Files
elna/boot/stage1.s
2025-08-30 01:29:00 +02:00

1065 lines
17 KiB
ArmAsm

# This Source Code Form is subject to the terms of the Mozilla Public License,
# v. 2.0. If a copy of the MPL was not distributed with this file, You can
# obtain one at https://mozilla.org/MPL/2.0/.
.equ SOURCE_BUFFER_SIZE, 81920
.equ SYS_READ, 63
.equ SYS_WRITE, 64
.equ SYS_EXIT, 93
.equ SYS_MMAP2, 222
.equ STDIN, 0
.equ STDOUT, 1
.equ STDERR, 2
.section .rodata
.type keyword_equ, @object
keyword_equ: .ascii ".equ"
.equ KEYWORD_EQU_SIZE, 4
.type keyword_section, @object
keyword_section: .ascii ".section"
.equ KEYWORD_SECTION_SIZE, 8
.type keyword_type, @object
keyword_type: .ascii ".type"
.equ KEYWORD_TYPE_SIZE, 5
.type keyword_type_object, @object
keyword_type_object: .ascii "object"
.equ KEYWORD_TYPE_OBJECT_SIZE, 6
.type keyword_type_function, @object
keyword_type_function: .ascii "function"
.equ KEYWORD_TYPE_FUNCTION_SIZE, 8
.type keyword_ret, @object
keyword_ret: .ascii "ret"
.equ KEYWORD_RET_SIZE, 3
.type keyword_global, @object
keyword_global: .ascii ".globl"
.equ KEYWORD_GLOBAL_SIZE, 6
.type keyword_proc, @object
keyword_proc: .ascii "proc "
.equ KEYWORD_PROC_SIZE, 5
.type keyword_end, @object
keyword_end: .ascii "end"
.equ KEYWORD_END_SIZE, 3
.type keyword_begin, @object
keyword_begin: .ascii "begin"
.equ KEYWORD_BEGIN_SIZE, 5
.type keyword_var, @object
keyword_var: .ascii "var"
.equ KEYWORD_VAR_SIZE, 3
.type asm_prologue, @object
asm_prologue: .string "\taddi sp, sp, -32\n\tsw ra, 28(sp)\n\tsw s0, 24(sp)\n\taddi s0, sp, 32\n"
.type asm_epilogue, @object
asm_epilogue: .string "\tlw ra, 28(sp)\n\tlw s0, 24(sp)\n\taddi sp, sp, 32\n\tret\n"
.type asm_type_directive, @object
asm_type_directive: .string ".type "
.type asm_type_function, @object
asm_type_function: .string ", @function\n"
.type asm_colon, @object
asm_colon: .string ":\n"
.type asm_call, @object
asm_call: .string "\tcall "
.section .bss
.type source_code, @object
source_code: .zero SOURCE_BUFFER_SIZE
.type source_code_position, @object
source_code_position: .word 0
.section .text
# Reads standard input into a buffer.
# a0 - Buffer pointer.
# a1 - Buffer size.
#
# Returns the amount of bytes written in a0.
.type _read_file, @function
_read_file:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
mv a2, a1
mv a1, a0
li a0, STDIN
li a7, SYS_READ
ecall
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Writes a character from a0 into the standard output.
.type _write_c, @function
_write_c:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
sb a0, 20(sp)
li a0, STDOUT
addi a1, sp, 20
li a2, 1
li a7, SYS_WRITE
ecall
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
add sp, sp, 32
ret
# Write null terminated string.
#
# Parameters:
# a0 - String.
.type _write_z, @function
_write_z:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
sw a0, 20(sp)
.write_z_loop:
# Check for 0 character.
lb a0, (a0)
beqz a0, .write_z_end
# Print a character.
li a0, STDOUT
lw a1, 20(sp)
li a2, 1
li a7, SYS_WRITE
ecall
# Advance the input string by one byte.
lw a0, 20(sp)
addi a0, a0, 1
sw a0, 20(sp)
j .write_z_loop
.write_z_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Detects if a0 is an uppercase character. Sets a0 to 1 if so, otherwise to 0.
.type _is_upper, @function
_is_upper:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
li t0, 'A' - 1
sltu t1, t0, a0 # t1 = a0 >= 'A'
sltiu t2, a0, 'Z' + 1 # t2 = a0 <= 'Z'
and a0, t1, t2 # t1 = a0 >= 'A' & a0 <= 'Z'
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Detects if a0 is an lowercase character. Sets a0 to 1 if so, otherwise to 0.
