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

[ZhangXR]

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

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

Thank you.

[Tesla DeLorean]

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

[ZhangXR]

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 · Accepted solution]

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

[ZhangXR]

Hello Erwan,

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

​Best regards

ZhangXR