Hi! I just saw that FreeRTOS+TCP uses a custom “%lxip” format specifier to print IP adresses. This format is not supported by newlib, and I can’t use the recommended printf-stdarg.c from the FreeRTOS demos either (LGPL license :/ ). So I would like to change that to a more portable “%d.%d.%d.%d”. Has anyone done this already? Would you accept a patch? best regards, Thomas

Hi Thomas, The format “%lxip” is supported by the module “printf-stdarg.c”, which was included in the original FreeRTOS+TCP distribution on freertos.org/tcp If that module is not included, the statement will print as e.g. “C0A80101ip”, instead of “192.168.1.1”.

This format is not supported by newlib, and I can’t use the recommended printf-stdarg.c from the FreeRTOS demos either (LGPL license :/ ).

I am not an expert on licensing, but I think that “printf-stdarg.c” has the same MIT-type licence as the FreeRTOS+TCP library.

The idea is to use a macro like this: ~~~

define FreeRTOSntohliptoprintf_args(IP)

(int)(FreeRTOS_ntohl(IP) >> 24) & 255,      
(int)(FreeRTOS_ntohl(IP) >> 16) & 255,      
(int)(FreeRTOS_ntohl(IP) >>  8) & 255,      
(int)(FreeRTOS_ntohl(IP) >>  0) & 255

~~~ and substitute: ~~~ FreeRTOSdebugprintf( ( “vDHCPProcess: acked %lxipn”, FreeRTOS_ntohl( xDHCPData.ulOfferedIPAddress ) ) ); ~~~ with: ~~~ FreeRTOSprintf( ( “vDHCPProcess: acked %d.%d.%d.%dn”, FreeRTOSntohliptoprintfargs( xDHCPData.ulOfferedIPAddress ) ) ); ~~~ I noticed that there are a lot of places, where ntohl() is missing, and sometimes it’s even mixed in the same printf() (see FreeRTOSTCPIP.c, line 1028): ~~~ FreeRTOSdebugprintf( ( “ARP for %lxip (using %lxip): rc=%d %02X:%02X:%02X %02X:%02X:%02Xn”, pxSocket->u.xTCP.ulRemoteIP, FreeRTOS_ntohl( ulRemoteIP ), ~~~ Is this by purpose? I would have expected that +TCP uses a consistent format internally, or at least uses different variable names to identify host and network order. I think I will use two different macros then. I’m also not so clear what names to use. Perhaps FreeRTOSnetiptoprintfargs () for network order and a plain FreeRTOSiptoprintf_args () for native order IPs?

Unfortunately, it’s LGPL: https://sourceforge.net/p/freertos/code/HEAD/tree/trunk/FreeRTOS-Plus/Demo/FreeRTOSPlusTCPMinimalWindows_Simulator/printf-stdarg.c