
li a0, 1
j .Ltoken_compare_end
.Ltoken_compare_equal:
li a0, 0
.Ltoken_compare_end:
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
_read_token:
# Prologue.
addi sp, sp, -16
sw ra, 12(sp)
sw s0, 8(sp)
addi s0, sp, 16
lbu t0, (s1) # t0 = Current character.
sw zero, 4(sp)
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
.Ltoken_character_loop_do: # Expect an identifier or a number.
lw t6, 4(sp)
add t1, s1, t6
lbu a0, (t1) # a0 = Current character.
call is_alnum
beqz a0, .Ltoken_character_end
lw t6, 4(sp)
addi t6, t6, 1
sw t6, 4(sp)
j .Ltoken_character_loop_do
.Ltoken_character_single:
lw t6, 4(sp)
addi t6, t6, 1
sw t6, 4(sp)
j .Ltoken_character_end
.Ltoken_character_colon:
lbu t0, 1(s1) # t0 = The character after the colon.
lw t6, 4(sp)
addi t6, t6, 1
sw t6, 4(sp)
li t1, '='
beq t0, t1, .Ltoken_character_single
j .Ltoken_character_end
.Ltoken_character_end:
lw a0, 4(sp)
# Epilogue.
lw ra, 12(sp)
lw s0, 8(sp)
addi sp, sp, 16
ret
# Generate entry point symbol.
.type _compile_begin, @function
_compile_begin:
# Prologue.
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
# Write initial assembler.
la a0, asm_begin
addi a1, zero, ASM_BEGIN_SIZE
call write_out
addi s1, s1, 5
# Epilogue.
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
# Generate program termination code.
.type _compile_end, @function
_compile_end:
# Prologue.
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
# Write closing assembler.
la a0, asm_end
addi a1, zero, ASM_END_SIZE
call write_out
addi s1, s1, 3
# Epilogue.
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
# Ignores the import.
.type _compile_import, @function
_compile_import:
# Prologue.
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
addi s1, s1, 6
call _skip_spaces
call _read_token
add s1, s1, a0 # Skip the imported module name.
# Epilogue.
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
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
addi a1, a0, 0
addi a0, s1, 0
la a2, token_close_paren
call _token_compare
beqz a0, .Lcompile_call_complete
.Lcompile_call_argument:
call _build_expression
la a0, instruction_sw
li a1, 2
call write_out
la a0, space
li a1, 1
call write_out
la a0, register_a0
li a1, 2
call write_out
la a0, comma
li a1, 1
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, 52
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
la a0, token_open_paren
li a1, 1
call write_out
la a0, register_sp
li a1, 2
call write_out
la a0, token_close_paren
li a1, 1
call write_out
la a0, new_line
li a1, 1
call write_out
call _skip_spaces
call _read_token
addi a1, a0, 0
addi a0, s1, 0
la a2, token_comma
call _token_compare
bnez a0, .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
la a0, instruction_lw
li a1, 2
call write_out
la a0, space
li a1, 1
call write_out
la a0, register_a
li a1, 1
call write_out
lw t0, 12(sp)
addi t0, t0, '0'
sw t0, 8(sp)
addi a0, sp, 8
li a1, 1
call write_out
la a0, comma
li a1, 1
call write_out
lw t0, 12(sp) # Argument count for a procedure call.
li t1, -4
mul t1, t0, t1
addi t1, t1, 52
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
la a0, token_open_paren
li a1, 1
call write_out
la a0, register_sp
li a1, 2
call write_out
la a0, token_close_paren
li a1, 1
call write_out
la a0, new_line
li a1, 1
call write_out
lw t0, 12(sp) # Increment.
addi t0, t0, 1
sw t0, 12(sp)
j .Lcompile_call_restore
.Lcompile_call_perform:
la a0, instruction_call
li a1, 4
call write_out
la a0, space
li a1, 1
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, new_line
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
.type _compile, @function
compile:
# Prologue.
addi sp, sp, -16
sw ra, 12(sp)
sw s0, 8(sp)
addi s0, sp, 16
# Write .bss section header for global variables.
la a0, asm_program
addi a1, zero, ASM_PROGRAM_SIZE
call write_out
call _skip_spaces
addi s1, s1, 7 # Skip "program" keyword.
