non blocking udp read (we still block on keypresses)

src/teeworlds_asmr.asm

@@ -95,6 +95,7 @@ section .data
     KEY_RETURN   equ         13
     AF_INET      equ         0x2
     SOCK_DGRAM   equ         0x2
+    MSG_DONTWAIT equ         64
 
     ; application constants
     HEX_TABLE   db "0123456789ABCDEF", 0
@@ -131,6 +132,8 @@ section .data
     l_s_blocking_read equ $ - s_blocking_read
     s_received_bytes db "[udp] received bytes: "
     l_s_received_bytes equ $ - s_received_bytes
+    s_udp_error db "[udp] error: "
+    l_s_udp_error equ $ - s_udp_error
     s_packer_size db "[packer] amount of bytes packed: "
     l_s_packer_size equ $ - s_packer_size
 
@@ -440,6 +443,7 @@ gametick:
     ; gametick
     ;
     ; main gameloop using recursion
+    call pump_network
     call keypresses
     jmp gametick
 

src/udp.asm

@@ -26,19 +26,31 @@ recv_udp:
     movzx rdi, byte [socket] ; then only set the lowest byte
     lea rsi, udp_recv_buf
     mov rdx, NET_MAX_PACKETSIZE
+    ; flags
     xor r10, r10
+    mov r10, MSG_DONTWAIT
     lea r8, udp_srv_addr
     lea r9, max_sockaddr_read_size
     syscall
     mov [udp_read_len], rax
 
+    ; error checking
+    test rax, rax
+    ; if recvfrom returned negative
+    ; we do not process the udp payload
+    js .recv_udp_error
+
     ; debug print
     print s_received_bytes
     mov rax, [udp_read_len]
     call print_uint32
     call print_newline
 
     ret
+.recv_udp_error:
+    print s_udp_error
+    call print_newline
+    ret
 
 send_udp:
     ; send_udp [rax] [rdi]