diff options
| -rw-r--r-- | cat.s | 100 |
1 files changed, 92 insertions, 8 deletions
@@ -15,17 +15,58 @@ process_fd: cmp rax, 1 jl .ret - ; TODO flag handling - ; write(1, buf, rax) + mov r8, rax ; buf size + mov r9, buf ; write pointer + mov r10, buf ; read pointer +.loop: + mov r11, r13 ; flags (for ANDing) + and r11, showends + cmp r11, 1 + jl .skipshowends + mov rcx, [r10] + and rcx, 0xff + cmp rcx, 0x0a + jne .skipshowends + call .flushbuf + mov rcx, "$" + mov [smallbuf], rcx + mov rax, smallbuf + push r8 + push r9 + push r10 + call outpstring + pop r10 + pop r9 + pop r8 +.skipshowends: + dec r8 + inc r10 + cmp r8, 0 + jl .contrwloop + jmp .loop + +.flushbuf: + mov rdx, r10 + sub rdx, r9 mov rdi, 1 - mov rsi, buf - mov rdx, rax + mov rsi, r9 mov rax, 1 + push r8 + push r9 + push r10 syscall + pop r10 + pop r9 + pop r8 + mov r9, r10 + ret +.contrwloop: ; continue loop + call .flushbuf mov rax, rbx jmp process_fd + .ret: ; return rax mov rax, rbx @@ -34,6 +75,8 @@ process_fd: _start: ; r12 = argc mov rbp, rsp + ; r14 = argv0 + mov r14, [rsp+8] mov r12, [rbp] cmp r12, 2 jl final.stdin @@ -94,6 +137,8 @@ _start: je .vt cmp r10, "u" je .inloop + cmp r10, "h" + je .help jmp usage .numbernonblankonly: @@ -127,6 +172,9 @@ _start: or r13, shownonprinting or r13, showtabs jmp .inloop +.help: + or r13, 0xff + jmp usage .cont: add rbp, 8 @@ -135,6 +183,9 @@ _start: ; actual FD processor loop final: + mov [smallbuf], r13 + mov rax, smallbuf + call pstring ; fix rbp and r12 mov rbp, rsp mov r12, [rbp] @@ -187,8 +238,17 @@ final: jmp .cont usage: - ; TODO: usage message - mov rax, usagemsg + ;usage w/ argv0 + mov rax, usagep1 + call pstring + mov rax, r14 + call pstring + mov rax, usagep2 + call pstring + cmp r13, 0xff + jne errorexit + ; r13 is set to 0xff when -h flag is set + mov rax, help call pstring jmp errorexit error: @@ -227,6 +287,28 @@ pstring: syscall ret + ; pstring to stdout +outpstring: + 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: + mov rdx, r8 + mov rsi, rax + mov rdi, 1 + mov rax, 1 + syscall + ret + exit: ;exit(0) mov rax, 60 @@ -234,11 +316,13 @@ exit: syscall section .data -usagemsg: db "Usage: % [-AbeEnstTuv] [file ...]", 10, 00 +usagep1: db "Usage: ", 00 +usagep2: db " [-h] [-AbeEnstTuv] [file ...]", 10, 00 +help: db "Concatenate FILE(s) to standard output.", 10, 10, "With no FILE, or when FILE is -, read standard input.", 10, 10, " -A equivalent to -vET", 10, " -b number (in hex) nonempty output lines, overrides -n", 10, " -e equivalent to -vE", 10, " -E display $ at end of each line", 10, " -n number (in hex) all output lines", 10, " -s suppress repeated empty output lines", 10, " -t equivalent to -vT", 10, " -T display TAB characters as ^I", 10, " -u (ignored)", 10, " -v use ^ and M- notation, except for LFD and TAB", 10, " -h display this help and exit", 10, 10, "Examples:", 10, " cat f - g Output f's contents, then standard input, then g's contents.", 10, " cat Copy standard input to standard output.", 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 +smallbuf: resb 8 bufSize: equ 65536 buf: resb bufSize |