.Lcharacter_loop_do:
call _skip_spaces
lbu t0, (s1) # t0 = Current character.
beqz t0, .Lcharacter_loop_end
call _read_token
sw a0, 4(sp) # Save the token length on the stack.
beqz a0, .Lcharacter_loop_end # No token read, there is unrecognized input.
lw a0, 4(sp)
call _handle_token
j .Lcharacter_loop_do
.Lcharacter_loop_end:
# Epilogue.
lw ra, 12(sp)
lw s0, 8(sp)
addi sp, sp, 16
ret
# Evalutes an expression and saves the result in a0.
.type _build_expression, @function
_build_expression:
# Prologue.
addi sp, sp, -16
sw ra, 12(sp)
sw s0, 8(sp)
addi s0, sp, 16
call _skip_spaces
call _read_token
sw s1, 4(sp)
sw a0, 0(sp)
# Integer literal.
addi a0, s1, 0
lb a0, (a0)
call is_digit
bnez a0, .Lbuild_expression_number_literal
# Named identifier.
la a0, instruction_la
li a1, 2
call write_out
la a0, space
li a1, 1
call write_out
la a0, register_a0
li a1, 2
call write_out
la a0, comma
li a1, 1
call write_out
lw a0, 4(sp)
lw a1, 0(sp)
call write_out
la a0, new_line
li a1, 1
call write_out
j .Lbuild_expression_end
.Lbuild_expression_number_literal:
la a0, instruction_li
li a1, 2
call write_out
la a0, space
li a1, 1
call write_out
la a0, register_a0
li a1, 2
call write_out
la a0, comma
li a1, 1
call write_out
lw a0, 4(sp)
lw a1, 0(sp)
call write_out
la a0, new_line
li a1, 1
call write_out
j .Lbuild_expression_end
.Lbuild_expression_end:
lw a0, 0(sp)
add s1, s1, a0
# Epilogue.
lw ra, 12(sp)
lw s0, 8(sp)
addi sp, sp, 16
ret
# Compiles a statement beginning with an identifier.
.type _compile_identifier, @function
_compile_identifier:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Save the pointer to the identifier and its length on the stack.
sw a0, 20(sp)
sw a1, 16(sp)
add s1, s1, a1
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
lw a0, 12(sp)
lw a1, 8(sp)
la a2, token_assign
call _token_compare
beqz a0, .Lcompile_identifier_assign
lw a0, 12(sp)
lw a1, 8(sp)
la a2, token_open_paren
call _token_compare
beqz a0, .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
la a0, instruction_addi
li a1, 4
call write_out
la a0, space
li a1, 1
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, comma
li a1, 1
call write_out
la a0, register_a0
li a1, 2
call write_out
la a0, comma
li a1, 1
call write_out
la a0, digit_zero
li a1, 1
call write_out
la a0, new_line
li a1, 1
call write_out
j .Lcompile_identifier_end
.Lcompile_identifier_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_var, @function
_compile_var:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Variable name.
addi s1, s1, 3
call _skip_spaces
call _read_token
sw s1, 20(sp)
sw a0, 16(sp)
add s1, s1, a0
# Skip the colon.
call _skip_spaces
call _read_token
add s1, s1, a0
call _skip_spaces
call _read_token
sw a0, 12(sp)
addi a0, s1, 0
lw a1, 12(sp)
la a2, token_open_square
call _token_compare
beqz a0, .Lcompile_var_array
j .Lcompile_var_end
.Lcompile_var_array:
call _skip_spaces
add s1, s1, 1 # Skip the opening square bracket.
