echo server, multiple clients, lines <256 bytes

client.s

@@ -0,0 +1,104 @@
+; Errors (in rax):
+; 0 - EOF
+; -1024 - line too long
+; other negative - from read(2)
+; Arguments:
+; rdi - fd
+; rsi - address of client within clients array
+; rdx - pollfds index
+client__pollin:
+    push rdi
+    push rsi
+    push rdx
+
+    mov r10, 0
+    mov r10b, [rsi + 4 + 2]  ; buffer_len
+
+    mov rdx, 0
+    mov dl, 255
+    sub dl, r10b  ; rdx = 255 - buffer_len
+    add rsi, 8
+    add rsi, r10
+    call readline
+
+    mov r10, rdi
+
+    pop rdx
+    pop rsi
+    pop rdi
+
+    cmp rax, 0
+    jle return
+
+    add [rsi + 4 + 2], al  ; buffer_len += rax
+
+    cmp r10, 0
+    jg client__pollin__complete_line
+
+    add [rsi + 4 + 1], al  ; line_len += rax
+    ret
+
+client__pollin__complete_line:
+    add [rsi + 4 + 1], r10b  ; line_len += r10
+    mov word [pollfds + rdx * pollfd_size + 4], POLLOUT
+    ret
+
+; rdi - fd
+; rsi - address of client within clients array
+; rdx - pollfds index
+client__pollout:
+    push rdi
+    push rsi
+    push rdx
+
+    mov rax, SYS_WRITE
+    mov rdx, 0
+    mov dl, [rsi + 4 + 1]
+    add rsi, 8
+    syscall
+
+    pop rdx
+    pop rsi
+    pop rdi
+
+    cmp rax, 0
+    jl return
+
+    mov r10, rsi
+    add r10, 8
+    mov r11, 0
+    mov r11b, [rsi + 4 + 2]
+    sub r11, rax
+    add r11, r10
+
+client__pollout__shunt:
+    cmp r10, r11
+    jge client__pollout__shunt__finished
+    mov r8b, [r10 + rax]
+    mov [r10], r8b
+    add r10, 1
+    jmp client__pollout__shunt
+
+client__pollout__shunt__finished:
+    sub [rsi + 4 + 2], al  ; buffer_len -= rax
+    sub [rsi + 4 + 1], al  ; line_len -= rax
+    cmp byte [rsi + 4 + 1], 0
+    je client__pollout__wrote_line
+    ret
+
+client__pollout__wrote_line:
+    mov word [pollfds + rdx * pollfd_size + 4], POLLIN
+    ret
+
+; rdi - fd
+client__shutdown_close:
+    mov rax, SYS_SHUTDOWN
+    push rdi
+    mov rsi, SHUT_RDWR
+    syscall
+
+    mov rax, SYS_CLOSE
+    pop rdi
+    syscall
+
+    ret