CODEWITHSUNDEEP
cmemory-managementcross-platform
jpen
jpen

Reputation: 2147

Use of memory management functions in cross platform library

I'm creating a cross platform library using C. I have a piece of code like the following, in which I'm using the libc memory management functions directly:

myObject* myObjectCreate(void)
{
    ...
    myObject *pObject = (myObject*)malloc(sizeof(*pObject));
    ...
}

void myObjectDestroy(myObject *pObject)
{
    ...
    free(pObject);
    ...
}

I understand these memory management functions are not always available, especially on embedded systems based on low-end microcontrollers. Unfortunately my library needs to be compilable on these systems.

To work around this problem, I suppose I'd have to make these functions customisable by my library client.

So, what are the recommended ways to achieve this?

Upvotes: 1

Views: 196

Answers (3)

Alexey Frunze
Alexey Frunze

Reputation: 62106

Use function pointers.

Define the following pointers in the library:

void* (*CustomMalloc)(size_t) = NULL;
void (*CustomFree)(void*) = NULL;

And prior to using of the library functions initialize these pointers to point to custom implementations of malloc() and free(). Or initialize them to point to the real malloc() and free().

Inside of the library replace malloc(size) with CustomMalloc(size) and free(pointer) with CustomFree(pointer).

Upvotes: 1

Summer_More_More_Tea
Summer_More_More_Tea

Reputation: 13446

Use conditional compile, i.e. define some macro's like LIBC_AVAIL, LIBC_NOT_AVAIL and include different code when compiling.

Upvotes: 0

user82238
user82238

Reputation:

There are many approaches.

I use #if, combined with compiler provided defines, to have per platform behaviour.

Should a given functionality (such as malloc) be found, #define MYLIB_MALLOC can be defined.

Then, later, you can check for #ifdef MYLIB_MALLOC and if not present, provide a dummy malloc function, which will allow your code to compile.

Upvotes: 2

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