call _skip_spaces
call _read_token
sw a0, 8(sp)
la a0, asm_type
li a1, ASM_TYPE_SIZE
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, asm_object
li a1, ASM_OBJECT_SIZE
call write_out
la a0, asm_size
li a1, ASM_SIZE_SIZE
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, comma
li a1, 1
call write_out
addi a0, s1, 0
lw a1, 8(sp)
call write_out
la a0, new_line
li a1, 1
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, colon
li a1, 1
call write_out
la a0, asm_zero
li a1, ASM_ZERO_SIZE
call write_out
addi a0, s1, 0
lw a1, 8(sp)
call write_out
la a0, new_line
li a1, 1
call write_out
la a0, asm_global
li a1, ASM_GLOBAL_SIZE
call write_out
lw a0, 20(sp)
lw a1, 16(sp)
call write_out
la a0, new_line
li a1, 1
call write_out
lw a0, 8(sp)
add s1, s1, a0
call _skip_spaces
add s1, s1, 1 # Skip the closing square bracket.
call _skip_spaces
call _read_token
sw a0, 12(sp)
j .Lcompile_var_end
.Lcompile_var_end:
lw a0, 12(sp)
add s1, s1, a0
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _handle_token, @function
_handle_token:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
sw a0, 20(sp)
# Detect what token has been read.
addi a0, s1, 0
lw a1, 20(sp)
la a2, token_begin
call _token_compare
beqz a0, .Lhandle_token_begin
addi a0, s1, 0
lw a1, 20(sp)
la a2, token_end
call _token_compare
beqz a0, .Lhandle_token_end
addi a0, s1, 0
lw a1, 20(sp)
la a2, token_import
call _token_compare
beqz a0, .Lhandle_token_import
addi a0, s1, 0
lw a1, 20(sp)
la a2, token_var
call _token_compare
beqz a0, .Lhandle_token_var
# If the first symbol in the token is a character, assume an identifier.
addi a0, s1, 0
lb a0, (a0)
call is_alpha
bnez a0, .Lhandle_token_identifier
# Ignore the unknown token.
lw t0, 20(sp)
add s1, s1, t0
j .Lhandle_token_return
.Lhandle_token_begin:
call _compile_begin
j .Lhandle_token_return
.Lhandle_token_end:
call _compile_end
j .Lhandle_token_return
.Lhandle_token_import:
call _compile_import
j .Lhandle_token_return
.Lhandle_token_var:
call _compile_var
j .Lhandle_token_return
.Lhandle_token_identifier:
addi a0, s1, 0
lw a1, 20(sp)
call _compile_identifier
j .Lhandle_token_return
.Lhandle_token_return:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
_start:
# Read the source from the standard input.
la a0, source_code
li a1, SOURCE_BUFFER_SIZE # Buffer size.
call read_file
la s1, source_code # s1 = Source code position.
call compile
# Call exit.
li a0, 0 # Use 0 return code.
call exit

727
boot/echo-boot.s → boot/stage1.s
View File

@@ -1,17 +1,143 @@
.global _start
.global _start # Program entry point.
# s1 - Contains the current position in the source text.
.equ SOURCE_BUFFER_SIZE, 40960
.section .rodata
SOURCE_BUFFER_SIZE: .long 20480
section_rodata: .ascii ".section .rodata\n"
.equ SECTION_RODATA_SIZE, . - section_rodata
section_text: .ascii ".section .text\n"
.equ SECTION_TEXT_SIZE, . - section_text
section_bss: .ascii ".section .bss\n"
.equ SECTION_BSS_SIZE, . - section_bss
global_start: .ascii ".global _start\n"
.equ GLOBAL_START_SIZE, . - global_start
prologue: .ascii "addi sp, sp, -96\nsw ra, 92(sp)\nsw s0, 88(sp)\naddi s0, sp, 96\n"
.equ PROLOGUE_SIZE, . - prologue
epilogue: .ascii "lw ra, 92(sp)\nlw s0, 88(sp)\naddi sp, sp, 96\nret\n"
.equ EPILOGUE_SIZE, . - epilogue
.section .bss
.type source_code, @object
.size source_code, 20480
source_code: .zero 20480
.size source_code, SOURCE_BUFFER_SIZE
source_code: .zero SOURCE_BUFFER_SIZE
.section .text
# Ignores the import.
.type _compile_import, @function
_compile_import:
# Prologue.
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
addi s1, s1, 6
call _skip_spaces
call _read_token
add s1, s1, a0 # Skip the imported module name.
