Re: free() does not call sbrk()

[Martin Walter <martin dot walter at gmail dot com>]

> ...
> For a discussion on the design see: http://g.oswego.edu/dl/html/malloc.html
> which is referenced in libc/stdlib/mallocr.c

Thanks for clarification!

> My simple test of mallocing a block of 4000 and freeing it back again in an
> infinite loop results in the same pointer being given back each time and no
> increment in memory usage. ?I do not know why you are not seeing similar
> behavior for your test. ?Is there something else in your loop other than
> malloc/free? (mine has a printf as well)

Actually no. Please take a look at my code:

#include "UART.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static void alloc (int size)
{
        char buf[128];
        int len;

        char *ptr = malloc (size);
        if (ptr != NULL)
        {
                len = sprintf (buf, "ptr: %d\r\n", (int)ptr);
                UART_write(0, buf, len);
                free (ptr);
        }
}

int main (int argc, char *argv[])
{
        register int i;

        for (i = 0; i < 10; ++i)
                alloc (4000);

        return 0;
}

And the output:

ptr: 2016
ptr: 6024
ptr: 10032
ptr: 14040
ptr: 18048
ptr: 22056
ptr: 26064
ptr: 30072
ptr: 34080
ptr: 38088

Kind regards,
Martin