.type _is_lower, @function
_is_lower:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
li t0, 'a' - 1
sltu t2, t0, a0 # t2 = a0 >= 'a'
sltiu t3, a0, 'z' + 1 # t3 = a0 <= 'z'
and a0, t2, t3 # t2 = a0 >= 'a' & a0 <= 'z'
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Detects if the passed character is a 7-bit alpha character or an underscore.
#
# Paramters:
# a0 - Tested character.
#
# Sets a0 to 1 if the character is an alpha character or underscore, sets it to 0 otherwise.
.type _is_alpha, @function
_is_alpha:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
sw a0, 20(sp)
call _is_upper
sw a0, 16(sp)
lw a0, 20(sp)
call _is_lower
lw t0, 20(sp)
xori t1, t0, '_'
seqz t1, t1
lw t0, 16(sp)
or a0, a0, t0
or a0, a0, t1
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Detects whether the passed character is a digit
# (a value between 0 and 9).
#
# Parameters:
# a0 - Exemined value.
#
# Sets a0 to 1 if it is a digit, to 0 otherwise.
.type _is_digit, @function
_is_digit:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
li t0, '0' - 1
sltu t1, t0, a0 # t1 = a0 >= '0'
sltiu t2, a0, '9' + 1 # t2 = a0 <= '9'
and a0, t1, t2
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Reads the next token.
#
# Returns token length in a0.
.type _read_token, @function
_read_token:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
la t0, source_code_position # Token pointer.
lw t0, (t0)
sw t0, 20(sp) # Current token position.
sw zero, 16(sp) # Token length.
.read_token_loop:
lb t0, (t0) # Current character.
# First we try to read a derictive.
# A derictive can contain a dot and characters.
li t1, '.'
beq t0, t1, .read_token_next
lw a0, 20(sp)
lb a0, (a0)
call _is_alpha
bnez a0, .read_token_next
lw a0, 20(sp)
lb a0, (a0)
call _is_digit
bnez a0, .read_token_next
j .read_token_end
.read_token_next:
# Advance the source code position and token length.
lw t0, 16(sp)
addi t0, t0, 1
sw t0, 16(sp)
lw t0, 20(sp)
addi t0, t0, 1
sw t0, 20(sp)
j .read_token_loop
.read_token_end:
lw a0, 16(sp)
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# a0 - First pointer.
# a1 - Second pointer.
# a2 - The length to compare.
#
# Returns 0 in a0 if memory regions are equal.
.type _memcmp, @function
_memcmp:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
mv t0, a0
li a0, 0
.Lmemcmp_loop:
beqz a2, .Lmemcmp_end
lbu t1, (t0)
lbu t2, (a1)
sub a0, t1, t2
bnez a0, .Lmemcmp_end
addi t0, t0, 1
addi a1, a1, 1
addi a2, a2, -1
j .Lmemcmp_loop
.Lmemcmp_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Advances the token stream by a0 bytes.
.type _advance_token, @function
_advance_token:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Skip the .equ directive.
la t0, source_code_position
lw t1, (t0)
add t1, t1, a0
sw t1, (t0)
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_section, @function
_compile_section:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Print the .section directive and a space after it.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
li a2, KEYWORD_SECTION_SIZE + 1
li a7, SYS_WRITE
ecall
# Skip the .equ directive.
li a0, KEYWORD_SECTION_SIZE + 1
call _advance_token
# Read the section name.
call _read_token
sw a0, 16(sp)
# Print the section name and newline.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 16(sp)
addi a2, a2, 1
li a7, SYS_WRITE
ecall
# Skip the section name.
lw a0, 16(sp)
addi a0, a0, 1
call _advance_token
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Prints and skips a line.
.type _skip_comment, @function
_skip_comment:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
la t0, source_code_position
lw t1, (t0)
.skip_comment_loop:
# Check for newline character.
lb t2, (t1)
li t3, '\n'
beq t2, t3, .skip_comment_end
# Advance the input string by one byte.
addi t1, t1, 1
sw t1, (t0)
j .skip_comment_loop
.skip_comment_end:
# Skip the newline.
addi t1, t1, 1
sw t1, (t0)
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Prints and skips a line.
