Initial commit
This commit is contained in:
parent
a8bf8841c2
commit
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GPG Key ID:
5FD0394ADBD72730
435
cat.s
435
cat.s
@ -1,8 +1,13 @@
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;; -*- mode: nasm -*-
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;; Select the one that matches your os
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%include "linux.s"
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;%include "freebsd.s"
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%define SYS_open 0x2
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%define SYS_close 0x3
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%define SYS_write 0x1
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%define SYS_read 0x0
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%define SYS_lseek 0x8
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%define SYS_exit 0x3c
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%define O_RDONLY 0x0
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%define SEEK_SET 0x0
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%define FD_stderr 2
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%define FD_stdout 1
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%define FD_stdin 0
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@ -12,290 +17,290 @@
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section .text
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global _start
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_start:
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pop rax ; argc
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pop QWORD [exec_name] ; argv[0]
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pop rax ; argc
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pop QWORD [exec_name] ; argv[0]
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check_arg_loop:
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mov rdi,[rsp] ; argv[i]
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; check for null
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cmp rdi,0
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je print_stdin_and_exit
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mov rdi,[rsp] ; argv[i]
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; check for null
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cmp rdi,0
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je print_stdin_and_exit
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; check for flags
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call check_flag
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cmp rax,0
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je print_files ; no more flags
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; check for flags
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call check_flag
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cmp rax,0
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je print_files ; no more flags
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pop rdi ; remove argv[i] (a flag)
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jmp check_arg_loop
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pop rdi ; remove argv[i] (a flag)
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jmp check_arg_loop
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print_files:
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mov rdi,[rsp] ; argv[i]
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cmp rdi,0
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je print_files_end
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mov rdi,[rsp] ; argv[i]
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cmp rdi,0
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je print_files_end
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; check if argv[i] is '-'
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mov rsi,dash_str
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call streql
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cmp rax,0
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jne print_files_stdin
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; check if argv[i] is '-'
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mov rsi,dash_str
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call streql
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cmp rax,0
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jne print_files_stdin
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; open file
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mov rdi,[rsp] ; argv[i]
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call open_file
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; open file
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mov rdi,[rsp] ; argv[i]
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call open_file
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; print file
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mov rdi,rax
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pop rsi ; argv[i]
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call print_file
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; print file
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mov rdi,rax
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pop rsi ; argv[i]
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call print_file
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jmp print_files
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jmp print_files
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print_files_stdin:
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pop rdi ; argv[i]
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mov rdi,FD_stdin
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mov rsi,stdin_name
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call print_file
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pop rdi ; argv[i]
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mov rdi,FD_stdin
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mov rsi,stdin_name
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call print_file
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; rewind stdin
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; rewind stdin
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mov rax,SYS_lseek
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mov rdi,FD_stdin
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mov rsi,0
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mov rdx,SEEK_SET
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syscall
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mov rdi,FD_stdin
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mov rsi,0
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mov rdx,SEEK_SET
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syscall
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jmp print_files
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jmp print_files
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print_files_end:
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xor rdi,rdi
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jmp exit
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xor rdi,rdi
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jmp exit
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open_file: ; int open_file(const char *path)
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push rdi ; path
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open_file: ; int open_file(const char *path)
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push rdi ; path
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; open file
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mov rax,SYS_open
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; rdi already set
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mov rsi,O_RDONLY
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syscall
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; open file
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mov rax,SYS_open
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; rdi already set
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mov rsi,O_RDONLY
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syscall
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; check return
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cmp rax,0
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jl open_error
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; check return
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cmp rax,0
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jl open_error
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pop rdi ; path
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ret
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pop rdi ; path
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ret
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open_error:
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call start_error
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call start_error
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,open_error_text
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mov rdx,open_error_text_len
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syscall
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,open_error_text
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mov rdx,open_error_text_len
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syscall
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; detail
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mov rdi,[rsp] ; path
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call strlen
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; detail
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mov rdi,[rsp] ; path
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call strlen
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; path
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syscall
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; path
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syscall
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call end_error
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call end_error
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mov rdi,1
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jmp exit
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mov rdi,1
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jmp exit
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print_stdin_and_exit:
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mov rdi,FD_stdin
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mov rsi,stdin_name
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call print_file
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xor rdi,rdi
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jmp exit
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mov rdi,FD_stdin
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mov rsi,stdin_name
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call print_file
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xor rdi,rdi
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jmp exit
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print_file: ; void print_file(int fd, const char *name)
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push rdi ; fd
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push rsi ; name
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print_file: ; void print_file(int fd, const char *name)
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push rdi ; fd
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push rsi ; name
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print_file_loop:
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mov rax,SYS_read
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mov rdi,[rsp + 8] ; fd
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mov rsi,read_buff
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mov rdx,BUFFER_SIZE
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syscall
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mov rax,SYS_read
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mov rdi,[rsp + 8] ; fd
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mov rsi,read_buff
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mov rdx,BUFFER_SIZE
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syscall
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; check error
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cmp rax,0
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jl read_file_error
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; check error
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cmp rax,0
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jl read_file_error
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; no more bytes
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je print_file_end
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; no more bytes
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je print_file_end
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; print message
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stdout
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mov rsi,read_buff
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syscall
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; print message
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stdout
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mov rsi,read_buff
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syscall
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jmp print_file_loop
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jmp print_file_loop
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print_file_end:
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pop rsi ; name
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pop rdi ; fd
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ret
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pop rsi ; name
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pop rdi ; fd
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ret
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read_file_error:
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call start_error
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call start_error
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,read_error_text
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mov rdx,read_error_text_len
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syscall
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,read_error_text
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mov rdx,read_error_text_len
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syscall