# Epilogue.
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
.type _build_binary_expression, @function
_build_binary_expression:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
li a0, 0
call _build_expression
call _skip_spaces
call _read_token
sw a0, 20(sp)
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, 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
/* DEBUG
mv a0, s1
li a1, 8
call _write_error */
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
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
call _write_out
j .Lbuild_binary_expression_end
.L_build_binary_expression_and:
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, 0x20646e61 # and_
sw t0, 4(sp)
addi a0, sp, 4
li a1, 15
call _write_out
j .Lbuild_binary_expression_end
.Lbuild_binary_expression_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Evalutes an expression and saves the result in a0.
#
# a0 - X in aX, the register number to save the result.
.type _build_expression, @function
_build_expression:
# Prologue.
@@ -20,63 +146,120 @@ _build_expression:
sw s0, 24(sp)
addi s0, sp, 32
addi a0, a0, '0' # Make the register number to a character.
sw a0, 20(sp) # And save it.
call _skip_spaces
call _read_token
sw s1, 20(sp)
sw a0, 16(sp)
sw s1, 16(sp)
sw a0, 12(sp)
# Integer literal.
addi a0, s1, 0
lb a0, (a0)
lbu a0, (a0)
call _is_digit
bnez a0, .Lbuild_expression_number_literal
bnez a0, .Lbuild_expression_literal
addi a0, s1, 0
lbu a0, (a0)
li t0, 0x5f # _
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.
li t0, 0x202c30 # 0,_
sw t0, 12(sp)
lw t1, 20(sp)
li t0, 0x00202c00 # \0,_
or t0, t0, t1
sw t0, 8(sp)
li t0, 0x6120616c # la a
sw t0, 8(sp)
addi a0, sp, 8
sw t0, 4(sp)
addi a0, sp, 4
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)
lw a1, 12(sp)
call _write_out
li t0, 0x0a # \n
sw t0, 8(sp)
addi a0, sp, 8
li a1, 1
call _write_out
j .Lbuild_expression_advance
.Lbuild_expression_identifier:
lw t1, 20(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
lw a0, 16(sp)
lw a1, 12(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, 8(sp)
li t0, 0x29707328 # (sp)
sw t0, 4(sp)
addi a0, sp, 4
li a1, 5
call _write_out
j .Lbuild_expression_advance
.Lbuild_expression_call:
lw a0, 16(sp)
lw a1, 12(sp)
add s1, s1, a1
addi s1, s1, 1
call _compile_call
j .Lbuild_expression_end
.Lbuild_expression_literal:
lw t1, 20(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
lw a0, 16(sp)
lw a1, 12(sp)
call _write_out
li t0, 0x0a # \n
sw t0, 8(sp)
addi a0, sp, 8
li a1, 1
call _write_out
j .Lbuild_expression_advance
.Lbuild_expression_advance:
lw a0, 12(sp)
add s1, s1, a0
.Lbuild_expression_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
@@ -120,11 +303,6 @@ _compile_identifier:
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 # (
@@ -140,7 +318,7 @@ _compile_identifier:
j .Lcompile_identifier_end
.Lcompile_identifier_assign:
call _build_expression
call _build_binary_expression
li t0, 0x202c30 # 0,_
sw t0, 12(sp)
@@ -198,6 +376,7 @@ _compile_call:
beq t0, t1, .Lcompile_call_complete
.Lcompile_call_argument:
li a0, 0
call _build_expression
li t0, 0x202c30 # 0,_
@@ -210,12 +389,12 @@ _compile_call:
lw t0, 12(sp) # Argument count for a procedure call.
