diff options
| -rw-r--r-- | cat.s | 147 |
1 files changed, 137 insertions, 10 deletions
@@ -38,6 +38,11 @@ _start: cmp r12, 2 jl final.stdin + ; r13 = our flag holder + xor r13, r13 + + add rbp, 8 * 2 + ; flag consumer loop .loop: cmp r12, 2 jl final @@ -45,14 +50,90 @@ _start: mov r11, [rbp] mov r11, [r11] and r11, 0xff - cmp r11, 0x2d ;'-' + cmp r11, "-" jne .cont + ; solid - is stdin + ; shouldnt be consumed + mov r11, [rbp] + add r11, 1 + mov r11, [r11] + and r11, 0xff + cmp r11, 0x00 + je .cont + + mov r11, [rbp] + xor r9, r9 + mov [rbp], r9 ; consume argument (should be ignored in final loop) + ; inner loop to process all flags +.inloop: + inc r11 + mov r10, [r11] + and r10, 0xff + cmp r10, 0x00 + je .cont + + ; basically switch() { case } + cmp r10, "b" + je .numbernonblankonly + cmp r10, "E" + je .showends + cmp r10, "n" + je .numberlines + cmp r10, "s" + je .squeezeblanks + cmp r10, "T" + je .showtabs + cmp r10, "v" + je .shownonprinting + cmp r10, "A" + je .showall + cmp r10, "e" + je .ve + cmp r10, "t" + je .vt + cmp r10, "u" + je .inloop + jmp usage + +.numbernonblankonly: + or r13, numbernonblankonly + jmp .inloop +.showends: + or r13, showends + jmp .inloop +.numberlines: + or r13, numberlines + jmp .inloop +.squeezeblanks: + or r13, squeezeblanks + jmp .inloop +.showtabs: + or r13, showtabs + jmp .inloop +.shownonprinting: + or r13, shownonprinting + jmp .inloop +.showall: + or r13, shownonprinting + or r13, showends + or r13, showtabs + jmp .inloop +.ve: + or r13, shownonprinting + or r13, showends + jmp .inloop +.vt: + or r13, shownonprinting + or r13, showtabs + jmp .inloop + .cont: add rbp, 8 sub r12, 1 jmp .loop + ; actual FD processor loop final: ; fix rbp and r12 mov rbp, rsp @@ -67,11 +148,13 @@ final: cmp r10, 1 jl .cont - ; arguments starting with "-" are special cases + ; at this point, all arguments starting with - + ; should only be -\0 (stdin) + ; (we can be lazy and skip checking) mov r11, [rbp] mov r11, [r11] and r11, 0xff - cmp r11, 0x2d ;'-' + cmp r11, "-" je .stdin ; open(rbp, 0, 0) @@ -105,29 +188,73 @@ final: usage: ; TODO: usage message + mov rax, usagemsg + call pstring jmp errorexit error: ;exit(1) ; TODO: process RAX to print meaningful message + mov rax, errormsg + call pstring errorexit: mov rax, 60 mov rdi, 1 syscall + ; function to print null terminated string + ; arg: rax is pointer +pstring: + ; r8 is length + ; r9 is a cached buffer for operations + xor r8, r8 + mov r9, rax +.loop: + mov r10, [r9] + and r10, 0xff + cmp r10, 0x00 + je .fin + + inc r8 + inc r9 + jmp .loop + +.fin: + ; print to stderr + mov rdx, r8 + mov rsi, rax + mov rdi, 2 + mov rax, 1 + syscall + ret + exit: + mov rax, r13 + mov [reg], rax + mov rax, 1 + mov rdi, 2 + mov rsi, reg + mov rdx, 8 + syscall ;exit(0) mov rax, 60 mov rdi, 0 syscall + section .data +usagemsg: db "Usage: % [-AbeEnstTuv] [file ...]", 10, 00 +errormsg: db "An error has occured! Unfortunately, this program isnt complex enough to display the error yet. Try using strace!", 10, 00 + section .bss +reg: resb 8 bufSize: equ 65536 buf: resb bufSize -numbernonblankonly: equ 0b000001 -showends: equ 0b000010 -numberlines: equ 0b000100 -squeezeblanks: equ 0b001000 -showtabs: equ 0b010000 -shownonprinting: equ 0b100000 - +numbernonblankonly: equ 0b000001 ; -b +showends: equ 0b000010 ; -E +numberlines: equ 0b000100 ; -n +squeezeblanks: equ 0b001000 ; -s +showtabs: equ 0b010000 ; -T +shownonprinting: equ 0b100000 ; -v +; -A = -vET +; -e = -vE +; -t = -vT |