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; detail
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mov rdi,[rsp] ; name
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call strlen
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; detail
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mov rdi,[rsp] ; name
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call strlen
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; name
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syscall
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; name
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syscall
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call end_error
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call end_error
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mov rdi,1
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jmp exit
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mov rdi,1
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jmp exit
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;; check arg for -u, exit if unknown flag
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;; return 1 if found, 0 otherwise
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check_flag: ; bool check_arg(const char *arg)
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xor rax,rax
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; check if arg[0] == '-'
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cmp BYTE [rdi],'-'
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jne check_flag_end
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check_flag: ; bool check_arg(const char *arg)
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xor rax,rax
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; check if arg[0] == '-'
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cmp BYTE [rdi],'-'
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jne check_flag_end
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inc rdi
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; rax still set
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inc rdi
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; rax still set
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check_flag_loop:
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; check null byte
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mov cl,[rdi]
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cmp cl,0
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je check_flag_end
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; check null byte
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mov cl,[rdi]
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cmp cl,0
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je check_flag_end
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; check for u
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cmp cl,'u'
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jne check_flag_error
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; check for u
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cmp cl,'u'
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jne check_flag_error
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mov rax,1
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inc rdi
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jmp check_flag_loop
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mov rax,1
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inc rdi
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jmp check_flag_loop
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check_flag_error:
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push rdi ; arg + i
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call start_error
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push rdi ; arg + i
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call start_error
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,arg_error_text
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mov rdx,arg_error_text_len
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syscall
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; message
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,arg_error_text
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mov rdx,arg_error_text_len
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syscall
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; character
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; arg + i
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mov rdx,1
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syscall
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; character
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mov rax,SYS_write
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mov rdi,FD_stderr
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pop rsi ; arg + i
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mov rdx,1
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syscall
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call end_error
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call end_error
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mov rdi,1
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jmp exit
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mov rdi,1
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jmp exit
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check_flag_end:
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ret
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ret
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;; print exec_name and a colon_space
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start_error: ; void start_error(void)
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mov rdi,[exec_name]
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call strlen
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,[exec_name]
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syscall
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start_error: ; void start_error(void)
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mov rdi,[exec_name]
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call strlen
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mov rdx,rax
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,[exec_name]
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syscall
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,colon_space
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mov rdx,colon_space_len
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syscall
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ret
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,colon_space
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mov rdx,colon_space_len
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syscall
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ret
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;; print newline
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end_error: ; void end_error(void)
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,newline_ptr
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mov rdx,1
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syscall
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ret
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end_error: ; void end_error(void)
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mov rax,SYS_write
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mov rdi,FD_stderr
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mov rsi,newline_ptr
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mov rdx,1
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syscall
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ret
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streql: ; bool streql(const char *s1, const char *s2)
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; check if both are zero
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mov cl,[rdi] ; s1[i]
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or cl,[rsi]
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jz streql_true
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streql: ; bool streql(const char *s1, const char *s2)
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; check if both are zero
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mov cl,[rdi] ; s1[i]
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or cl,[rsi]
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jz streql_true
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; check if equal
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mov cl,[rdi]
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xor cl,[rsi]
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jnz streql_false
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; check if equal
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mov cl,[rdi]
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xor cl,[rsi]
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jnz streql_false
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inc rdi
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inc rsi
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jmp streql
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inc rdi
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inc rsi
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jmp streql
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streql_true:
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mov rax,1
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ret
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mov rax,1
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ret
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streql_false:
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xor rax,rax
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ret
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xor rax,rax
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ret
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exit: ; NORETURN void exit(int status)
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mov rax,SYS_exit
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syscall
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exit: ; NORETURN void exit(int status)
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mov rax,SYS_exit
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syscall
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strlen: ; uint64 strlen(const char *str)
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mov rax,rdi
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strlen: ; uint64 strlen(const char *str)
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mov rax,rdi
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strlen_loop:
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cmp BYTE [rax],0
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je strlen_end
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inc rax
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jmp strlen_loop
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cmp BYTE [rax],0
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je strlen_end
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inc rax
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jmp strlen_loop
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strlen_end:
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sub rax,rdi
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ret
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sub rax,rdi
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ret
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section .bss
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exec_name resq 1
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read_buff resb BUFFER_SIZE
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exec_name resq 1
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read_buff resb BUFFER_SIZE
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section .data
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dash_str db "-",0x0
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colon_space db ": "
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colon_space_len equ $ - colon_space
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newline_ptr db 0xA
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stdin_name db "<stdin>",0x0
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arg_error_text db "unknown flag: "
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arg_error_text_len equ $ - arg_error_text
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read_error_text db "read error: "
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read_error_text_len equ $ - read_error_text
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open_error_text db "could not open file for reading: "
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open_error_text_len equ $ - open_error_text
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dash_str db "-",0x0
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colon_space db ": "
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colon_space_len equ $ - colon_space
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newline_ptr db 0xA
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stdin_name db "<stdin>",0x0
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arg_error_text db "unknown flag: "
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arg_error_text_len equ $ - arg_error_text
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read_error_text db "read error: "
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read_error_text_len equ $ - read_error_text
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open_error_text db "could not open file for reading: "
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open_error_text_len equ $ - open_error_text
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12
freebsd.s
12
freebsd.s
@ -1,12 +0,0 @@
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;; -*- mode: nasm -*-
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;; FreeBSD system calls
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%define SYS_open 0x5
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%define SYS_close 0x6
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%define SYS_write 0x4
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%define SYS_read 0x3
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%define SYS_lseek 0x1de
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%define SYS_exit 0x1
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;; FreeBSD constants
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%define O_RDONLY 0x0
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%define SEEK_SET 0x0
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