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3. Write your own malloc, and free

Answer:

static unsigned char our_memory[1024 * 1024]; //reserve 1 MB for malloc

static size_t next_index = 0;



static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;



void *malloc(size_t sz)

{

    void *mem;

    pthread_mutex_lock(&lock);

    if(sizeof our_memory - next_index < sz){

        pthread_mutex_unlock(&lock);

        return NULL;

    }



    mem = &our_memory[next_index];

    next_index += sz;

    pthread_mutex_unlock(&lock);

    return mem;

}



void free(void *mem)

{

   //we cheat, and don't free anything.

}

Avind
10 Feb, 2019 12:15 AM

static unsigned char our_memory[1024 * 1024]; //reserve 1 MB for malloc

static size_t next_index = 0;



static pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER;



void *malloc(size_t sz)

{

    void *mem;

    pthread_mutex_lock(&lock);

    if(sizeof our_memory - next_index < sz){

        pthread_mutex_unlock(&lock);

        return NULL;

    }



    mem = &our_memory[next_index];

    next_index += sz;

    pthread_mutex_unlock(&lock);

    return mem;

}



void free(void *mem)

{

   //we cheat, and don't free anything.

}