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ZhangXR
ZhangXR
Associate II
August 18, 2020
Solved

SPC5Studio cannot use the malloc() and free() functions in the stdlib.h standard library.

  • August 18, 2020
  • 4 replies
  • 1934 views

SPC5Studio cannot use the malloc() and free() functions in the stdlib.h standard library.

​

For Example:

char * str = (char *) malloc(1024);
free(str);

​

​

I've added the GCC standard header path to SPC5Studio, and other library functions are used normally, and I can't compile through when using the malloc function, reporting the following error:

​

c:/spc5studio/eclipse/plugins/com.st.tools.spc5.tools.gnu.gcc.ppcvle.win32_4.9.4.20190604105544/toolchain/bin/../lib/gcc/powerpc-eabivle/4.9.4/../../../../powerpc-eabivle/lib\libc.a(lib_a-sbrkr.o): In function `_sbrk_r':
sbrkr.c:(.text._sbrk_r+0x1a): undefined reference to `sbrk'
collect2.exe: error: ld returned 1 exit status
make: *** [build/out.elf] Error 1

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How do I solve the problem that malloc and free are not available, or how do I dynamically allocate memory in SPC5Studio?

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Thank you.

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    This topic has been closed for replies.
    Best answer by Erwan YVIN

    Hello Zhang ,

    you can create a sbrk function in your code.

    Do not forget to free the pointer.

    /*
 * ---------------------------------------------------------------------------------------------------
 *
 *---------------------------------------------------------------------------------------------------
 */
 
void *sbrk(size_t incr) {
 extern uint8_t __heap_base__;
 extern uint8_t __heap_end__;
 static uint8_t *p = &__heap_base__;
 static uint8_t *newp;
 
 newp = p + incr;
 if (newp > &__heap_end__) {
 errno = ENOMEM;
 return (void *)-1;
 }
 return p = newp;
}

    Best regards

    Erwan

    4 replies

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 18, 2020

    Assume you'll have to create an allocator if not in a syscall.c or newlibs.c file

    https://codereview.stackexchange.com/questions/226231/implementing-sbrk-for-a-custom-allocator-in-c

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    ZhangXR
    ZhangXRAuthor
    Associate II
    August 18, 2020

    Hello,

    My project doesn't have an RTOS, so I don't have a syscall.c file. Can you explain in detail how I can use the malloc function?

    Thank you.

    Erwan YVIN
    Erwan YVINBest answer
    ST Technical Moderator
    August 18, 2020

    Hello Zhang ,

    you can create a sbrk function in your code.

    Do not forget to free the pointer.

    /*
 * ---------------------------------------------------------------------------------------------------
 *
 *---------------------------------------------------------------------------------------------------
 */
 
void *sbrk(size_t incr) {
 extern uint8_t __heap_base__;
 extern uint8_t __heap_end__;
 static uint8_t *p = &__heap_base__;
 static uint8_t *newp;
 
 newp = p + incr;
 if (newp > &__heap_end__) {
 errno = ENOMEM;
 return (void *)-1;
 }
 return p = newp;
}

    Best regards

    Erwan

    In order to give better visibility on the answered topics, please click on 'Best answer' on the reply which solved your issue or answered your question.
    ZhangXR
    ZhangXRAuthor
    Associate II
    August 19, 2020

    Hello Erwan,

    Problem solved, compiled and approved, thank you very much!

    ​Best regards

    ZhangXR

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