# Only 8 arguments are supported with a0-a7.
# 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, 84
addi t1, t1, 60
li t2, 10
div t3, t1, t2
rem t4, t1, t2
@@ -258,10 +437,10 @@ _compile_call:
sw zero, 12(sp)
.Lcompile_call_restore:
# Just go through all a0-a7 registers and read them from stack.
# 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, 7
li t1, 5
bgt t0, t1, .Lcompile_call_perform
li t0, 0x6120776c # lw a
@@ -274,7 +453,7 @@ _compile_call:
li t1, -4
mul t1, t0, t1
addi t1, t1, 84
addi t1, t1, 60
li t2, 10
div t3, t1, t2
rem t4, t1, t2
@@ -367,7 +546,16 @@ _read_token:
li t1, ']'
beq t0, t1, .Ltoken_character_single
.Ltoken_character_loop_do: # Expect an identifier or a number.
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.
@@ -491,55 +679,33 @@ _compile_assembly:
.type _compile_program, @function
_compile_program:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
# .global _start
li t0, 0x0a7472 # rt\n
sw t0, 20(sp)
li t0, 0x6174735f # _sta
sw t0, 16(sp)
li t0, 0x206c6162 # bal_
sw t0, 12(sp)
li t0, 0x6f6c672e # .glo
sw t0, 8(sp)
addi a0, sp, 8
li a1, 15
la a0, global_start
li a1, GLOBAL_START_SIZE
call _write_out
addi s1, s1, 8 # program\n.
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
.type _compile_constant_section, @function
_compile_constant_section:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
# .section .rodata
li t0, 0x0a # \n
sw t0, 20(sp)
li t0, 0x61746164 # data
sw t0, 16(sp)
li t0, 0x6f722e20 # _.ro
sw t0, 12(sp)
li t0, 0x6e6f6974 # tion
sw t0, 8(sp)
li t0, 0x6365732e # .sec
sw t0, 4(sp)
addi a0, sp, 4
li a1, 17
la a0, section_rodata
li a1, SECTION_RODATA_SIZE
call _write_out
addi s1, s1, 6 # const\n.
@@ -555,9 +721,9 @@ _compile_constant_section:
.Lcompile_constant_section_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
.type _compile_constant, @function
@@ -611,23 +777,13 @@ _compile_constant:
.type _compile_variable_section, @function
_compile_variable_section:
# Prologue.
addi sp, sp, -24
sw ra, 20(sp)
sw s0, 16(sp)
addi s0, sp, 24
addi sp, sp, -8
sw ra, 4(sp)
sw s0, 0(sp)
addi s0, sp, 8
# .section .bss
li t0, 0x0a73 # s\n
sw t0, 12(sp)
li t0, 0x73622e20 # _.bs
sw t0, 8(sp)
li t0, 0x6e6f6974 # tion
sw t0, 4(sp)
li t0, 0x6365732e # .sec
sw t0, 0(sp)
addi a0, sp, 0
li a1, 14
la a0, section_bss
li a1, SECTION_BSS_SIZE
call _write_out
addi s1, s1, 4 # var\n.
@@ -643,9 +799,9 @@ _compile_variable_section:
.Lcompile_variable_section_end:
# Epilogue.
lw ra, 20(sp)
lw s0, 16(sp)
addi sp, sp, 24
lw ra, 4(sp)
lw s0, 0(sp)
addi sp, sp, 8
ret
.type _compile_variable, @function
@@ -836,63 +992,61 @@ _compile_procedure:
