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Using sprintf, strstr and memset functions in the UART ISR Callback

Hi Team,

In the UART TX & RX Completion, we have a requirement to use sprintf, memset and strstr functions in the callback function.

Are they safe to use in the ISR Context. 

Thank You & Regards,


  • Hello Team,

    Any suggestion in using sprint or strstr funcitons inside a ISR Callback functions on BF-70x processors.



  • Hi,

    Only a limited number of the runtime library functions are available to call from within ISRs. Not all C run-time library functions are interrupt-safe (and can therefore be called from an interrupt service routine). For a run-time function to be classified as interrupt-safe:
         • It must not update any global data, such as errno
         • It must not write to (or maintain) any private static data
    It is recommended that none of the functions defined in the math.h header file, nor the string conversion functions defined in the stdlib.h header file, be called from an ISR as these functions are commonly defined to update the global variable errno. Similarly, the functions defined in the stdio.h header file maintain static tables for currently opened streams and should not be called from an ISR. The memory allocation routines (such as malloc, calloc, realloc, and free), the C++ operators new and delete, and any variants, read and update global tables and are not interrupt-safe; they should not be called from an ISR.
    The following library functions are not interrupt-safe because they use private static data.
    asctime      gmtime      localtime
    rand         srand       strtok
    Please refer the chapter "Calling a Library Function From an ISR" from the below C/C++ Compiler and Library Manual for Blackfin Processors in the below link:



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