.type _compile_line, @function
_compile_line:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
la a0, source_code_position
lw a1, (a0)
.compile_line_loop:
# Check for newline character.
lb t0, (a1)
li t1, '\n'
beq t0, t1, .compile_line_end
# Print a character.
li a0, STDOUT
li a2, 1
li a7, SYS_WRITE
ecall
# Advance the input string by one byte.
la a0, source_code_position
lw a1, (a0)
addi a1, a1, 1
sw a1, (a0)
j .compile_line_loop
.compile_line_end:
# Print and skip the newline.
li a0, STDOUT
li a2, 1
li a7, SYS_WRITE
ecall
la a0, source_code_position
lw a1, (a0)
addi a1, a1, 1
sw a1, (a0)
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_object, @function
_compile_object:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
call _compile_line
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_function_statements, @function
_compile_function_statements:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
.compile_function_statements_loop:
la t0, source_code_position
lw t1, (t0)
addi t1, t1, 1 # Skip the tab.
mv a0, t1
la a1, keyword_ret
li a2, KEYWORD_RET_SIZE
call _memcmp
beqz a0, .compile_function_statements_end
call _compile_line
j .compile_function_statements_loop
.compile_function_statements_end:
call _compile_line
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_call, @function
_compile_call:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
call _read_token
sw a0, 20(sp)
la a0, asm_call
call _write_z
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 20(sp)
li a7, SYS_WRITE
ecall
# Skip parens, semicolon and newline.
lw a0, 20(sp)
addi a0, a0, 4
call _advance_token
li a0, '\n'
call _write_c
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_statement, @function
_compile_statement:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# This is a call if the statement starts with an underscore.
la t0, source_code_position
lw t0, (t0)
# First character after alignment tab.
addi t0, t0, 1
lb t0, (t0)
li t1, '_'
beq t0, t1, .compile_statement_call
call _compile_line
j .compile_statement_end
.compile_statement_call:
li a0, 1
call _advance_token
call _compile_call
j .compile_statement_end
.compile_statement_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_procedure_body, @function
_compile_procedure_body:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
.compile_procedure_body_loop:
la a0, source_code_position
lw a0, (a0)
la a1, keyword_end
li a2, KEYWORD_END_SIZE
call _memcmp
beqz a0, .compile_procedure_body_epilogue
call _compile_statement
j .compile_procedure_body_loop
.compile_procedure_body_epilogue:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_procedure, @function
_compile_procedure:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Skip "proc ".
li a0, KEYWORD_PROC_SIZE
call _advance_token
call _read_token
sw a0, 20(sp) # Save the procedure name length.
# Write .type _procedure_name, @function.
la a0, asm_type_directive
call _write_z
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 20(sp)
li a7, SYS_WRITE
ecall
la a0, asm_type_function
call _write_z
# Write procedure label, _procedure_name:
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 20(sp)
li a7, SYS_WRITE
ecall
la a0, asm_colon
call _write_z
# Skip the function name and trailing parens, semicolon, "begin" and newline.
lw a0, 20(sp)
addi a0, a0, KEYWORD_BEGIN_SIZE + 1 + 4
call _advance_token
la a0, asm_prologue
call _write_z
call _compile_procedure_body
# Write the epilogue.
la a0, asm_epilogue
call _write_z
li a0, KEYWORD_END_SIZE + 2
call _advance_token
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_function, @function
_compile_function:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Write the function header.
call _compile_line
call _compile_function_statements
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_type, @function
_compile_type:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Print the .type directive and a space after it.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
li a2, KEYWORD_TYPE_SIZE + 1
li a7, SYS_WRITE
ecall
# Skip the .type directive.
li a0, KEYWORD_TYPE_SIZE + 1
call _advance_token
# Read and print the symbol name.
call _read_token
sw a0, 20(sp)
# Print the symbol name, comma, space and @.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 20(sp)
addi a2, a2, 3
li a7, SYS_WRITE
ecall
# Skip the constant name, comma, space and @.
lw a0, 20(sp)