bnez a0, .Lcompile_procedure_begin
# Generate the procedure prologue with a predefined stack size.
li t0, 0x69646461 # addi
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
call _write_out
li t0, 0x2c707320 # _sp,
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
call _write_out
addi a0, sp, 12
li a1, 4
call _write_out
li t0, 0x0a36392d # -96\n
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
la a0, prologue
li a1, PROLOGUE_SIZE
call _write_out
# Save passed arguments on the stack.
li t0, 0x0a29 # )\n
sw t0, 12(sp)
li t0, 0x70732832 # 2(sp
sw t0, 8(sp)
li t0, 0x39202c61 # a, 9
sw t0, 4(sp)
li t0, 0x72207773 # sw r
sw t0, 0(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, 0x0a29 # )\n
sw t0, 12(sp)
li t0, 0x70732838 # 2(sp
li t0, 0x70732834 # 4(sp
sw t0, 8(sp)
li t0, 0x38202c30 # 0, 8
sw t0, 4(sp)
li t0, 0x73207773 # sw s
li t0, 0x61207773 # sw a
sw t0, 0(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, 0x0a363920 # _96\n
sw t0, 12(sp)
li t0, 0x2c707320 # _sp,
sw t0, 8(sp)
li t0, 0x2c307320 # _s0,
li t0, '0'
sb t0, 8(sp)
li t0, 0x38202c31 # 1, 8
sw t0, 4(sp)
li t0, 0x69646461 # addi
sw t0, 0(sp)
addi a0, sp, 0
li a1, 16
li a1, 14
call _write_out
li t0, '6'
sb t0, 8(sp)
li t0, 0x37202c32 # 2, 7
sw t0, 4(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, '2'
sb t0, 8(sp)
li t0, 0x37202c33 # 3, 7
sw t0, 4(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, '8'
sb t0, 8(sp)
li t0, 0x36202c34 # 4, 6
sw t0, 4(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, '4'
sb t0, 8(sp)
li t0, 0x36202c35 # 5, 6
sw t0, 4(sp)
addi a0, sp, 0
li a1, 14
call _write_out
# Generate the body of the procedure.
@@ -917,57 +1071,8 @@ _compile_procedure:
add s1, s1, 4 # Skip end\n.
# Generate the procedure epilogue with a predefined stack size.
li t0, 0x0a29 # )\n
sw t0, 12(sp)
li t0, 0x70732832 # 2(sp
sw t0, 8(sp)
li t0, 0x39202c61 # a, 9
sw t0, 4(sp)
li t0, 0x7220776c # lw r
sw t0, 0(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, 0x0a29 # )\n
sw t0, 12(sp)
li t0, 0x70732838 # 2(sp
sw t0, 8(sp)
li t0, 0x38202c30 # 0, 8
sw t0, 4(sp)
li t0, 0x7320776c # lw s
sw t0, 0(sp)
addi a0, sp, 0
li a1, 14
call _write_out
li t0, 0x69646461 # addi
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
call _write_out
li t0, 0x2c707320 # _sp,
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
call _write_out
addi a0, sp, 12
li a1, 4
call _write_out
li t0, 0x0a3639 # 96\n
sw t0, 12(sp)
addi a0, sp, 12
li a1, 3
call _write_out
li t0, 0x0a746572 # ret\n
sw t0, 12(sp)
addi a0, sp, 12
li a1, 4
la a0, epilogue
li a1, EPILOGUE_SIZE
call _write_out
# Epilogue.
@@ -1018,8 +1123,100 @@ _token_compare:
.Ltoken_compare_end:
ret
.type _compile_goto, @function
_compile_goto:
# Prologue.
addi sp, sp, -16
sw ra, 12(sp)
sw s0, 8(sp)
addi s0, sp, 16
addi s1, s1, 4 # Skip the goto keyword.
li t0, 0x206a # j_
sw t0, 8(sp)
addi a0, sp, 8
li a1, 2
call _write_out
call _skip_spaces
sw s1, 8(sp) # We should be on dot the label is beginning with.
addi s1, s1, 1
call _read_token
add s1, s1, a0
addi a1, a0, 1 # Label length and the dot.
lw a0, 8(sp) # Saved dot position.
call _write_out
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
# Epilogue.
lw ra, 12(sp)
lw s0, 8(sp)
addi sp, sp, 16
ret
# a0 - Line length.
.type _compile_label, @function
_compile_label:
# Prologue.
addi sp, sp, -16
sw ra, 12(sp)
sw s0, 8(sp)
addi s0, sp, 16
sw a0, 0(sp) # Save the line length.
