Printf of a floating point in ARM and stack alignment
Technical Note 85413
Arkitekturer:
ARM
Komponent:
general
Uppdaterad:
2020-07-23 15:28
Introduction
In some cases, printf of floating point (%f) does not seem to work.
Solution
The IAR C/C++ Compiler for ARM requires the Stack Pointer to be aligned at 8 bytes. 8-byte alignment is required by AEABI (and some instructions generated by the compiler for some cores).
The default cstartup code automatically initializes the ARM core stack(s) to an 8-byte aligned address. Make sure that your application and/or RTOS also does this.
Background
According to the MQX release notes, stack alignment is not ensured in MQX 3.7. The behavior is corrected in MQX 3.8. This problem has also been observed with other RTOSes.
All product names are trademarks or registered trademarks of their respective owners.