# non-ASM statement in naked function is not supported (port.c module for FreeRTOS) **URL:** \ **Category:** Microchip\ **Created:** [November 28, 2021, 1:33am UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964 "2021-11-28T01:33:04Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![jmulchin](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@jmulchin](https://forums.freertos.org/u/jmulchin)\ **Post date:** [November 28, 2021, 1:33am UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/1 "2021-11-28T01:33:04Z")
I have a port.c file for FreeRTOS that throws an error message under AS7 indicating that a naked function can not support any statement types except ASM statements when a “naked” attribute is declared. Now lets make things a little more confusing … The same two functions will compile just fine under AS7 on a ATmega128A project I have, but not under a ATXmega128A project. Same AS7 program, same exact functions, but different processors. I don’t think it’s processor related myself. The code is below: ```auto /* * Manual context switch. The first thing we do is save the registers so we * can use a naked attribute. */ void vPortYield( void ) __attribute__ ( ( naked ) ); void vPortYield( void ) { portSAVE_CONTEXT(); vTaskSwitchContext(); portRESTORE_CONTEXT(); asm volatile ( "ret" ); } /*-----------------------------------------------------------*/ /* * Context switch function used by the tick. This must be identical to * vPortYield() from the call to vTaskSwitchContext() onwards. The only * difference from vPortYield() is the tick count is incremented as the * call comes from the tick ISR. */ void vPortYieldFromTick( void ) __attribute__ ( ( naked ) ); void vPortYieldFromTick( void ) { portSAVE_CONTEXT(); if( xTaskIncrementTick() != pdFALSE ) { vTaskSwitchContext(); } portRESTORE_CONTEXT(); asm volatile ( "reti" ); } /*-----------------------------------------------------------*/ ``` What is the solution to this problem? Thanks Jerry ---
**Author:** ![rtel](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/rtel/32/31_2.png) [@rtel](https://forums.freertos.org/u/rtel)\ **Post date:** [November 28, 2021, 2:11am UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/2 "2021-11-28T02:11:02Z")
What is AS7? Please post the compiler command line and output - at least the output that shows the error. ---
**Author:** ![jmulchin](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@jmulchin](https://forums.freertos.org/u/jmulchin)\ **Post date:** [November 28, 2021, 5:34am UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/3 "2021-11-28T05:34:41Z")
AS7 is Atmel Studio 7 (Microchip Studio since the buyout). It uses GCC for the compiler, but I’m not sure what version. But it is pretty recent. I do not know the command to generate the error as it is part of the Studio 7 build process. The exact error message (two of them) is: “(N) 2465:non-ASM statement in naked function is not supported” That’s all I have. ---
**Author:** ![htibosch](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/htibosch/32/62_2.png) [@htibosch](https://forums.freertos.org/u/htibosch)\ **Post date:** [November 28, 2021, 7:01am UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/4 "2021-11-28T07:01:43Z")
I had to look it up and found that several compilers do not allow to put C-statements in a functions which has the naked attribute. The reason is that it is considered [not safe](https://stackoverflow.com/questions/47316611/clang-error-non-asm-statement-in-naked-function-is-not-supported?rq=1). Now I wonder if it is allowed to call the C-function from within an inline statement: ```auto extern "C" void vPortYield( void ) __attribute__ ( ( naked ) ); void vPortYield( void ) { portSAVE_CONTEXT(); /* Call vTaskSwitchContext() */ asm volatile ( "call vTaskSwitchContext" ); portRESTORE_CONTEXT(); asm volatile ( "ret" ); } ``` Note that portSAVE/portRESTORE only contain ASM statements. Can you try this? **NOTE** : I used the prefix `extern "C"` because I testing the compilation with a C++ compiler. ---
**Author:** ![jmulchin](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@jmulchin](https://forums.freertos.org/u/jmulchin)\ **Post date:** [November 28, 2021, 7:26pm UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/5 "2021-11-28T19:26:29Z")
Hein, Thanks for your help. Your solution solves the compiler problem and now GCC is happy. Thanks again Jerry ---
**Author:** ![htibosch](https://d3iykfbgfh8zhg.cloudfront.net/user_avatar/forums.freertos.org/htibosch/32/62_2.png) [@htibosch](https://forums.freertos.org/u/htibosch)\ **Post date:** [November 30, 2021, 12:55pm UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/6 "2021-11-30T12:55:42Z")
Good to hear. Did you get FreeRTOS running now? ---
**Author:** ![jmulchin](https://avatars.discourse-cdn.com/v4/letter/j/c37758/32.png) [@jmulchin](https://forums.freertos.org/u/jmulchin)\ **Post date:** [November 30, 2021, 7:07pm UTC](https://forums.freertos.org/t/non-asm-statement-in-naked-function-is-not-supported-port-c-module-for-freertos/13964/7 "2021-11-30T19:07:29Z")
Hein, Yes I have 8 task toggling LEDs on an XMega128A1 part. Your suggestion was actually a very good one. Especially with what must be changes in GCC that caused this problem. I always include a Heartbeat LED that’s toggled from inside the ISR handler to let me know that the CPU is at least processing interrupts. But in order to do that, I placed an asm volatile (“hb\_togl”); to a function called void hb\_togl(void) that bumps a counter, checks if the counter has reached 1000, if yes, set the counter to zero and toggle the LED. That function is in C code, and the heartbeat LED toggles as well. I also looked at the .LSS listing to see if the asm statements were actually calling the required function, and they are. Another warm fuzzy feeling that it had a possibility of working. So it was a great learning experience. Thanks Again Jerry