186 lines
4.0 KiB
ArmAsm
186 lines
4.0 KiB
ArmAsm
;; Copyright (C) 2017 Jeremiah Orians
|
|
;; This file is part of stage0.
|
|
;;
|
|
;; stage0 is free software: you can redistribute it and/or modify
|
|
;; it under the terms of the GNU General Public License as published by
|
|
;; the Free Software Foundation, either version 3 of the License, or
|
|
;; (at your option) any later version.
|
|
;;
|
|
;; stage0 is distributed in the hope that it will be useful,
|
|
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
;; GNU General Public License for more details.
|
|
;;
|
|
;; You should have received a copy of the GNU General Public License
|
|
;; along with stage0. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
section .text
|
|
global _start
|
|
|
|
; Where the ELF Header is going to hit
|
|
; Simply jump to _start
|
|
; Our main function
|
|
_start:
|
|
pop rax ;·Get·the·number·of·arguments
|
|
pop rdi ;·Get·the·program·name
|
|
pop rdi ;·Get·the·actual·input name
|
|
mov rsi, 0 ;·prepare·read_only
|
|
mov rax, 2 ;·the·syscall·number·for·open()
|
|
syscall ; Now open that damn file
|
|
mov r9, rax ; Preserve the file pointer we were given
|
|
|
|
pop rdi ;·Get·the·actual·output name
|
|
mov rsi, 577 ; Prepare file as O_WRONLY|O_CREAT|O_TRUNC
|
|
mov rdx, 448 ; Prepare file as RWX for owner only (700 in octal)
|
|
mov rax, 2 ;·the·syscall·number·for·open()
|
|
syscall ; Now open that damn file
|
|
mov r10, rax ; Preserve the file pointer we were given
|
|
|
|
; Our flag for byte processing
|
|
mov r15, -1
|
|
|
|
; temp storage for the sum
|
|
mov r14, 0
|
|
|
|
loop:
|
|
; Read a byte
|
|
call Read_byte
|
|
|
|
; process byte
|
|
call hex
|
|
|
|
; Deal with -1 values
|
|
cmp rax, 0
|
|
jl loop
|
|
|
|
; deal with toggle
|
|
cmp r15, 0
|
|
jge print
|
|
|
|
; process first byte of pair
|
|
mov r14, rax
|
|
mov r15, 0
|
|
jmp loop
|
|
|
|
; process second byte of pair
|
|
print:
|
|
; update the sum and store in output
|
|
shl r14, 4
|
|
add rax, r14
|
|
mov [output], al
|
|
|
|
; flip the toggle
|
|
mov r15, -1
|
|
|
|
call write_byte
|
|
|
|
jmp loop
|
|
|
|
hex:
|
|
; Purge Comment Lines (#)
|
|
cmp rax, 35
|
|
je purge_comment
|
|
|
|
; Purge Comment Lines (;)
|
|
cmp rax, 59
|
|
je purge_comment
|
|
|
|
; deal all ascii less than 0
|
|
cmp rax, 48
|
|
jl ascii_other
|
|
|
|
; deal with 0-9
|
|
cmp rax, 58
|
|
jl ascii_num
|
|
|
|
; deal with all ascii less than A
|
|
cmp rax, 65
|
|
jl ascii_other
|
|
|
|
; deal with A-F
|
|
cmp rax, 71
|
|
jl ascii_high
|
|
|
|
;deal with all ascii less than a
|
|
cmp rax, 97
|
|
jl ascii_other
|
|
|
|
;deal with a-f
|
|
cmp rax, 103
|
|
jl ascii_low
|
|
|
|
; The rest that remains needs to be ignored
|
|
jmp ascii_other
|
|
|
|
purge_comment:
|
|
; Read a byte
|
|
call Read_byte
|
|
|
|
; Loop if not LF
|
|
cmp rax, 10
|
|
jne purge_comment
|
|
|
|
; Otherwise return -1
|
|
mov rax, -1
|
|
ret
|
|
|
|
ascii_num:
|
|
sub rax, 48
|
|
ret
|
|
|
|
ascii_low:
|
|
sub rax, 87
|
|
ret
|
|
|
|
ascii_high:
|
|
sub rax, 55
|
|
ret
|
|
|
|
ascii_other:
|
|
mov rax, -1
|
|
ret
|
|
|
|
Done:
|
|
; program completed Successfully
|
|
mov rdi, 0 ; All is well
|
|
mov rax, 60 ; put the exit syscall number in eax
|
|
syscall ; Call it a good day
|
|
|
|
write_byte:
|
|
; Print our Hex
|
|
mov rdx, 1 ; set the size of chars we want
|
|
mov rsi, output ; What we are writing
|
|
mov rdi, r10 ; Where are we writing to
|
|
mov rax, 1 ; the syscall number for write
|
|
syscall ; call the Kernel
|
|
ret
|
|
|
|
Read_byte:
|
|
; Attempt to read 1 byte from STDIN
|
|
mov rdx, 1 ; set the size of chars we want
|
|
mov rsi, input ; Where to put it
|
|
mov rdi, r9 ; Where are we reading from
|
|
mov rax, 0 ; the syscall number for read
|
|
syscall ; call the Kernel
|
|
|
|
test rax, rax ; check what we got
|
|
je Done ; Got EOF call it done
|
|
|
|
; load byte
|
|
mov al, [input] ; load char
|
|
movzx rax, al ; We have to zero extend it to use it
|
|
ret
|
|
|
|
|
|
section .data
|
|
ELF_end:
|
|
; Where we are putting our output
|
|
output:
|
|
; Reserve 4bytes of Zeros
|
|
dq 0
|
|
|
|
; Where we get our input
|
|
input:
|
|
; Reserve 4bytes of Zeros
|
|
dq 0
|