diff options
| -rw-r--r-- | cat.s | 42 |
1 files changed, 15 insertions, 27 deletions
@@ -15,7 +15,7 @@ process_fd: cmp rax, 1 jl .ret - ; TODO special case handling + ; TODO flag handling ; write(1, buf, rax) mov rdi, 1 mov rsi, buf @@ -32,8 +32,11 @@ process_fd: ret _start: + ; TODO: cmd flag consumer + ; r12 = argc mov rbp, rsp + mov r13, [rbp] mov r12, [rbp] cmp r12, 2 jl .stdin @@ -44,13 +47,16 @@ _start: ; if no more entries; exit cmp r12, 2 jl exit + mov r10, [rbp] + cmp r10, 1 + jl .cont ; arguments starting with "-" are special cases mov r11, [rbp] mov r11, [r11] and r11, 0xff cmp r11, 0x2d ;'-' - je .special + je .stdin ; open(rbp, 0, 0) mov rax, 2 @@ -61,7 +67,7 @@ _start: ; make sure fd exists cmp rax, 1 - jl .error + jl error ; print file call process_fd ; returns input @@ -71,41 +77,23 @@ _start: syscall ; prepare registers for next loop +.cont: add rbp, 8 sub r12, 1 jmp .loop - ; unreachable. insurance - jmp exit - -.special: - ;special case handler (TODO) - ; get second character - mov r11, [rbp] - add r11, 1 - mov r10, [r11] - and r10, 0xff - - ; just a single - - cmp r10, 0x00 - je .stdin - - jmp .usage - ; stdin passthrough .stdin: mov rax, 0 call process_fd - add rbp, 8 - sub r12, 1 - jmp .loop + jmp .cont -.usage: +usage: ; TODO: usage message - jmp .errorexit -.error: + jmp errorexit +error: ;exit(1) ; TODO: process RAX to print meaningful message -.errorexit: +errorexit: mov rax, 60 mov rdi, 1 syscall |