addi a0, a0, 3
call _advance_token
# Read the symbol type.
call _read_token
sw a0, 16(sp)
la t0, source_code_position
lw t0, (t0)
sw t0, 12(sp)
# Print the symbol type and newline.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 16(sp)
addi a2, a2, 1
li a7, SYS_WRITE
ecall
lw a0, 16(sp)
addi a0, a0, 1
call _advance_token
lw a0, 12(sp)
la a1, keyword_type_object
li a2, KEYWORD_TYPE_OBJECT_SIZE
call _memcmp
beqz a0, .compile_type_object
lw a0, 12(sp)
la a1, keyword_type_function
li a2, KEYWORD_TYPE_FUNCTION_SIZE
call _memcmp
beqz a0, .compile_type_function
j .compile_type_end
.compile_type_object:
call _compile_object
j .compile_type_end
.compile_type_function:
call _compile_function
j .compile_type_end
.compile_type_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _compile_equ, @function
_compile_equ:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Print the .equ directive and a space after it.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
li a2, KEYWORD_EQU_SIZE + 1
li a7, SYS_WRITE
ecall
# Skip the .equ directive.
li a0, KEYWORD_EQU_SIZE + 1
call _advance_token
# Read and print the constant name.
call _read_token
sw a0, 20(sp)
# Print the constant name, comma and space.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 20(sp)
addi a2, a2, 2
li a7, SYS_WRITE
ecall
# Skip the constant name, comma and the space after it.
lw a0, 20(sp)
addi a0, a0, 2
call _advance_token
# Read the constant value.
call _read_token
sw a0, 16(sp)
# Print the constant value and newline.
li a0, STDOUT
la a1, source_code_position
lw a1, (a1)
lw a2, 16(sp)
addi a2, a2, 1
li a7, SYS_WRITE
ecall
lw a2, 16(sp)
addi a2, a2, 1
call _advance_token
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
.type _skip_newlines, @function
_skip_newlines:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Skip newlines.
la t0, source_code_position
lw t1, (t0)
.skip_newlines_loop:
lb t2, (t1)
li t3, '\n'
bne t2, t3, .skip_newlines_end
beqz t2, .skip_newlines_end
addi t1, t1, 1
sw t1, (t0)
j .skip_newlines_loop
.skip_newlines_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Process the source code and print the generated code.
.type _compile, @function
_compile:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
.compile_loop:
call _skip_newlines
la t0, source_code_position
lw t0, (t0)
lb t0, (t0)
beqz t0, .compile_end
li t1, '#'
beq t0, t1, .compile_comment
la a0, source_code_position
lw a0, (a0)
la a1, keyword_equ
li a2, KEYWORD_EQU_SIZE
call _memcmp
beqz a0, .compile_equ
la a0, source_code_position
lw a0, (a0)
la a1, keyword_section
li a2, KEYWORD_SECTION_SIZE
call _memcmp
beqz a0, .compile_section
la a0, source_code_position
lw a0, (a0)
la a1, keyword_type
li a2, KEYWORD_TYPE_SIZE
call _memcmp
beqz a0, .compile_type
la a0, source_code_position
lw a0, (a0)
la a1, keyword_proc
li a2, KEYWORD_PROC_SIZE
call _memcmp
beqz a0, .compile_procedure
la a0, source_code_position
lw a0, (a0)
la a1, keyword_global
li a2, KEYWORD_GLOBAL_SIZE
call _memcmp
beqz a0, .compile_global
j .compile_end # Not a known token, exit.
.compile_equ:
call _compile_equ
j .compile_loop
.compile_section:
call _compile_section
j .compile_loop
.compile_type:
call _compile_type
j .compile_loop
.compile_global:
call _compile_line
j .compile_loop
.compile_comment:
call _skip_comment
j .compile_loop
.compile_procedure:
call _compile_procedure
j .compile_loop
.compile_end:
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret
# Entry point.
.globl _start
.type _start, @function
_start:
# Prologue.
addi sp, sp, -32
sw ra, 28(sp)
sw s0, 24(sp)
addi s0, sp, 32
# Read the source from the standard input.
la a0, source_code
li a1, SOURCE_BUFFER_SIZE # Buffer size.
call _read_file
# Save the pointer to the beginning of the source code in a global variable.
la t0, source_code
la t1, source_code_position
sw t0, (t1)
call _compile
# Call exit.
li a0, 0 # Use 0 return code.
li a7, SYS_EXIT
ecall
# Epilogue.
lw ra, 28(sp)
lw s0, 24(sp)
addi sp, sp, 32
ret