# Write the whole line as is.
mv a0, s1
lw a1, 0(sp)
call _write_out
lw t0, 0(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
li t0, 0x3a # :
sw t0, 4(sp)
addi a0, sp, 4
li a1, 1
call _write_out
.Lcompile_label_colon:
li t0, 0x0a # \n
sw t0, 4(sp)
addi a0, sp, 4
li a1, 1
call _write_out
lw a0, 0(sp)
addi a0, a0, 1 # Skip the new line as well.
add s1, s1, a0 # Skip the line.
# 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
# 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.
.type _compile_line, @function
@@ -1030,7 +1227,9 @@ _compile_line:
sw s0, 24(sp)
addi s0, sp, 32
sw a0, 20(sp) # a0 - Line length.
# Preserve passed arguments.
sw a0, 20(sp)
sw a1, 16(sp)
beqz a0, .Lcompile_line_empty # Skip an empty line.
@@ -1039,75 +1238,108 @@ _compile_line:
beq t0, t1, .Lcompile_line_comment
li t0, 0x0a6d6172 # ram\n
sw t0, 16(sp)
li t0, 0x676f7270 # prog
sw t0, 12(sp)
li t0, 0x676f7270 # prog
sw t0, 8(sp)
mv a0, s1
addi a1, sp, 12
addi a1, sp, 8
li a2, 8
call _memcmp
beqz a0, .Lcompile_line_program
li t0, 0x0a74 # t\n
sw t0, 16(sp)
li t0, 0x736e6f63 # cons
sw t0, 12(sp)
li t0, 0x736e6f63 # cons
sw t0, 8(sp)
mv a0, s1
addi a1, sp, 12
addi a1, sp, 8
li a2, 6
call _memcmp
beqz a0, .Lcompile_line_const
li t0, 0x0a726176 # var\n
sw t0, 16(sp)
sw t0, 12(sp)
mv a0, s1
addi a1, sp, 16
addi a1, sp, 12
li a2, 4
call _memcmp
beqz a0, .Lcompile_line_var
li t0, 0x20 # _
sw t0, 16(sp)
li t0, 0x636f7270 # proc
sw t0, 12(sp)
li t0, 0x636f7270 # proc
sw t0, 8(sp)
mv a0, s1
addi a1, sp, 12
addi a1, sp, 8
li a2, 5
call _memcmp
beqz a0, .Lcompile_line_procedure
li t0, 0x0a6e # n\n
sw t0, 16(sp)
li t0, 0x69676562 # begi
sw t0, 12(sp)
li t0, 0x69676562 # begi
sw t0, 8(sp)
mv a0, s1
addi a1, sp, 12
addi a1, sp, 8
li a2, 6
call _memcmp
beqz a0, .Lcompile_line_begin
li t0, 0x2e646e65 # end.
sw t0, 16(sp)
sw t0, 12(sp)
mv a0, s1
addi a1, sp, 16
addi a1, sp, 12
li a2, 4
call _memcmp
beqz a0, .Lcompile_line_exit
li t0, 0x61636f6c # loca
sw t0, 16(sp)
sw t0, 12(sp)
mv a0, s1
addi a1, sp, 16
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
lbu t0, (s1)
li t1, '.'
beq t0, t1, .Lcompile_line_label
li t1, '_'
beq t0, t1, .Lcompile_line_identifier
j .Lcompile_line_unchanged # Else.
.Lcompile_line_label:
lw a0, 20(sp)
call _compile_label
j .Lcompile_line_section
.Lcompile_line_goto:
call _compile_goto
j .Lcompile_line_section
.Lcompile_line_import:
call _compile_import
j .Lcompile_line_section
.Lcompile_line_identifier:
call _compile_identifier
j .Lcompile_line_section
@@ -1117,6 +1349,10 @@ _compile_line:
j .Lcompile_line_section
.Lcompile_line_begin:
lw a1, 16(sp)
bnez a1, .Lcompile_line_compile_entry
call _compile_text_section
.Lcompile_line_compile_entry:
call _compile_entry_point
li a0, 1
j .Lcompile_line_end
@@ -1126,6 +1362,10 @@ _compile_line:
j .Lcompile_line_section
.Lcompile_line_procedure:
lw a1, 16(sp)
bnez a1, .Lcompile_line_compile_procedure
call _compile_text_section
.Lcompile_line_compile_procedure:
call _compile_procedure
li a0, 1
j .Lcompile_line_end
@@ -1162,6 +1402,7 @@ _compile_line:
addi sp, sp, 32
ret
# Prints ".section .text" and exits.
.type _compile_text_section, @function
_compile_text_section:
# Prologue.
@@ -1170,18 +1411,8 @@ _compile_text_section:
sw s0, 16(sp)
addi s0, sp, 24
# .section .text
li t0, 0x0a7478 # xt\n
sw t0, 12(sp)
li t0, 0x65742e20 # _.te
sw t0, 8(sp)
li t0, 0x6e6f6974 # tion
sw t0, 4(sp)
li t0, 0x6365732e # .sec
sw t0, 0(sp)
addi a0, sp, 0
li a1, 15
la a0, section_text
li a1, SECTION_TEXT_SIZE
call _write_out
# Epilogue.
@@ -1291,14 +1522,23 @@ _compile:
sw s0, 8(sp)
addi s0, sp, 16
sw zero, 4(sp) # 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.
call _skip_indentation
call _read_line
lw a1, 4(sp)
call _compile_line
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)
j .Lcompile_do
.Lcompile_end:
@@ -1313,8 +1553,7 @@ _compile:
_start:
# Read the source from the standard input.
la a0, source_code
la a1, SOURCE_BUFFER_SIZE # Buffer size.
lw a1, (a1)
li a1, SOURCE_BUFFER_SIZE # Buffer size.
call _read_file
la s1, source_code # s1 = Source code position.

693
boot/stage2.elna
View File

File diff suppressed because it is too large Load Diff

46
run.rb
View File

@@ -1,46 +0,0 @@
#!/usr/bin/env ruby
require 'open3'
require 'fileutils'
require 'pathname'
TMP = Pathname.new 'build'
CROSS_GCC = '../riscv32-ilp32d--glibc/bin/riscv32-linux-gcc'
SYSROOT = '../riscv32-ilp32d--glibc/riscv32-buildroot-linux-gnu/sysroot'
COMMON_BOOT_OBJECT = TMP + 'common-boot.o'
FileUtils.rm_rf TMP
FileUtils.mkdir_p TMP
FileUtils.cp 'boot/asm-boot.s', TMP
def stage(source_elna, stage_name, output)
boot_exe = (TMP + stage_name).to_path
stage_path = TMP + "#{stage_name}.s"
arguments = [CROSS_GCC, '-nostdlib', '-o', boot_exe, stage_path.to_path, COMMON_BOOT_OBJECT.to_path]
puts(arguments * ' ')
system *arguments, exception: true
arguments = ['qemu-riscv32', '-L', SYSROOT, boot_exe]
puts(arguments * ' ')
puts
Open3.popen2(*arguments) do |qemu_in, qemu_out|
qemu_in.write source_elna
qemu_in.close
IO.copy_stream qemu_out, output
qemu_out.close
end
end
system CROSS_GCC, '-nostdlib', '-c', '-o', COMMON_BOOT_OBJECT.to_path, 'boot/common-boot.s', exception: true
source_elna = File.read 'boot/goto-boot.elna'
next_stage = TMP + 'goto-boot.s'
File.open next_stage, 'w' do |output|
stage source_elna, 'asm-boot', output
end
stage(source_elna, 'goto-boot', $stdout)